depositional and dewatering behaviour of uranium mill tailings a...
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Depositional and Dewatering Behaviour of Uranium Mill Tailings
A Thesis
Submitted to the Faculty of Graduate Studies and Research
In Partial Fulfillment of the Requirements
For the Degree of
Master of Applied Science
in
Environmental Systems Engineering
University of Regina
By
Md. Imteaz Ferdoush Bhuiyan
Regina, Saskatchewan
August, 2014
Copyright 2014: Md. Imteaz Ferdoush Bhuiyan
UNIVERSITY OF REGINA
FACULTY OF GRADUATE STUDIES AND RESEARCH
SUPERVISORY AND EXAMINING COMMITTEE
Md. Imteaz Ferdoush Bhuiyan, candidate for the degree of Master of Applied Science in Environmental Systems Engineering, has presented a thesis titled, Depositional and Dewatering Behaviour of Uranium Mill Tailings, in an oral examination held on August 1, 2014. The following committee members have found the thesis acceptable in form and content, and that the candidate demonstrated satisfactory knowledge of the subject material. External Examiner: Dr. Hussameldin Ibrahim, Industrial Systems Engineering
Supervisor: Dr. Shahid Azam, Environmental Systems Engineering
Committee Member: *Dr. Tsun Wai Kelvin Ng, Environmental Systems Engineering
Committee Member: Dr. Ezeddin Shirif, Petroleum Systems Engineering
Chair of Defense: Dr. Shelagh Campbell, Faculty of Business Administration *Not present at defense
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ABSTRACT
The Key Lake operation in Saskatchewan, Canada, is the largest uranium mill in the
world. This mill process generates tailings that are deposited into an onsite storage area
called the Deilmann Tailings Management Facility (DTMF). An effective tailings
management scheme requires a clear understanding of slurry behaviour throughout the
life-cycle, starting from production thorough the deposition to dewatering in the storage
facility. The main objective of this research was to investigate the depositional and
dewatering behaviour of uranium mill tailings (4%, 5%, and 6% mill tailings) from the
Key Lake operation under laboratory and field conditions. All of the samples exhibited
the same trend for yield strength development during the tests for rheological properties.
A negligible strength (0.4 kPa) was found to have at 60% solids content (s) followed by a
rapid increase thereafter. The settling and segregation tests were performed under
different initial solids contents (si). The 4% mill tailings exhibited a lower rate and total
amount of settlement than 5% and 6% mill tailings in the settling tests. The initial
hydraulic conductivity (ki) decreased by two orders of magnitude (10-2 m/s to 10-4 m/s)
with a decrease in initial void ratio (ei) from 16 to 4 (15% < si < 40%) and a decrease in
final void ratio (ef) from 8 to 4 (30% < si < 45%) such that 4% mill tailings showed one
order of magnitude lower values than the 5% and 6% mill tailings. The corresponding
settling potential (SP) decreased ten times (50% to 5%) for 4% mill tailings and four
times (60% to 15%) for 5% and 6% mill tailings. The effective stress (σ') increased from
80 Pa to 260 Pa in the settling tests. The average solids content after settling was 35%
(20% < s < 42%) for 4% mill tailings, 40% (15% < s < 60%) for 5% mill tailings, and
39% (18% < s < 54%) for 6% mill tailings with a corresponding normalized solids
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content deviation of ±3%, ±8%, ±6%, respectively. The 4% tailings were less prone to
segregation when compared with 5% and 6% tailings. Nevertheless, all materials were
essentially non-segregating at 40% initial solids content. The large strain consolidation
tests were conducted by using a customized and fabricated consolidation test system.
During the tests, the total strains were 31% to 42% for all investigated mill tailings in an
effective stress range of 0.3 kPa to 8 kPa. The change in void ratio was higher for 4%
mill tailings (Δe = 2.5) than 5% and 6% mill tailings (Δe = 1.3 to 1.7). The lowest
measurable effective stress was 0.3 kPa for all investigated mill tailings. The void ratios
were found to be 3.8, 3.1, and 3.4 at σ' of 1 kPa and further reduced to 3.3, 2.8, and 3.1 at
σ' of 8 kPa for 4%, 5%, and 6% mill tailings. The k values showed an initial scatter
before attaining a steady value and were found to range from 10-7 m/s to 10-8 m/s. The test
results provided the volume compressibility and hydraulic conductivity relationships for
current (4%) and future (5% and 6%) mill tailings. The large strain consolidation
behaviour in the DTMF was investigated by analyzing survey data from 1996 to 2008,
laboratory testing of the current (4%) mill tailings, and history matching of the deposited
tailings using numerical modeling. The numerical modeling results closely approximated
the consolidated tailings elevations and effective profiles in the DTMF over the period of
1996 to 2008. The field effective stress values correlated quite well with the modeling
results thereby validating the predictions. Overall, the results indicate that the effective
stress increased from 0 kPa at the surface to the following values at the DTMF bottom:
200 kPa in 1999, 530 kPa in 2005, and 680 kPa in 2008.
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ACKNOWLEDGEMENTS
I would like to acknowledge and express my profound gratitude to my supervisor,
mentor, and coach, Dr. Shahid Azam, for his persistent guidance, support, and
encouragement throughout my graduate studies at the University of Regina. Without his
constructive criticism and timely suggestions, this endeavour would not have been
successful. I am very thankful to him for the academic training and industrial research
opportunity from which I have gained professional knowledge to advance my career.
My sincere thanks to Cameco Corporation, Canada, for providing materials and
financial assistance. I am grateful to Dr. Patrick Landine and Dr. Jeff Warner from
Cameco Corporation for their suggestions on this work from an industrial perspective.
Thanks are also given to the Natural Sciences and Engineering Research Council and the
Faculty of Graduate Studies and Research for additional financial supports and to the
University of Regina for providing computing and research facilities.
I feel very much indebted to my parents, Abdul Awal Bhuiyan and Ferdoushi
Awal, for their boundless love and blessings. Without their greatest motivation and
encouragement, it would have been impossible for me to complete this research.
Additionally, I am very thankful to all my fellow colleagues and friends for their
generous help and encouragement throughout the coursework and this research. Special
thanks to my sisters Sayeda Fatema and Tahmina Chowdhury and my friend Shifullah
Md Khaled for their inspiration during this journey.
Finally I wish to thank my best friend and my Asma Chowdhury who has
provided me with continual encouragement, support, patience, and love, enabling me to
complete my graduate work. Without you, I would be lost.
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POST DEFFENCE ACKNOWLEDGEMENTS
The time and inputs of Dr. Hussameldin Ibrahim (external examiner) from the Faculty of
Engineering and Applied Science, Dr. Kelvin Ng (supervisory committee member) and
Dr. Ezeddin Shirif (supervisory committee member) from the Faculty of Engineering and
Applied Science, and Dr. Shelagh Campbell (thesis defense chair) from the Faculty of
Business Administration are appreciated for serving on my thesis committee.
vi
TABLE OF CONTENTS
ACKNOWLEDGEMENTS ............................................................................................ iv
POST DEFFENCE ACKNOWLEDGEMENTS ........................................................... v
TABLE OF CONTENTS ................................................................................................ vi
LIST OF FIGURES ......................................................................................................... ix
LIST OF ABBREVIATIONS ......................................................................................... xi
CHAPTER 1 ...................................................................................................................... 1
INTRODUCTION .......................................................................................................... 1
1.1 Problem Statement .................................................................................................... 1
1.2 Research Objective ................................................................................................... 3
1.3 Thesis Outline ........................................................................................................... 3
CHAPTER 2 ...................................................................................................................... 4
LITERATURE REVIEW ............................................................................................... 4
2.1 General ...................................................................................................................... 4
2.2 Industrial Practice ..................................................................................................... 6
2.2.1 Mining operation ................................................................................................ 6
2.2.2 Tailings production ............................................................................................ 8
2.2.4 Tailings Segregation ........................................................................................ 14
2.2.5 Tailings Dewatering ......................................................................................... 15
2.3 Rheology ................................................................................................................. 16
2.4 Segregation ............................................................................................................. 17
2.5 Dewatering .............................................................................................................. 21
2.5.1 Self-Weight Settling......................................................................................... 21
2.5.2 Large Strain Consolidation .............................................................................. 22
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CHAPTER 3 .................................................................................................................... 26
RESEARCH METHODOLOGY.................................................................................. 26
3.1 General .................................................................................................................... 26
3.2 Uranium Mill Tailings ............................................................................................ 26
3.2.1 Material Properties ........................................................................................... 26
3.2.2 Safety protocol ................................................................................................. 27
3.3 Laboratory Investigation ......................................................................................... 28
3.3.1 Rheological Test .............................................................................................. 28
3.3.2 Settling Test ..................................................................................................... 28
3.3.3 Segregation Test............................................................................................... 30
3.3.4 Large Strain Consolidation Test ...................................................................... 31
3.3.4.1 Fabrication of Apparatus........................................................................... 31
3.3.4.1 Consolidation Test .................................................................................... 37
3.4 Numerical Modeling ............................................................................................... 38
CHAPTER 4 .................................................................................................................... 43
RESULTS AND DISCUSSION ................................................................................... 43
4.1 General .................................................................................................................... 43
4.2 Depositional Behaviour .......................................................................................... 43
4.2.1 Rheological Properties ..................................................................................... 43
4.2.2 Initial Hydraulic Conductivity ......................................................................... 45
4.2.3 Settling Potential .............................................................................................. 48
4.2.4 Effective Stress ................................................................................................ 48
4.2.5 Segregation Behaviour ..................................................................................... 50
4.3 Dewatering behaviour ............................................................................................. 55
4.3.1 Large Strain Consolidation .............................................................................. 55
viii
4.3.2 Volume Compressibility and Hydraulic Conductivity Relationships .............. 59
4.4 Consolidation Behaviour in the DTMF .................................................................. 61
4.4.1 Tailings Deposition .......................................................................................... 61
4.4.2 Numerical Modeling Results ........................................................................... 64
CHAPTER 5 .................................................................................................................... 68
CONCLUSIONS AND RECOMMENDATIONS ....................................................... 68
5.1 Conclusions ............................................................................................................. 68
5.2 Recommendations ................................................................................................... 70
REFERENCES ................................................................................................................ 71
APPENDIX A .................................................................................................................. 83
APPENDIX B ................................................................................................................ 102
APPENDIX C ................................................................................................................ 121
APPENDIX D ................................................................................................................ 140
ix
LIST OF FIGURES
Figure 2.1: Uranium mining in Saskatchewan.................................................................... 5
Figure 2.2: Simplified flowchart of uranium mining operation.......................................... 7
Figure 2.3: Schematic of uranium mill tailings production.............................................. 10
Figure 2.4: The pervious surround concept in tailings disposal facility........................... 13
Figure 2.5: Typical Segregation process in the settling column and tailings disposal
facility............................................................................................................................... 19
Figure 3.1: Schematic of the large strain consolidation test system................................. 32
Figure 3.2: Calibration of devices used for the consolidation test................................ 36
Figure 3.3: Numerical modeling scheme.......................................................................... 39
Figure 4.1: Yield stress versus solids content for the investigated mill tailings............... 44
Figure 4.2: Initial hydraulic conductivity with respect to the following: (a) initial void
ratio (b) initial solids content (c) final void ratio (d) final solids content......................... 46
Figure 4.3: Settling potential with respect to the following: (a) initial void ratio (b) initial
solids content (c) final void ratio (d) final solids content................................................. 47
Figure 4.4: Final effective stress with respect to the following: (a) initial void ratio (b)
initial solids content (c) final void ratio (d) final solids content....................................... 49
Figure 4.5: Solids content versus normalized solids content deviation............................ 51
Figure 4.6: Fines content versus normalized solids content deviation..............................53
Figure 4.7: Initial solids content versus segregation......................................................... 54
Figure 4.8: Settling curves: (i) Interface height (ii) void ratio and (iii) solids content
versus elapsed time during large strain consolidation test for (a) 4% (b) 5%, and (c) 6%
mill tailings....................................................................................................................... 56
Figure 4.9: Hydraulic conductivity versus time data in large strain settling test.............. 58
Figure 4.10: Volume compressibility and hydraulic conductivity relationship................ 60
x
Figure 4.11: Schematic of DTMF (a) Plan (b) Section A-A' (c) Section B-B' of
consolidated tailings elevations; and (c) Section B-B' of consolidated tailings
elevations.......................................................................................................................... 62
Figure 4.12: Historical tailings elevation in the DTMF from 1996 through
2008.................................................................................................................................. 63
Figure 4.13: History matching of tailings elevation in the DTMF from 1996 through
2008................................................................................................................................... 65
Figure 4.14: Effective stress profiles in the DTMF: (a) 1999 borehole investigations; (b)
2004/05 borehole investigations; and (c) 2008 borehole
investigations.................................................................................................................... 66
Figure D1: Grain size distribution curves of 4%, 5% and 6% mill tailings (GSD test data
reported by Khaled (2012), reproduced with permission from the author).................... 139
Figure D2: Determination of initial hydraulic conductivity from settling test (data
reported by Khaled (2012), reproduced with permission from the author).................... 140
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LIST OF ABBREVIATIONS
AGTMF: Above Ground Tailings Management Facility
BaCl2: Barium Chloride
CCD: Counter Current Decantation
cv : Coefficient of Consolidation
DTMF: Deilmann Tailings Management Facility
DS: Degree of Saturation
e: Void Ratio
��∗: Void Ratio at Fluid Limit
ef : Final Void Ratio
ei : Initial Void Ratio
∆e: Difference of Initial and Final Void Ratio
f: Fines Content
Gs: Specific gravity of solids
GSD: Grain Size Distribution
h: Height of the Slurry Sediment
h1: Initial Hydraulic Head
h2: Final hydraulic head
hi / ht: Normalized Height of the Slurry
k: Hydraulic Conductivity
ki : Initial Hydraulic Conductivity
xii
masl: Meters above Sea Level
(NH4)2SO4: Ammonium Sulphate
pH: Measure of Acidity or Alkalinity
r2: Coefficient of Determination
S: Segregation
s: Solids Content
si : Initial Solids Content
Savg: Average Solids Content of the sediment
Sd: Solids Content Deviation
u: Pore Pressure
U3O8: Yellowcake/ Triuranium Octoxide
Vs : Settling Velocity
w: Gravimetric Water Content
WNA: World Nuclear Association
σ': Effective Stress
T: Time Factor
τy: Yield Stress
�s: Unit Weight of Solids
�w: Unit weight of Water
ζ : Consolidation Ratio
: Relative Degree of Compression
1
CHAPTER 1
INTRODUCTION
1.1 Problem Statement
The Key Lake operation in Saskatchewan, Canada, is the largest uranium mill in the
world (Cameco, 2012), producing 13% of the world’s uranium (World Nuclear
Association, 2012). The Key Lake site receives high grade ores (up to 21% U3O8 in 2010,
as reported by Yun et al. (2011)) from McArthur River, which are diluted to a nominal
4% grade using Deilmann special waste, Gaertner special waste, and mineralized waste
from McArthur prior to milling. Currently, Cameco is assessing the feasibility of milling
higher grade of ore up to 6% U3O8. Mill tailings refer to the solid waste materials that
result from the processing of the uranium ore. The tailings management is an essential
activity related to ore processing at the Key Lake operation since the storage capacity of a
tailings management facility depends on the dewatering behaviour of the deposited
material (Ito and Azam, 2013).
The geotechnical investigations on depositional and dewatering behaviour of
uranium tailings are hardly observed in the literature. Previous geotechnical
investigations on uranium tailings include the following: liquefaction assessment of
tailings embankment at Elliot Lake, Ontario (Matyas et al., 1984), tailings consolidation
at Thuringia, Germany (Wales et al., 2000), historical tailings performance at Key Lake,
Saskatchewan (Azam et al., 2014), and a summary of experience with containment
facility design in Saskatchewan (Mittal and Landine, 2013). Most such studies have
focused on tailings behaviour in the containment facilities. An efficient containment
design requires a clear understanding of slurry behaviour throughout the tailings life-
2
cycle starting from tailings production thorough the deposition to dewatering in the
containment facilities. Rheological properties are important in optimizing slurry transport
through pipes to the disposal areas. In Key Lake operations, tailings are pumped from the
mill to a thickener (achieves a solids content of 35% to 40%), and subsequently deposited
from the thickener underflow to the containment facility, called the Deilmann Tailings
Management Facility (DTMF). Post-deposition, tailings segregate due to preferential
settling of coarse particles with respect to the fines. This process affects the rate and
amount of tailings dewatering, thereby influencing the storage capacity of the
containment facility. Furthermore, the segregated tailings can produce zones of higher
and lower hydraulic conductivity, which could result in higher fluxes through the slurries
after closure of tailings management facility.
The DTMF is currently approved to store tailings up to a consolidated elevation
of 466 masl. According to Cameco (2010a), the total volume of sediments was estimated
to be 6.66 × 106 m3 in the DTMF. Based on current production plans, additional tailings
storage capacity is required to support a continued operation of the mill. An
environmental assessment is currently being conducted by Cameco to evaluate the
potential impact and feasibility of raising the final elevation of consolidated tailings to
505 masl. In order to ensure the efficient use of storage facility for different production
and mining schedules, a clear understanding of the tailings dewatering behaviour is
required for the current mill tailings (4%) and future (5% and 6%) mill tailings.
Therefore, there is a need to investigate the tailings dewatering behaviour and assess the
historical dewatering performance in the DTMF.
3
1.2 Research Objective
The main objective of this study was to investigate the depositional and dewatering
behaviour of current (4%) and future (5% and 6%) mill tailings. The specified objectives
are as follows:
To investigate the depositional behaviour of uranium mill tailings by laboratory
tests (rheological, settling, and segregation).
To examine the dewatering behaviour (volume compressibility, hydraulic
conductivity, and numerical modeling of consolidation) of uranium mill tailings
in the Deilmann Tailings Management Facility (DTMF).
1.3 Thesis Outline
This thesis is comprised of five chapters. A brief description of each chapter is outlined
as follows: Chapter 1 provides an introduction to the research and establishes the need,
and research objectives of this work. Chapter 2 presents the literature review related to
industrial operation of uranium mining, theoretical background of depositional and
dewatering behaviour, and a review of tailings production and disposal practices. The
geotechnical issues, challenges of tailings management in finite storage capacity are
highlighted. Chapter 3 outlines the research methodology of this work. The laboratory
investigation methods, fabrication of large strain consolidation test system, and the
numerical modeling procedure were discussed in this chapter. Chapter 4 presents the
results and discussion of laboratory investigations and the results of numerical modeling
for consolidation behaviour in the DTMF. Chapter 5 summarizes the main conclusions
obtained from this research and provides recommendations for future work. This is
followed by a list of references and appendices.
4
CHAPTER 2
LITERATURE REVIEW
2.1 General
In the 1950s, the emergence of civil nuclear power reactors demonstrated an enormous
potential of nuclear fission for generating electricity. From a small beginning in 1951,
when four light-bulbs were lit with nuclear electricity, the nuclear power industry
currently supplies about 11% of global electricity from 437 nuclear power reactors world-
wide (WNA, 2013; Cameco, 2014). There was a big gap between the world uranium
supply and reactor requirements since 1990s. The world total uranium production was
about 30,000 tonnes in 1995 (50% of global demand), which was found about twice as
58,394 tonnes in 2012 (WNA, 2013). Many companies over the globe are currently
extending their mill facilities and opening up of new mine sites due to this increasing
demand for uranium.
Canada is a major mineral producer, and mining is a major contributor to the
country's economy. Canada produced 15% of world total production in 2012, and most
uranium is generated from mines in northern Saskatchewan. McArthur River, the world's
largest mine was the source of 7,520 tonnes of uranium, processed at the Key Lake mill
facility in northern Saskatchewan (WNA, 2013). The Athabasca basin in northern
Saskatchewan, Canada, (shown in Figure 2.1), has the world's richest uranium ore
reserve. The ore grades (about 16%) at this deposit are 100 times higher than the world
average (Cameco, 2014). Recently, a new uranium mine has begun operation at Cigar
Lake in Canada, due to an increasing uranium requirement over the world.
Figure 2.1: Uranium mining in SaskatchewanResearch and Response Applications (TERRA) laboratory,
Uranium mining in Saskatchewan (Data source: TerraServer, The Environmental Research and Response Applications (TERRA) laboratory, University of Regina)
5
The Environmental University of Regina)
6
2.2 Industrial Practice
2.2.1 Mining operation
Uranium mining uses the same processes used to mine many other metals such as copper,
gold, or nickel, etc. Figure 2.2 shows a simplified flow chart of uranium ore processing
from mining to the production of concentrate (U3O8). Mining process is done in one of
the three ways depending on ore deposit type. Open pit and underground mining are the
conventional uranium mining methods. Open pit mining is used for relatively shallow
deposits, generally less than 100 metres deep. It is generally not economical to use the
open pit mining to extract uranium from an ore body located more than 100 meters below
the surface. Underground mining methods are used in this case however the ore deposit
grade should be higher on this method. In-situ leach method is used for uranium deposits
located below the water table in a confined aquifer. This process dissolves the uranium
while still underground and then pumps a uranium-bearing solution to the surface for
milling. For example, the high grade ore deposits in McArthur River are located between
400 and 600 metres below the surface and underground mining method is used for this
mining operation (Cameco, 2014). The conventional mining and in-situ leach mining
methods produced 49% and 44% of world uranium production respectively and
remaining amount is produced by-product (WNA, 2013).
After mined out the uranium deposits, ores are processed in the mill facility. The
Key Lake mill process is a typical example of uranium milling operation. This mill
receives ore from on site deposits and from McArthur River mine. The process comprised
of the following components: crushing and grinding, sulphuric acid leaching, counter
current decantation, solvent extraction, yellowcake precipitation, and product
7
Figure 2.2: Simplified flowchart of uranium mining operation (after WNA, 2013)
Open pit mining
Undergorundmining
Crushing &grinding
Leaching
Seperate solidsTailings production
& disposal
Extract U in liquor
Recyclebarren liquor
PrecipitateUranium
Separate solids
Recyclebarren liquor
Drying
Uranium oxide concentrate U3O8 (yellowcake)
Conains approximately 85% by weight of uranium
8
crystallization. In the first stage, large chunks of Key Lake special waste rock are crushed
and blended with mineralized wastes from McArthur River using mill process water. The
resulting slurry is mixed with the high grade McArthur River ore slurry and Falcon
concentrator rejects. The Falcon concentrator separates uranium-rich materials from
concrete-rich materials contained in the mineralized waste rock from McArthur River.
The uranium-rich materials are fed to the mill along with the ore whereas the rejects are
mixed with the tailings (Cameco 2010a). Through a combination of atmospheric and
pressure leaching process using sulphuric acid, the uranium is dissolved, along with other
metals and salts. The slurry is then transferred to the counter current decantation circuit.
This circuit completes the leaching process and separates the barren solids from the
uranium bearing solution through a series of thickeners (circular vessels with inverted
conical bases). The wash solution is gradually impregnated with uranium as it flows
downstream. The pregnant solution is clarified by passing through sand filters, that is fed
to the solvent extraction circuit for purification and concentration through selective
extraction from the pregnant liquor. Uranium is then stripped off the aqueous solution
using (NH4)2SO4 and the loaded strip solution is precipitated as yellowcake. This material
is converted to uranium oxide concentrate (U3O8) by heating to 800oC in the calcining
circuit and the product is put in drums for shipment. The uranium oxide concentrate
(U3O8) contains approximately 85% by weight of uranium.
2.2.2 Tailings production
The uranium content of the ore is often between only 0.1% and 0.2% (WISE Uranium,
2014). Therefore, the amount of tailings generated is nearly the same as that of the ore
milled. At a grade of 0.1% uranium, 99.9% of the material is left over. A large amount of
9
tailings produced from uranium milling process and these tailings are generally
engineered on-site (thickening using polymers, pH adjustment using BaCl2) before
depositing into the disposal facility.
Figure 2.3 is a simplified schematic of the tailings production process in the Key
Lake mill facility. Refer back to the Key Lake mining operation on previous section, the
slurry (leach residue) from the counter current decantation (CCD) circuit, the underflow
streams from bulk neutralization thickeners, and underflow solids from clarifier tank after
pH adjustment, are fed to a mix box (tailings feed box). The bulk neutralization process
consists of a series of four neutralization pachucas (high narrow tank with air agitation)
followed by a molybdenum/selenium removal thickener. The pH adjustment is done
using two small air-agitated tanks and a clarifier tank. The tailings neutralization section
consists of a small splitter tailings feed box and two large agitated tailings holding tanks
connected to the tailings pumps. The combined slurry flows to the two tailings holding
tanks where it is adjusted to a pH of 10.5 to 11.0 using lime (Shaw et al., 2011) and such
that the elevated pH values were used to raffinate and precipitate minerals present in
tailings (Mahoney et al., 2006). The slurry is then pumped to a 30 m diameter thickener
where it achieves a solids content of 35 to 40%. Depending on a varieties of factors (such
as mineralogy, extraction process, degree of grinding, specific gravity, and grain size
distribution), tailings are thickened at different solids content prior to disposal in order to
get better performance in the disposal facility (Palkovits, 2007).
2.2.3 Tailings Disposal
Tailings usually exhibit non-Newtonian behaviour, which requires an understanding of
the rheological behaviour in order to economically pump the material from the thickener
10
Figure 2.3: Schematic of uranium mill tailings production
Molybdenum and Selenium Thickener
Underflow
Lamela ThickenerUnderflow
Clarifier Tank Underflow
Counter Current Decantation Underflow
Tailings Feed Box
Barium Chloride (BaCl2)
Tailings Tanks
Tailings Thickener(35-40% Solids)
Lime
Slurry
Slurry Slurry
Slurry
Deilmann Tailings Management Facility ( DTMF )
11
to the disposal (Sofra and Boger, 2002). The rheological behaviour of various tailings is
not unique in mining different industry (Boger, 2013; Mihireitu, 2009). Depending on
rheological behaviour, tailings are thickened at an optimal solids content so that it can be
pumped or transposed in a financially viable way (Boger et. al, 2002). The rheological
properties of the slurry can also be engineered to deposit tailings without segregation and
to increase consolidation of the overall slurry by storing the fine particles in the voids of
the larger grains (Talmon et. al, 2014). Tailings in slurry form are usually pumped from
mill and disposed to containment facility using either subaqueous or sub-aerial
techniques. Sub-aerial deposition is a technique to disposed tailings above the water line
or on the ground. This method is generally exercised at tailings facilities that have
multiple outlets or points of discharge. The frequency of discharge point rotation and the
number of deposition zones is dependent on the climate, production rate of tailings,
drying characteristics of tailings and the shape of disposal facility (Gipson 1998).
Subaqueous deposition is a method tailings disposal under water and recommended for
those tailings having potential of producing acid by oxidizing (Tremblay, 1998). This
method is also used for uranium tailings to reduced radon exposure from the tailings
surface (Mittal and Landine, 2013).
In milling process at Key Lake, the thickener underflow (final tailings) is
transferred using positive displacement pumps to the disposal facility. There are two
Gould’s SRL heavy duty slurry pumps are used under the thickener for pumping tailings
to the spigots in the disposal facility. The pipe distance from the thickener to the
discharge point for each active spigot is about 2 kilometres. Tailings are being deposited
using a single tremie pipeline and tailings deposition barge at end of each spigot. The end
12
of the pipe is submerged about 2 m below of the tailings surface to prevent free fall of
thickened tailings (Mittal and Landine, 2013).
In the 1950s and 1960s, the tailings management practices were found to be
consisted of finding the cheapest way of taking the waste away from mill to the most
convenient topographic depression (Landine and Moldovan, 2010). For example,
uranium tailings were being deposited to Fookes Lake adjacent to the Beaverlodge mill in
northern Saskatchewan during this period. This was not an unique case, similar
depositional practices were observed in many sites over the world in 1950s. Because of
environmental concerns about these sediments in the water and other issues, tailings
storage areas or ponds began to be constructed, which were bounded by impoundments or
dams. The practice of above ground tailings management facility (AGTMF) was started
during 1970s. This types of tailings management facility usually involve the construction
of engineered earthen dams at the ends of a valley created by two parallel ridges. The
decant water from tailings is treated with chemical solutions and sand filtering system
prior to discharge to the environment. Modern tailings management facility includes an
advancement of storage technology with the development of the pervious surround
concept. Many facilities are storing tailings in a mined out pit by engineered with the
pervious surround which allows for enhanced consolidation during operation, as well as
effective control of contaminant migration (Landine and Moldovan, 2010).
Figure 2.4 shows a schematic diagram of the in-pit pervious surround concept.
The Deilmann Tailings Management Facility (DTMF) is an example of modern tailings
management facility which represents a refinement of the in-pit pervious surround
concept. The DTMF is engineered from a mined out pit called Deilmann pit. This facility
13
Figure 2.4: The pervious surround concept in tailings disposal facility. (Modified after Landine and Moldovan, 2010)
14
started receiving tailings from Key Lake operation since 1996. The pond is 1300 meters
long, 600 meters wide and 170 meters deep. It receives tailings at a rate ranging between
1500 m3/day and 2400 m3/day. The facility was initially designed for sub-aerial tailings
deposition followed by a switch to sub-aqueous deposition in 1999. Azam et al. (2014)
provided a chronological summery of tailings deposition and management in the DTMF.
The sub-aqueous deposition in the facility provided a benefit of preventing ice formation
and resulted reduced water treatment (Landine and Moldovan, 2010). The lower portions
of the facility include an engineered side-drain and bottom-drain system to facilitate the
collection of consolidation water via the raise well and the peripheral dewatering system.
2.2.4 Tailings Segregation
The tailings characteristics have influence in their behaviour after they are discharged to
the storage facility. Generally, segregation occurs after deposition of tailings as coarse
size particles settle out leaving fines on the top. The degree of this segregation essentially
depends on the grain size distribution of the tailings and the solids content of the slurry
(Vick, 1990). Segregation was also reported as a function of initial condition of slurry,
that is increasing the solids content by densification, or increasing the fines content
through enrichment of fines tailings, would change a segregating mixture to a non-
segregating one (Azam and Scott, 2005; Matthews et al., 2002). Azam (2003) found that
the initial solids content lower than 15% results segregation in laterite slurries. The
tailings is transported by pipeline to tailings management facility where it segregates
upon disposal, separation of some or all fractions of the coarse solids (Caughill et al.,
1993). The segregation of tailings upon disposal hinders consolidation process and
subsequently affects the proper use of storage facility and reclamation of land etc. When
15
dispersed fine size particles are present in a tailings stream, the very slow settling and
consolidation of fine‐graded mine tailings presents a serious issues with the storage
capacity and potential reclamation of settling ponds (Talmon et al., 2014).
During the deposition of tailings, segregation can occur depending on grain size
distribution of the materials. Van Kesteren et al. (2007) reported that the acceleration in
the vertical section of the deposition system is required to control to minimize
segregation of slurries containing cohesive fines and sand. They further reported that the
slurry deposition can be controlled by a multiple tremie or diffuser system by increasing
the friction in the vertical pipe section. Costello et al. (2008) showed segregation distance
was found to be dropped from 25 meters to 10 meters by using multiple tremie or diffuser
system for uranium mine tailings in McClean Lake, Canada.
2.2.5 Tailings Dewatering
In the modern practice of tailings management, tailings dewatering is the most important
issue in the mining industry in terms of impoundment capacity, land reclamation, water
recovery, and reuse. Dewatering behaviour of tailings largely depends on material grain
sizes. Coarse particles (sand, silt) dewaters quickly due to the inert nature whereas fine
particles takes considerable amount of time to release water due their chemically active
nature. There is also an extreme need to recycle and reuse the decant water in the mill
process from the tailings storage facilities in the arid and semi-arid regions due to the
scarcity of water. The poor dewatering characteristics of tailings will result a shortage of
storage capacity and subsequently reduce the life of milling operations, or increase the
land use by creating the need of a new facility. In the several mining industries, it takes a
long time for dewatering because of having substantial amount of fine particles in the
16
tailings. Therefore, many advanced technologies have been developed and implemented
in uranium, gold, oil sand, and other mining industry for tailings dewatering (Taylor,
2007; Ritcey, 2005; Mikula et al., 2008; Mpofu et al., 2003). The widely used
technologies are as follows: thickened tailings disposal, centrifuged technology, polymer
added disposal, and thin-lift drying etc.
2.3 Rheology
An essential depositional requirement for delivering tailings to the disposal point is
having a sufficient yield stress (τy), that can carry the largest particles by ensuring a
homogeneous suspension where segregation does not occur. The relationship between
solids content and yield stress should be determined in the first instance to indicate the
minimum solids content necessary to obtain the required yield stress in tailings
depositional scheme (Boger et al., 2002). It was observed in the study for non-Newtonian
fluid mechanics that, the significant presence of fine particles contributes to the
rheological characteristics in a suspension system (Valentik and Whitmore, 1965; Ansley
and Smith, 1967).
Tailings disposal scheme should have some rheological properties that are stable,
easily transportable and yielding low volume at storage. So yield stress measurement has
become significant in evaluating the geotechnical suitability of tailings deposits. In the
observation of flow characteristics effect on segregation behaviour, the vane shear
method was generally used to calculate the yield stress of tailings. The four bladed vane
technique is generally used for yield stress measurement in the high stress range
(Mihireitu, 2009) whereas rheometer can be used in the low stress range (Boger, 2013).
The vane, attached to a torsion measuring head, is carefully inserted into the test material
17
and rotated at a low speed where the torque as a function of time is measured. The
maximum torque (Tm) is related to the yield stress (τy). Denoting the diameter of the vane
by Dv and the aspect ratio of the vane cylinder by H/Dv, the maximum torque can be
written by the following equation:
(2.1)
Mihiretu (2009) examined the solids content level at which the rheological
properties of fines play a significant role. His experimental results indicated that the
composition of the fines play a major role in the phenomena of segregation and clay
particles are the main contributors for the rheological behaviours and the yield stress.
Since yield stress is strongly dependent on solids content, the vane shear test data were
usually used to observe the relationship of yield stress with different solid content. There
are different ways in which yield stress is correlated to the solid content of the slurry. For
the experimental work, the yield stress is conveniently plotted as a function of the solid
content (s) of the slurry, the above relation can be rewritten in terms of solid content,
specific gravity (Gs) and a fitting parameter (A) as follows (Mihiretu, 2009):
(2.2)
2.4 Segregation
Segregation is the affinity of solid fractions (or part of it) to settle by creating a
concentration gradient within the mass (Suthaker, 1995). Solids tend to segregate by
virtue of differences in the size, shape, density, and other properties of particles.
Segregation is a common problem with a wide significance and it has been a matter of
�� = �
2 �� �
�
��+
1
3� ��
�� = � �� (�� − 1)
� + ��(1 − �)�
23−�
18
interest to physicists, geologist, engineers, and industrial communities. The studies of
segregation are associated with different problems as sedimentation, consolidation,
fluidization, erosion, and mass transport. The tailings stream is transported by pipeline to
the tailings pond, where upon disposal the coarse particles settle out leaving the fines on
top of the pond. Such deposition results in segregation of the tailings. The major
problems associated with a segregating type of tailings are as followings: high operating
and monitoring cost, large storage volume, liquefaction susceptibility, low strength,
toxicity and high environmental risks, slow consolidation rate, less quantity of water to
recycle, and difficulty in land reclamation (Mihiretu, 2009). Therefore, the handling of
mine waste requires an optimal tailings disposal scheme. Currently, the production of non
segregating tailings is being considered as a solution to either the existing tailings
management challenges or future planning.
One may define the term segregation as a tendency for certain sizes or
components with similar properties to preferentially collect in one or another physical
zone of collective (de Silva et al., 1999). The segregation phenomena occurs or not in a
tailings containment depends on particle shape and size distribution, initial solid content,
and flow characteristics of tailings. Figure 2.5 shows a typical segregation process during
self-weight settling. During self-weight settling where two distinct particle sizes of equal
density are involved, it will results in four zones. From top to bottom these zones are:
clear liquid, suspension of smaller particle size only, suspension of both particle sizes,
and the sediment (Mirza and Richardson 1979). In this process the particle attractive
forces are at a minimum, and the particles tend to be dispersed.
19
Figure 2.5: Typical Segregation process in the (a) settling column (b) tailings disposal facility.
20
Segregation characteristics depend largely on the amount of fine particles present
in tailings. The relatively coarse particles tend to settle, but the fines remain suspended in
the slurry when deposited. Coarser grain particles (size greater than 0.075 mm) settle
with minimum to no segregation, unlike finer grain particles (size smaller than 0.075
mm), which undergo substantial segregation during self-weight settling process
(Dimitrova, 2011). The segregation is highly affected by the solids content in the
deposition of tailings; lower solids content generally exhibits a higher segregation (Major
2003). At higher solids content segregation is increasingly suppressed and eventually
inhibited due to a combination of grain-fluid coupling and particle interlocking (Lockett
and Al-Habbooby, 1974; Davies and Kaye, 1971). At low solids content, particle
interactions are negligible and the effect of fluid counter flow enhances segregation of
particles. Mihiretu (2009) examined the segregation phenomena theoretically and
experimentally with emphasis on identifying the effect of grain size composition. He
found that the segregating nature of slurry can be predicted based on the observation of
rheological responses in addition to grain size distribution and initial conditions.
It is important to define the degree of segregation or segregation index in a
depositional scheme of tailings management. Several attempts was taken on this regard to
quantify the segregation of tailings. To explain segregation behaviour, a quantitative
index, called segregation index, was introduced by different researchers (Suthaker, 1995;
Tang, 1997, Chalaturnyk and Scott, 2001; Azam, 2003). Denoting the average solids
content and height of slurry at time t by Savg and H, the initial solids content by So and the
initial height of slurry by Ho, this segregation index (Is) is calculated after self-weight
settling test and can be defined by the following equation:
21
(2.3)
Mihiretu (2009) proposed an another method to define Segregation Index (SI),
which can be written by correlating with the solid content Si of sample section height of
Hi, as the following equation:
(2.4)
A simplified form of the above equations with similar basis (that is, solids content
deviation and layer-wise heights) was used later in this study to define segregation.
2.5 Dewatering
Dewatering is the water recovery from tailings which can also be said as the solid-liquid
separation. To understand tailings dewatering, it is fundamental to have a clear idea about
the self-weight settling behaviour, consolidation behaviour, and the factors affecting
dewatering.
2.5.1 Self-Weight Settling
Self-weight settling of tailings is a complex phenomenon which involves three different
phases: initial flocculation, sedimentation, and consolidation (Imai, 1981). These phases
stages are either inter-related or can be happened simultaneously. A typical self-weight
settling process of tailings in a settling column can be described by using Figure 2.5.
Initially, flocculation is occurred which ceases quickly as the slurry settles with a rapid
decrease in the interface height. This occurrence provides a clear water-solid interface
line. As slurry starts to settle, void ratio decreases gradually and solids content of slurry
�� = � �1
2 �
��
����− 1� ��
�
���
�+1
− ��
���
�−1
�� ∗ 100%
�
�=1
�� = �∑ ����� − ���� �
2
∑ ��
22
increases at the bottom. The process continues until a soil like structure, sediment is
formed. Once, the particles start transmitting effective stress due to inter granular contact,
consolidation takes place and the behaviour is governed by consolidation theory
(Terzaghi et al., 1996). Jeeravipoolvarn (2010) reported that sedimentation and
consolidation can be identified by absence or presence of effective stress. Self-weight
settling ends after certain period of time until no further change is observed in interface
height. After self-weight settling, a clear water layer exists at top and sediment with a
measurable effective stress exists at the bottom.
2.5.2 Large Strain Consolidation
It has been recognized that the major assumptions in classical small strain theory are
highly restrictive for analysis of slurry type materials during consolidation. Terzaghi
(1925) develop the first approach to define the 1D consolidation. This theory is the most
widely used for consolidation analysis despite of having the well-known limitations. The
major assumptions of this approach are: strains are relatively small and the material
properties remain constant throughout the consolidation process. The major limitation of
this approach was explaining volume change behaviour of tailings, since tailings exhibit
significant changes in void ratios during changes in the applied stress. To distinguish the
application between small strain and large strain theory is essential for assessing tailings
consolidation behaviours. The large strain theory should be considered for tailings
deposition for a thickness higher than 30 meters in the containment facility (Schiffman et
al., 1988). Besson et al. (2010) reported that there is a disappearance of classical small
strain hypothesis to the large strain phenomena at a strain of about 10% or higher when
materials are in compression (such as consolidation).
23
The theory of slurry consolidation was originally develop by McNabb (1960) and
later expanded by Gibson et al. (1967) in material coordinate system as follows:
���
��− 1�
�
�� �
�
����
��
��+ �
�
�� (���) ���
�� ��
��� +
��
��= 0 (2.5)
Here, �s and �w are unit weight of solids and fluid (water). The hydraulic conductivity,
void ratio and effective stress are denoted by k, e and σ' respectively. After this theory,
several formulations of the finite strain consolidation theory have been observed in the
literature of geotechnical engineering, but all the formulations are based on same
fundamental principles. Berry and Poskitt (1972) modified the theory which considered
the effect of secondary compression. Monte and Krizek (1976) incorporated the initial
“stress-free” state using finite element approach. Schiffman (1980) updated the theories
by using Lagrangian coordinates so that the variation throughout the soil depth can be
taken into the account. Huerta et al. (1988) developed a one-dimensional mathematical
model with large strain theory to solve seepage induced consolidation phenomena.
Table 2.1 shows a chronological summery for the development of consolidation
theory. The solution of large strain consolidation theory became more important for
practical use as the problem of mine tailings disposal required more exact analyses.
Poskitt (1969) solved the nonlinear large strain consolidation equation by Perturbation
method using a power series. Cargill (1984) developed graphical solution charts based on
linearization and normalization of Gibson et al. (1967) theory. Mikasa and Takada (1986)
developed three different approaches: a standard method with a primary consolidation
ratio correction, a method for finite strain in which coefficient of consolidation (Cv) is
constant, and a method for finite strain with a variable Cv. McVay et al. (1986) compared
the experimental and theoretical prediction of consolidation of soft soil and revealed
24
Table 2.1: Chronological summery for the development of consolidation theory
Assumption/Significance Solution/Equation
Terzaghi (1925) The first approach to define consolidation. Strains are small and the material properties remain constant.
��
��= ��
���
���
McNabb (1960) This theory is a landmark in slurry consolidation theory because of the inherent allowance for large deformations.
��
�� = -
�
�� �
�
��(���) ���
���
Mikasa (1965) Considered the self weight of the deposit, variable permeability and compressibility.
Gibson et al. (1967) This first derived equation without the limitation of the infinitesimal strain in the normal consolidation theory.
���
��− 1�
�
�� �
�
����
��
��+ �
� (�)
�� (���) ���
�� ��
��� +
��
��= 0
Poskitt (1969) Nonlinear large strain consolidation equation was solved by perturbation method.
Monte and Krizek
(1976) Developed large strain consolidation theory that considers the initial, “stress-free” state.
�
�� �
����∗
��� �
�
��� �
���
��+
������
����∗ �� +
�
�� �
�
����∗�
Schiffman (1980) A new approach which considers the variation throughout the soil depth.
�
�� �
�
�� ���
��� ±
�
���
�(�����)
�� (����)� =
��
����
���
��
Cargill (1984) Prediction of consolidation of soft soil. Graphical solution charts based on Gibson et al. (1967)
McVay et al. (1986) Compared the experimental and theoretical prediction of consolidation of soft soil.
Semi-empirical and analytical solution
Huerta et al. (1988) 1D model with large strain theory to solve seepage induced consolidation phenomena.
Kiousis et al. (1988) A computational model based on advanced elasto-plastic large strain deformation.
Analytical solution approach using the finite element method.
Yao et al. (2002) Numerical solution for consolidation of soft soils by two time-dependent non-linear partial differential equations.
(1 − ��)�
���
�
����
��
��−
�
���
�(����)
��(���)
���
��
��
��� =
�
����
��
��
Morris (2002) The settlement estimation for unconsolidated soil based on Gibson et al. (1967) and Cargill (1984).
Analytical solutions and solution charts
Fox and Qiu (2004) Developed a piecewise-linear model for compressibility of the pore fluid in addition to the consolidation.
Numerical solution
Jeeravipoolvarn et al. (2008)
Numerical solution using three approaches: pre-consolidation, creep compression and layering consolidation.
�
���
��(�)
��(���)�
��
��+
��(�)
��(���)
���
��� + �. �. �. exp[−�. ���]. ��(���) ��
��= 0
��
�� = �2
�
��0 ���
��
��0�
�
�� �(1 + ��)
��
��� =
��
��
��
��=
�
���
�
�� (1 + �)�
��
��
25
nonlinear approach is more realistic than linear attempts. Somogyi (1980) proposed the
power law function for volume compressibility (e-σ') and hydraulic conductivity (k-e)
relationships with four fitting parameters (A, B, C, D) by the following equations:
e = Aσ' B (2.6)
k = Ce D (2.7)
Later Liu and Znidarcic (1991) proposed an extended power law for one
dimensional compression behaviour. This void ratio and effective stress relationship
encountered the deficiency of defining void ratio at low effective stress or any effective
stresses. Fox and Berles (1997) developed a piecewise-linear model which is numerical
attempt based on constitutive relationship of the soil. This model offered a relatively
simple technique to apply and modify with the different initial and boundary conditions.
The major concerns with the tailings consolidation test are the apparatus must be
capable of accommodating large strains (Gan et al., 2011) and have the ability to apply
low loads at early stages to represent operating condition of tailings disposal facilities
(Qiu and Sego, 2001). Upon completion of the consolidation test and hydraulic
conductivity measurement, the compressibility and hydraulic conductivity relationships
are generally determined using the test results. These correlations are the essential
constitutive relationships for predicting the long-term behaviour by numerical modeling.
The consolidation theory has been implemented to a number of numerical
computer programs that are used to solve various consolidation behaviours, such as:
CONDES (Yao and Znidarcic, 1997) and FSCONSOL (GWP Software, 1999). These
programs typically used to calculate the tailings settlements and the capacity of tailing
storage facilities (Geier et al., 2011; Gjerapic et al., 2008).
26
CHAPTER 3
RESEARCH METHODOLOGY
3.1 General
This chapter presents the research methodology of this study. A comprehensive research
investigation program was developed to understand the depositional and dewatering
behaviour of current (4%) and future uranium mill tailings (5% and 6%). First, the
materials are described including the safety protocol maintained in the laboratory
throughout the research program. Next, the complete laboratory investigation program
has been provided followed by the detailed descriptions of the various tests conducted in
this research. These descriptions include tests for rheological properties, self-weight
settling, grain size distribution, segregation, and large strain consolidation. Finally, a
detail description is provided for numerical modeling of tailings consolidation behaviour.
3.2 Uranium Mill Tailings
3.2.1 Material Properties
The Key Lake Operation of Cameco Corporation, Canada, provided the uranium mill
tailings samples, containing Falcon concentrator rejects at 1:1 ratio. Khaled (2012)
reported the index properties of these three types of tailings (4%, 5% and 6% mill
tailings). The specific gravity (Gs) was measured according to ASTM 854-10 and the
grain size distribution (GSD) was determined according to ASTM D422-63 (2007) using
wet sieving followed by hydrometer analyses on material finer than 0.075 mm. The grain
size distribution curves (Appendix D) were plotted by fitting the GSD test data with the
unimodal (4%) and bimodal (5% and 6%) fit (Fredlund et al., 2000). The unimodal fit
27
was found to best describe (r2 = 0.994) the grain size distribution of the current (4%) mill
tailings whereas the bimodal fits were found to best describe (r2 = 0.994) the grain size
distribution of the future (5% and 6%) mill tailings. The GSD curves were used to
characterize the index properties of materials, and further used to interpret the
depositional and dewatering behaviours. Hydrometer data were analyzed to determine the
amount of fines present in the materials, defined as fines content (f) in this study.
3.2.2 Safety protocol
The mill tailings samples for this investigation program were received in a 20 L plastic
pail and was stored in a radioactive shielded sealed box. Using a specialized heat-paneled
vehicle that precluded the effect of freezing, the sample was shipped from the mill to the
Radioactive Tailings Research Laboratory at the University of Regina where these were
stored at 22oC. All of the laboratory tests were performed in this research facility which
licensed by Canadian Nuclear Safety Commission (CNSC). The safety protocol was
maintained by performing weekly wipe test using a scintillation counter, regular radiation
detection survey using a Geiger counter and maintaining radiation inventories of
radioactive substances. These safety practices were maintained in accordance with the
radiation safety policy of the University and CNSC regulations and the safety protocol
was regularly monitored by the Radiation Safety Officer (RSO). During the investigation
program, it was ensured that all legislative requirements are met for the safe use, storage,
transfer, and disposal of radiation and radioactive materials by using the ALARA
principle (as low as reasonably achievable). After the completion of laboratory
investigation program, the used samples were shipped back to the mill for disposal into
the tailings storage facility.
28
3.3 Laboratory Investigation
3.3.1 Rheological Test
The yield stress was measured at various solids content in accordance with ASTM
D4648-10 using the vane shear apparatus comprising a 12.7 mm blade height and 12.7
mm diameter (1:1 vane blade). The slurry was placed in the cylindrical mould. The vane,
attached to the upper shaft of apparatus, was lowered by rotating the drive wheel and
pushed into the slurry sample up to a depth equal to the height of the vane. The vane
blade was rotated at a rate of 2 rpm. The resistance offered by the soil to the rotating
blade was measured and used to calculate the yield stress (τy). The applied torque
(product of the maximum angular rotation of the torsion springs and the calibration factor
of the spring) was divided by the vane dimension constant to determine the yield stress.
The gravimetric water content (w) was measured after each of the above tests according
to ASTM D2216-10 using representative samples from the cylindrical mould. Slurry
samples were initially oven dried overnight at 105ºC to evaporate the bulk of the tailings
water. Thereafter, several hours of additional oven drying (at a lower temperature of
60ºC) was carried out until the weight stabilized, to obtain completely dry samples
(Cameco, 2010b). The low temperature was used to prevent the removal of structural
water from gypsum (present in the tailings), thereby ensuring an accurate determination
of gravimetric water content.
3.3.2 Settling Test
Settling tests were conducted using 85 mm diameter graduated cylinders. The initial
sample height was also set at 85 mm in order to make the height to diameter ratio of 1.0
29
to minimize wall effects (Azam et al., 2005). The top of the graduated cylinder was
covered with a plastic wrap to prevent evaporation. Prior to each test, the initial solids
content was adjusted by adding the decant water. The estimated solid content was
confirmed by taking a representative sample from the graduated cylinder and measuring
the water content. A clear solid-liquid interface movement (brown mud line observed
through a white background screen) was monitored at regular intervals of time until no
further change was observed. These data were confirmed by taking photographs using a
digital camera with macro lenses of up to six times magnification. After test completion,
the recorded data were plotted as interface height versus time (Appendix D). The slope of
the initial straight-line portion of the settling curve was used to determine the initial
hydraulic conductivity (ki), based on a method described by Pane and Schiffman, (1997).
Using the settling velocity (Vs) of the solid-liquid interface, the initial void ratio (ei) and
the unit weights of soil solids (γs), and water (γw), ki was determined as follows (Pane and
Schiffman, 1997):
ki = [{γwVs (1 + ei)} / (γs – γw)] (3.1)
The settling potential (SP) was calculated using ei and the difference between the
initial and the final void ratio (∆e) as follows (Azam, 2012):
SP = (100 ∆e) / (1 + ei) (3.2)
Using the final void ratio (ef), unit weight of water (γw), height of the slurry
sediment (h), and specific gravity (Gs), the effective stress (σ') at the end of the self-
weight settling test was calculated according to the following equation (Holtz et al.,
2010):
σ' = {(Gs – 1) / (1 + ef)}γw h (3.3)
30
The settling tests were conducted at two initial solids contents (si = 15% and
20%) in this study. The settling tests data (as reported by Khaled, 2012) of these
materials for higher initial solids content (≥ 25%) were also used to determine the initial
hydraulic conductivity and settling potential of tailings.
3.3.3 Segregation Test
Upon the completion of the self-weight settling test, water above the sediment was
removed and the sediment was divided into six equal layers for water content
measurement. The water content data were converted to solids content (s) using the
following equation:
s = 1 / (1 + w) (3.4)
The normalized solids content deviation (Sd) was calculated using the solids
content of a given layer (Si) and the average solids content (Savg) of the sediment along
with a normalized height (hi / ht), where hi denoted the individual layer height and ht was
the total sediment height. Using a similar rationale as described earlier (in relation to
Eqns. 2.3 and 2.4), the following equation was used to quantify segregation:
Sd (%) = (Si – Savg) hi / ht (3.5)
To obtain an absolute value for each initial condition (si), segregation (S) was
defined in this study as the square root of the average of the squares of normalized solids
content deviation in each layer. This can be expressed by the following equation:
S (%) = [1/n {(Sd1)2 + (Sd2)
2 + (Sd3)2+ (Sd4)
2 + (Sd5)2+ (Sd6)
2}] 0.5 (3.6)
To account for the limited amount of materials in each layer the grain size
distribution tests were done by combining two consecutive layers using the previously
mentioned procedure. The fines contents (f) obtained from the test results were used to
31
investigate segregation behaviour. The GSD tests were conducted for three different
layers at the each of two initial solids contents (si = 15% and 20%) in this study upon
completion of the settling tests. The GSD test data (as reported by Khaled, 2012) for
higher initial solids content (≥ 25%) were also analyzed to calculate the amount fines
content (f) presents in the 4%, 5% and 6% mill tailings.
3.3.4 Large Strain Consolidation Test
The large strain consolidation test is generally used for materials showing at least 10%
volumetric deformation (Besson et al., 2010) and the test results are applicable to the
containment facilities of at least 30 meters of height (Schiffman et al., 1988). The test
apparatus must be capable of accommodating large strains (Gan et al., 2011) and should
allow the application of low loads which pertains to the early stages of tailings disposal
(Qiu and Sego, 2001). Therefore, there was a need to design and fabricate a consolidation
test apparatus to investigate the large strain consolidation behaviour of uranium tailings,
3.3.4.1 Fabrication of Apparatus
Figure 3.1 shows a schematic of the large strain consolidation test system that was
designed, fabricated, and used in the Radioactive Tailings Research Laboratory at the
University of Regina. The primary components of this apparatus were as follows:
consolidometer cell, top plate, hydraulic conductivity measurement system, and data
acquisition. All the materials used in components of the apparatus were selected based on
required strength, chemical/corrosion resistance, and durability criteria that were
identified during the conceptual design phase.
(a) Consolidometer Cell: The consolidometer cell (100 mm diameter and 200 mm high),
was fabricated from acrylic sheet (Plexiglas®) to allow visual inspection of solid-liquid
32
Figure 3.1: Schematic of the large strain consolidation test system
33
interface change and also to avoid corrosion problems during long-term testing (30 to 40
days). The cost effectiveness and ease of machining the Plexiglas® compared to stainless
steel was also an important reason to choose this material. The cell (200 mm high) was
made from a 1000 mm long Plexiglas® tube and was graduated using a measuring scale
with 1 mm marks. The cell was designed for a slurry sample with an initial size of 100
mm diameter and 100 mm high such that it accommodated the expected large vertical
strains. The additional height in the cell served as a guide cylinder for the loading piston
to travel through as a result of vertical deformation during testing. The cell was fixed
with a base plate (length 152.4 mm, width 152.4 mm, and thickness of 36 mm), that was
also made from the Plexiglas®. The base plate was indented with radial and
circumferential grooves (5 mm diameter) that reported to an outlet that allowed drainage
through the bottom. A porous plate (96 mm diameter and 7.35 mm thickness) along with
a geotextile (2.80 mm thickness) was placed at the cell bottom to preclude fines
migration. The valve at the base plate was closed off for during load application and
opened during hydraulic conductivity measurement. The porous plate was waxed in the
peripheral area to preclude the fines escape through the sides.
(b) Top Plate: The top plate consists of a loading piston with piston shaft, a bubble level
vial, a linear strain gauge, and a porous plate along with a geotextile. Different
alternatives were evaluated for the vertical loading arrangement during the design phase.
Because of the large expected deformations, a lever systems loading could lead to
eccentric or uneven loading. Therefore, a vertical loading arrangement was chosen that
included a loading piston with piston shaft and a bubble level vial. The exclusion of
eccentricity and uneven loading were confirmed by monitoring the level using bubble
34
vial attached to the loading shaft. Therefore, this arrangement ensured that regardless of
the strain level, the load will remain constant and vertical throughout the test. A linear
strain gauge with measuring range of 0.4 inch (10.16 mm) and 0.0001 inch (0.0025 mm)
graduation was used to measure the vertical displacement of the consolidating sample.
Once again, a porous plate along with a geotextile were placed on the top of the sample to
preclude fines migration during upward drainage. The combined weight of this
arrangement (loading piston, piston shaft, porous plate, and geotextile) ensured the
application of the low initial stress (1 kPa) on the sample (sample calculation of
consolidation loading is provided in the Appendix D9). The loading piston was also
equipped with a plastic container (50 mm diameter) at the bottom to provide a provision
of adjusting small loads. A number of small lead pellets (3.6 mm diameter and weight of
0.25 gm) were placed in the plastic container to achieve desired loading condition at the
early stages of loading.
(c) Hydraulic Conductivity Measurement System: A falling head test arrangement was
used for the measurement of hydraulic conductivity. The arrangement comprised of a 25
mL graduated burette with 0.2 mL graduations, a connectivity tube, the top and bottom
cell outlets, and an outflow beaker. The burette, fixed to a retort stand with a clamp, was
connected to the bottom outlet of the cell through a connectivity tube. To expel any
trapped air bubbles from the tube, a suction was applied on the connectivity tube to get
the water flowing before connecting to the outlet. The bottom outlet was opened to allow
upward drainage through porous stones and that established a falling head condition in
the graduated burette. The top outlet was opened during hydraulic conductivity
35
measurements to maintain a constant water level in the sample. The overflow of water
was collected in the outflow beaker.
(d) Data Acquisition: A linear strain gauge measured the vertical displacement of the top
plate due to load application and it was connected to the data acquisition system in the
computer. The data acquisition system enabled the data to be acquired and viewed within
a spreadsheet application during the test. The settlement data were also cross-referenced
by visual inspection of the soil-liquid interface changes during the test and also by taking
photographs using a digital camera at regular time interval (each 1 min up to 10 min and
every 10 min thereafter). A digital single-lens reflex (SLR) camera, Nikon D300S, was
used for this purpose. The exposure time, length of time the camera's shutter was open
when taking a photograph, was 1/60 sec, with a focal length of 34 mm. The output
images were in 2136 pixels in width and 3216 pixels in height with 300 dpi resolution.
(e) Calibration: The individual components of the consolidation test apparatus were
calibrated. Figure 3.2 gives the calibration of graduated burette, linear strain gauge, and
digital camera. The volumetric burette (25 mL graduated burette) was calibrated by
allowing flow of water from it to a 200 mL beaker and weighing the water in the beaker.
The actual volume of water was measured using the volume to weight conversion factor
for water (1 mL = 0.9982 gm at 20oC ± 2oC). Likewise, the strain gauge was calibrated
using the vane shear apparatus (described earlier in rheological test). The apparatus has
an upper shaft that can be lowered by 12.7 mm (vane height) by applying six revolution
though a drive wheel. The gauge was attached to the driver wheel and different
revolutions were applied to calibrate the gauge. Finally, the digital camera was calibrated
with the visual observations of solid-liquid interface.
36
Figure 3.2: Calibration of individual components of the consolidation test
90 92 94 96 98 100Visual Reading of Interface Height (mm)
90
92
94
96
98
100
Cam
era
Rea
din
g (m
m)
0 1 2 3 4Angular Displacement (revolutions)
0
2
4
6
8
10
Dia
l G
auge
Rea
ding
(m
m)
0 5 10 15 20 25Measured Volume (mL)
0
5
10
15
20
25
Bur
ette
Rea
din
g (m
L)
a) BuretteY = 1.038 X + 0.1797R2 = 0.999
b) Linear Strain GaugeY = 1.999 X + 1.569R2 = 0.999
c) CameraY = 0.956 X + 0.429R2 = 0.992
37
3.3.4.1 Consolidation Test
The uranium mill tailing samples at an initial solids content of 35% (±2%) was poured in
the 100 mm diameter graduated Plexiglas cylinder up to a height of 100 mm. The 35%
(±2%) initial solids content is associated with a non-segregating slurry and the height to
diameter ratio was 1.0 at the starting of test that minimizes the wall effects (Khaled and
Azam, 2014). The degree of saturation (DS = 100%) for investigated tailings were
confirmed (calculation provided in the Appendix D8) by using its relationship with the
specific gravity (Gs), void ratio (e), and water content as follows (Holtz et al., 2010):
DS× e = w×Gs (3.7)
The slurry was initially allowed to settle under self weight. Thereafter, the
sediment was incrementally loaded in the effective stress range of 1 kPa to 8 kPa, thereby
capturing the behaviour of freshly deposited tailings. As described earlier, a linear strain
gauge was used to monitor the vertical deformations and the data were collected using a
data acquisition system. The change of solid-liquid interface was also recorded at equal
time intervals by using a digital camera with macro lenses for a image magnification of
up to six times (Azam, 2011). The captured image files were processed and cross-
referenced with the with the strain data. The entire test data were plotted with respect to
time in the form of interface height, void ratio and solids content.
The hydraulic conductivity was determined using the falling head method after
each load increment by allowing upward drainage. The porous plates and geotextiles
above and below the sample ensured an evenly distributed applied load and precluded
fines migration during hydraulic conductivity measurement (Suthaker and Scott, 1996).
The hydraulic gradient was kept lower than the critical gradient (0.3 to 0.4) to prevent
38
sample boiling and to prevent any volume change during hydraulic conductivity
measurement. A constant water level was maintained in the cell by continuously
collecting the decant water in an outflow beaker. Denoting the burette cross-sectional
area by a (m2), sample length by L (m), sample cross-sectional area by A (m2), the initial
hydraulic head by h1 (m), the final head after time t (s) by h2 (m), the hydraulic
conductivity (k, m/s) was measured according to the following equation (Holtz et al.,
2010):
k = (aL/At) ln (h1/h2) (3.8)
3.4 Numerical Modeling
The large strain consolidation test results were converted to constitutive relationships
describing the consolidation process. The extended power law function was selected
because it captures slurry behaviour under initial conditions, that is, at low effective
stresses. Denoting the effective stress by σ' (kPa), void ratio by e, the fit parameters by A
(kPa-1), B (dimensionless) and Z (kPa), volume compressibility was expressed using the
following equation (Liu and Znidarcic, 1991):
e = A(σ' + Z)B (3.9)
Denoting the two empirical parameters by C (m/s) and D (dimensionless), the
power law function (Somogyi, 1980) was used for hydraulic conductivity relationship as
follows:
39
Figure 3.3: Numerical modeling scheme
Volume Compressibility
Hydraulic Conductivity
Index Properties
Material Properties
Initial Condition
Stage Filling Data Processing
Boundery Conditions
Modeling Scheme
Modeling Program
Settlement-TimeCurve
Effective Stress Profile
40
k = CeD (3.10)
Figure 3.2 describes the consolidation modeling process. The one-dimensional
finite difference modeling program, CONDES, was used utilizing the large strain
consolidation theory (Gibson et al., 1967). The program required five input parameters
related to tailings properties as mentioned in equation (3.8) and (3.9), and the initial
conditions of the materials. Denoting the specific gravity of tailings by Gs, Lagrangian
coordinate system by a (positive upward), unit weight of pore fluid by γw (kN/m3), the
program solves the governing equation, a non-linear second order partial differential
equation that formulated for one dimensional compression as follows:
(1 − ��)�
���
�
����
��
��−
�
���
�(����)
��(���)
���
��
��
��� =
�
����
��
�� (3.11)
A detail formulation of the governing equation were given by Yao et al. (2002).
From the field application of consolidation processes, the Dirichlet boundary condition
(stress type) can be imposed for the governing equation of one-dimensional compression.
The Dirichilet type boundary condition is also referred to as the stress type or first
boundary condition (Cheng and Cheng, 2005) because it is a stress-related boundary
condition. The stresses on the boundary will be converted into void ratios (e) using the
volume compressibility relationship, equation (3.10). The program uses a mixed form of
central and forward difference methods with an implicit time integration scheme for the
numerical solution of the governing equation (Yao and Znidarcic, 1997). The implicit
scheme solves the governing equation involving both the current state of the system and
the subsequent state of the system. This scheme is numerically very stable and takes
much less computational time for multiple time steps. The program employs an uniform
mesh for the spatial discretization and automatically generates a non-uniform mesh for
41
certain cases when a finer mesh is required. The CONDES is capable of simulating
various boundary conditions (pervious at the bottom) and staged filling sequences
(Gjerapic et al., 2009), which are the major reasons for choosing this program for
numerical analyses of consolidation behaviour in the DTMF.
The historical multi-stage filling data from 1996 to 2008 were provided to the
program in terms of depositional height of tailings in the DTMF. A series of tailings
investigation programs were conducted in the DTMF by Cameco in 1999, 2004/05, and
2008/09. Based on these investigation program, the incremental tailings heights were
determined from volume-area measurements using discharge rates (m3/day), operating
durations (days) and the variable width (m) at different height (m) of the facility. These
heights were corrected to account for the volume of sloughed sand in 2001 and 2005. The
program outputs were obtained in the form a continuous settlement-time curve as well as
the effective stress profile at each selected time.
The assumptions of the modeling program were as follows (Yao and Znidarcic,
1997): (i) the soil is fully saturated throughout the consolidation process; (ii) the soil is
homogeneous; (iii) water flow is vertical that resulted from vertical deformation during
one-dimensional compression; (iv) creep is negligible; (v) water and solid are
incompressible and their properties are constant; and (vi) Darcy’s law and with the
conservation of mass are applicable.
The limitations of modeling program were as follows: The program was unable to
incorporate the spatial variability of tailings in the storage facility, that is, different soil
properties in different layer. Likewise, the program was unable to incorporate a pre-
42
existing soil layer of prior to filling and, as such, a zero initial height was provided at the
beginning of stage filling process. Furthermore, the program considered a self-adjusting
boundary for bottom drainage. However, it was incapable to accommodate a sidewall
drainage system like the drainage system present in the DTMF. Finally, the convergence
problem could occur in the program if the number of iterations is greater than 600 (that
is, the analysis converges either at a very slow rate or does not converge at all). However,
it did not occur in this study. This numerical problem was overcome by providing
appropriate material characteristics and boundary conditions.
43
CHAPTER 4
RESULTS AND DISCUSSION
4.1 General
This chapter outlines the laboratory test data, analysis of laboratory tests results, and
numerical modeling results. First, the tests data for yield stress, initial hydraulic
conductivity, settling potential, and segregation are presented. Next, laboratory test data
for dewatering behaviour are presented in terms of compressibility and hydraulic
conductivity during the tests. The volume compressibility and hydraulic conductivity
relationships are presented using the test results. Finally, the analysis of historical
consolidation behaviour in the DTMF is presented and matched with the results of
numerical modeling.
4.2 Depositional Behaviour
4.2.1 Rheological Properties
Figure 4.1 plots the yield stress versus solid content for 4%, 5% mill tailings sample. All
samples followed a similar trend, that is, a negligible strength up to s = 60% followed by
a rapid increase thereafter. This is attributed to similar particle shape originated identical
tailings production processes. Based on grain size distribution analysis, all sample were
characterized as sandy silts and classified as SM according to the Unified Soil
Classification System (USCS). The 4% mill tailings were found as well graded with 29%
material finer than 0.075 mm whereas the 5% and 6% mill tailings were observed as gap-
graded with 50% fines. The effect of different grain size distributions was insignificant
44
Figure 4.1: Yield stress versus solids content for the investigated mill tailings
20 30 40 50 60 70 80Solids Content (%)
0
2
4
6
8
10
Yie
ld s
tres
s (k
Pa)
4% Mill Tailings
5% Mill Tailings
6% Mill Tailings
Oil Sand Tailings(Mihiretu, 2009)
Nickel Tailings(Boger, 2013)
Clay Tailings(Boger, 2013)
This Study
45
and the inflexion point occurred at τy = 0.4 kPa. This is similar to other types of tailings
(from clay, nickel, and oil sand processing) where the inflexion point occurs at a yield
stress between 0.2-0.4 kPa (Boger, 2013; Mihiretu, 2009). The variation in inflexion
point for solids content ranging from 20% to 55%, depends on grain size distribution,
clay type and water chemistry (Sobkowicz and Morgenstern, 2009). The relatively higher
solids content at the inflexion point for Uranium tailings is attributed to the nature of the
investigated material. The rheological properties of mine tailings varies within and
among industries, dependent on particle size distribution and colloid-liquid interaction
(Boger, 2013; Mihiretu, 2009). On the other hand, increasing the fraction of silt and sand
size particles shifts the curve towards the right, that is, the yield stress occurs at higher
solids content due to the electrochemically inactive nature of the soil particles. In general,
clayey materials developed yield stress at lower solids content and vice versa. This is
because the presence of higher amounts of clay size along with their electrochemically
active nature increases solid-liquid interactions in slurries at low solids content.
4.2.2 Initial Hydraulic Conductivity
Figure 4.2 plots ki (rate of dewatering) with respect to the following: initial void ratio,
initial solids content (si), final void ratio, and final solids content (sf). The initial test
conditions were used to highlight their effect on slurry dewatering, whereas the final test
conditions were used to identify the range of dewatering achieved during the self weight
settling tests. Separate correlations (with r2 > 0.8) were found to describe the behaviour of
uranium tailings: one for 4% mill tailings and one for 5% and 6% mill tailings together.
The ki decreased by two orders of magnitude (10-2 m/s to 10-4 m/s) with a decrease in ei
from 16 to 4 (15% < si < 40%) and a decrease in ef from 8 to 4 (30% < si < 45%) such
46
Figure 4.2 : Initial hydraulic conductivity with respect to the following: (a) initial void ratio (b) initial solids content (c) final void ratio (d) final solids content
0 4 8 12 16Initial Void Ratio
10-5
10-4
10-3
10-2
10-1
Init
ial
Hyd
rual
ic C
ond
ucti
vity
(m
/s)
ln ki = 0.44 ei - 9.9
r2 = 0.88
ln ki = 0.58 ei - 12.0
r2 = 0.90
0 10 20 30 40 50Initial Solids Content (%)
10-5
10-4
10-3
10-2
10-1
Init
ial
Hyd
rual
ic C
ondu
ctiv
ity
(m/s
)
0 4 8 12 16Final Void Ratio
10-5
10-4
10-3
10-2
10-1
Init
ial
Hyd
rual
ic C
ondu
ctiv
ity
(m/s
)
0 10 20 30 40 50Final Solids Content (%)
10-5
10-4
10-3
10-2
10-1
Init
ial
Hyd
rual
ic C
ond
ucti
vity
(m
/s)
(a) (b)
(d)(c)
ln ki = -0.26 si + 0.1
r2 = 0.89
ln ki = -0.21 si - 0.4
r2 = 0.97
ln ki = 1.82 ef - 14.6
r2 = 0.95
ln ki = 1.73 ef - 16.9
r2 = 0.87
ln ki = -0.41 sf + 6.80
r2 = 0.82
ln ki = -0.36 sf + 7.5
r2 = 0.96
4% Mill Tailings 5% Mill Tailings 6% Mill Tailings Best Fit
47
Figure 4.3: Settling potential with respect to the following: (a) initial void ratio (b) initial solids content (c) final void ratio (d) final solids content
0 4 8 12 16Initial Void Ratio
0
20
40
60
Set
tlin
g P
ote
nti
al (
%)
SP = 3.64 ei + 3.4r2 = 0.95
SP = 3.75 ei - 8.14
r2 = 0.98
0 10 20 30 40 50Initial Solids Content (%)
0
20
40
60
Set
tlin
g P
ote
ntia
l (%
)
SP = -1.65 si + 79.7
r2 = 0.98
SP = 3.75 si - 8.14r2 = 0.98
(a) (b)
0 4 8 12 16Final Void Ratio
0
20
40
60
Set
tlin
g P
ote
ntia
l (%
)
SP = 14.30 ef - 32.3
r2 = 0.95
SP = 11.27 ef - 40.0r2 = 0.97
0 10 20 30 40 50Final Solids Content (%)
0
20
40
60
Set
tlin
g P
ote
ntia
l (%
) SP = -2.80 sf + 140.0
r2 = 0.94
SP = -2.70 sf + 114.4
r2 = 0.91
(c) (d)
4% Mill Tailings 5% Mill Tailings 6% Mill Tailings Best Fit
48
that about one order of magnitude lower values were observed for 4% mill tailings when
compared with 5% and 6% tailings. Overall, the decrease in hydraulic conductivity
during hindered sedimentation (settling of a 3-D network of soil particles with no
effective stress (Pane and Schiffman, 1997)) is attributed to a decrease in total pore space,
an increase in dead end pores, and an increase in tortuousity (Suthaker and Scott, 1996).
4.2.3 Settling Potential
Figure 4.3 is a series of plots of SP (amount of dewatering) with respect to the above
mentioned parameters. Separate linear correlations (r2 > 0.95) were found to best describe
the behaviour of uranium tailings: one for 4% mill tailings and one for 5% and 6% mill
tailings together. For the above mentioned ranges of void ratios and solids contents given
in Figure 4.3, SP decreased ten times (50% to 5%) for 4% mill tailings and four times
(60% to 15%) for 5% and 6% mill tailings. The above reasons governing the rate of fluid
flowing through the tailings also affect the amount of fluid migrated through the tailings.
This means that the rate and amount of dewatering are directly proportional for the
investigated uranium tailings. This is similar to the behaviour of tailings from residual
laterite ores, as reported by Azam (2012).
4.2.4 Effective Stress
Figure 4.4 plots the final effective stress versus the above mentioned parameters. A single
fit was found to best describe σ' variation with respect to the initial conditions whereas
separate correlations (one for 4% and another for 5 and 6% combined) were found for
final conditions. As expected, the compressibility relationships (effective stress versus
void ratio) were found to be non-linear whereas the slurry concentration relationships
49
Figure 4.4: Final effective stress with respect to the following: (a) initial void ratio (b) initial solids content (c) final void ratio (d) final solids content
0 10 20 30 40 50Initial Solids Content (%)
100
200
300
Fin
al E
ffec
tive
Str
ess
(Pa)
0 10 20 30 40 50Final Solids Content (%)
100
200
300
Fin
al E
ffec
tive
Str
ess
(Pa)
r2 = 0.99
'f = 12.18 sf - 244.6
'f = 12.82 sf - 325.7r2 = 0.97
'f = 7.42 si - 43.2
r2 = 0.98
0 4 8 12 16Final Void Ratio
0
100
200
300
Fin
al E
ffec
tiv
e S
tres
s (P
a)
ln 'f = -1.94 ln ef + 7.9r2 = 0.97
ln 'f = -1.74 ln ef + 8.0
r2 = 0.97
0 4 8 12 16Initial Void Ratio
0
100
200
300
Fin
al E
ffec
tiv
e S
tres
s (P
a)
ln 'f = -0.92 ln ei + 6.9
r2 = 0.94
(a) (b)
(c) (d)
4% Mill Tailings 5% Mill Tailings 6% Mill Tailings Best Fit
50
(effective stress versus solids content) were found to be linear. The r2 values were close to
0.9 for all of the correlations. The final effective stress increased from 80 Pa to 260 Pa
with a decrease in ei from 16 to 4 (solids content increased from 15% to 40%) and a
decrease of ef from 8 to 4 (solids content increased from 30% to 45%). The presence of
measurable effective stress change over a wide range of void ratio confirms the large
strain consolidation behaviour of the slurry where the effective stress is transmitted
through inter-granular contact (Terzaghi et al., 1996).
4.2.5 Segregation Behaviour
Figure 4.5 plots solids content versus normalized solids content deviation from the
average. The average solids content after settling was found to be 35% (20% < s < 42%)
for 4% mill tailings, 40% (15% < s < 60%) for 5% mill tailings and 39% (18% < s <
54%) for 6% mill tailings with a corresponding normalized deviation of ±3%, ±8%, ±6%,
respectively. The above narrow ranges for 4% tailings mean low segregation and the
reverse is true for the other two mill tailings. This is because of the well graded grain size
distribution of the 4% mill tailings compared to the gap graded nature of 5% and 6% mill
tailings. Mihiretu (2009) reported significant segregation of sand grains from fines in
gap-graded oil sand tailings. From a practical standpoint (operational control and facility
planning), the ±2% solids content deviation is considered as acceptable based on
historical DTMF performance (Azam et al., 2014). This means that the 4% mill tailings
can be deposited at an si of as low as 25%, while the 5% and 6% mill tailings would
require an si higher than 30%. Furthermore, the low solids content along with the
negative values of normalized solids content deviation characterized the top layers of the
slurry and the opposite parameters characterized the bottom layers of the slurry. The
51
Figure 4.5: Solids content versus normalized solids content deviation
4% Mill Tailingssi = 15.1%
si = 20.2%
si = 26.0%
si = 30.3%
si = 35.9%
si = 40.0%
10
20
30
40
50
60
70
Sol
ids
Con
ten
t (%
)
5% Mill Tailingssi = 15.2%
si = 20.4%
si = 25.0%
si = 30.1%
si = 36.1%
si = 41.8%
10
20
30
40
50
60
70
So
lids
Con
tent
(%
)
10/70
6% Mill Tailingssi = 15.2%
si = 20.0%
si = 25.5%
si = 30.0%
si = 35.0%
si = 40.1%
-10 -8 -6 -4 -2 0 2 4 6 8 10
Normalized Solids Content Deviation (%)
10
20
30
40
50
60
70
So
lid
s C
onte
nt (
%)
10/70
Best Fit
Best Fit
Best Fit
52
leaner (low initial solids content) mixtures exhibited a wider range of solids content
deviation when compared with thicker (high initial solids content) mixtures. The
increased segregation in the leaner mixtures is attributed to the absence of a three
dimensional particle network during the settling process (Shimoska et al., 2013). This
was also observed during the laboratory experimentation in the form of preferential
particle settling. Regardless of the ore grade, segregation was found to decease as si
increased, that is, most data for high si values tended to zero normalized solids content
deviation.
Figure 4.6 shows fines content versus normalized solids content deviation. The
average fines content was found to be 42% (35% < f < 42%) for 4% mill tailings, 56%
(23% < f < 95%) for 5% mill tailings and 56% (26% < f < 95%) for 6% mill tailings with
a corresponding normalized deviation of ±3%, ±8%, ±6%, respectively. The high fines
content along with negative values of normalized solids content deviation are found in
the top layers of slurry (because of preferential settling of the coarse grains) while low
fines content and positive deviations are found in the bottom layers. Again, the narrow
ranges for 4% indicate low segregation over a wider range of si, while the 5% and 6%
mill tailings show increasing segregation as si decreases. The lower segregation range for
4% mill tailings is attributed to the well graded nature despite its low fines content (29%)
whereas the higher segregation of the other two slurries (5% and 6%) were observed due
to the gap graded nature despite their higher fines content (49%).
Figure 4.7 correlates segregation with the initial solids content. Separate linear
correlations were found for 4% mill tailings (r2 = 0.97) and for 5% and 6% mill tailings
together (r2 = 0.9). As expected, segregation was found to decrease with increasing initial
53
Figure 4.6: Fines content versus normalized solids content deviation
-10 -8 -6 -4 -2 0 2 4 6 8 10
Normalized Solids Content Deviation (%)
20
40
60
80
100
Fin
es C
onte
nt
(%) 6% Mill Tailings
si = 15.2%
si = 20.0%
si = 25.5%
si = 30.0%
si = 35.0%
si = 40.1%
20
40
60
80
100
Fin
es C
ont
ent
(%) 4% Mill Tailings
si = 15.1%
si = 20.2%
si = 26.0%
si = 30.30%
si = 35.90%
si = 40.0%
20
40
60
80
100
Fin
es C
onte
nt (
%) 5% Mill Tailings
si = 15.2%
si = 20.4%
si = 25.0%
si = 30.1%
si = 36.1%
si = 41.8%
20/100
20/100
Best Fit
Best Fit
Best Fit
54
Figure 4.7: Initial solids content versus segregation
0 1 2 3 4Segregation (%)
10
20
30
40
50
Init
ial
Sol
ids
Con
tent
(%
) 4% Mill Tailings
5% Mill Tailings
6% Mill Tailings
si = -7.53 S - 40.3
r 2 = 0.90
si = -21.42 S + 41.0
r2 = 0.97
Best fit
55
solids content. The two curves merged at 40% initial solids content where segregation
was negligible. The steeper slope for 4% mill tailings (narrower segregation range)
means that segregation of this material is less susceptible to changes in initial solids
content, whereas the flatter slope for the 5% and 6% mill tailings (wider range of
segregation) indicates that segregation in these materials is more sensitive to the initial
solids content. From an operational perspective, this figure indicates that high grade mill
tailings have less room for error during slurry preparation, which is, achieving the desired
initial solids content.
4.3 Dewatering behaviour
4.3.1 Large Strain Consolidation
Figure 4.8 plots the large strain consolidation test results in the form of interface height,
void ratio and solids content versus elapsed time. In 4% mill tailings, the interface height
changed from 10 cm to 8.4 cm due to self-weight consolidation and the height was
further reduced to 5.8 cm due to applied loads (up to σ' of 8 kPa) during large strain
consolidation tests. The total strain was calculated using the ratio of height change to the
initial height and found to be 42% for 4% mill tailings. The interface height changed to
7.6 cm and 8.0 cm during self-weight consolidation whereas the final height was found to
be 6.2 cm and 6.9 cm for 5% and 6% mill tailings. The total strains were calculated as
38% and 31% respectively. A similar height reduction under comparable effective stress
was observed by Pedroni and Aubertin (2013) for fine silty sludge. Similar interface
change behaviour was observed during consolidation test of treated oil sand tailings
(Moore et al, 2013) and laterite slurries (Azam et al., 2005) but a higher stain were
observed in laterite slurry due to having a lower initial solids content.
56
Figure 4.8: Settling curves: (i) interface height (ii) void ratio and (iii) solids content versus elapsed time during large strain consolidation test for (a) 4% (b) 5% and (c) 6% mill tailings.
5
6
7
8
9
10
11In
terf
ace
heig
ht (
cm)
2
3
4
5
6
Voi
d R
atio
0.1 1 10 100 1000 10000
Elapsed Time (min)
30
35
40
45
50
55
Sol
ids
Con
ten
t (%
)
0.1 1 10 100 1000 10000
Elapsed Time (min)
0.1 1 10 100 1000 10000
Elapsed Time (min)
5/6
2/55
104
/0.1
Self-Weight 1 kPa 2 kPa 4 kPa 8 kPa
(a) 4% Mill Tailings (b) 5% Mill Tailings (c) 6% Mill Tailings
(i) (i)(i)
(ii) (ii)(ii)
(iii) (iii)(iii)
104
/0.1104
57
The void ratio versus time curves can be characterized by two conditions: self-
weight and large strain consolidation test curves. The slurry settled from a void ratio of
5.8 to 4.8 under self-weight and void ratio further reduced to 3.3 at σ' = 8 kPa for 4% mill
tailings. The corresponding void ratio change was observed from 4.5 to 3.4 and 4.6 to 3.6
during self-weight consolidation whereas it further reduced to a final void ratio of 2.8 and
3.1 for 5% and 6% mill tailings. Tailings behaviour is often influenced by self-weight
settling for low initial solids contents. But it is not the case for higher solids content,
which attain sufficient consistency for preventing relative movement between different
size particles Geier et al. (2011). The solids content increased from 31.9% to 36.4% due
to self-weight and to 45.5% final solids content for 4% mill tailings. The corresponding
solids contents were found to be 37.8% to 44.4% and 37.5% to 43% due to self-weight
and to 49.3% and 46.8% final solids content for 5% and 6% mill tailings after the tests.
Figure 4.9 gives the hydraulic conductivity data measured after each load
increment in the large strain consolidation test for (a) 4% mill tailings (b) 5% mill tailings
and (c) 6% mill tailings on a semi logarithmic scale. Under each load increment, the data
showed an initial scatter before attaining a steady state value. This is attributed to
equilibration of inertia with the hydraulic gradient required to move water through the
soil and redistribution of pore sizes during this process. The range of scatter decreased
with higher loads because of a reduced capacity of the tailings to undergo further pore
sizes changes. The k values for the all investigated tailings were found to be ranging from
10-7 to 10-8 m/s. The 4% mill tailings shows a higher range of k values when compared
with 5% and 6% mill tailings. The steady state k values were obtained after about 30 min
for all mill tailings and were used in subsequent analyses.
58
Figure 4.9: Hydraulic conductivity versus time data in large strain settling test
0 20 40 60Elapsed Time (min)
(c) 6% Mill TailingsSelf Weight
1 kPa
2 kPa
4 kPa
8 kPa
0 20 40 60Elapsed Time (min)
(b) 5% Mill TailingsSelf Weight
1 kPa
2 kPa
4 kPa
8 kPa
0 20 40 60Elapsed Time (min)
10-8
10-7
10-6
Hyd
raul
ic C
ondu
ctiv
ity
(m/s
)
(a) 4% Mill TailingsSelf Weight
1 kPa
2 kPa
4 kPa
8 kPa
60/0 60/0
k = 6.1×10-7 m/s
k = 1.3×10-7 m/s
k = 1.5×10-7 m/s
k = 4.3×10-8 m/s
k = 4.7×10-7 m/s
k = 8.9×10-8 m/s
k = 1.5×10-7 m/s
k = 1.9×10-7 m/s
k = 2.7×10-7 m/s
k = 5.0×10-8 m/s
k = 5.7×10-8 m/s
k = 7.9×10-8 m/sk = 1.1×10-7 m/s
k = 1.9×10-7 m/s
k = 2.7×10-7 m/s
59
4.3.2 Volume Compressibility and Hydraulic Conductivity Relationships
Figure 4.10 plots the volume compressibility and hydraulic conductivity relationships for
the investigated mill tailings. The compressibility curve was fitted to the extended power
law function. The lowest measurable effective stress was approximately 0.3 kPa for all
tailings at void ratio e = 4.8, 3.4 and 3.6 for 4%, 5% and 6% mill tailings respectively.
The void ratio at the effective stress of 1 kPa was found to be 3.8, 3.1 and 3.4
respectively. A similar range of value of void ratio (e = 2.6 to 4.6) was also reported by
Mittal and Landine (2013) for the various uranium tailings from Northern Saskatchewan.
With comparatively higher change in void ratio (from e = 4.8 to 3.3), the 4% mill tailings
was observed to have higher compressibility behaviour. A relative small change in void
ratio (Δe = 0.5 ~ 0.6) was observed for both 5% and 6% mill tailings. This is attributed to
the higher amount of silt size materials presence, gap graded nature of particle
distribution and the initial conditions for 5% and 6% mill tailings.
The curve of hydraulic conductivity relationship was fitted with the conventional
power law function. The hydraulic conductivity at the end of self-weight consolidation
was measured to be 6.1×10-7 m/s at e = 4.8 for 4% mill tailings. During load-induced
consolidation (e = 4.8 to e = 3.3), hydraulic conductivity varied from 2.6×10-7 m/s to
1.7×10-7 m/s. At the end of self-weight consolidation, The hydraulic conductivity was
measured to be 1.5×10-7 m/s and 4.6×10-7 m/s at e = 3.4 and 3.6 for 5% and 6% mill
tailings respectively. During load-induced consolidation (e = 3.4 to e = 2.8 and e = 3.6 to
3.1), hydraulic conductivity decreased from 7.9×10-8 m/s to 4.4×10-8 m/s and 2.7×10-8 to
8.9×10-8. The lower k values of 5% and 6% mill tailings are attributed to higher water
retention capability that, in turn, is derived from the presence of higher amount of silt size
60
Figure 4.10: Volume compressibility and hydraulic conductivity relationship.
2.5 3 3.5 4 4.5 5
Void Ratio
10-8
10-7
10-6
Hyd
rauli
c C
ondu
ctiv
ity
(m/s
)
4% : k = 1.16 x 10-9 e4.0
5% : k = 5.92 x 10-11 e6.4
6% : k = 1.74 x 10-13 e-11.5
0.1
1
10
Eff
ecti
ve S
tres
s (k
Pa)
4% : e = 3.9 ( '+0.03)-0.10
5% : e = 3.2 ( '+0.01)-0.06
6% : e = 3.5 ( '+0.01) -0.05
10-6/0.1
61
materials in the slurry. Mittal and Landine (2013) reported a similar range of value of k
(10-7 to 10-8 m/s) for the various uranium tailings from Northern Saskatchewan. The
observed compressibility and hydraulic conductivity relationships provided the essential
constitutive relationships for predicting and managing long-term performance of uranium
tailings in containment facility.
4.4 Consolidation Behaviour in the DTMF
4.4.1 Tailings Deposition
Figure 4.11 shows the schematics of the DTMF. All of the coordinates are based on the
Key Lake mine grid system, whereas the elevations are referenced to the geodetic datum.
The pit boundary (crest line) is based on the aerial photographic survey data of 2005
(Cameco 2005), whereas the actual tailings surface in 2005 and the average tailings
surface in 2008 were derived from bathymetric surface surveys (Cameco 2009). From
1996 to 1999, tailings were deposited in the East Cell while ore was still being mined
from the west part of the pit. A series of field investigation programs were conducted
during 1999, 2004/05 and 2008. Borehole locations for these programs are shown on
figures. The annual consolidated tailings elevations (1996 through 2008), given in
sections A-A' and B-B', are based on monthly topographical surveys (1996-1999) and
annual bathymetric surface surveys (1999-2008). The entire DTMF geometry is not given
in section A-A' because of negligible tailings amount in the West Cell. The average
consolidated tailings surface in the East Cell was 450 masl, as recorded in 2008. The
facility was initially operated in sub-aerial deposition mode and was then switched to
sub-aqueous deposition in December 1998 to prevent ice formation (Landine and
62
Figure 4.11: Schematic of DTMF: (a) Plan view; (b) Section A-A' of consolidated tailings elevations; and (c) Section B-B' of consolidated tailings elevations
63
Figure 4.12: Historical tailings elevation in the DTMF from 1996 through 2008
May-95 May-00 May-05 May-10
Time
350
375
400
425
450
475
Tai
ling
s E
lev
atio
n (m
asl) Field Data Depositional Stages
Sand Sloughing
Subaerial Discharge
Subaqueous Discharge
64
Moldovan, 2010). Slope instability developed in October 2001 when the water level rose
above the lower-most level of the outwash sand in the West Cell. Sloughing continued in
a series of events up to May 2005, when further water level rise was halted. With a
maximum thickness of up to 40 m (from 410 masl to 450 masl), the sloughed sands are
shown as a wedge in section A-A' and as a 10 m layer in section B-B'.
Figure 4.12 gives the consolidated tailings elevation in the DTMF from 1996
through 2008. The average cumulative surface height shows four distinct stages: (i) rapid
increase of 13 m/year in the first three years due to a smaller base area; (ii) steady height
increase of 2.5 m/year over the next four years due to the gradual increase in surface area;
(iii) relatively large height increase of about 7 m/year in the next three years due to sand
sloughing displacing the tailings; and (iv) a steady height increase of 3 m/year over the
next three years due production increase. The average consolidated tailings elevation in
the containment facility increased from 376 masl to 451 masl during 1996 to 2008.
4.4.2 Numerical Modeling Results
Figure 4.10 provided the required input for numerical modeling of consolidation
behaviour that is, the volume compressibility and hydraulic conductivity parameters (A =
3.9 kPa-1, B = -0.10, C = 1.2×10-9 m/s, D = 4.0 and Z = 0.03 kPa) for current (4%) mill
tailings. The history matching of settlement-time curve in the DTMF from 1996 to 2008
for investigated mill tailings was presented in Figure 4.13. The consolidated heights
closely matched the model predictions.
Figure 4.14 presents observed and modelled effective stress profiles in the DTMF.
Generally, the model results matched quite well with the average values reported by
Azam et al. (2014) as well as with measured values (Cameco, 2005). The predictions of
65
Figure 4.13: History matching of tailings elevation in the DTMF from 1996 through 2008
May-95 May-00 May-05 May-10
Time
350
375
400
425
450
475
Tai
lin
gs E
leva
tion
(m
asl) Field Data Model Prediction
66
Figure 4.14: Effective stress profiles in the DTMF: (a) 1999 borehole investigations; (b) 2004/05 borehole investigations; and (c) 2008 borehole investigations.
350
375
400
425
450
475
Tai
ling
s E
leva
tion
(m
asl)
350
375
400
425
450
475
Tai
ling
s E
leva
tion
(m
asl)
0 100 200 300 400 500 600 700
Effective Stress (kPa)
350
375
400
425
450
475
Tai
ling
s E
leva
tion
(m
asl)
350/475
350/475
ModeledE8E2
E6E2 Piezocone E6 Piezocone
ModeledE12E3
E9
ModeledE8E2
E6
(a)
(b)
(c)
67
1999 exhibited the best match when compared with the average effective stress (albeit the
latter were linear) because of the small size of the DTMF ensuing similar depositional
history in all three borehole locations (E3, E9, and E12). The 2004/05 and the 2008
predictions clearly exhibited the nonlinear behaviour of the deposited tailings. The
variations of the modeling results (pertaining to the entire DTMF) from the average
effective stresses are attributed to the dissimilar depositional histories in the various
areas. The effect of sand sloughing is visible in boreholes E2 in the form of two different
slopes whereas the higher tailings deposition towards the east area after sand sloughing is
evident at location E8. The intermediate borehole location E6 was closest to the overall
conditions in the DTMF up to about 400 masl. At the DTMF bottom, the model was
corrected for the volume of sand sloughed thereby predicting higher effective stresses.
The measured effective stress (piezocone values in 2004/05) correlated quite well with
the modeling results thereby validating the predictions. This is attributed to the silty sand
nature of the investigated tailings that showed a significant amount of dewatering takes
place at low effective stresses (42% at σ' = 8 kPa), as depicted in Figure 4.8. Overall, the
model results indicate that the effective stress increased from 0 kPa at the surface to the
following values at the DTMF bottom: 200 kPa in 1999, 530 kPa in 2005, and 680 kPa in
2008 along with a vertical hydraulic conductivity in the order of 10-8 m/s.
68
CHAPTER 5
CONCLUSIONS AND RECOMMENDATIONS
5.1 Conclusions
Knowledge of depositional and dewatering behaviour of tailings is fundamental to
efficient tailings management. A detailed laboratory investigation and geotechnical
analysis were conducted to understand these behaviours of uranium mill tailings from
Key Lake, Saskatchewan, Canada. The main conclusions of this research are summarized
as follows:
All of the samples exhibited the same trend for yield strength development. A
negligible strength was found to have at 60% solids content followed by a rapid
increase thereafter. The inflexion point occurred at a yield stress of 0.4 kPa.
The 4% mill tailings exhibited a lower rate and total amount of settlement than 5%
and 6% mill tailings. The ki decreased by two orders of magnitude (10-2 m/s to 10-4
m/s) with a decrease in ei from 16 to 4 (15% < si < 40%) and a decrease in ef from 8 to
4 (30% < si < 45%) such that 4% mill tailings showed one order of magnitude lower
values than the 5% and 6% mill tailings. The corresponding SP decreased ten times
(50% to 5%) with increasing si for 4% mill tailings and four times (60% to 15%) for
5% and 6% mill tailings. The effective stress increased from 80 Pa to 260 Pa in the
self-weight settling tests.
The 4% tailings were less segregating when compared with 5% and 6% tailings. The
average solids content after settling was 35% (20% < s < 42%) for 4% mill tailings,
40% (15% < s < 60%) for 5% mill tailings and 39% (18% < s < 54%) for 6% mill
69
tailings with a corresponding normalized solids content deviation of ±3%, ±8%, ±6%,
respectively. Considering that ±2% solids content deviation is acceptable, the 4% mill
tailings can be deposited at an si of as low as 25%, while the 5% and 6% mill tailings
would require an si higher than 30%. Furthermore, the high grade mill tailings have
less room for error during slurry preparation.
The large strain consolidation tests were conducted by using a customized and
fabricated consolidation test system. During the consolidation tests (σ' = 0.3 kPa to 8
kPa), the tailings settled from a void ratio of ei = 5.8 to ef = 3.3 for 4% mill tailings
and the initial void ratio reduced from 4.5 to 2.8 and 4.6 to 3.1 for 5% and 6% mill
tailings. With an si of 31.9%, 4% mill tailings achieved an sf of 45.5% after the
consolidation tests. The solids content increased from 37.8% to 49.3% and 37.5% to
46.8 for 5% and 6% mill tailings. The k values showed an initial scatter before
attaining a steady value under each load increment for all investigated mill tailings.
The test results provided the volume compressibility and hydraulic conductivity
relationships for current (4%) and future (5% and 6%) mill tailings. The lowest
measurable effective stress was approximately 0.3 kPa for all mill tailings. The 4%
mill tailings was observed to have higher change in void ratio (Δe = 1.5) compared to
small change in void ratio (Δe = 0.5~0.6) in both 5% and 6% mill tailings. The k
varied from 6.0×10-7 m/s to 1.0×10-7 m/s for 4% mill tailings, whereas for 5% and 6%
mill k varied from 4.7×10-7 to 4.4×10-8 m/s.
The large strain consolidation behaviour in the DTMF was investigated by analyzing
survey data from 1996 to 2008, laboratory testing of the current (4%) mill tailings,
and history matching of the deposited tailings using numerical modeling.
70
The average consolidated tailings height in the DTMF has four distinct stages from
1996 to 2008: (i) rapid increase of 13 m/year in the first three years, (ii) steady height
increase of 2.5 m/year over the next four years, (iii) relatively large height increase of
about 7 m/year in the next three years, and (iv) a steady height increase of 3 m/year
over the next three years.
The numerical modeling results closely approximated the consolidated tailings
elevations and effective stresses in the DTMF over the period of 1996 to 2008. The
measured effective stresses values correlated quite well with the modeling results
thereby validating the predictions. Overall, the results indicate that the effective stress
increased from 0 kPa at the surface to the following values at the DTMF bottom: 200
kPa in 1999, 530 kPa in 2005, and 680 kPa in 2008.
5.2 Recommendations
The future recommendations are as follows:
Rheological properties of uranium tailings should be further investigated by
conducting laboratory tests for the determination of viscosity and yield stress at
different shear rates in order to assess the optimum depositional conditions.
Shear induced segregation behaviour should be examined for uranium tailings
depositional scheme with a single tremie to achieve a non-segregation condition.
The developed volume compressibility and hydraulic conductivity relationship for
uranium tailings should be calibrated at higher consolidation loads in large scale tests.
A consolidation model that accommodates the multi-layer slurries with different
compressibility and hydraulic conductivity during multi-stage pond filling will further
explain the dewatering behaviour of uranium mill tailings.
71
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83
APPENDIX A
Laboratory test data of 4% mill tailings sample
Table A1: Vane shear test data of 4% mill tailings sample
Test No
Max. Angular Rotation
(Deg)
Height, H (mm)
Width, D (mm)
Vane Constant, K (mm3)
Spring No
Calibration factor
(N-mm/Deg)
Torque, M
(N-mm)
Yield stress
τ (kPa)
Weight (gm)
Water content, w (%)
Solid content,
s (%)
Can Can + wet
slurry
Can + Dry
slurry
1 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 15.54 28.04 17.52 531.31 15.84
2 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 15.52 26.34 17.78 378.76 20.89
3 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 15.54 27.54 18.62 289.61 25.67
4 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 15.49 40.92 23.26 227.28 30.55
5 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 15.53 34.53 21.77 204.49 32.84
6 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 15.54 26.78 19.55 180.30 35.68
7 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 15.56 25.04 19.16 163.33 37.97
8 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 31.94 80.50 51.98 142.32 41.27
9 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 31.8 89.67 57.26 127.30 44.00
10 1 12.7 12.7 4290.12 2 1.71 1.71 0.40 31.95 83.27 60.87 77.46 56.35
11 6 12.7 12.7 4290.12 2 1.71 10.26 2.39 32.07 77.97 62.67 50.00 66.67
12 5 12.7 12.7 4290.12 3 2.61 13.05 3.04 31.52 65.06 54.09 48.60 67.29
13 6 12.7 12.7 4290.12 3 2.61 15.66 3.65 32.03 71.17 59.28 43.63 69.62
14 33 12.7 12.7 4290.12 3 2.61 86.13 20.08 31.54 74.2 62.51 37.75 72.60
15 42 12.7 12.7 4290.12 3 2.61 109.62 25.55 31.8 48.7 44.28 35.42 73.85
84
Table A2: Self-weight settling test data of 4% mill tailings sample
Test condition si = 20.2% si = 15.1%
Elapsed time (min) Interface height (cm) Interface height (cm)
0.1 8.50 8.50
1 8.45 8.40
2 8.40 7.70
3 8.40 7.40
4 8.35 7.20
5 8.35 7.00
6 8.30 6.80
7 8.25 6.60
8 8.25 6.40
9 8.20 6.30
10 8.20 6.25
20 7.80 5.65
30 7.50 5.30
40 7.30 5.10
50 7.15 4.90
60 7.00 4.75
70 6.85 4.60
80 6.70 4.50
90 6.60 4.40
100 6.50 4.35
200 5.90 4.30
300 5.40 4.25
400 5.20 4.20
500 5.10 4.20
1000 5.10 4.20
1200 5.10 4.20
1440 5.10 4.20
85
Table A3: Segregation test data of 4% mill tailings sample (si = 20.2%)
Layer depth (cm) Weight (g) w (%) s (%)
From To can + wet can + dry can water solid
5.10 4.25 80.87 41.05 31.88 39.82 9.17 4.34 18.72
4.25 3.40 96.86 49.38 31.73 47.48 17.65 2.69 27.10
3.40 2.55 90.25 49.14 31.95 41.11 17.19 2.39 29.49
2.55 1.70 97.44 52.07 31.90 45.37 20.17 2.25 30.78
1.70 0.85 94.65 52.31 32.04 42.34 20.27 2.09 32.38
0.85 0.00 66.22 44.87 31.64 21.35 13.23 1.61 38.26
Table A4: Segregation test data of 4% mill tailings sample (si = 15.1%)
Layer depth (cm) Weight (g) w (%) s (%)
From To can + wet can + dry can water solid
4.20 3.50 92.69 41.20 31.72 51.49 9.48 5.43 15.55
3.50 2.80 82.03 43.96 31.81 38.07 12.15 3.13 24.19
2.80 2.10 72.85 43.22 31.92 29.63 11.30 2.62 27.61
2.10 1.40 73.92 44.59 32.09 29.33 12.50 2.35 29.88
1.40 0.70 77.88 46.83 31.71 31.05 15.12 2.05 32.75
0.70 0.00 72.13 48.59 32.91 23.54 15.68 1.50 39.98
86
Table A5: Grain size analysis (sieve and hydrometer) of 4% mill tailings sample at si = 20.2% (top layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 92.62 92.62 0.00 0.00 0.00 100.00
18 92.62 92.62 0.00 0.00 0.00 100.00
40 96.84 97.14 0.30 1.08 1.08 98.92
70 106.02 111.10 5.08 18.31 19.39 80.61
100 87.55 90.77 3.22 11.61 31.00 69.00
140 116.92 119.73 2.81 10.13 41.13 58.87
200 92.72 94.79 2.07 7.46 48.59 51.41
pan 473.03 487.29 14.26
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 19 18 -0.35 13.65 20 13.018 26.036 0.0138 71.04475 36.5212 0.070415 100
1 17 18 -0.35 11.65 18 13.3462 13.3462 0.0138 60.63526 31.17011 0.050415 85.34799
2 15 18 -0.35 9.65 16 13.6744 6.8372 0.0138 50.22577 25.81902 0.036084 70.69597
4 14 18 -0.35 8.65 15 13.8385 3.459625 0.0138 45.02103 23.14347 0.025668 63.36996
8 12 18 -0.35 6.65 13 14.1667 1.770838 0.0138 34.61154 17.79238 0.018364 48.71795
15 10 18 -0.35 4.65 11 14.4949 0.966327 0.0138 24.20206 12.44129 0.013566 34.06593
30 9 18 -0.35 3.65 10 14.659 0.488633 0.0138 18.99731 9.765742 0.009647 26.73993
60 8 18 -0.35 2.65 9 14.8231 0.247052 0.0138 13.79257 7.090196 0.006859 19.41392
120 8 18 -0.35 2.65 9 14.8231 0.123526 0.0138 13.79257 7.090196 0.00485 19.41392
240 8 18 -0.35 2.65 9 14.8231 0.061763 0.0138 13.79257 7.090196 0.00343 19.41392
480 8 18 -0.35 2.65 9 14.8231 0.030881 0.0138 13.79257 7.090196 0.002425 19.41392
1440 8 18 -0.35 2.65 9 14.8231 0.010294 0.0138 13.79257 7.090196 0.0014 19.41392
2880 8 18 -0.35 2.65 9 14.8231 0.005147 0.0138 13.79257 7.090196 0.00099 19.41392
87
Table A6: Grain size analysis (sieve and hydrometer) of 4% mill tailings sample at si = 20.2% (mid layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 92.62 92.62 0.00 0.00 0.00 100.00
18 92.62 92.62 0.00 0.00 0.00 100.00
40 96.84 97.51 0.67 1.75 1.75 98.25
70 106.02 114.39 8.37 21.91 23.66 76.34
100 87.54 92.39 4.85 12.70 36.36 63.64
140 116.89 120.72 3.83 10.03 46.39 53.61
200 92.72 95.54 2.82 7.38 53.77 46.23
pan 473.00 490.66 17.66
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 19 18 -0.35 13.65 20 13.018 26.036 0.0138 71.04475 32.84425 0.070415 100
1 17 18 -0.35 11.65 18 13.3462 13.3462 0.0138 60.63526 28.0319 0.050415 85.34799
2 16 18 -0.35 10.65 17 13.5103 6.75515 0.0138 55.43052 25.62573 0.035867 78.02198
4 15 18 -0.35 9.65 16 13.6744 3.4186 0.0138 50.22577 23.21956 0.025515 70.69597
8 14 18 -0.35 8.65 15 13.8385 1.729813 0.0138 45.02103 20.81339 0.01815 63.36996
15 12 18 -0.35 6.65 13 14.1667 0.944447 0.0138 34.61154 16.00104 0.013411 48.71795
30 10 18 -0.35 4.65 11 14.4949 0.483163 0.0138 24.20206 11.1887 0.009592 34.06593
60 9 18 -0.35 3.65 10 14.659 0.244317 0.0138 18.99731 8.782527 0.006821 26.73993
120 8 18 -0.35 2.65 9 14.8231 0.123526 0.0138 13.79257 6.376356 0.00485 19.41392
240 8 18 -0.35 2.65 9 14.8231 0.061763 0.0138 13.79257 6.376356 0.00343 19.41392
480 8 18 -0.35 2.65 9 14.8231 0.030881 0.0138 13.79257 6.376356 0.002425 19.41392
1440 8 18 -0.35 2.65 9 14.8231 0.010294 0.0138 13.79257 6.376356 0.0014 19.41392
2880 8 18 -0.35 2.65 9 14.8231 0.005147 0.0138 13.79257 6.376356 0.00099 19.41392
88
Table A7: Grain size analysis (sieve and hydrometer) of 4% mill tailings sample at si = 20.2% (bottom layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 92.62 92.62 0.00 0.00 0.00 100.00
18 92.62 92.62 0.00 0.00 0.00 100.00
40 96.85 97.76 0.91 2.65 2.65 97.35
70 106.02 114.80 8.78 25.53 28.18 71.82
100 87.52 92.04 4.52 13.14 41.32 58.68
140 116.88 120.00 3.12 9.07 50.39 49.61
200 92.71 95.08 2.37 6.89 57.28 42.72
pan 473.01 487.70 14.69
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 22 14 -1.35 15.65 23 12.5257 25.0514 0.0138 81.45423 34.79391 0.069071 100
1 20 13 -1.6 13.4 21 12.8539 12.8539 0.0138 69.74356 29.79159 0.049476 85.623
2 18 12 -1.85 11.15 19 13.1821 6.59105 0.0138 58.03289 24.78927 0.035429 71.24601
4 17 11 -2.1 9.9 18 13.3462 3.33655 0.0138 51.52696 22.01021 0.025207 63.25879
8 13 10 -2.35 5.65 14 14.0026 1.750325 0.0138 29.4068 12.56138 0.018257 36.10224
15 11 10 -2.35 3.65 12 14.3308 0.955387 0.0138 18.99731 8.114874 0.013489 23.32268
30 10 10 -2.35 2.65 11 14.4949 0.483163 0.0138 13.79257 5.891621 0.009592 16.93291
60 9 10 -2.35 1.65 10 14.659 0.244317 0.0138 8.587826 3.668368 0.006821 10.54313
120 8 9 -2.6 0.4 9 14.8231 0.123526 0.0138 2.081897 0.889301 0.00485 2.555911
240 8 9 -2.6 0.4 9 14.8231 0.061763 0.0138 2.081897 0.889301 0.00343 2.555911
480 8 9 -2.6 0.4 9 14.8231 0.030881 0.0138 2.081897 0.889301 0.002425 2.555911
1440 8 9 -2.6 0.4 9 14.8231 0.010294 0.0138 2.081897 0.889301 0.0014 2.555911
2880 8 9 -2.6 0.4 9 14.8231 0.005147 0.0138 2.081897 0.889301 0.00099 2.555911
89
Table A8: Grain size analysis (sieve and hydrometer) of 4% mill tailings sample at si = 15.1% (top layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 92.62 92.62 0.00 0.00 0.00 100.00
18 92.62 92.62 0.00 0.00 0.00 100.00
40 96.83 96.89 0.06 0.27 0.27 99.73
70 106.04 108.58 2.54 11.38 11.65 88.35
100 87.54 89.95 2.41 10.80 22.45 77.55
140 116.89 119.03 2.14 9.59 32.03 67.97
200 92.68 94.40 1.72 7.71 39.74 60.26
pan 473.02 486.47 13.45
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 19 18 -0.35 13.65 20 13.018 26.036 0.0138 71.04475 42.81146 0.070415 100
1 17 18 -0.35 11.65 18 13.3462 13.3462 0.0138 60.63526 36.53872 0.050415 85.34799
2 16.5 18 -0.35 11.15 17.5 13.42825 6.714125 0.0138 58.03289 34.97053 0.035758 81.68498
4 15 18 -0.35 9.65 16 13.6744 3.4186 0.0138 50.22577 30.26598 0.025515 70.69597
8 14 18 -0.35 8.65 15 13.8385 1.729813 0.0138 45.02103 27.12961 0.01815 63.36996
15 13 18 -0.35 7.65 14 14.0026 0.933507 0.0138 39.81629 23.99324 0.013333 56.04396
30 12 18 -0.35 6.65 13 14.1667 0.472223 0.0138 34.61154 20.85687 0.009483 48.71795
60 11 18 -0.35 5.65 12 14.3308 0.238847 0.0138 29.4068 17.7205 0.006744 41.39194
120 10 18 -0.35 4.65 11 14.4949 0.120791 0.0138 24.20206 14.58412 0.004796 34.06593
240 10 18 -0.35 4.65 11 14.4949 0.060395 0.0138 24.20206 14.58412 0.003391 34.06593
480 10 18 -0.35 4.65 11 14.4949 0.030198 0.0138 24.20206 14.58412 0.002398 34.06593
1440 10 18 -0.35 4.65 11 14.4949 0.010066 0.0138 24.20206 14.58412 0.001385 34.06593
2880 10 18 -0.35 4.65 11 14.4949 0.005033 0.0138 24.20206 14.58412 0.000979 34.06593
90
Table A9: Grain size analysis (sieve and hydrometer) of 4% mill tailings sample at si = 15.1% (mid layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 92.62 92.62 0.00 0.00 0.00 100.00
18 92.62 92.62 0.00 0.00 0.00 100.00
40 96.84 97.04 0.20 0.81 0.81 99.19
70 106.03 111.10 5.07 20.61 21.42 78.58
100 87.55 90.55 3.00 12.20 33.62 66.38
140 116.90 119.42 2.52 10.24 43.86 56.14
200 92.71 94.39 1.68 6.83 50.69 49.31
pan 473.02 485.15 12.13
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 20 18 -0.35 14.65 21 12.8539 25.7078 0.0138 76.24949 37.59782 0.06997 100
1 18 18 -0.35 12.65 19 13.1821 13.1821 0.0138 65.84 32.46501 0.050104 86.34812
2 17 18 -0.35 11.65 18 13.3462 6.6731 0.0138 60.63526 29.89861 0.035649 79.52218
4 16 18 -0.35 10.65 17 13.5103 3.377575 0.0138 55.43052 27.3322 0.025362 72.69625
8 15 18 -0.35 9.65 16 13.6744 1.7093 0.0138 50.22577 24.7658 0.018042 65.87031
15 14 18 -0.35 8.65 15 13.8385 0.922567 0.0138 45.02103 22.19939 0.013255 59.04437
30 12 18 -0.35 6.65 13 14.1667 0.472223 0.0138 34.61154 17.06659 0.009483 45.39249
60 10 18 -0.35 4.65 11 14.4949 0.241582 0.0138 24.20206 11.93378 0.006783 31.74061
120 9 18 -0.35 3.65 10 14.659 0.122158 0.0138 18.99731 9.367374 0.004823 24.91468
240 9 18 -0.35 3.65 10 14.659 0.061079 0.0138 18.99731 9.367374 0.003411 24.91468
480 9 18 -0.35 3.65 10 14.659 0.03054 0.0138 18.99731 9.367374 0.002412 24.91468
1440 9 18 -0.35 3.65 10 14.659 0.01018 0.0138 18.99731 9.367374 0.001392 24.91468
2880 9 18 -0.35 3.65 10 14.659 0.00509 0.0138 18.99731 9.367374 0.000985 24.91468
91
Table A10: Grain size analysis (sieve and hydrometer) of 4% mill tailings sample at si = 15.1% (bottom layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 92.62 92.62 0.00 0.00 0.00 100.00
18 92.62 92.62 0.00 0.00 0.00 100.00
40 96.84 98.13 1.29 3.98 3.98 96.02
70 106.02 116.11 10.09 31.10 35.08 64.92
100 87.53 91.82 4.29 13.22 48.30 51.70
140 116.90 119.69 2.79 8.60 56.91 43.09
200 92.69 94.61 1.92 5.92 62.82 37.18
pan 472.97 485.03 12.06
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 22 14 -1.35 15.65 23 12.5257 25.0514 0.0138 81.45423 30.28169 0.069071 100
1 20 13 -1.6 13.4 21 12.8539 12.8539 0.0138 69.74356 25.92809 0.049476 85.623
2 18 12 -1.85 11.15 19 13.1821 6.59105 0.0138 58.03289 21.5745 0.035429 71.24601
4 16 11 -2.1 8.9 17 13.5103 3.377575 0.0138 46.32222 17.2209 0.025362 56.86901
8 14 10 -2.35 6.65 15 13.8385 1.729813 0.0138 34.61154 12.8673 0.01815 42.49201
15 13 10 -2.35 5.65 14 14.0026 0.933507 0.0138 29.4068 10.93237 0.013333 36.10224
30 12 10 -2.35 4.65 13 14.1667 0.472223 0.0138 24.20206 8.997435 0.009483 29.71246
60 11 10 -2.35 3.65 12 14.3308 0.238847 0.0138 18.99731 7.062503 0.006744 23.32268
120 10 9 -2.6 2.4 11 14.4949 0.120791 0.0138 12.49138 4.643838 0.004796 15.33546
240 10 9 -2.6 2.4 11 14.4949 0.060395 0.0138 12.49138 4.643838 0.003391 15.33546
480 10 9 -2.6 2.4 11 14.4949 0.030198 0.0138 12.49138 4.643838 0.002398 15.33546
1440 10 9 -2.6 2.4 11 14.4949 0.010066 0.0138 12.49138 4.643838 0.001385 15.33546
2880 10 9 -2.6 2.4 11 14.4949 0.005033 0.0138 12.49138 4.643838 0.000979 15.33546
92
Table A11: Consolidation test data of 4% mill tailings sample (self-weight)
Elapsed Time (min) Interface height (cm) Solids content (%) Void Ratio
0.1 10.00 31.94 5.75
1 10.00 32.42 5.75
2 9.95 32.53 5.72
3 9.95 32.53 5.72
4 9.90 32.64 5.70
5 9.90 32.64 5.70
6 9.90 32.64 5.70
7 9.85 32.75 5.67
8 9.85 32.75 5.67
9 9.80 32.86 5.64
10 9.80 32.86 5.64
20 9.75 32.98 5.61
30 9.70 33.09 5.58
40 9.65 33.21 5.55
50 9.60 33.32 5.52
60 9.55 33.44 5.49
70 9.50 33.55 5.47
80 9.40 33.79 5.41
90 9.35 33.91 5.38
100 9.25 34.15 5.32
200 8.9 35.02 5.12
300 8.7 35.54 5.01
400 8.6 35.81 4.95
500 8.5 36.08 4.89
1000 8.4 36.35 4.83
1200 8.4 36.35 4.83
1440 8.4 36.35 4.83
93
Table A12: Consolidation test data of 4% mill tailings sample (σ' = 1.03 kPa)
Elapsed Time (min) Interface height (cm) Solids content (%) Void Ratio
0.1 8.40 36.35 4.83
1 8.30 36.64 4.77
2 8.20 36.92 4.72
3 8.10 37.21 4.66
4 8.00 37.50 4.60
5 7.90 37.80 4.54
6 7.80 38.10 4.49
7 7.70 38.40 4.43
8 7.60 38.71 4.37
9 7.55 38.87 4.34
10 7.50 39.02 4.31
20 7.20 40.00 4.14
30 7.00 40.68 4.03
40 6.85 41.20 3.94
50 6.75 41.56 3.88
60 6.70 41.74 3.85
70 6.70 41.74 3.85
80 6.70 41.74 3.85
90 6.70 41.74 3.85
100 6.70 41.74 3.85
200 6.65 41.92 3.82
300 6.65 41.92 3.82
400 6.6 42.11 3.80
500 6.6 42.11 3.80
1000 6.6 42.11 3.80
1200 6.6 42.11 3.80
1440 6.6 42.11 3.80
2880 6.6 42.11 3.80
94
Table A13: Consolidation test data of 4% mill tailings sample (σ' = 2.01 kPa)
Elapsed Time (min) Interface height (cm) Solids content (%) Void Ratio
0.1 6.60 42.11 3.80
1 6.52 42.36 3.76
2 6.50 42.45 3.74
3 6.48 42.54 3.73
4 6.46 42.59 3.72
5 6.44 42.66 3.71
6 6.43 42.71 3.70
7 6.42 42.76 3.69
8 6.41 42.80 3.69
9 6.39 42.85 3.68
10 6.38 42.89 3.68
20 6.30 43.21 3.63
30 6.25 43.41 3.60
40 6.22 43.53 3.58
50 6.20 43.61 3.57
60 6.19 43.65 3.56
70 6.18 43.69 3.56
80 6.17 43.71 3.55
90 6.17 43.73 3.55
100 6.17 43.74 3.55
200 6.14 43.83 3.54
300 6.13 43.87 3.53
400 6.13 43.89 3.53
500 6.12 43.91 3.52
1000 6.11 43.95 3.52
1200 6.11 43.96 3.52
1440 6.11 43.98 3.52
2880 6.10 44.01 3.51
95
Table A14: Consolidation test data of 4% mill tailings sample (σ' = 4.03 kPa)
Elapsed Time (min) Interface height (cm) Solids content (%) Void Ratio
0.1 6.10 44.01 3.51
1 6.09 44.04 3.51
2 6.09 44.06 3.50
3 6.09 44.07 3.50
4 6.08 44.08 3.50
5 6.08 44.08 3.50
6 6.08 44.11 3.50
7 6.07 44.13 3.49
8 6.06 44.16 3.49
9 6.06 44.16 3.49
10 6.06 44.17 3.49
20 6.04 44.24 3.48
30 6.03 44.29 3.47
40 6.02 44.33 3.47
50 6.01 44.36 3.46
60 6.01 44.38 3.46
70 6.00 44.40 3.46
80 6.00 44.42 3.45
90 5.99 44.44 3.45
100 5.99 44.46 3.45
200 5.97 44.55 3.44
300 5.96 44.58 3.43
400 5.95 44.61 3.43
500 5.95 44.62 3.42
1000 5.94 44.68 3.42
1200 5.94 44.69 3.42
1440 5.93 44.70 3.41
2880 5.93 44.72 3.41
96
Table A15: Consolidation test data of 4% mill tailings sample (σ' = 8.33 kPa)
Elapsed Time (min) Interface height (cm) Solids content (%) Void Ratio
0.1 5.93 44.72 3.41
1 5.92 44.79 3.40
2 5.91 44.82 3.40
3 5.90 44.85 3.39
4 5.89 44.88 3.39
5 5.89 44.89 3.39
6 5.89 44.90 3.39
7 5.89 44.91 3.39
8 5.88 44.92 3.38
9 5.88 44.93 3.38
10 5.88 44.94 3.38
20 5.87 44.99 3.37
30 5.85 45.06 3.37
40 5.84 45.08 3.36
50 5.84 45.09 3.36
60 5.84 45.11 3.36
70 5.84 45.11 3.36
80 5.83 45.13 3.36
90 5.83 45.14 3.35
100 5.83 45.15 3.35
200 5.82 45.18 3.35
300 5.78 45.35 3.33
400 5.78 45.37 3.32
500 5.78 45.37 3.32
1000 5.77 45.41 3.32
1200 5.76 45.42 3.32
1440 5.76 45.44 3.31
2880 5.76 45.46 3.31
97
Table A16: Hydraulic conductivity test data of 4% mill tailings sample (self-weight)
Elapsed time
Sample height (cm)
a (sq.cm)
A (sq.cm)
Initial head at burette, h1 (cm)
Initial time,
t1 (sec)
Final head at burette, h2 (cm)
Final time,
t2 (sec)
Hydraulic Conductivity
(m/Sec)
0 8.4 1.5 78.54 - - - - -
1 8.4 1.5 78.54 51.3 0 49.7 60 8.47×10-07
2 8.4 1.5 78.54 49.7 60 48.2 120 8.01×10-07
3 8.4 1.5 78.54 48.2 120 46.8 180 7.88×10-07
4 8.4 1.5 78.54 46.8 180 45.6 240 6.94×10-07
5 8.4 1.5 78.54 45.6 240 44.6 300 6.32×10-07
6 8.4 1.5 78.54 44.6 300 43.4 360 7.30×10-07
7 8.4 1.5 78.54 43.4 360 42.4 420 6.24×10-07
8 8.4 1.5 78.54 42.4 420 41.4 480 6.17×10-07
9 8.4 1.5 78.54 41.4 480 40.4 540 6.76×10-07
10 8.4 1.5 78.54 40.4 540 39.4 600 6.25×10-07
12 8.4 1.5 78.54 39.4 600 37.4 720 6.96×10-07
14 8.4 1.5 78.54 37.4 720 35.8 840 5.84×10-07
16 8.4 1.5 78.54 35.8 840 34.2 960 6.11×10-07
18 8.4 1.5 78.54 34.2 960 32.6 1080 6.67×10-07
20 8.4 1.5 78.54 32.6 1080 30.9 1200 7.02×10-07
22 8.4 1.5 78.54 30.9 1200 29.5 1320 6.20×10-07
24 8.4 1.5 78.54 29.5 1320 28.1 1440 6.50×10-07
26 8.4 1.5 78.54 28.1 1440 26.7 1560 6.83×10-07
28 8.4 1.5 78.54 26.7 1560 25.5 1680 6.15×10-07
30 8.4 1.5 78.54 25.5 1680 24.4 1800 6.08×10-07
35 8.4 1.5 78.54 24.4 1800 21.7 2100 6.12×10-07
40 8.4 1.5 78.54 21.7 2100 19.4 2400 6.07×10-07
45 8.4 1.5 78.54 19.4 2400 17.3 2700 6.13×10-07
50 8.4 1.5 78.54 17.3 2700 15.4 3000 6.11×10-07
55 8.4 1.5 78.54 15.4 3000 13.8 3300 6.11×10-07
60 8.4 1.5 78.54 13.8 3300 12.3 3600 6.11×10-07
98
Table A17: Hydraulic conductivity test data of 4% mill tailings sample (σ' = 1.03 kPa)
Elapsed time
Sample height (cm)
a (sq.cm)
A (sq.cm)
Initial head at burette, h1 (cm)
Initial time,
t1 (sec)
Final head at burette, h2 (cm)
Final time,
t2 (sec)
Hydraulic Conductivity
(m/Sec)
0 6.6 1.5 78.54 - - - - -
1 6.6 1.5 78.54 51.3 0 50.1 60 4.97×10-07
2 6.6 1.5 78.54 50.1 60 49.4 120 2.81×10-07
3 6.6 1.5 78.54 49.4 120 48.8 180 2.85×10-07
4 6.6 1.5 78.54 48.8 180 48.2 240 2.60×10-07
5 6.6 1.5 78.54 48.2 240 47.6 300 2.34×10-07
6 6.6 1.5 78.54 47.6 300 47.1 360 2.37×10-07
7 6.6 1.5 78.54 47.1 360 46.4 420 2.99×10-07
8 6.6 1.5 78.54 46.4 420 45.9 480 2.43×10-07
9 6.6 1.5 78.54 45.9 480 45.3 540 2.76×10-07
10 6.6 1.5 78.54 45.3 540 44.7 600 2.80×10-07
12 6.6 1.5 78.54 44.7 600 43.6 720 2.54×10-07
14 6.6 1.5 78.54 43.6 720 42.4 840 2.93×10-07
16 6.6 1.5 78.54 42.4 840 41.5 960 2.34×10-07
18 6.6 1.5 78.54 41.5 960 40.4 1080 2.74×10-07
20 6.6 1.5 78.54 40.4 1080 39.3 1200 2.99×10-07
22 6.6 1.5 78.54 39.3 1200 38.3 1320 2.71×10-07
24 6.6 1.5 78.54 38.3 1320 37.4 1440 2.40×10-07
26 6.6 1.5 78.54 37.4 1440 36.4 1560 2.84×10-07
28 6.6 1.5 78.54 36.4 1560 35.6 1680 2.33×10-07
30 6.6 1.5 78.54 35.6 1680 34.7 1800 2.69×10-07
35 6.6 1.5 78.54 34.7 1800 32.6 2100 2.71×10-07
40 6.6 1.5 78.54 32.6 2100 30.5 2400 2.71×10-07
45 6.6 1.5 78.54 30.5 2400 28.6 2700 2.70×10-07
50 6.6 1.5 78.54 28.6 2700 26.8 3000 2.73×10-07
55 6.6 1.5 78.54 26.8 3000 25.2 3300 2.69×10-07
60 6.6 1.5 78.54 25.2 3300 23.6 3600 2.70×10-07
99
Table A18: Hydraulic conductivity test data of 4% mill tailings sample (σ' = 2.01 kPa)
Elapsed time
Sample height (cm)
a (sq.cm)
A (sq.cm)
Initial head at burette, h1 (cm)
Initial time,
t1 (sec)
Final head at burette, h2 (cm)
Final time,
t2 (sec)
Hydraulic Conductivity
(m/Sec)
0 6.1 1.5 78.54 - - - - -
1 6.1 1.5 78.54 51.2 0.0 50.5 60 2.54×10-07
2 6.1 1.5 78.54 50.5 60.0 50.0 120 2.06×10-07
3 6.1 1.5 78.54 50.0 120.0 49.5 180 1.82×10-07
4 6.1 1.5 78.54 49.5 180.0 49.0 240 2.10×10-07
5 6.1 1.5 78.54 49.0 240.0 48.6 300 1.59×10-07
6 6.1 1.5 78.54 48.6 300.0 48.1 360 1.87×10-07
7 6.1 1.5 78.54 48.1 360.0 47.7 420 1.62×10-07
8 6.1 1.5 78.54 47.7 420.0 47.3 480 1.91×10-07
9 6.1 1.5 78.54 47.3 480.0 46.9 540 1.65×10-07
10 6.1 1.5 78.54 46.9 540.0 46.5 600 1.66×10-07
12 6.1 1.5 78.54 46.5 600.0 45.7 720 1.69×10-07
14 6.1 1.5 78.54 45.7 720.0 45.0 840 1.50×10-07
16 6.1 1.5 78.54 45.0 840.0 44.2 960 1.67×10-07
18 6.1 1.5 78.54 44.2 960.0 43.5 1080 1.48×10-07
20 6.1 1.5 78.54 43.5 1080.0 42.8 1200 1.65×10-07
22 6.1 1.5 78.54 42.8 1200.0 42.0 1320 1.83×10-07
24 6.1 1.5 78.54 42.0 1320.0 41.3 1440 1.71×10-07
26 6.1 1.5 78.54 41.3 1440.0 40.6 1560 1.58×10-07
28 6.1 1.5 78.54 40.6 1560.0 39.9 1680 1.77×10-07
30 6.1 1.5 78.54 39.9 1680.0 39.1 1800 1.89×10-07
35 6.1 1.5 78.54 39.1 1800.0 37.3 2100 1.86×10-07
40 6.1 1.5 78.54 37.3 2100.0 35.5 2400 1.85×10-07
45 6.1 1.5 78.54 35.5 2400.0 33.9 2700 1.87×10-07
50 6.1 1.5 78.54 33.9 2700.0 32.3 3000 1.88×10-07
55 6.1 1.5 78.54 32.3 3000.0 30.7 3300 1.89×10-07
60 6.1 1.5 78.54 30.7 3300.0 29.3 3600 1.86×10-07
100
Table A19: Hydraulic conductivity test data of 4% mill tailings sample (σ' = 4.03 kPa)
Elapsed time
Sample height (cm)
a (sq.cm)
A (sq.cm)
Initial head at burette, h1 (cm)
Initial time,
t1 (sec)
Final head at burette, h2 (cm)
Final time,
t2 (sec)
Hydraulic Conductivity
(m/Sec)
0 5.9 1.5 78.54 - - - - -
1 5.9 1.5 78.54 51.2 0.0 50.6 60 2.21×10-07
2 5.9 1.5 78.54 50.6 60.0 50.3 120 1.24×10-07
3 5.9 1.5 78.54 50.3 120.0 49.9 180 1.25×10-07
4 5.9 1.5 78.54 49.9 180.0 49.5 240 1.51×10-07
5 5.9 1.5 78.54 49.5 240.0 49.2 300 1.27×10-07
6 5.9 1.5 78.54 49.2 300.0 48.8 360 1.40×10-07
7 5.9 1.5 78.54 48.8 360.0 48.5 420 1.16×10-07
8 5.9 1.5 78.54 48.5 420.0 48.2 480 1.29×10-07
9 5.9 1.5 78.54 48.2 480.0 47.9 540 1.30×10-07
10 5.9 1.5 78.54 47.9 540.0 47.5 600 1.31×10-07
12 5.9 1.5 78.54 47.5 600.0 46.8 720 1.46×10-07
14 5.9 1.5 78.54 46.8 720.0 46.2 840 1.21×10-07
16 5.9 1.5 78.54 46.2 840.0 45.5 960 1.50×10-07
18 5.9 1.5 78.54 45.5 960.0 44.8 1080 1.39×10-07
20 5.9 1.5 78.54 44.8 1080.0 44.1 1200 1.55×10-07
22 5.9 1.5 78.54 44.1 1200.0 43.4 1320 1.43×10-07
24 5.9 1.5 78.54 43.4 1320.0 42.8 1440 1.31×10-07
26 5.9 1.5 78.54 42.8 1440.0 42.1 1560 1.55×10-07
28 5.9 1.5 78.54 42.1 1560.0 41.5 1680 1.42×10-07
30 5.9 1.5 78.54 41.5 1680.0 40.8 1800 1.52×10-07
35 5.9 1.5 78.54 40.8 1800.0 39.2 2100 1.50×10-07
40 5.9 1.5 78.54 39.2 2100.0 37.7 2400 1.50×10-07
45 5.9 1.5 78.54 37.7 2400.0 36.2 2700 1.53×10-07
50 5.9 1.5 78.54 36.2 2700.0 34.7 3000 1.52×10-07
55 5.9 1.5 78.54 34.7 3000.0 33.3 3300 1.55×10-07
60 5.9 1.5 78.54 33.3 3300.0 32.0 3600 1.53×10-07
101
Table A20: Hydraulic conductivity test data of 4% mill tailings sample (σ' = 8.33 kPa)
Elapsed time
Sample height (cm)
a (sq.cm)
A (sq.cm)
Initial head at burette, h1 (cm)
Initial time,
t1 (sec)
Final head at burette, h2 (cm)
Final time,
t2 (sec)
Hydraulic Conductivity
(m/Sec)
0 5.6 1.5 78.54 - - - - -
1 5.6 1.5 78.54 51.2 0.0 50.7 60 1.63×10-07
2 5.6 1.5 78.54 50.7 60.0 50.4 120 1.18×10-07
3 5.6 1.5 78.54 50.4 120.0 50.1 180 1.18×10-07
4 5.6 1.5 78.54 50.1 180.0 49.7 240 1.31×10-07
5 5.6 1.5 78.54 49.7 240.0 49.4 300 1.08×10-07
6 5.6 1.5 78.54 49.4 300.0 49.1 360 1.21×10-07
7 5.6 1.5 78.54 49.1 360.0 48.7 420 1.22×10-07
8 5.6 1.5 78.54 48.7 420.0 48.4 480 1.10×10-07
9 5.6 1.5 78.54 48.4 480.0 48.1 540 1.35×10-07
10 5.6 1.5 78.54 48.1 540.0 47.7 600 1.24×10-07
12 5.6 1.5 78.54 47.7 600.0 47.0 720 1.32×10-07
14 5.6 1.5 78.54 47.0 720.0 46.3 840 1.34×10-07
16 5.6 1.5 78.54 46.3 840.0 45.7 960 1.29×10-07
18 5.6 1.5 78.54 45.7 960.0 45.0 1080 1.31×10-07
20 5.6 1.5 78.54 45.0 1080.0 44.4 1200 1.20×10-07
22 5.6 1.5 78.54 44.4 1200.0 43.7 1320 1.35×10-07
24 5.6 1.5 78.54 43.7 1320.0 43.1 1440 1.23×10-07
26 5.6 1.5 78.54 43.1 1440.0 42.5 1560 1.39×10-07
28 5.6 1.5 78.54 42.5 1560.0 41.9 1680 1.27×10-07
30 5.6 1.5 78.54 41.9 1680.0 41.3 1800 1.29×10-07
35 5.6 1.5 78.54 41.3 1800.0 39.8 2100 1.29×10-07
40 5.6 1.5 78.54 39.8 2100.0 38.4 2400 1.28×10-07
45 5.6 1.5 78.54 38.4 2400.0 37.1 2700 1.26×10-07
50 5.6 1.5 78.54 37.1 2700.0 35.8 3000 1.27×10-07
55 5.6 1.5 78.54 35.8 3000.0 34.5 3300 1.25×10-07
60 5.6 1.5 78.54 34.5 3300.0 33.3 3600 1.26×10-07
102
APPENDIX B
Laboratory test data of 5% mill tailings sample
Table B1: Vane shear test data of 5% mill tailings sample
Test No
Max. Angular Rotation
(Deg)
Height, H (mm)
Width, D (mm)
Vane Constant, K (mm3)
Spring No
Calibration factor
(N-mm/Deg)
Torque, M
(N-mm)
Yield stress
τ (kPa)
Weight (gm)
Water content, w (%)
Solid content,
s (%)
Can Can + wet
slurry
Can + Dry
slurry
1 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 15.84 15.54 28.04 17.52 531.31
2 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 20.89 15.52 26.34 17.78 378.76
3 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 25.67 15.54 27.54 18.62 289.61
4 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 30.55 15.49 40.92 23.26 227.28
5 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 32.84 15.53 34.53 21.77 204.49
6 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 35.68 15.54 26.78 19.55 180.30
7 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 37.97 15.56 25.04 19.16 163.33
8 0.2 12.7 12.7 4290.12 2 1.71 0.34 0.08 40.18 15.55 42.93 26.55 148.91
9 0.3 12.7 12.7 4290.12 2 1.71 0.51 0.12 51.86 15.48 51.96 34.40 92.81
10 0.5 12.7 12.7 4290.12 2 1.71 0.86 0.20 53.61 15.52 59.54 39.12 86.53
11 1 12.7 12.7 4290.12 2 1.71 1.71 0.40 59.82 15.48 63.96 44.48 67.17
12 1.5 12.7 12.7 4290.12 2 1.71 2.57 0.60 62.60 15.54 64.20 46.00 59.75
13 6 12.7 12.7 4290.12 2 1.71 10.26 2.39 69.57 15.52 56.73 44.19 43.74
14 18.5 12.7 12.7 4290.12 2 1.71 31.64 7.37 70.83 15.54 62.61 48.88 41.18
15 22 12.7 12.7 4290.12 2 1.71 37.62 8.77 72.27 15.54 49.47 40.06 38.38
16 29 12.7 12.7 4290.12 2 1.71 49.59 11.56 74.68 15.52 47.12 39.12 33.90
103
Table B2: Self-weight settling test data of 5% mill tailings sample
Test condition si = 20.4% si = 15.2%
Elapsed time (min) Interface height (cm) Interface height (cm)
0.1 8.50 8.50
1 8.30 8.20
2 8.10 7.90
3 7.90 7.60
4 7.70 7.30
5 7.55 7.10
6 7.40 6.90
7 7.25 6.70
8 7.10 6.50
9 7.00 6.35
10 6.90 6.20
20 5.50 4.60
30 5.25 4.20
40 5.10 4.00
50 4.95 3.80
60 4.80 3.70
70 4.70 3.60
80 4.65 3.50
90 4.60 3.45
100 4.55 3.40
200 4.50 3.35
300 4.40 3.30
400 4.40 3.25
500 4.40 3.25
1000 4.40 3.25
1200 4.40 3.25
1440 4.40 3.25
104
Table B3: Segregation test data of 5% mill tailings sample (si = 20.4%)
Layer depth (cm) Weight (g) w (%) s (%)
From To can + wet can + dry can water solid
4.40 3.67 87.78 39.71 31.88 48.07 7.83 6.14 14.01
3.67 2.93 92.20 46.93 31.73 45.27 15.20 2.98 25.14
2.93 2.20 78.40 45.95 31.96 32.45 13.99 2.32 30.12
2.20 1.47 85.23 50.81 31.90 34.42 18.91 1.82 35.46
1.47 0.73 78.50 53.07 32.06 25.43 21.01 1.21 45.24
0.73 0.00 89.82 71.56 31.64 18.26 39.92 0.46 68.61
Table B4: Segregation test data of 5% mill tailings sample (si = 15.2%)
Layer depth (cm) Weight (g) w (%) s (%)
From To can + wet can + dry can water solid
3.25 2.708 76.92 37.55 31.92 39.37 5.63 6.99 12.51
2.71 2.168 67.35 38.38 31.88 28.97 6.50 4.46 18.33
2.17 1.628 62.98 39.53 31.98 23.45 7.55 3.11 24.35
1.63 1.088 64.09 40.19 31.96 23.90 8.23 2.90 25.61
1.09 0.548 74.94 49.47 32.10 25.47 17.37 1.47 40.55
0.55 0.008 69.95 62.02 31.70 7.93 30.32 0.26 79.27
105
Table B5: Grain size analysis (sieve and hydrometer) of 5% mill tailings sample at si = 20.4% (top layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 105.57 105.57 0.00 0.00 0.00 100.00
18 421.04 421.04 0.00 0.00 0.00 100.00
40 371.66 371.71 0.05 0.22 0.22 99.78
70 361.74 362.45 0.71 3.10 3.32 96.68
100 350.26 350.85 0.59 2.58 5.90 94.10
140 344.86 345.68 0.82 3.58 9.48 90.52
200 326.20 327.70 1.50 6.56 16.04 83.96
pan 369.75 388.96 19.21
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 22.0 18 -0.35 16.7 23.0 12.5 25.0514 0.0138 86.66 72.76 0.0691 100.00
1 21.0 18 -0.35 15.7 22.0 12.7 12.6898 0.0138 81.45 68.39 0.0492 93.99
2 20.0 18 -0.35 14.7 21.0 12.9 6.4270 0.0138 76.25 64.02 0.0350 87.99
4 20.0 18 -0.35 14.7 21.0 12.9 3.2135 0.0138 76.25 64.02 0.0247 87.99
8 19.0 18 -0.35 13.7 20.0 13.0 1.6273 0.0138 71.04 59.65 0.0176 81.98
15 17.0 18 -0.35 11.7 18.0 13.3 0.8897 0.0138 60.64 50.91 0.0130 69.97
30 16.0 18 -0.35 10.7 17.0 13.5 0.4503 0.0138 55.43 46.54 0.0093 63.96
60 15.0 18 -0.35 9.7 16.0 13.7 0.2279 0.0138 50.23 42.17 0.0066 57.96
120 15.0 18 -0.35 9.7 16.0 13.7 0.1140 0.0138 50.23 42.17 0.0047 57.96
240 14.0 18 -0.35 8.7 15.0 13.8 0.0577 0.0138 45.02 37.80 0.0033 51.95
480 10.0 18 -0.35 4.7 11.0 14.5 0.0302 0.0138 24.20 20.32 0.0024 27.93
1440 10.0 18 -0.35 4.7 11.0 14.5 0.0101 0.0138 24.20 20.32 0.0014 27.93
2880 10.0 18 -0.35 4.7 11.0 14.5 0.0050 0.0138 24.20 20.32 0.0010 27.93
106
Table B6: Grain size analysis (sieve and hydrometer) of 5% mill tailings sample at si = 20.4% (mid layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 105.57 105.57 0.00 0.00 0.00 100.00
18 421.04 421.04 0.00 0.00 0.00 100.00
40 371.66 371.71 0.05 0.15 0.15 99.85
70 361.74 362.61 0.87 2.61 2.76 97.24
100 350.26 352.80 2.54 7.63 10.39 89.61
140 344.86 350.31 5.45 16.36 26.75 73.25
200 326.20 329.78 3.58 10.75 37.50 62.50
pan 369.75 390.57 20.82
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 24.0 18 -0.35 18.7 21.0 12.9 25.7078 0.0138 97.07 60.67 0.0700 100.00
1 22.0 18 -0.35 16.7 20.0 13.0 13.0180 0.0138 86.66 54.17 0.0498 89.28
2 20.0 18 -0.35 14.7 19.0 13.2 6.5911 0.0138 76.25 47.66 0.0354 78.55
4 19.0 18 -0.35 13.7 18.0 13.3 3.3366 0.0138 71.04 44.41 0.0252 73.19
8 17.0 18 -0.35 11.7 17.0 13.5 1.6888 0.0138 60.64 37.90 0.0179 62.47
15 16.0 18 -0.35 10.7 16.0 13.7 0.9116 0.0138 55.43 34.65 0.0132 57.10
30 15.0 18 -0.35 9.7 15.0 13.8 0.4613 0.0138 50.23 31.39 0.0094 51.74
60 13.0 18 -0.35 7.7 14.0 14.0 0.2334 0.0138 39.82 24.89 0.0067 41.02
120 11.0 18 -0.35 5.7 13.0 14.2 0.1181 0.0138 29.41 18.38 0.0047 30.29
240 10.0 18 -0.35 4.7 12.0 14.3 0.0597 0.0138 24.20 15.13 0.0034 24.93
480 10.0 18 -0.35 4.7 11.0 14.5 0.0302 0.0138 24.20 15.13 0.0024 24.93
1440 10.0 18 -0.35 4.7 11.0 14.5 0.0101 0.0138 24.20 15.13 0.0014 24.93
2880 10.0 18 -0.35 4.7 11.0 14.5 0.0050 0.0138 24.20 15.13 0.0010 24.93
107
Table B7: Grain size analysis (sieve and hydrometer) of 5% mill tailings sample at si = 20.4% (bottom layer)
Sieve# Tare Dry mass % retained Cumulative % Passing 4 92.62 92.62 0.00 0.00 0.00 100.00
10 105.57 105.57 0.00 0.00 0.00 100.00
18 421.04 421.04 0.00 0.00 0.00 100.00
40 371.66 373.46 1.80 2.92 2.92 97.08
70 361.74 384.23 22.49 36.53 39.45 60.55
100 350.26 361.15 10.89 17.69 57.14 42.86
140 344.86 352.35 7.49 12.17 69.30 30.70
200 326.20 330.57 4.37 7.10 76.40 23.60
pan 369.75 384.28 14.53
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 22.0 18 -0.35 16.7 23.0 12.5 25.0514 0.0138 86.66 20.45 0.0691 100.00
1 20.0 18 -0.35 14.7 21.0 12.9 12.8539 0.0138 76.25 17.99 0.0495 87.99
2 19.0 18 -0.35 13.7 20.0 13.0 6.5090 0.0138 71.04 16.77 0.0352 81.98
4 17.0 18 -0.35 11.7 18.0 13.3 3.3366 0.0138 60.64 14.31 0.0252 69.97
8 15.0 18 -0.35 9.7 16.0 13.7 1.7093 0.0138 50.23 11.85 0.0180 57.96
15 14.0 18 -0.35 8.7 15.0 13.8 0.9226 0.0138 45.02 10.62 0.0133 51.95
30 13.0 18 -0.35 7.7 14.0 14.0 0.4668 0.0138 39.82 9.40 0.0094 45.95
60 12.0 18 -0.35 6.7 13.0 14.2 0.2361 0.0138 34.61 8.17 0.0067 39.94
120 11.0 18 -0.35 5.7 12.0 14.3 0.1194 0.0138 29.41 6.94 0.0048 33.93
240 10.0 18 -0.35 4.7 11.0 14.5 0.0604 0.0138 24.20 5.71 0.0034 27.93
480 10.0 18 -0.35 4.7 11.0 14.5 0.0302 0.0138 24.20 5.71 0.0024 27.93
1440 10.0 18 -0.35 4.7 11.0 14.5 0.0101 0.0138 24.20 5.71 0.0014 27.93
2880 10.0 18 -0.35 4.7 11.0 14.5 0.0050 0.0138 24.20 5.71 0.0010 27.93
108
Table B8: Grain size analysis (sieve and hydrometer) of 5% mill tailings sample at si = 15.2% (top layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 92.62 92.62 0.00 0.00 0.00 100.00
18 92.62 92.62 0.00 0.00 0.00 100.00
40 96.85 96.87 0.02 0.15 0.15 99.85
70 106.02 106.11 0.09 0.69 0.84 99.16
100 87.50 87.61 0.11 0.84 1.68 98.32
140 116.90 116.97 0.07 0.53 2.21 97.79
200 92.72 93.08 0.36 2.75 4.96 95.04
pan 473.05 485.50 12.45
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 20.0 18 -0.35 14.7 21.0 12.9 25.7078 0.0138 76.25 72.47 0.0700 100.00
1 18.0 18 -0.35 12.7 19.0 13.2 13.1821 0.0138 65.84 62.57 0.0501 86.35
2 17.0 18 -0.35 11.7 18.0 13.3 6.6731 0.0138 60.64 57.63 0.0356 79.52
4 16.0 18 -0.35 10.7 17.0 13.5 3.3776 0.0138 55.43 52.68 0.0254 72.70
8 14.0 18 -0.35 8.7 15.0 13.8 1.7298 0.0138 45.02 42.79 0.0182 59.04
15 13.0 18 -0.35 7.7 14.0 14.0 0.9335 0.0138 39.82 37.84 0.0133 52.22
30 12.0 18 -0.35 6.7 13.0 14.2 0.4722 0.0138 34.61 32.89 0.0095 45.39
60 11.0 18 -0.35 5.7 12.0 14.3 0.2388 0.0138 29.41 27.95 0.0067 38.57
120 10.0 18 -0.35 4.7 11.0 14.5 0.1208 0.0138 24.20 23.00 0.0048 31.74
240 10.0 18 -0.35 4.7 11.0 14.5 0.0604 0.0138 24.20 23.00 0.0034 31.74
480 10.0 18 -0.35 4.7 11.0 14.5 0.0302 0.0138 24.20 23.00 0.0024 31.74
1440 10.0 18 -0.35 4.7 11.0 14.5 0.0101 0.0138 24.20 23.00 0.0014 31.74
2880 10.0 18 -0.35 4.7 11.0 14.5 0.0050 0.0138 24.20 23.00 0.0010 31.74
109
Table B9: Grain size analysis (sieve and hydrometer) of 5% mill tailings sample at si = 15.2% (mid layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 92.62 92.62 0.00 0.00 0.00 100.00
18 92.62 92.62 0.00 0.00 0.00 100.00
40 96.85 96.87 0.02 0.12 0.12 99.88
70 106.02 106.27 0.25 1.51 1.63 98.37
100 87.50 87.83 0.33 1.99 3.62 96.38
140 116.90 117.45 0.55 3.32 6.94 93.06
200 92.72 94.05 1.33 8.03 14.98 85.02
pan 473.00 487.08 14.08
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 21.0 18 -0.35 15.7 22.0 12.7 25.3796 0.0138 81.45 69.26 0.0695 100.00
1 19.0 18 -0.35 13.7 20.0 13.0 13.0180 0.0138 71.04 60.41 0.0498 87.22
2 17.0 18 -0.35 11.7 18.0 13.3 6.6731 0.0138 60.64 51.55 0.0356 74.44
4 16.0 18 -0.35 10.7 17.0 13.5 3.3776 0.0138 55.43 47.13 0.0254 68.05
8 14.0 18 -0.35 8.7 15.0 13.8 1.7298 0.0138 45.02 38.28 0.0182 55.27
15 13.0 18 -0.35 7.7 14.0 14.0 0.9335 0.0138 39.82 33.85 0.0133 48.88
30 12.0 18 -0.35 6.7 13.0 14.2 0.4722 0.0138 34.61 29.43 0.0095 42.49
60 11.0 18 -0.35 5.7 12.0 14.3 0.2388 0.0138 29.41 25.00 0.0067 36.10
120 10.0 18 -0.35 4.7 11.0 14.5 0.1208 0.0138 24.20 20.58 0.0048 29.71
240 9.0 18 -0.35 3.7 10.0 14.7 0.0611 0.0138 19.00 16.15 0.0034 23.32
480 9.0 18 -0.35 3.7 10.0 14.7 0.0305 0.0138 19.00 16.15 0.0024 23.32
1440 9.0 18 -0.35 3.7 10.0 14.7 0.0102 0.0138 19.00 16.15 0.0014 23.32
2880 9.0 18 -0.35 3.7 10.0 14.7 0.0051 0.0138 19.00 16.15 0.0010 23.32
110
Table B10: Grain size analysis (sieve and hydrometer) of 5% mill tailings sample at si = 15.2% (bottom layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 92.62 92.62 0.00 0.00 0.00 100.00
18 92.62 92.62 0.00 0.00 0.00 100.00
40 96.83 98.21 1.38 3.62 3.62 96.38
70 106.05 112.68 6.63 17.37 20.99 79.01
100 87.54 95.87 8.33 21.83 42.82 57.18
140 116.90 124.04 7.14 18.71 61.53 38.47
200 92.70 96.98 4.28 11.22 72.75 27.25
pan 473.01 483.41 10.40
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 22.0 14 -1.35 15.7 23.0 12.5 25.0514 0.0138 81.45 22.20 0.0691 100.00
1 20.0 13 -1.60 13.4 21.0 12.9 12.8539 0.0138 69.74 19.01 0.0495 85.62
2 18.0 12 -1.85 11.2 19.0 13.2 6.5911 0.0138 58.03 15.82 0.0354 71.25
4 17.0 11 -2.10 9.9 18.0 13.3 3.3366 0.0138 51.53 14.04 0.0252 63.26
8 16.0 10 -2.35 8.7 17.0 13.5 1.6888 0.0138 45.02 12.27 0.0179 55.27
15 15.0 10 -2.35 7.7 16.0 13.7 0.9116 0.0138 39.82 10.85 0.0132 48.88
30 13.0 10 -2.35 5.7 14.0 14.0 0.4668 0.0138 29.41 8.01 0.0094 36.10
60 12.0 10 -2.35 4.7 13.0 14.2 0.2361 0.0138 24.20 6.60 0.0067 29.71
120 11.0 9 -2.60 3.4 12.0 14.3 0.1194 0.0138 17.70 4.82 0.0048 21.73
240 10.0 9 -2.60 2.4 11.0 14.5 0.0604 0.0138 12.49 3.40 0.0034 15.34
480 10.0 9 -2.60 2.4 11.0 14.5 0.0302 0.0138 12.49 3.40 0.0024 15.34
1440 10.0 9 -2.60 2.4 11.0 14.5 0.0101 0.0138 12.49 3.40 0.0014 15.34
2880 10.0 9 -2.60 2.4 11.0 14.5 0.0050 0.0138 12.49 3.40 0.0010 15.34
111
Table B11: Consolidation test data of 5% mill tailings sample (self-weight)
Elapsed Time (min) Interface height (cm) Solids content (%) Void Ratio
0.1 10.00 37.80 4.54
1 9.85 38.16 4.47
2 9.80 38.28 4.45
3 9.80 38.28 4.45
4 9.75 38.40 4.43
5 9.75 38.40 4.43
6 9.75 38.40 4.43
7 9.70 38.52 4.41
8 9.70 38.52 4.41
9 9.70 38.52 4.41
10 9.70 38.52 4.41
20 9.60 38.76 4.36
30 9.50 39.01 4.31
40 9.45 39.14 4.29
50 9.35 39.39 4.25
60 9.30 39.52 4.22
70 9.20 39.78 4.18
80 9.15 39.91 4.16
90 9.05 40.17 4.11
100 9.00 40.31 4.09
200 8.3 42.27 3.77
300 7.90 43.48 3.59
400 7.75 43.95 3.52
500 7.70 44.11 3.50
1000 7.6 44.43 3.45
1200 7.6 44.43 3.45
1440 7.6 44.43 3.45
112
Table B12: Consolidation test data of 5% mill tailings sample (σ' = 1.05 kPa)
Elapsed Time (min) Interface height (cm) Solids content (%) Void Ratio
0.1 7.60 44.98 3.45
1 7.60 44.45 3.45
2 7.59 44.46 3.45
3 7.59 44.48 3.45
4 7.57 44.53 3.44
5 7.55 44.61 3.43
6 7.54 44.64 3.42
7 7.53 44.67 3.42
8 7.52 44.71 3.41
9 7.50 44.77 3.40
10 7.49 44.82 3.40
20 7.37 45.21 3.34
30 7.28 45.50 3.31
40 7.21 45.75 3.27
50 7.15 45.94 3.25
60 7.10 46.13 3.22
70 7.06 46.27 3.20
80 7.02 46.40 3.19
90 6.99 46.52 3.17
100 6.96 46.63 3.16
200 6.81 47.17 3.09
300 6.78 47.27 3.08
400 6.77 47.32 3.07
500 6.76 47.35 3.07
1000 6.74 47.41 3.06
1200 6.74 47.41 3.06
1440 6.74 47.42 3.06
2880 6.73 47.45 3.06
113
Table B13: Consolidation test data of 5% mill tailings sample (σ' = 2.14 kPa)
Elapsed Time (min) Interface height (cm) Solids content (%) Void Ratio
0.1 6.73 47.45 3.06
1 6.72 47.47 3.05
2 6.72 47.49 3.05
3 6.71 47.51 3.05
4 6.70 47.53 3.05
5 6.70 47.55 3.04
6 6.70 47.56 3.04
7 6.69 47.58 3.04
8 6.69 47.59 3.04
9 6.68 47.61 3.04
10 6.68 47.61 3.04
20 6.65 47.72 3.02
30 6.63 47.80 3.01
40 6.62 47.86 3.01
50 6.60 47.91 3.00
60 6.59 47.95 3.00
70 6.58 47.98 2.99
80 6.58 48.01 2.99
90 6.57 48.03 2.99
100 6.57 48.04 2.98
200 6.55 48.13 2.97
300 6.54 48.15 2.97
400 6.54 48.17 2.97
500 6.53 48.18 2.97
1000 6.52 48.22 2.96
1200 6.52 48.22 2.96
1440 6.52 48.23 2.96
2880 6.52 48.24 2.96
114
Table B14: Consolidation test data of 5% mill tailings sample (σ' = 4.17 kPa)
Elapsed Time (min) Interface height (cm) Solids content (%) Void Ratio
0.1 6.52 48.24 2.96
1 6.52 48.22 2.96
2 6.51 48.28 2.96
3 6.50 48.30 2.95
4 6.50 48.31 2.95
5 6.50 48.33 2.95
6 6.49 48.34 2.95
7 6.49 48.35 2.95
8 6.49 48.35 2.95
9 6.49 48.35 2.95
10 6.49 48.36 2.95
20 6.47 48.43 2.94
30 6.45 48.49 2.93
40 6.44 48.53 2.93
50 6.43 48.57 2.92
60 6.43 48.59 2.92
70 6.42 48.62 2.92
80 6.42 48.64 2.91
90 6.41 48.65 2.91
100 6.41 48.67 2.91
200 6.39 48.75 2.90
300 6.38 48.78 2.90
400 6.38 48.79 2.90
500 6.37 48.81 2.90
1000 6.37 48.84 2.89
1200 6.36 48.85 2.89
1440 6.36 48.85 2.89
2880 6.35 48.88 2.89
115
Table B15: Consolidation test data of 5% mill tailings sample (σ' = 8.55 kPa)
Elapsed Time (min) Interface height (cm) Solids content (%) Void Ratio
0.1 6.36 48.88 2.89
1 6.34 48.90 2.88
2 6.33 48.93 2.88
3 6.33 48.95 2.88
4 6.32 48.97 2.88
5 6.32 48.99 2.87
6 6.31 49.01 2.87
7 6.31 49.03 2.87
8 6.31 49.04 2.87
9 6.30 49.05 2.87
10 6.30 49.07 2.86
20 6.29 49.09 2.86
30 6.29 49.10 2.86
40 6.29 49.11 2.86
50 6.28 49.14 2.86
60 6.28 49.16 2.85
70 6.27 49.18 2.85
80 6.27 49.19 2.85
90 6.27 49.20 2.85
100 6.27 49.20 2.85
200 6.25 49.25 2.84
300 6.25 49.28 2.84
400 6.24 49.29 2.84
500 6.24 49.30 2.84
1000 6.24 49.32 2.84
1200 6.23 49.33 2.83
1440 6.23 49.34 2.83
2880 6.23 49.34 2.83
116
Table B16: Hydraulic conductivity test data of 5% mill tailings sample (self-weight)
Elapsed time
Sample height (cm)
a (sq.cm)
A (sq.cm)
Initial head at burette, h1 (cm)
Initial time,
t1 (sec)
Final head at burette, h2 (cm)
Final time,
t2 (sec)
Hydraulic Conductivity
(m/Sec)
0 7.6 1.5 78.54 - - - - -
1 7.6 1.5 78.54 51.3 0 50.6 60 3.16×10-07
2 7.6 1.5 78.54 50.6 60 50.0 120 2.88×10-07
3 7.6 1.5 78.54 50.0 120 49.5 180 2.59×10-07
4 7.6 1.5 78.54 49.5 180 49.1 240 1.96×10-07
5 7.6 1.5 78.54 49.1 240 48.8 300 1.65×10-07
6 7.6 1.5 78.54 48.8 300 48.4 360 1.99×10-07
7 7.6 1.5 78.54 48.4 360 47.9 420 2.35×10-07
8 7.6 1.5 78.54 47.9 420 47.6 480 1.69×10-07
9 7.6 1.5 78.54 47.6 480 47.2 540 2.04×10-07
10 7.6 1.5 78.54 47.2 540 46.8 600 1.89×10-07
12 7.6 1.5 78.54 46.8 600 46.2 720 1.47×10-07
14 7.6 1.5 78.54 46.2 720 45.6 840 1.76×10-07
16 7.6 1.5 78.54 45.6 840 45.0 960 1.51×10-07
18 7.6 1.5 78.54 45.0 960 44.3 1080 1.81×10-07
20 7.6 1.5 78.54 44.3 1080 43.8 1200 1.56×10-07
22 7.6 1.5 78.54 43.8 1200 43.2 1320 1.67×10-07
24 7.6 1.5 78.54 43.2 1320 42.6 1440 1.50×10-07
26 7.6 1.5 78.54 42.6 1440 42.0 1560 1.71×10-07
28 7.6 1.5 78.54 42.0 1560 41.5 1680 1.54×10-07
30 7.6 1.5 78.54 41.5 1680 41.0 1800 1.50×10-07
35 7.6 1.5 78.54 41.0 1800 39.7 2100 1.50×10-07
40 7.6 1.5 78.54 39.7 2100 38.5 2400 1.50×10-07
45 7.6 1.5 78.54 38.5 2400 37.3 2700 1.50×10-07
50 7.6 1.5 78.54 37.3 2700 36.1 3000 1.50×10-07
55 7.6 1.5 78.54 36.1 3000 35.0 3300 1.50×10-07
60 7.6 1.5 78.54 35.0 3300 33.9 3600 1.50×10-07
117
Table B17: Hydraulic conductivity test data of 5% mill tailings sample (σ' = 1.05 kPa)
Elapsed time
Sample height (cm)
a (sq.cm)
A (sq.cm)
Initial head at burette, h1 (cm)
Initial time,
t1 (sec)
Final head at burette, h2 (cm)
Final time,
t2 (sec)
Hydraulic Conductivity
(m/Sec)
0 6.7 1.5 78.54 - - - - -
1 6.7 1.5 78.54 51.3 0 50.9 60 1.68×10-07
2 6.7 1.5 78.54 50.9 60 50.7 120 8.43×10-08
3 6.7 1.5 78.54 50.7 120 50.5 180 8.47×10-08
4 6.7 1.5 78.54 50.5 180 50.3 240 7.08×10-08
5 6.7 1.5 78.54 50.3 240 50.1 300 8.53×10-08
6 6.7 1.5 78.54 50.1 300 50.0 360 7.13×10-08
7 6.7 1.5 78.54 50.0 360 49.8 420 8.59×10-08
8 6.7 1.5 78.54 49.8 420 49.6 480 7.19×10-08
9 6.7 1.5 78.54 49.6 480 49.4 540 7.21×10-08
10 6.7 1.5 78.54 49.4 540 49.2 600 8.68×10-08
12 6.7 1.5 78.54 49.2 600 48.9 720 6.55×10-08
14 6.7 1.5 78.54 48.9 720 48.6 840 8.06×10-08
16 6.7 1.5 78.54 48.6 840 48.3 960 6.64×10-08
18 6.7 1.5 78.54 48.3 960 47.9 1080 8.17×10-08
20 6.7 1.5 78.54 47.9 1080 47.6 1200 7.48×10-08
22 6.7 1.5 78.54 47.6 1200 47.2 1320 8.29×10-08
24 6.7 1.5 78.54 47.2 1320 46.9 1440 7.59×10-08
26 6.7 1.5 78.54 46.9 1440 46.5 1560 7.65×10-08
28 6.7 1.5 78.54 46.5 1560 46.2 1680 7.70×10-08
30 6.7 1.5 78.54 46.2 1680 45.9 1800 7.91×10-08
35 6.7 1.5 78.54 45.9 1800 45.0 2100 7.86×10-08
40 6.7 1.5 78.54 45.0 2100 44.2 2400 7.81×10-08
45 6.7 1.5 78.54 44.2 2400 43.4 2700 7.82×10-08
50 6.7 1.5 78.54 43.4 2700 42.6 3000 7.90×10-08
55 6.7 1.5 78.54 42.6 3000 41.8 3300 7.98×10-08
60 6.7 1.5 78.54 41.8 3300 41.1 3600 7.92×10-08
118
Table B18: Hydraulic conductivity test data of 5% mill tailings sample (σ' = 2.14 kPa)
Elapsed time
Sample height (cm)
a (sq.cm)
A (sq.cm)
Initial head at burette, h1 (cm)
Initial time,
t1 (sec)
Final head at burette, h2 (cm)
Final time,
t2 (sec)
Hydraulic Conductivity
(m/Sec)
0 6.5 1.5 78.54 - - - - -
1 6.5 1.5 78.54 51.2 0.0 50.9 60 1.08×10-07
2 6.5 1.5 78.54 50.9 60.0 50.7 120 8.17×10-08
3 6.5 1.5 78.54 50.7 120.0 50.6 180 6.83×10-08
4 6.5 1.5 78.54 50.6 180.0 50.4 240 6.85×10-08
5 6.5 1.5 78.54 50.4 240.0 50.3 300 5.50×10-08
6 6.5 1.5 78.54 50.3 300.0 50.1 360 5.51×10-08
7 6.5 1.5 78.54 50.1 360.0 50.0 420 5.53×10-08
8 6.5 1.5 78.54 50.0 420.0 49.9 480 5.54×10-08
9 6.5 1.5 78.54 49.9 480.0 49.7 540 5.56×10-08
10 6.5 1.5 78.54 49.7 540.0 49.6 600 5.57×10-08
12 6.5 1.5 78.54 49.6 600.0 49.4 720 4.89×10-08
14 6.5 1.5 78.54 49.4 720.0 49.1 840 6.33×10-08
16 6.5 1.5 78.54 49.1 840.0 48.8 960 5.65×10-08
18 6.5 1.5 78.54 48.8 960.0 48.5 1080 6.40×10-08
20 6.5 1.5 78.54 48.5 1080.0 48.3 1200 5.00×10-08
22 6.5 1.5 78.54 48.3 1200.0 48.0 1320 6.47×10-08
24 6.5 1.5 78.54 48.0 1320.0 47.7 1440 5.06×10-08
26 6.5 1.5 78.54 47.7 1440.0 47.4 1560 6.54×10-08
28 6.5 1.5 78.54 47.4 1560.0 47.2 1680 5.12×10-08
30 6.5 1.5 78.54 47.2 1680.0 46.9 1800 5.73×10-08
35 6.5 1.5 78.54 46.9 1800.0 46.3 2100 5.70×10-08
40 6.5 1.5 78.54 46.3 2100.0 45.7 2400 5.72×10-08
45 6.5 1.5 78.54 45.7 2400.0 45.0 2700 5.80×10-08
50 6.5 1.5 78.54 45.0 2700.0 44.4 3000 5.75×10-08
55 6.5 1.5 78.54 44.4 3000.0 43.8 3300 5.77×10-08
60 6.5 1.5 78.54 43.8 3300.0 43.2 3600 5.73×10-08
119
Table B19: Hydraulic conductivity test data of 5% mill tailings sample (σ' = 4.17 kPa)
Elapsed time
Sample height (cm)
a (sq.cm)
A (sq.cm)
Initial head at burette, h1 (cm)
Initial time,
t1 (sec)
Final head at burette, h2 (cm)
Final time,
t2 (sec)
Hydraulic Conductivity
(m/Sec)
0 6.4 1.5 78.54 - - - - -
1 6.4 1.5 78.54 51.2 0.0 51.0 60 9.23×10-08
2 6.4 1.5 78.54 51.0 60.0 50.8 120 6.62×10-08
3 6.4 1.5 78.54 50.8 120.0 50.6 180 6.64×10-08
4 6.4 1.5 78.54 50.6 180.0 50.5 240 6.13×10-08
5 6.4 1.5 78.54 50.5 240.0 50.3 300 5.88×10-08
6 6.4 1.5 78.54 50.3 300.0 50.2 360 5.36×10-08
7 6.4 1.5 78.54 50.2 360.0 50.1 420 5.38×10-08
8 6.4 1.5 78.54 50.1 420.0 49.9 480 5.39×10-08
9 6.4 1.5 78.54 49.9 480.0 49.8 540 5.40×10-08
10 6.4 1.5 78.54 49.8 540.0 49.7 600 5.42×10-08
12 6.4 1.5 78.54 49.7 600.0 49.4 720 5.44×10-08
14 6.4 1.5 78.54 49.4 720.0 49.2 840 4.78×10-08
16 6.4 1.5 78.54 49.2 840.0 48.9 960 4.81×10-08
18 6.4 1.5 78.54 48.9 960.0 48.7 1080 4.14×10-08
20 6.4 1.5 78.54 48.7 1080.0 48.5 1200 4.85×10-08
22 6.4 1.5 78.54 48.5 1200.0 48.3 1320 4.18×10-08
24 6.4 1.5 78.54 48.3 1320.0 48.1 1440 4.89×10-08
26 6.4 1.5 78.54 48.1 1440.0 47.9 1560 4.21×10-08
28 6.4 1.5 78.54 47.9 1560.0 47.6 1680 5.65×10-08
30 6.4 1.5 78.54 47.6 1680.0 47.4 1800 4.97×10-08
35 6.4 1.5 78.54 47.4 1800.0 46.8 2100 4.98×10-08
40 6.4 1.5 78.54 46.8 2100.0 46.2 2400 5.10×10-08
45 6.4 1.5 78.54 46.2 2400.0 45.6 2700 4.99×10-08
50 6.4 1.5 78.54 45.6 2700.0 45.1 3000 5.05×10-08
55 6.4 1.5 78.54 45.1 3000.0 44.5 3300 4.99×10-08
60 6.4 1.5 78.54 44.5 3300.0 44.0 3600 5.00×10-08
120
Table B20: Hydraulic conductivity test data of 5% mill tailings sample (σ' = 8.55 kPa)
Elapsed time
Sample height (cm)
a (sq.cm)
A (sq.cm)
Initial head at burette, h1 (cm)
Initial time,
t1 (sec)
Final head at burette, h2 (cm)
Final time,
t2 (sec)
Hydraulic Conductivity
(m/Sec)
0 6.2 1.5 78.54 - - - - -
1 6.2 1.5 78.54 51.2 0.0 51.0 60 7.76×10-08
2 6.2 1.5 78.54 51.0 60.0 50.9 120 5.19×10-08
3 6.2 1.5 78.54 50.9 120.0 50.8 180 3.90×10-08
4 6.2 1.5 78.54 50.8 180.0 50.7 240 3.91×10-08
5 6.2 1.5 78.54 50.7 240.0 50.5 300 5.23×10-08
6 6.2 1.5 78.54 50.5 300.0 50.4 360 3.93×10-08
7 6.2 1.5 78.54 50.4 360.0 50.3 420 3.94×10-08
8 6.2 1.5 78.54 50.3 420.0 50.2 480 5.26×10-08
9 6.2 1.5 78.54 50.2 480.0 50.1 540 3.95×10-08
10 6.2 1.5 78.54 50.1 540.0 50.0 600 4.49×10-08
12 6.2 1.5 78.54 50.0 600.0 49.8 720 3.71×10-08
14 6.2 1.5 78.54 49.8 720.0 49.6 840 4.66×10-08
16 6.2 1.5 78.54 49.6 840.0 49.4 960 3.34×10-08
18 6.2 1.5 78.54 49.4 960.0 49.2 1080 4.02×10-08
20 6.2 1.5 78.54 49.2 1080.0 49.0 1200 4.71×10-08
22 6.2 1.5 78.54 49.0 1200.0 48.8 1320 3.38×10-08
24 6.2 1.5 78.54 48.8 1320.0 48.6 1440 4.07×10-08
26 6.2 1.5 78.54 48.6 1440.0 48.4 1560 3.41×10-08
28 6.2 1.5 78.54 48.4 1560.0 48.2 1680 4.79×10-08
30 6.2 1.5 78.54 48.2 1680.0 48.0 1800 4.12×10-08
35 6.2 1.5 78.54 48.0 1800.0 47.5 2100 4.15×10-08
40 6.2 1.5 78.54 47.5 2100.0 47.0 2400 4.20×10-08
45 6.2 1.5 78.54 47.0 2400.0 46.5 2700 4.24×10-08
50 6.2 1.5 78.54 46.5 2700.0 46.0 3000 4.29×10-08
55 6.2 1.5 78.54 46.0 3000.0 45.5 3300 4.33×10-08
60 6.2 1.5 78.54 45.5 3300.0 45.0 3600 4.38×10-08
121
APPENDIX C
Laboratory test data of 6% mill tailings sample
Table C1: Vane shear test data of 6% mill tailings sample
Test No
Max. Angular Rotation
(Deg)
Height, H (mm)
Width, D (mm)
Vane Constant, K (mm3)
Spring No
Calibration factor
(N-mm/Deg)
Torque, M
(N-mm)
Yield stress
τ (kPa)
Weight (gm)
Water content, w (%)
Solid content,
s (%) Can
Can + wet slurry
Can + Dry
slurry
1 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 15.84 15.54 28.04 17.52 531.31
2 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 20.89 15.52 26.34 17.78 378.76
3 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 25.67 15.54 27.54 18.62 289.61
4 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 30.55 15.49 40.92 23.26 227.28
5 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 32.84 15.53 34.53 21.77 204.49
6 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 35.68 15.54 26.78 19.55 180.30
7 0.5 12.7 12.7 4290.12 1 0.89 0.45 0.10 62.21 31.92 85.00 64.94 60.75
8 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 60.89 31.65 79.59 60.84 64.23
9 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 61.99 31.84 95.95 71.58 61.32
10 0 12.7 12.7 4290.12 1 0.89 0.00 0.00 61.01 31.45 87.75 65.80 63.90
11 7 12.7 12.7 4290.12 2 1.71 11.97 2.79 67.22 31.92 77.71 62.70 48.77
12 2.5 12.7 12.7 4290.12 2 1.71 4.28 1.00 62.45 32.02 77.13 60.19 60.13
13 16 12.7 12.7 4290.12 2 1.71 27.36 6.38 70.39 31.5 74.7 61.91 42.06
14 58 12.7 12.7 4290.12 2 1.71 99.18 23.12 72.43 31.87 73.98 62.37 38.07
15 10.5 12.7 12.7 4290.12 2 1.71 17.96 4.19 70.02 31.75 80.89 66.16 42.81
16 8.5 12.7 12.7 4290.12 2 1.71 14.54 3.39 68.27 31.92 75.38 61.59 46.48
17 25.5 12.7 12.7 4290.12 2 1.71 43.61 10.16 71.10 31.49 84.05 68.86 40.65
122
Table C2: Self-weight settling test data of 6% mill tailings sample
Test condition si = 20% si = 15.2%
Elapsed time (min) Interface height (cm) Interface height (cm)
0.1 8.50 8.50
1 8.20 8.10
2 8.00 7.85
3 7.70 7.55
4 7.50 7.30
5 7.30 7.10
6 7.10 6.85
7 6.90 6.60
8 6.60 6.35
9 6.30 6.10
10 6.10 5.80
20 5.20 4.70
30 4.90 4.30
40 4.70 4.10
50 4.50 4.00
60 4.45 3.85
70 4.40 3.80
80 4.35 3.70
90 4.35 3.65
100 4.30 3.65
200 4.20 3.60
300 4.10 3.55
400 4.10 3.50
500 4.10 3.50
1000 4.10 3.50
1200 4.10 3.50
1440 4.10 3.50
123
Table C3: Segregation test data of 6% mill tailings sample (si = 20%)
Layer depth (cm) Weight (g) w (%) s (%)
From To can + wet can + dry can water solid
4.10 3.42 81.90 39.67 31.85 42.23 7.82 5.40 15.62
3.42 2.73 76.94 42.40 31.73 34.54 10.67 3.24 23.60
2.73 2.05 75.94 45.14 31.93 30.80 13.21 2.33 30.02
2.05 1.37 72.77 45.78 31.87 26.99 13.91 1.94 34.01
1.37 0.68 86.85 53.04 31.64 33.81 21.40 1.58 38.76
0.68 0.00 85.29 65.40 32.04 19.89 33.36 0.60 62.65
Table C4: Segregation test data of 6% mill tailings sample (si = 15.2%)
Layer depth (cm) Weight (g) w (%) s (%)
From To can + wet can + dry can water solid
3.50 2.92 76.61 38.28 31.86 38.33 6.42 5.97 14.35
2.92 2.33 69.00 39.89 31.75 29.11 8.14 3.58 21.85
2.33 1.75 76.12 43.11 31.93 33.01 11.18 2.95 25.30
1.75 1.17 63.36 41.13 31.86 22.23 9.27 2.40 29.43
1.17 0.58 75.40 50.38 32.02 25.02 18.36 1.36 42.32
0.58 0.00 73.56 58.90 31.63 14.66 27.27 0.54 65.04
124
Table C5: Grain size analysis (sieve and hydrometer) of 6% mill tailings sample at si = 20.0% (top layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 92.62 92.62 0.00 0.00 0.00 100.00
18 92.62 92.62 0.00 0.00 0.00 100.00
40 96.83 96.85 0.02 0.10 0.10 99.90
70 106.03 106.06 0.03 0.16 0.26 99.74
100 87.52 87.55 0.03 0.16 0.42 99.58
140 116.90 117.14 0.24 1.25 1.67 98.33
200 92.71 93.32 0.61 3.19 4.86 95.14
pan 126.42 144.64 18.22
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 19.0 18 -0.35 13.7 20.0 13.0 26.0360 0.0138 71.04 67.59 0.0704 100.00
1 17.0 18 -0.35 11.7 18.0 13.3 13.3462 0.0138 60.64 57.69 0.0504 85.35
2 16.0 18 -0.35 10.7 17.0 13.5 6.7552 0.0138 55.43 52.74 0.0359 78.02
4 15.0 18 -0.35 9.7 16.0 13.7 3.4186 0.0138 50.23 47.79 0.0255 70.70
8 13.0 18 -0.35 7.7 14.0 14.0 1.7503 0.0138 39.82 37.88 0.0183 56.04
15 12.0 18 -0.35 6.7 13.0 14.2 0.9444 0.0138 34.61 32.93 0.0134 48.72
30 11.0 18 -0.35 5.7 12.0 14.3 0.4777 0.0138 29.41 27.98 0.0095 41.39
60 10.0 18 -0.35 4.7 11.0 14.5 0.2416 0.0138 24.20 23.03 0.0068 34.07
120 9.0 18 -0.35 3.7 10.0 14.7 0.1222 0.0138 19.00 18.07 0.0048 26.74
240 9.0 18 -0.35 3.7 10.0 14.7 0.0611 0.0138 19.00 18.07 0.0034 26.74
480 9.0 18 -0.35 3.7 10.0 14.7 0.0305 0.0138 19.00 18.07 0.0024 26.74
1440 9.0 18 -0.35 3.7 10.0 14.7 0.0102 0.0138 19.00 18.07 0.0014 26.74
2880 9.0 18 -0.35 3.7 10.0 14.7 0.0051 0.0138 19.00 18.07 0.0010 26.74
125
Table C6: Grain size analysis (sieve and hydrometer) of 6% mill tailings sample at si = 20.0% (mid layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 92.62 92.62 0.00 0.00 0.00 100.00
18 92.62 92.62 0.00 0.00 0.00 100.00
40 96.84 96.87 0.03 0.11 0.11 99.89
70 106.00 106.85 0.85 3.07 3.17 96.83
100 87.48 88.92 1.44 5.19 8.37 91.63
140 116.89 119.32 2.43 8.76 17.13 82.87
200 92.69 95.82 3.13 11.29 28.42 71.58
pan 473.03 492.88 19.85
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 20.0 18 -0.35 14.7 21.0 12.9 25.7078 0.0138 76.25 54.58 0.0700 100.00
1 18.0 18 -0.35 12.7 19.0 13.2 13.1821 0.0138 65.84 47.13 0.0501 86.35
2 17.0 18 -0.35 11.7 18.0 13.3 6.6731 0.0138 60.64 43.40 0.0356 79.52
4 16.0 18 -0.35 10.7 17.0 13.5 3.3776 0.0138 55.43 39.68 0.0254 72.70
8 15.0 18 -0.35 9.7 16.0 13.7 1.7093 0.0138 50.23 35.95 0.0180 65.87
15 13.0 18 -0.35 7.7 14.0 14.0 0.9335 0.0138 39.82 28.50 0.0133 52.22
30 12.0 18 -0.35 6.7 13.0 14.2 0.4722 0.0138 34.61 24.78 0.0095 45.39
60 11.0 18 -0.35 5.7 12.0 14.3 0.2388 0.0138 29.41 21.05 0.0067 38.57
120 10.0 18 -0.35 4.7 11.0 14.5 0.1208 0.0138 24.20 17.32 0.0048 31.74
240 10.0 18 -0.35 4.7 11.0 14.5 0.0604 0.0138 24.20 17.32 0.0034 31.74
480 10.0 18 -0.35 4.7 11.0 14.5 0.0302 0.0138 24.20 17.32 0.0024 31.74
1440 10.0 18 -0.35 4.7 11.0 14.5 0.0101 0.0138 24.20 17.32 0.0014 31.74
2880 10.0 18 -0.35 4.7 11.0 14.5 0.0050 0.0138 24.20 17.32 0.0010 31.74
126
Table C7: Grain size analysis (sieve and hydrometer) of 6% mill tailings sample at si = 20.0% (bottom layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 92.62 92.62 0.00 0.00 0.00 100.00
18 92.62 92.62 0.00 0.00 0.00 100.00
40 96.84 97.41 0.57 1.03 1.03 98.97
70 106.00 120.84 14.84 26.77 27.80 72.20
100 87.48 96.63 9.15 16.51 44.31 55.69
140 116.89 123.81 6.92 12.48 56.79 43.21
200 92.69 97.57 4.88 8.80 65.60 34.40
pan 118.97 138.04 19.07
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 21.0 14 -1.35 14.7 22.0 12.7 25.3796 0.0138 76.25 26.23 0.0695 100.00
1 19.0 13 -1.60 12.4 20.0 13.0 13.0180 0.0138 64.54 22.20 0.0498 84.64
2 18.0 12 -1.85 11.2 19.0 13.2 6.5911 0.0138 58.03 19.97 0.0354 76.11
4 17.0 11 -2.10 9.9 18.0 13.3 3.3366 0.0138 51.53 17.73 0.0252 67.58
8 15.0 10 -2.35 7.7 16.0 13.7 1.7093 0.0138 39.82 13.70 0.0180 52.22
15 14.0 10 -2.35 6.7 15.0 13.8 0.9226 0.0138 34.61 11.91 0.0133 45.39
30 12.0 10 -2.35 4.7 13.0 14.2 0.4722 0.0138 24.20 8.33 0.0095 31.74
60 11.0 10 -2.35 3.7 12.0 14.3 0.2388 0.0138 19.00 6.54 0.0067 24.91
120 11.0 9 -2.60 3.4 12.0 14.3 0.1194 0.0138 17.70 6.09 0.0048 23.21
240 10.0 9 -2.60 2.4 11.0 14.5 0.0604 0.0138 12.49 4.30 0.0034 16.38
480 10.0 9 -2.60 2.4 11.0 14.5 0.0302 0.0138 12.49 4.30 0.0024 16.38
1440 10.0 9 -2.60 2.4 11.0 14.5 0.0101 0.0138 12.49 4.30 0.0014 16.38
2880 10.0 9 -2.60 2.4 11.0 14.5 0.0050 0.0138 12.49 4.30 0.0010 16.38
127
Table C8: Grain size analysis (sieve and hydrometer) of 6% mill tailings sample at si = 15.2% (top layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 92.62 92.62 0.00 0.00 0.00 100.00
18 92.62 92.62 0.00 0.00 0.00 100.00
40 96.86 96.86 0.00 0.00 0.00 100.00
70 106.01 106.02 0.01 0.08 0.08 99.92
100 87.52 87.56 0.04 0.31 0.39 99.61
140 116.92 116.99 0.07 0.55 0.94 99.06
200 92.69 93.13 0.44 3.45 4.39 95.61
pan 473.04 485.23 12.19
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 20.0 18 -0.35 14.7 21.0 12.9 25.7078 0.0138 76.25 72.90 0.0700 100.00
1 18.0 18 -0.35 12.7 19.0 13.2 13.1821 0.0138 65.84 62.95 0.0501 86.35
2 16.0 18 -0.35 10.7 17.0 13.5 6.7552 0.0138 55.43 53.00 0.0359 72.70
4 15.0 18 -0.35 9.7 16.0 13.7 3.4186 0.0138 50.23 48.02 0.0255 65.87
8 13.0 18 -0.35 7.7 14.0 14.0 1.7503 0.0138 39.82 38.07 0.0183 52.22
15 12.0 18 -0.35 6.7 13.0 14.2 0.9444 0.0138 34.61 33.09 0.0134 45.39
30 11.0 18 -0.35 5.7 12.0 14.3 0.4777 0.0138 29.41 28.12 0.0095 38.57
60 10.0 18 -0.35 4.7 11.0 14.5 0.2416 0.0138 24.20 23.14 0.0068 31.74
120 9.0 18 -0.35 3.7 10.0 14.7 0.1222 0.0138 19.00 18.16 0.0048 24.91
240 9.0 18 -0.35 3.7 10.0 14.7 0.0611 0.0138 19.00 18.16 0.0034 24.91
480 9.0 18 -0.35 3.7 10.0 14.7 0.0305 0.0138 19.00 18.16 0.0024 24.91
1440 9.0 18 -0.35 3.7 10.0 14.7 0.0102 0.0138 19.00 18.16 0.0014 24.91
2880 9.0 18 -0.35 3.7 10.0 14.7 0.0051 0.0138 19.00 18.16 0.0010 24.91
128
Table C9: Grain size analysis (sieve and hydrometer) of 6% mill tailings sample at si = 15.2% (mid layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 92.62 92.62 0.00 0.00 0.00 100.00
18 92.62 92.62 0.00 0.00 0.00 100.00
40 96.86 96.89 0.03 0.13 0.13 99.87
70 106.01 106.27 0.26 1.12 1.25 98.75
100 87.52 87.96 0.44 1.90 3.15 96.85
140 116.92 118.59 1.67 7.21 10.37 89.63
200 92.69 94.84 2.15 9.29 19.65 80.35
pan 126.42 145.02 18.60
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 21.0 18 -0.35 15.7 22.0 12.7 25.3796 0.0138 81.45 65.44 0.0695 100.00
1 19.0 18 -0.35 13.7 20.0 13.0 13.0180 0.0138 71.04 57.08 0.0498 87.22
2 18.0 18 -0.35 12.7 19.0 13.2 6.5911 0.0138 65.84 52.90 0.0354 80.83
4 17.0 18 -0.35 11.7 18.0 13.3 3.3366 0.0138 60.64 48.72 0.0252 74.44
8 15.0 18 -0.35 9.7 16.0 13.7 1.7093 0.0138 50.23 40.35 0.0180 61.66
15 14.0 18 -0.35 8.7 15.0 13.8 0.9226 0.0138 45.02 36.17 0.0133 55.27
30 12.0 18 -0.35 6.7 13.0 14.2 0.4722 0.0138 34.61 27.81 0.0095 42.49
60 11.0 18 -0.35 5.7 12.0 14.3 0.2388 0.0138 29.41 23.63 0.0067 36.10
120 10.0 18 -0.35 4.7 11.0 14.5 0.1208 0.0138 24.20 19.45 0.0048 29.71
240 10.0 18 -0.35 4.7 11.0 14.5 0.0604 0.0138 24.20 19.45 0.0034 29.71
480 10.0 18 -0.35 4.7 11.0 14.5 0.0302 0.0138 24.20 19.45 0.0024 29.71
1440 10.0 18 -0.35 4.7 11.0 14.5 0.0101 0.0138 24.20 19.45 0.0014 29.71
2880 10.0 18 -0.35 4.7 11.0 14.5 0.0050 0.0138 24.20 19.45 0.0010 29.71
129
Table C10: Grain size analysis (sieve and hydrometer) of 6% mill tailings sample at si = 15.2% (bottom layer)
Sieve# Tare Dry mass % retained Cumulative % Passing
4 92.62 92.62 0.00 0.00 0.00 100.00
10 92.62 92.62 0.00 0.00 0.00 100.00
18 92.62 92.62 0.00 0.00 0.00 100.00
40 96.86 97.50 0.64 1.39 1.39 98.61
70 106.01 119.14 13.13 28.47 29.86 70.14
100 87.52 95.15 7.63 16.54 46.40 53.60
140 116.92 123.72 6.80 14.74 61.14 38.86
200 92.69 98.31 5.62 12.19 73.33 26.67
pan 119.00 131.30 12.30
Elapsed Hydrometer Temp Ct Corr. Hyd. Hyd. Corr. only Eff. Depth
Adjusted Diameter Percentage
Time (min) Reading (C)
Reading for meniscus L (cm) L/t K % Finer % Finer (mm) of Fine
0
0.5 22.0 14 -1.35 15.7 23.0 12.5 25.0514 0.0138 81.45 21.72 0.0691 100.00
1 20.0 13 -1.60 13.4 21.0 12.9 12.8539 0.0138 69.74 18.60 0.0495 85.62
2 19.0 12 -1.85 12.2 20.0 13.0 6.5090 0.0138 63.24 16.87 0.0352 77.64
4 18.0 11 -2.10 10.9 19.0 13.2 3.2955 0.0138 56.73 15.13 0.0251 69.65
8 16.0 10 -2.35 8.7 17.0 13.5 1.6888 0.0138 45.02 12.01 0.0179 55.27
15 14.0 10 -2.35 6.7 15.0 13.8 0.9226 0.0138 34.61 9.23 0.0133 42.49
30 12.0 10 -2.35 4.7 13.0 14.2 0.4722 0.0138 24.20 6.45 0.0095 29.71
60 11.0 10 -2.35 3.7 12.0 14.3 0.2388 0.0138 19.00 5.07 0.0067 23.32
120 10.0 9 -2.60 2.4 11.0 14.5 0.1208 0.0138 12.49 3.33 0.0048 15.34
240 10.0 9 -2.60 2.4 11.0 14.5 0.0604 0.0138 12.49 3.33 0.0034 15.34
480 10.0 9 -2.60 2.4 11.0 14.5 0.0302 0.0138 12.49 3.33 0.0024 15.34
1440 10.0 9 -2.60 2.4 11.0 14.5 0.0101 0.0138 12.49 3.33 0.0014 15.34
2880 10.0 9 -2.60 2.4 11.0 14.5 0.0050 0.0138 12.49 3.33 0.0010 15.34
130
Table C11: Consolidation test data of 6% mill tailings sample (self-weight)
Elapsed Time (min) Interface height (cm) Solids content (%) Void Ratio
0.1 10.00 37.50 4.57
1 9.90 37.91 4.52
2 9.85 38.03 4.50
3 9.85 38.03 4.50
4 9.85 38.03 4.50
5 9.80 38.15 4.48
6 9.80 38.15 4.48
7 9.80 38.15 4.48
8 9.80 38.15 4.48
9 9.80 38.15 4.48
10 9.80 38.15 4.48
20 9.70 38.39 4.43
30 9.60 38.63 4.38
40 9.50 38.88 4.34
50 9.40 39.13 4.29
60 9.30 39.39 4.25
70 9.20 39.65 4.20
80 9.10 39.91 4.16
90 9.05 40.04 4.13
100 9.00 40.17 4.11
200 8.35 41.99 3.81
300 8.10 42.73 3.70
400 8.05 42.88 3.68
500 8.00 43.04 3.65
1000 8.00 43.04 3.65
1200 8.00 43.04 3.65
1440 8.00 43.04 3.65
131
Table C12: Consolidation test data of 6% mill tailings sample (σ' = 1.08 kPa)
Elapsed Time (min) Interface height (cm) Solids content (%) Void Ratio
0.1 8.00 43.04 3.65
1 8.00 43.06 3.65
2 8.00 43.06 3.65
3 8.00 43.07 3.65
4 8.00 43.07 3.65
5 8.00 43.07 3.65
6 8.00 43.07 3.65
7 8.00 43.07 3.65
8 8.00 43.07 3.65
9 8.00 43.07 3.65
10 8.00 43.07 3.65
20 7.99 43.08 3.65
30 7.97 43.15 3.64
40 7.92 43.29 3.62
50 7.89 43.40 3.60
60 7.86 43.50 3.58
70 7.83 43.59 3.57
80 7.80 43.67 3.56
90 7.79 43.72 3.55
100 7.78 43.75 3.55
200 7.69 44.03 3.51
300 7.66 44.12 3.50
400 7.66 44.14 3.49
500 7.65 44.16 3.49
1000 7.63 44.22 3.48
1200 7.62 44.27 3.47
1440 7.55 44.48 3.44
2880 7.50 44.65 3.42
132
Table C13: Consolidation test data of 6% mill tailings sample (σ' = 2.08 kPa)
Elapsed Time (min) Interface height (cm) Solids content (%) Void Ratio
0.1 74.98 7.50 44.65
1 74.97 7.50 44.66
2 74.96 7.50 44.67
3 74.96 7.50 44.67
4 74.96 7.50 44.67
5 74.96 7.50 44.67
6 74.94 7.49 44.67
7 74.92 7.49 44.68
8 74.91 7.49 44.68
9 74.89 7.49 44.69
10 74.86 7.49 44.70
20 74.65 7.47 44.77
30 74.50 7.45 44.82
40 74.40 7.44 44.85
50 74.30 7.43 44.88
60 74.25 7.42 44.90
70 74.20 7.42 44.92
80 74.17 7.42 44.93
90 74.14 7.41 44.94
100 74.13 7.41 44.94
200 74.02 7.40 44.98
300 73.99 7.40 44.99
400 73.97 7.40 45.00
500 73.95 7.40 45.00
1000 73.92 7.39 45.01
1200 73.90 7.39 45.02
1440 73.89 7.39 45.02
2880 73.84 7.38 45.04
133
Table C14: Consolidation test data of 6% mill tailings sample (σ' = 4.09 kPa)
Elapsed Time (min) Interface height (cm) Solids content (%) Void Ratio
0.1 7.38 45.04 3.37
1 7.38 45.04 3.37
2 7.37 45.08 3.36
3 7.36 45.12 3.36
4 7.35 45.15 3.35
5 7.33 45.19 3.35
6 7.33 45.22 3.34
7 7.32 45.25 3.34
8 7.31 45.28 3.34
9 7.29 45.33 3.33
10 7.28 45.36 3.32
20 7.22 45.57 3.30
30 7.19 45.69 3.28
40 7.17 45.76 3.27
50 7.15 45.81 3.27
60 7.15 45.84 3.26
70 7.14 45.86 3.26
80 7.13 45.88 3.26
90 7.13 45.88 3.26
100 7.13 45.90 3.25
200 7.12 45.94 3.25
300 7.11 45.95 3.25
400 7.11 45.97 3.24
500 7.11 45.97 3.24
1000 7.11 45.97 3.24
1200 7.11 45.97 3.24
1440 7.11 45.97 3.24
2880 7.11 45.97 3.24
134
Table C15: Consolidation test data of 6% mill tailings sample (σ' = 8.25 kPa)
Elapsed Time (min) Interface height (cm) Solids content (%) Void Ratio
0.1 7.11 45.97 3.24
1 7.10 46.01 3.24
2 7.09 46.05 3.23
3 7.07 46.12 3.22
4 7.06 46.15 3.22
5 7.05 46.19 3.22
6 7.05 46.21 3.21
7 7.04 46.24 3.21
8 7.03 46.26 3.21
9 7.03 46.28 3.20
10 7.03 46.27 3.20
20 6.99 46.41 3.19
30 6.97 46.49 3.18
40 6.96 46.52 3.17
50 6.95 46.56 3.17
60 6.94 46.58 3.17
70 6.94 46.59 3.16
80 6.94 46.60 3.16
90 6.93 46.61 3.16
100 6.93 46.62 3.16
200 6.92 46.68 3.15
300 6.91 46.70 3.15
400 6.91 46.72 3.15
500 6.90 46.73 3.15
1000 6.89 46.76 3.14
1200 6.89 46.78 3.14
1440 6.89 46.78 3.14
2880 6.88 46.80 3.14
135
Table C16: Hydraulic conductivity test data of 6% mill tailings sample (self-weight)
Elapsed time
Sample height (cm)
a (sq.cm)
A (sq.cm)
Initial head at burette, h1 (cm)
Initial time, t1 (sec)
Final head at burette, h2 (cm)
Final time, t2 (sec)
Hydraulic Conductivity
(m/Sec)
0 8.0 1.5 78.54 - - - - -
1 8.0 1.5 78.54 51.3 0 49.6 60 8.75×10-07
2 8.0 1.5 78.54 49.6 60 48.4 120 6.24×10-07
3 8.0 1.5 78.54 48.4 120 47.4 180 4.96×10-07
4 8.0 1.5 78.54 47.4 180 46.8 240 3.60×10-07
5 8.0 1.5 78.54 46.8 240 45.9 300 4.76×10-07
6 8.0 1.5 78.54 45.9 300 45.2 360 4.10×10-07
7 8.0 1.5 78.54 45.2 360 44.5 420 3.79×10-07
8 8.0 1.5 78.54 44.5 420 43.7 480 4.62×10-07
9 8.0 1.5 78.54 43.7 480 43.0 540 4.31×10-07
10 8.0 1.5 78.54 43.0 540 42.1 600 4.99×10-07
12 8.0 1.5 78.54 42.1 600 40.6 720 4.62×10-07
14 8.0 1.5 78.54 40.6 720 39.3 840 4.25×10-07
16 8.0 1.5 78.54 39.3 840 37.9 960 4.62×10-07
18 8.0 1.5 78.54 37.9 960 36.5 1080 4.91×10-07
20 8.0 1.5 78.54 36.5 1080 35.3 1200 4.14×10-07
22 8.0 1.5 78.54 35.3 1200 34.1 1320 4.40×10-07
24 8.0 1.5 78.54 34.1 1320 32.8 1440 4.82×10-07
26 8.0 1.5 78.54 32.8 1440 31.6 1560 4.74×10-07
28 8.0 1.5 78.54 31.6 1560 30.5 1680 4.78×10-07
30 8.0 1.5 78.54 30.5 1680 29.4 1800 4.68×10-07
35 8.0 1.5 78.54 29.4 1800 26.8 2100 4.72×10-07
40 8.0 1.5 78.54 26.8 2100 24.4 2400 4.71×10-07
45 8.0 1.5 78.54 24.4 2400 22.2 2700 4.74×10-07
50 8.0 1.5 78.54 22.2 2700 20.3 3000 4.72×10-07
55 8.0 1.5 78.54 20.3 3000 18.5 3300 4.74×10-07
60 8.0 1.5 78.54 18.5 3300 16.8 3600 4.72×10-07
136
Table C17: Hydraulic conductivity test data of 6% mill tailings sample (σ' = 1.08 kPa)
Elapsed time
Sample height (cm)
a (sq.cm)
A (sq.cm)
Initial head at burette, h1 (cm)
Initial time, t1 (sec)
Final head at burette, h2 (cm)
Final time, t2 (sec)
Hydraulic Conductivity
(m/Sec)
0 7.5 1.5 78.54 - - - - -
1 7.5 1.5 78.54 51.3 0 49.6 60 7.88×10-07
2 7.5 1.5 78.54 49.6 60 48.7 120 4.53×10-07
3 7.5 1.5 78.54 48.7 120 48.1 180 2.96×10-07
4 7.5 1.5 78.54 48.1 180 47.5 240 3.00×10-07
5 7.5 1.5 78.54 47.5 240 47.0 300 2.70×10-07
6 7.5 1.5 78.54 47.0 300 46.5 360 2.38×10-07
7 7.5 1.5 78.54 46.5 360 46.0 420 2.75×10-07
8 7.5 1.5 78.54 46.0 420 45.5 480 2.44×10-07
9 7.5 1.5 78.54 45.5 480 45.0 540 2.81×10-07
10 7.5 1.5 78.54 45.0 540 44.4 600 2.85×10-07
12 7.5 1.5 78.54 44.4 600 43.6 720 2.35×10-07
14 7.5 1.5 78.54 43.6 720 42.6 840 2.77×10-07
16 7.5 1.5 78.54 42.6 840 41.8 960 2.26×10-07
18 7.5 1.5 78.54 41.8 960 41.0 1080 2.31×10-07
20 7.5 1.5 78.54 41.0 1080 40.2 1200 2.35×10-07
22 7.5 1.5 78.54 40.2 1200 39.3 1320 2.60×10-07
24 7.5 1.5 78.54 39.3 1320 38.4 1440 2.87×10-07
26 7.5 1.5 78.54 38.4 1440 37.5 1560 2.73×10-07
28 7.5 1.5 78.54 37.5 1560 36.7 1680 2.57×10-07
30 7.5 1.5 78.54 36.7 1680 35.9 1800 2.74×10-07
35 7.5 1.5 78.54 35.9 1800 33.8 2100 2.79×10-07
40 7.5 1.5 78.54 33.8 2100 32.0 2400 2.71×10-07
45 7.5 1.5 78.54 32.0 2400 30.2 2700 2.71×10-07
50 7.5 1.5 78.54 30.2 2700 28.5 3000 2.71×10-07
55 7.5 1.5 78.54 28.5 3000 27.0 3300 2.70×10-07
60 7.5 1.5 78.54 27.0 3300 25.5 3600 2.73×10-07
137
Table C18: Hydraulic conductivity test data of 6% mill tailings sample (σ' = 2.08 kPa)
Elapsed time
Sample height (cm)
a (sq.cm)
A (sq.cm)
Initial head at burette, h1 (cm)
Initial time, t1 (sec)
Final head at burette, h2 (cm)
Final time, t2 (sec)
Hydraulic Conductivity
(m/Sec)
0 7.4 1.5 78.54 - - - - -
1 7.4 1.5 78.54 51.2 0.0 50.5 60 3.39×10-07
2 7.4 1.5 78.54 50.5 60.0 49.9 120 2.50×10-07
3 7.4 1.5 78.54 49.9 120.0 49.5 180 2.21×10-07
4 7.4 1.5 78.54 49.5 180.0 49.1 240 1.91×10-07
5 7.4 1.5 78.54 49.1 240.0 48.6 300 2.24×10-07
6 7.4 1.5 78.54 48.6 300.0 48.2 360 1.94×10-07
7 7.4 1.5 78.54 48.2 360.0 47.9 420 1.63×10-07
8 7.4 1.5 78.54 47.9 420.0 47.5 480 1.97×10-07
9 7.4 1.5 78.54 47.5 480.0 47.0 540 2.32×10-07
10 7.4 1.5 78.54 47.0 540.0 46.6 600 2.01×10-07
12 7.4 1.5 78.54 46.6 600.0 45.9 720 1.86×10-07
14 7.4 1.5 78.54 45.9 720.0 45.1 840 2.07×10-07
16 7.4 1.5 78.54 45.1 840.0 44.5 960 1.57×10-07
18 7.4 1.5 78.54 44.5 960.0 43.8 1080 1.86×10-07
20 7.4 1.5 78.54 43.8 1080.0 43.0 1200 2.08×10-07
22 7.4 1.5 78.54 43.0 1200.0 42.3 1320 1.84×10-07
24 7.4 1.5 78.54 42.3 1320.0 41.6 1440 1.96×10-07
26 7.4 1.5 78.54 41.6 1440.0 40.9 1560 2.18×10-07
28 7.4 1.5 78.54 40.9 1560.0 40.2 1680 1.93×10-07
30 7.4 1.5 78.54 40.2 1680.0 39.5 1800 1.96×10-07
35 7.4 1.5 78.54 39.5 1800.0 38.0 2100 1.90×10-07
40 7.4 1.5 78.54 38.0 2100.0 36.5 2400 1.89×10-07
45 7.4 1.5 78.54 36.5 2400.0 35.0 2700 1.93×10-07
50 7.4 1.5 78.54 35.0 2700.0 33.6 3000 1.96×10-07
55 7.4 1.5 78.54 33.6 3000.0 32.2 3300 1.95×10-07
60 7.4 1.5 78.54 32.2 3300.0 30.9 3600 1.89×10-07
138
Table C19: Hydraulic conductivity test data of 6% mill tailings sample (σ' = 4.09 kPa)
Elapsed time
Sample height (cm)
a (sq.cm)
A (sq.cm)
Initial head at burette, h1 (cm)
Initial time, t1 (sec)
Final head at burette, h2 (cm)
Final time, t2 (sec)
Hydraulic Conductivity
(m/Sec)
0 7.1 1.5 78.54 - - - - -
1 7.1 1.5 78.54 51.2 0.0 50.7 60 2.37×10-07
2 7.1 1.5 78.54 50.7 60.0 50.4 120 1.19×10-07
3 7.1 1.5 78.54 50.4 120.0 50.1 180 1.50×10-07
4 7.1 1.5 78.54 50.1 180.0 49.8 240 1.06×10-07
5 7.1 1.5 78.54 49.8 240.0 49.6 300 1.06×10-07
6 7.1 1.5 78.54 49.6 300.0 49.3 360 1.22×10-07
7 7.1 1.5 78.54 49.3 360.0 49.1 420 1.23×10-07
8 7.1 1.5 78.54 49.1 420.0 48.8 480 1.23×10-07
9 7.1 1.5 78.54 48.8 480.0 48.5 540 1.24×10-07
10 7.1 1.5 78.54 48.5 540.0 48.3 600 1.09×10-07
12 7.1 1.5 78.54 48.3 600.0 47.9 720 1.02×10-07
14 7.1 1.5 78.54 47.9 720.0 47.4 840 1.11×10-07
16 7.1 1.5 78.54 47.4 840.0 46.9 960 1.28×10-07
18 7.1 1.5 78.54 46.9 960.0 46.4 1080 1.13×10-07
20 7.1 1.5 78.54 46.4 1080.0 45.9 1200 1.31×10-07
22 7.1 1.5 78.54 45.9 1200.0 45.4 1320 1.16×10-07
24 7.1 1.5 78.54 45.4 1320.0 45.0 1440 1.00×10-07
26 7.1 1.5 78.54 45.0 1440.0 44.5 1560 1.18×10-07
28 7.1 1.5 78.54 44.5 1560.0 44.1 1680 1.11×10-07
30 7.1 1.5 78.54 44.1 1680.0 43.7 1800 1.12×10-07
35 7.1 1.5 78.54 43.7 1800.0 42.6 2100 1.12×10-07
40 7.1 1.5 78.54 42.6 2100.0 41.5 2400 1.15×10-07
45 7.1 1.5 78.54 41.5 2400.0 40.5 2700 1.10×10-07
50 7.1 1.5 78.54 40.5 2700.0 39.5 3000 1.13×10-07
55 7.1 1.5 78.54 39.5 3000.0 38.5 3300 1.16×10-07
60 7.1 1.5 78.54 38.5 3300.0 37.6 3600 1.11×10-07
139
Table C20: Hydraulic conductivity test data of 6% mill tailings sample (σ' = 8.25 kPa)
Elapsed time
Sample height (cm)
a (sq.cm)
A (sq.cm)
Initial head at burette, h1 (cm)
Initial time, t1 (sec)
Final head at burette, h2 (cm)
Final time, t2 (sec)
Hydraulic Conductivity
(m/Sec)
0 6.9 1.5 78.54 - - - - -
1 6.9 1.5 78.54 51.2 0.0 50.9 60 1.43×10-07
2 6.9 1.5 78.54 50.9 60.0 50.7 120 8.63×10-08
3 6.9 1.5 78.54 50.7 120.0 50.5 180 8.66×10-08
4 6.9 1.5 78.54 50.5 180.0 50.3 240 8.70×10-08
5 6.9 1.5 78.54 50.3 240.0 50.1 300 8.73×10-08
6 6.9 1.5 78.54 50.1 300.0 49.9 360 8.77×10-08
7 6.9 1.5 78.54 49.9 360.0 49.7 420 8.80×10-08
8 6.9 1.5 78.54 49.7 420.0 49.5 480 8.84×10-08
9 6.9 1.5 78.54 49.5 480.0 49.3 540 8.87×10-08
10 6.9 1.5 78.54 49.3 540.0 49.1 600 8.91×10-08
12 6.9 1.5 78.54 49.1 600.0 48.7 720 8.96×10-08
14 6.9 1.5 78.54 48.7 720.0 48.3 840 9.04×10-08
16 6.9 1.5 78.54 48.3 840.0 47.9 960 9.11×10-08
18 6.9 1.5 78.54 47.9 960.0 47.5 1080 9.19×10-08
20 6.9 1.5 78.54 47.5 1080.0 47.1 1200 7.72×10-08
22 6.9 1.5 78.54 47.1 1200.0 46.8 1320 8.55×10-08
24 6.9 1.5 78.54 46.8 1320.0 46.4 1440 7.83×10-08
26 6.9 1.5 78.54 46.4 1440.0 46.1 1560 8.68×10-08
28 6.9 1.5 78.54 46.1 1560.0 45.7 1680 8.91×10-08
30 6.9 1.5 78.54 45.7 1680.0 45.3 1800 8.98×10-08
35 6.9 1.5 78.54 45.3 1800.0 44.4 2100 8.85×10-08
40 6.9 1.5 78.54 44.4 2100.0 43.5 2400 8.97×10-08
45 6.9 1.5 78.54 43.5 2400.0 42.6 2700 8.95×10-08
50 6.9 1.5 78.54 42.6 2700.0 41.8 3000 9.00×10-08
55 6.9 1.5 78.54 41.8 3000.0 40.9 3300 8.97×10-08
60 6.9 1.5 78.54 40.9 3300.0 40.1 3600 8.94×10-08
140
APPENDIX D
Geotechnical index properties, settling test summary, and sample calculation
Table D1: Summary of index properties based on Grain Size Distribution curves (GSD
test data reported by Khaled (2012), reproduced with permission from author)
Sample 4% Mill Tailings 5% Mill Tailings 6% Mill Tailings
Gs 2.70 2.76 2.74
– 0.075 mm, % 29 49 49
– 0.002 mm, % 2 2 3
D10 (mm) 0.029 0.007 0.009
D30 (mm) 0.078 0.029 0.014
D60 (mm) 0.173 0.107 0.121
Cu = (D60/D10) 6.0 15.3 13.4
Cc = {D302/( D60 × D10)} 1.2 1.1 0.2
USCS Soil Classification SM (Silty sands) SM (Silty sands) SM (Silty sands)
Table D2: Settling test summary of 4% mill tailings from this study for si < 25% and
Khaled (2012) for si ≥ 25% (data reproduced with permission from author)
si
(%) Hi
(cm) ei Vs
(cm/s) ki
(cm/s) sf
(%) Hf
(cm) ef SP
(%) σ'f
(Pa)
15.1 8.5 15.52 239×10-3 2.3236 26.47 4.2 7.67 47.52 78.43
20.2 8.5 10.92 30×10-3 1.6766 29.63 5.1 6.55 36.66 109.28
26 8.5 7.86 7×10-3 0.0365 32.16 6.3 5.82 23.02 149.48
30.3 8.5 6.35 4×10-3 0.0173 34.55 7 5.23 15.24 181.91
35.9 8.5 4.93 3×10-3 0.0105 38.5 7.6 4.41 8.77 227.55
40 8.5 4.14 2×10-3 0.006 42.08 7.8 3.8 6.61 263.08
Table D3: Settling test summary of 5% mill tailings from this study for si < 25% and
Khaled (2012) for si ≥ 25% (data reproduced with permission from author)
si
(%) Hi
(cm) ei
Vs
(cm/s2) ki
(cm/s) sf
(%) Hf
(cm) ef
SP (%)
σ'f (Pa)
15.2 8.5 15.52 222×10-3 2.1583 31.75 3.25 5.93 58.05 75.87
20.4 8.5 10.92 155×10-3 1.0873 32.8 4.4 5.65 44.21 107.02
25 8.5 8.28 115×10-3 0.6079 35.71 5.1 4.97 35.67 115.97
30.1 8.5 6.41 18.5×10-3 0.0779 40.4 5.4 4.07 31.58 172.34
36.1 8.5 4.89 8.5×10-3 0.0284 42.87 6.4 3.68 20.54 221.43
41.8 8.5 3.84 5.6×10-3 0.0154 46.58 7 3.16 14.05 272.06
141
Table D4: Settling test summary of 6% mill tailings from this study for si < 25% and
Khaled (2012) for si ≥ 25% (data reproduced with permission from author)
si
(%) Hi
(cm) ei
Vs
(cm/s2) ki
(cm/s) sf
(%) Hf
(cm) ef
SP (%)
σ'f (Pa)
15.2 8.5 15.4 241×10-3 2.3260 30.33 3.5 6.34 55.24 77.18
20 8.5 11.04 219×10-3 1.5517 34.14 4.1 5.33 47.43 104.92
25.5 8.5 8.01 85×10-3 0.4401 36.78 5 4.71 36.63 141.77
30 8.5 6.39 19×10-3 0.0807 38.58 5.8 4.36 27.47 175.07
35.1 8.5 5.07 11×10-3 0.0384 41.8 6.4 3.81 20.76 214.87
40.1 8.5 4.09 6×10-3 0.0175 44.49 7.1 3.42 13.16 260.08
Table D5: Layer-wise grain size distribution test summary of 4% mill tailings from this
study for si < 25% and data analyzed after Khaled (2012) for si ≥ 25%
si
(%) Layer
Average solids content savg (%)
Fines content f (%)
Normalized solids content deviation sd (%)
15.1
Top 19.871 60.260 -2.819
Middle 28.745 49.309 0.140
Bottom 36.364 37.176 2.679
20.2
Top 22.909 51.406 -2.181
Middle 30.130 46.230 0.226
Bottom 35.317 42.716 1.955
26
Top 30.457 43.367 -1.460
Middle 35.375 40.110 0.179
Bottom 38.680 36.728 1.281
30.3
Top 32.814 40.130 -0.990
Middle 36.620 37.580 0.278
Bottom 37.919 38.667 0.712
35.9
Top 36.927 41.768 -0.606
Middle 38.985 42.550 0.080
Bottom 40.320 41.908 0.525
40.0
Top 40.208 37.097 -0.313
Middle 40.987 37.511 -0.054
Bottom 42.248 35.949 0.367
142
Table D6: Layer-wise grain size distribution test summary of 5% mill tailings from this
study for si < 25% and data analyzed after Khaled (2012) for si ≥ 25%
si
(%) Layer
Average solids content savg (%)
Fines content f (%)
Normalized solids content deviation sd (%)
15.2
Top 15.418 95.038 -6.010
Middle 24.985 85.024 -2.819
Bottom 59.907 27.254 8.829
20.4
Top 19.572 83.960 -5.620
Middle 32.792 62.504 -1.213
Bottom 56.928 23.599 6.832
25.0
Top 19.477 88.676 -5.680
Middle 39.257 56.840 0.913
Bottom 50.820 34.630 4.767
30.1
Top 35.499 55.562 -1.980
Middle 42.138 54.446 0.233
Bottom 46.681 49.144 1.747
36.1
Top 39.925 52.350 -1.790
Middle 45.620 50.120 0.110
Bottom 50.325 44.013 1.680
41.8
Top 46.070 51.160 -0.910
Middle 49.320 49.220 0.170
Bottom 50.960 47.970 0.730
Table D7: Layer-wise grain size distribution test summary of 6% mill tailings from this
study for si < 25% and data analyzed after Khaled (2012) for si ≥ 25%
si
(%) Layer
Average solids content savg (%)
Fines content f (%)
Normalized solids content deviation sd (%)
15.2 Top 18.099 95.608 -4.983
Middle 27.364 80.346 -1.895 Bottom 53.680 26.670 6.877
20.0 Top 19.613 95.144 -4.832
Middle 32.013 71.583 -0.699 Bottom 50.704 34.404 5.531
25.5 Top 24.499 53.800 -4.856
Middle 41.493 49.980 0.829 Bottom 50.994 44.660 4.017
30.0 Top 35.499 53.762 -1.854
Middle 42.138 51.134 0.242 Bottom 46.681 48.281 1.808
35.1 Top 38.754 54.274 -1.317
Middle 43.791 52.432 0.362 Bottom 45.571 45.859 0.955
40.1 Top 42.483 51.157 -0.817
Middle 45.440 49.215 0.169 Bottom 46.880 50.180 0.648
143
Figure D1: Grain size distribution curves of 4%, 5% and 6% mill tailings (GSD test data
reported by Khaled (2012), reproduced with permission from the author)
0.0001 0.001 0.01 0.1 1Grain Size (mm)
0
20
40
60
80
100
Per
cen
t F
iner
(%
)
Best Fit: 4% Mill Tailings (This Study)
Best Fit: 5% Mill Tailings (This Study)
Best Fit: 6% Mill Tailings (This Study)
4% Mill Tailings Data (Khaled, 2012)
5% Mill Tailings Data (Khaled, 2012)
6% Mill Tailings Data (Khaled, 2012)
Clay Size (< 0.002 mm) Silt Size Sand Size (>0.075 mm)
r2 = 0.994
r2 = 0.996
r2 = 0.996
144
Figure D2: Determination of initial hydraulic conductivity from settling test (data
reported by Khaled (2012), reproduced with permission from the author)
0
3
6
9
Inte
rfac
e H
eigh
t (c
m)
5 % Mill TailingsThis Study
si = 15.2%
si = 20.4%
Khaled (2012)
si = 25.0 %
si = 30.1 %
si = 36.1 %
si = 41.8 %
0 100 200 300 400 500Elapsed Time (min)
0
3
6
9
Inte
rfac
e H
eigh
t (c
m)
6 % Mill TailingsThis Study
15.2%
20.0%
Khaled (2012)
25.5 %
30.0 %
35.1 %
40.1 %
0
3
6
9
Inte
rfac
e H
eigh
t (c
m)
4 % Mill TailingsThis Study
si = 15.1%
si = 20.2%
Khaled (2012)
si = 26.0 %
si = 30.3 %
si = 35.9 %
si = 40.0 %
3/9
3/9
145
Table D8: Initial conditions of sample for consolidation tests
Parameters 4% mill tailings 5% mill tailings 6% mill tailings
Water content, w (%) 213.50 164.60 166.70 Void ratio, e 5.75 4.54 4.57 Specific gravity, Gs 2.70 2.76 2.74 Degree of saturation, DS (%) 100 100 100 D9: Sample calculation of consolidation loading for 4% mill tailings
Initial water content, w = 213.50%
Initial solids content, s = (1/1+w) = 31.94%
Specific gravity, Gs = 2.70
Diameter (D) of the sample = 10 cm Height (h) of the sample = 10 cm Area of sample, A = 1/4 (πD2) = 78.54 Sq.cm Volume of sample, V = A h = 785.40 cc Initial solids content, s = 31.94%
Initial weight of slurry, W = 983.09 gm Initial weight of solids Ws = s × W 313.61 gm Initial weight of water Ww = W-Ws 669.49 gm
Unit weight of water, γw = 1 gm/cc Initial unit weight of slurry, γ = W/V 1.25 gm/cc Void ratio, e = {(1+w) Gsγw / γ}- 1 = 5.75
Stress of 1 kPa, σ = 1 kPa Equivalent load required, P = σ / A 7.85 Newton (a) Required mass, m =(P/g) = 0.80 kg g = 9.81; acceleration due to gravity 800.6 gm
Sample height after self weight settling, h1 = 8.4 cm Solids content, s = 36.4% Void ratio, e = 4.83 Unit weight, γ = γw {(Gs+e) / (1+e)} 1.29 gm/cc Effective unit weight, γ' = γ - γw = 0.29 gm/cc Effective unit weight, γ' = 2.86 N per cubic metre
(1) Effective stress after settling, σ' = (γ - γw) h1 0.24 kPa
Load 1: 1 kPa
(2) Loading piston and plastic container = 367 gm (3) Porous stone = 114 gm Equivalent applied stress with self weight (1+2+3) = 0.84 kPa
Additional weight for 1 kPa = (1 - 0.84) × (a) 128 gm