peter jansson - outotec (usa) inc - iron ore tailings reprocessing to maximize ore production
DESCRIPTION
The Americas Iron Ore Conference is one of the most respected annual gatherings for North and South American iron ore markets and the agenda covers: iron ore industry and market developments; new project developments and expansions in North and South America; overview of steel demand; iron ore spot market price; infrastructure and transport challenges and investment opportunities. For more information please visit: http://bit.ly/1vlo1DDTRANSCRIPT
Iron Ore Tailings Reprocessing to Maximize Ore Production
America Iron Ore Conference 2014
© Outotec – All rights reserved
Overview
Why the need for tailing
processing?
Decreasing Fe grade of Iron ore reserves
Need for sophistication of processing plants due to
inter-grown ore bodies
Increase in demand of iron
ore incoherence
with increase in steel demand
The Fe content of the tailings
varies and reaches more than 55% Fe in
some Asian regions
Valuable mineral in
tailings dumps due to lack of
suitable processing
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Outotec’s Focus
• Minimize tailing production.
• Improvement of existing processing plants.
• Sustainable operation by optimized tailing disposal and water
recovery management.
• Re-processing tailings resulting from former operations.
• Beneficiation using modular units consisting of SLon in series with
desliming, WLIMS or gravity separation
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Working Principle of Outotec SLon High Gradient Magnetic Separator Vertical carousel
• Mag flushing in opposite direction of feed
• Mags are not washed through the matrix
• Reduced matrix plugging
Pulsation Bath
• Reduce particle momentum
• Minimize entrapment
Rod Matrix
• High magnetic force while minimizing entrapment of particles
• Ensure all particles see high gradient zones
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© Outotec – All rights reserved
Working Principle of Outotec SLon High Gradient Magnetic Separator
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PROCESS DEVELOPMENT TESTING ON TAILING SAMPLES FROM OPERATIONS
WORLDWIDE
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COMPANHIA SIDERURGICA NACIONAL (CSN) - BRAZIL • (CSN) is the second major
steel-maker company in Brazil
• Flotation rejects and thickener underflow tested using SLon lab unit for plant optimization
• Slon recoveried upto 66.6% Fe from flotation rejects and upto 59.9% Fe from thickener underflow
• Increase in magnetic field intensity increased in iron recovery but also increase in SiO2, Al2O3 and Mn which reduced Fe grade
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0
10
20
30
40
50
60
70
62
62.5
63
63.5
64
64.5
65
65.5
66
66.5
0 0.2 0.4 0.6 0.8 1 1.2
Fe R
eco
very
(%
)
Fe G
rad
e (
%)
Magnetic Intensity (Tesla)
Fe Grade (%)Flotation Rejects
Fe Grade (%) Slimes
Fe Recovery (%)Flotation Rejects
Fe Recovery (%)Slimes
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SAMARCO MINERACAO – BRAZIL SLON 100 TESTING
• Feasibility testing was done on flotation tailing sample with 6 to 7 % iron.
• Test showed the increase in recovery of Fe content in magnetic fraction with increase in magnetic field from 0.15 to 0.5 t
• Screening of feed before the SLon feed showing a big improvement removing the coarse silica.
Test # Products Test
Conditions
Mass % Fe Assay Fe
Recovery
1 Mag 0.5 Tesla
Pulsation
240
21.82 33.81 78.46
N-mag 78.18 2.59 21.54
2 Mag 0.3 Tesla
Pulsation
240
17.80 36.40 67.00
N-mag 82.20 3.88 33.00
3 Mag 0.15 Tesla
Pulsation
240
10.54 40.78 44.45
N-mag 89.45 6.00 55.55
The coarse particle (+150 mesh) were removed by screening. 47.73% by weight -
150 mesh.
4 Mag 0.5 Tesla
Pulsation
240
27.14 47.68 79.70
N-mag 72.86 4.52 20.30
The coarse particle (+200 mesh) were removed by screening. 32.02% by weight -
200 mesh.
5 Mag 0.5 Tesla
Pulsation
240
34.12 55.27 82.35
N-mag 65.88 6.13 17.65
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SAMARCO MINERACAO – BRAZIL PILOT SCALE TESTING WITH SLON 500
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• Increase in Fe receovery with
increase in magnetic field.
• Fe grades increases till 0.48 T
with maximum grade of approx
34% with 82% iron recovery
• Silica recovery increases with the
magnetic field too but the rate of
increase is very low from 0.29T
to 0.48T
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BUCHANAN IRON ORE– SOUTH AFRICA SLON 100 TESTING
•Tailing sample with 48.9% Fe.
•Screened at 250um to remove
oversize resulting in minor iron losses
of 0.8%
•Pre-treated using LIMS to remove
magnetite form the sample
•Operating variables
magnetic intensity (0.1 – 1.0T)
pulsating frequency (0-300
ppm)
matrix size (1, 1.5, 2, 3 and
4mm).
•A combined concentrate grading 66%
iron could be achieved at recoveries of
60% to 75%.
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BUCHANAN IRON ORE– SOUTH AFRICA SLON 100 TESTING
•Tailing sample with 47% Fe.
•Screened at 250um ( minor iron
losses of 1.4%)
•Pre-treated using LIMS to remove
magnetite form the sample
•Operating variables
magnetic intensity (0.1 – 1.0T)
pulsating frequency (0-300
ppm)
matrix size (1, 1.5, 2, 3 and
4mm).
•A combined concentrate grading 63%
to 64% iron at a recovery of 50% to
66%
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BUCHANAN IRON ORE– SOUTH AFRICA SLON 750 TESTING
•The two composites were combined
and screened at 250 micron and pre-
treated using LIMS
•Operating variables
magnetic intensity (1.0T)
pulsating frequency (200 - 300
ppm)
matrix size (1.5 mm).
% Solids ( 12% & 21%)
•Lower solids content in feed and 250
rpm of pulsating frequency were
chosen with Fe grade of 65.5 % at a
recovery of 77.7 %.
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BUCHANAN IRON ORE– SOUTH AFRICA SLON 750 TESTING MASS BALANCING
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MIKHAILOVSKY GOK(MGOK) – RUSSIA SLON 100 TESTING
Test # Products Test
Conditions
Mass % Fe Grade % Fe
Recovery
1
LIMS Mags
0.5 Tesla
Pulsation
220
21.52 57.78 30.58
SLon Mags 41.82 50.01 51.43
LIMS+SLon
Mags 63.34 52.65 82.01
Nonmags 36.66 19.96 17.99
Feed 100.00 40.67 100.00
2
LIMS Mags
0.3 Tesla
Pulsation
220
20.72 57.78 29.66
SLon Mags 32.70 51.84 42.00
LIMS+SLon
Mags 53.42 54.14 71.66
Nonmags 46.58 24.55 28.34
Feed 100.00 40.36 100.00
3
LIMS Mags
0.3 Tesla
Pulsation
250
22.03 57.78 31.51
SLon Mags 29.34 52.69 38.27
LIMS+SLon
Mags 51.37 54.88 69.78
Nonmags 48.63 25.13 30.22
Feed 100.00 40.40 100.00
• Testing of Mikhailovsky iron ore
sample containing 40.36% iron
using SLon 100 and 900 Gauss
LIMS.
• Magnetic separation effectively
produced maximum grade of
54.88% Fe with 69.78%
recovery
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MIKHAILOVSKY GOK(MGOK) – RUSSIA SLON 500 TESTING
• Testing of sample with 40.3% Fe
and 39.6% SiO2 using SLon 500 in
series with 1000 Gauss LIMS
• Pre-treatment : Grinding using rod
mill to reduce the sample size from
100% of -5mm to P80% of 82
microns (labeled as Sample II)
• A combined concentrate grading
53.2% Fe with 85.2% recovery.
Test Products Test
Conditions
Mass % Fe Grade
%
Fe
Recovery
%
Sample II
LIMS+SL
on Mags
0.5T
Pulsation
stroke: 20
mm,
Pulsation:
250,
Ring
speed:
2.5 rpm.
64.62
53.2
85.2
Non-
mags 35.38
16.7
14.8
Feed 100.0 40.3 100
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MIKHAILOVSKY GOK(MGOK) – RUSSIA SLON 500 TESTING
•The magnetic separation feed
of the sample-I have a coarser
grinding fineness than the test
feed of sample II.
•Finer grinding enabled higher
grade and recovery.
•Magnetic concentrate was then
tested for flotation circuit for
further upgradation.
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LONDON MINING – SIERRA LEONE (MARAMPA IRON ORE TAILINGS) SLON 100 TESTING
•Flowsheet designing for Phase 1a,1.8 Mt/a tailing processing plant
using a two stage SLon magnetic separation circuit
Testing for Rougher Circuit
• Operating conditions : - Matrix – 2mm, 3mm - Pulsation frequency (200, 250 or 300 ppm) - Magnetic field (0.5, 0.6, 0.7 and 0.8 Tesla)
• Optimum conditions were 0.6 Tesla utilizing 3 mm rod matrix at 300ppm
Testing for Cleaner Circuit
• Same operating conditions as rougher
• Optimum conditions were 0.35 T, 3 mm matrix at 300ppm
• Cleaner tailings at 12.1% of head feed with 47% Fe were used for Scavenger testing
Testing for Scavenger Circuit
• Optimum conditions produced concentrate weighing 7 to 8% of the head feed at 63.7% Fe grade and 76.5% Fe recovery.
Conc. Tails
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LONDON MINING – SIERRA LEONE (MARAMPA IRON ORE TAILINGS) SLON 100 TESTING
Sample Fe Fe2O3 SiO2 Al2O3 MgO CaO Na2O K2O TiO2 MnO P2O5 Cr2O3
Rougher
SLon Feed
22.0 31.4 54.1 8.46 0.64 0.09 0.02 0.2 0.17 0.88 0.09 0.03
Cleaner
SLon
Concentrate
66.1 94.4 1.74 1.09 0.15 0.07 0.02 0.14 0.35 1.37 0.05 0.03
Scavenger
SLon
Concentrate
63.7 91.0 3.05 1.86 0.26 0.11 0.04 0.30 0.34 1.73 0.06 0.03
Final
Estimated
Concentrate
65.5 93.5 2.08 1.29 0.18 0.08 0.03 0.18 0.35 1.46 0.05 0.03
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LONDON MINING – SIERRA LEONE (MARAMPA IRON ORE TAILINGS) SLON 750 PILOT TESTING
•100 kg (-1mm) subsample was
subjected to rougher – cleaner circuit
lock cycle testing (seven cycles)
•Rougher conditions were 0.6 T, 3 mm
matrix, 300 ppm & 169 kg/h feed rate.
•Cleaner conditions were 0.35 T, 3 mm
matrix, 300 ppm & 87 kg/h feed rate.
•The cleaner stage tailings from
previous cycle were proportionally
added to the next cycle’s rougher feed.
• The results showed the process
stability.
London Mining - Marampa Tailings Lock Cycle Testing
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
Cycle 1 Cycle 2 Cycle 3 Cycle 4 Cycle 5 Cycle 6 Cycle 7%
RO wt%
CL wt%
RO Fe
CL Fe
RO SiO2+Al2O3
CL SiO2+Al2O3
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LONDON MINING – SIERRA LEONE (MARAMPA IRON ORE TAILINGS) PLANT
• London Mining currently has two processing plants which operate a
total of 22 SLon 2500 units.
• Both plants are identical and have a rougher/cleaner WHIMS circuit.
• Feed which is a mixture of old tailings and weathered ore (20 – 25 %
Fe) is screened at 1mm prior to SLon processing.
• The Rougher Stage design throughput capacity is 875 T/Hr/Plant (7
SLon 2500 units) at 40% solids.
• The Cleaner Stage design throughput capacity is 360 T/Hr/Plant (4
Slon 2500 units) at 21% solids.
• Product grade produced – 65.0% Fe
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IRON ORE TAILING PROCESSING PLANT – USA SLON 100 TESTING
• The testing was done for facility that extracts and processes iron-
bearing tailings leftover from previous iron mining operations
• Slon 100 testing parameters feed charge (200g and 270g)
matrix rod size (1.5, 2 and 3mm)
pulsation frequency (200 or 300 ppm)
magnetic intensity (0.6, 0.8 and 1T)
• At the conditions evaluated, the SLon recovered from 54 to 81% of
the iron from tails at grades ranging from 61% to 52% Fe.
• SLon 2500 and SLon 2000 has been installed in Rougher – Cleaner
circuit respectively for processing the tailing from upstream
processing circuit processes the mined leftover tailings.
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TESTING CONCLUSION
• Research is being conducted to enhance iron recovery from a tailing
stream containing hematite using gravity, magnetic and flotation
separation techniques
• Outotec’s SLon VPHIMS proved to be effective in recovering Iron
from various tailing samples around the world with Iron grade
ranging from 6% all way to 48%
• In some cases, Fe grades were improved with pre-processing
consisting of de-sliming, LIMS or post processing consisting of
flotation.
• Implementation of SLon in tailing beneficiation will: Increase iron ore production
Increase the life of tailing sumps
Increase the life of current reserves by optimizing the tailing processing
circuit
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