cytec solutions 2013

7/27/2019 Cytec Solutions 2013

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CYTEC SOLUTIONS

IN PROCESS SEPARATION

for Solvent Extraction, Mineral Processingand Alumina Processing

DELIVERING TECHNOLOGY BEYONDOUR CUSTOMERS IMAGINATION

VOLUME 17


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Letter from the Vice President

To our Valued Customers,

Advancements in our new product development effort as well as mergers and acquisitions over

the past several years has transformed Cytecs business portfolio. These changes have created a

leading high growth specialty chemical business.

What does this mean for our mining customers? We continue to collaborate with you to address

challenges and meet them with our technology and products. With economic challenges,

changes in ore grades, and the demand for natural resources, Cytec is committed to finding

sustainable, quality solutions to help you keep up with these challenges.

To help meet the growing demand from our customers, Cytec has made significant investments

in our manufacturing assets to improve reliability and increase capacity. One of the most significant investments includes a

several hundred million dollar investment to expand our site in Niagara Falls, Canada. This site produces both mining products

and phosphine derivates. We are also investing in assets to increase R&D capabilities at other global sites.

We at Cytec want to help bring about solutions to your current and future operations success and we have a well balanced

portfolio of products and expertise that are unmatched. The major benefits of our products include increasing revenue

through improved production, reducing operating costs, and reducing capital expenditure to build new plants. We have a

significant focus on technology development and you can rely on Cytec to bring you the latest technology with our steady

stream of new products that ensures you always have the best option by partnering with Cytec.

In this edition, we highlight some of these new product advances. These include a scale controlling solution for phosphoric

acid product plants with our innovative PHOSFLOW technology, an alternative to traditional hazardous modifiers with our

AERO7260 HFP, and nitration residence with our ACORGANR series reagents. We are also pleased to share that our MAX HT

Bayer sodalite scale inhibitor was awarded the 2012 EPA Presidential Green Chemistry Challenge Award.

I have been with Cytec for over 18 years and in many roles that have helped prepare me for my new role to lead the In

Process Separation business. Now, I am excited to lead a business that is focused on our valued customers and partners in

the mining industry. I am dedicated along with my team to provide you with the service and solutions you are looking for

now and in the future.

Thank you for your interest and business,

Michael Radossich

Vice President, In Process Separation


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Solvent Extraction, Mineral Processing and Alumina Processing


Table of Contents:

Solvent Extractions

Crud Processing Improvements Using ACORGACB 1000Crud Busting Reagent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Use of ACORGANR Reagents in the Presence of Nitrate Ions in SX:

The State of the Art . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Mineral Processing

AERO7260 HFP Depressant: Novel, Safe and Sustainable Alternative to TraditionalHazardous Modifiers NaSH, Nokes, Na2S, and Cyanide . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Rejection of Pyrite: Challenges and Sustainable Chemical Solutions . . . . . . . . . . . . . . . 23

Alumina Processing

MAX HTBayer Sodalite Scale Inhibitor:A Green Solution to Energy Consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Performance Evaluation of CYFLOCULTRA HX-5300 A New HXPAM Red Mud Flocculant Applied in CBA(Companhia Brasileira de Aluminio) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Industrial Minerals

Scale Controlling Chemical Additives for Phosphoric Acid Production Plants . . . . . . . . 42


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Crud Processing Improvements Using ACORGACB 1000 Crud Busting Reagent

Tyler McCallum, Troy Bednarski, and Matthew Soderstrom

Cytec has developed a unique crud treatment process utilizing both chemical and mechanicalmeans to enhance the solid/liquid separation, improve recovered organic quality, and reduceoperational costs.

Crud (a complex solid stabilized emulsion of aqueous andorganic) is a common concern in most solvent extractionprocesses[1,3]. If crud is allowed to build up in the circuit,aqueous and organic velocities within the settlers willincrease, resulting in higher entrainments and operationalcosts. Crud movement between stages can causecontinuities to flip and may require a significant reduction inplant flows or a plant shutdown to stabilize the operation[2].To prevent these events, interfacial pumping is typicallycarried out to remove crud from the circuit and process itfor organic recovery[4]. Crud processing can be very timeconsuming, and the recovered organic quality is often lower

than desired with current processing methods.

Cytec has developed a unique crud treatment processutilizing both chemical and mechanical means to enhancethe solid/liquid separation, improve recovered organicquality, and reduce operational costs. The use of ACORGACB 1000 crud busting reagent allows a rapid separationof solids from the organic phase. ACORGA CB 1000 is anSX qualified chemical additive, which aids in the recoveryof organic from crud. The process involves breaking thestabilized crud emulsion, freeing the associated organic,and settling the solids very rapidly. This process allows

operations to return clean organic back to the plant moreefficiently and may enable operations to process more crud.In addition to the improvement in processing time, the crudbuster process enables more efficient clay treatment andtherefore can improve the quality of organic that is returnedto the SX circuit.

The crud buster process involves mixing the crud withorganic (under organic continuity) then breaking the crudemulsion through the addition of hydrophilic solids (clay).Once the emulsion has been temporarily broken, theaddition of ACORGA CB 1000 will bind to the solids causingthem to settle and preventing the emulsion from re-forming.Following the clay and ACORGA CB 1000 addition, theagitator may be stopped, allowing the phases to separateand quickly recover the majority of the organic freed fromthe crud emulsion. This organic can then be more efficientlyclay treated and returned to the process quickly without thetypical issues associated with filtration of an emulsion.

The solids remaining after the primary separation (containingsome residual organic and aqueous, which was freed fromthe crud emulsion) can then be processed using typicalmethods for a secondary solid/liquid separation and furtherorganic recovery. The volume of the secondary separationis substantially less; therefore limited time is required forprocessing. Any organic recovered from the secondaryseparation should also be subjected to clay treatment.

The laboratory test shown in Figure 2 illustrates the effect ofACORGA CB 1000 in breaking the crud emulsion and freeing

the associated organic. For this test, crud was dispersed inan organic continuous mix of diluent. The picture on theleft is the organic continuous mix before clay addition; themiddle picture is after addition of clay and ACORGA CB1000; and the picture on the right is the immediate resultafter agitation was ended. As shown, a very clear organicphase is evident using the process and recovery of thisorganic can be quickly achieved.


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FIGURE 2:

ACORGA CB 1000 MIXINGAND SETTLING

Crud Buster

BenefitsCrud processing using ACORGACB 1000 can offersignificant time savings due to the rapid chemical separationof organic from crud without requiring the initial step ofusing a press or centrifuge to break the crud emulsion. Theorganic that is quickly recovered is a very clean stream

largely free of suspended solids. This clean organic streamcan then be clay treated more efficiently producing a highquality recovered organic. The small amount of ACORGACB 1000 remaining in the organic after the solid/liquidseparation is removed by the clay during clay treatment.

Time SavingsEliminating the need of a press or centrifuge for the initialrupturing of the crud emulsion to free organic allows

significant time savings. The crud emulsion can blind filtercloths when using a plate and frame filter press (requiring

additional time to drop and recharge the press). Centrifugesare limited by the flow rate and crud volume to be processed.

The crud buster process allows a rapid solid/liquid separationwithout the additional steps/equipment.

Total Suspended Solids (TSS)Current crud treatment methods (regardless if using acentrifuge or filter press) are often inefficient and frequentlyallow suspended solids to be left in the recovered organic.The return of organic with these now finely dispersed solidscan be the cause of additional operational difficulties.

The amount of solids remaining in the organic following

mechanical processing can vary greatly and is dependent on

the equipment being utilized. High TSS in recovered organicis common.

Figure 3 shows solids removed from the organic duringeach step of processing. The top row of pictures gives anindication of the TSS present in the organic phase after eachstep using a traditional filter press process without ACORGA

CB 1000. The bottom row of pictures represents the crudbuster process after each step.


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Visually it is easy to see that the final organic productreturned to the circuit post clay treatment was much cleaner

using the crud buster process than the process using onlymechanical separation.

Interfacial Tension (IFT)Mechanical rupturing of crud often results in surface activespecies associated with crud being transferred to the organic,lowering the IFT and organic quality. This is in addition tothe problem of solids often being redistributed.

Figure 4 shows the interfacial tension of various organicsamples from operating plants. Traditional mechanicalrupturing processes return organic with a lower IFT than

the circuit organic. This reduction in organic IFT is true foroperations using plate and frame filter presses or centrifuges.The figure also shows that both the plant organic and crudprocessed organic have the potential to be of higher qualitywith efficient clay treatment. Without clay treatment of therecovered organic, the associated surface active species from

the crud are often returned to the circuit.


FIGURE 4:

IFT OF CIRCUIT ORGANIC, RECOVEREDORGANIC, AND CLAY TREATED ORGANIC

FIGURE 3:

TSS OF STANDARD FILTER PRESS ANDCRUD BUSTER PROCESS

40

35

30

25

20Sample 1 Sample 2 Sample 3 Sample 4

29.3 29.230

27.6

26.8

22.3

InterfacialTension(dynes/cm)

Plant Organic

Recovered Organic from Crud

Clay Treated Organic34.6

35.3 34.9

29.1

27

34.4


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The use of ACORGA CB 1000 efficiently separates the

organic from the solids/aqueous emulsion, enabling the

organic to be treated with the appropriate clay dosage

without deactivation of the clay.

Benefits of Higher Organic QualityPilot plant testing was completed to compare organicrecovered by crud buster to organic recovered by

typical mechanical crud processing means. This work wascompleted using a 2E + 1S configuration at 6 lpm feed flowand results are shown in Table 1.

TABLE 1. Pilot Plant Comparison

CBProcessed Organic Typical Processed Organic

IFT (dynes/cm) 33.5.9 29.2

Extract PDT Org Cont. (seconds) 51 229

Extract PDT Aq Cont. (seconds) 63 66

Strip PDT Org Cont. (seconds) 50 191

Dispersion Band Org Cont. (% of org depth) 0% 61.2%

Organic Entertainment 34% decrease

Aqueous Entertainment 18% decrease

Cu:Fe Transfer Ration 1032 645

Operations that practice clay treatment of recovered organictypically only utilize 0.1 0.3 wt% clay due to pluggingconcerns. This is rarely sufficient to remove all surfactantsfrom the organic, and the clay is often deactivated by

aqueous remaining with the organic. As shown in Figure 5,an excess of 2% clay is required to restore the organic IFT(of this specific plant organic) to its maximum value.

FIGURE 5:

CLAY TREATMENT VS.INTERFACIAL TENSION

Clay Concentration (wt%)

InterfacialTension

Time(dynes/cm)

39

37

35

33

31

29

27

0 1 2 3 4 5 6

Recovery Organic Clay Treatment Curve


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The crud buster process (enabling efficient clay treatment)produced an organic with a higher IFT and better overallorganic quality. This resulted in a significant improvement inphase disengagement times, dispersion band depth, organicand aqueous entrainments, and Cu:Fe selectivity.

Note: Lower Fe transfer (along with reduced aqueousentrainment) would be expected to result in a significantreduction in operating costs through electrolyte bleedreduction.

ConclusionCurrent crud treatment and organic recovery practicesare often not efficient in producing a high quality organicproduct. Use of mechanical equipment to break the crud

emulsion is effective, but often leaves suspended solidsand surfactants in the organic. It is critical to clay treatrecovered organic (although not always practiced). Whenclay treatment is performed, the clay concentration usedis often lower than optimal because of concerns related toplugging of the filtration equipment. The resulting organicreturned to the circuit leads to redistribution of solids,poor phase disengagement, and higher entrainments.Metallurgical performance can also be negatively impacted.

The crud buster process enables efficient clay treatmentand results in a high quality recovered organic in a timelymanner. Crud buster is expected to produce an organic with

a lower TSS and a higher IFT than current processes. Theseimprovements in organic quality have been shown to resultin improved SX performance (break times, entrainments,kinetics, stage efficiency, Cu/Fe selectivity) and are expectedto bring operational cost savings.

References1. R.F. Dalton, C.J. Maes, and K.J. Severs, Aspects of Crud Formation

in Solvent Extraction Systems, Arizona Conference of the AIME,

Tucson, AZ., 1983.

2. Cytec Industries Inc., Crud: How It Forms and Techniques for

Controlling It, Marketing Publication, 2006.

3. T. Burniston, J.N. Greenshields, and P.E. Tetlow, Crud control inCopper SX Plants, E&MJ, 1992, (Jan) pp. 32-35.

4. M. Cox, Liquid-Liquid Extraction and Liquid Membranes in thePerspective of the Twenty-First Century, Solvent Extraction and

Liquid Membranes, 2008, pp. 1-19.

For more information on this subject and other Cytec technologies, please visit our website at www.cytec.com.

TRADEMARK NOTICE: The indicates a Registered Trademark in the United States and the indicates a trademark in the United States. The markmay also be registered, subject of an application for registration, or a trademark in other countries.


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Use of ACORGANR Reagents in the Presence of

Nitrate Ions in SX: The State of the ArtRodrigo Zambra*, Alejandro Quilodran, Gonzalo Rivera, and Osvaldo Castro

Given the relevance of the nitration threat in Chile due to high nitrate containing ores in someplants and the lack of an available practical solution for the industry, Cytec developed a superiorline of modified aldoxime extractants.

This work presents the results of studies of different solventextraction operations in the north of Chile where nitrationconcerns are the greatest. While all copper solvent extractionoperations have some nitrates present, this paper is focusedon the four copper SX plants that have the potential forappreciable levels of nitrate ions in their leach solutions.

Nitration is a phenomenon that initially attracted theinterest of the copper mining industry in the late 90s dueto the experience at Lomas Bayas where they experiencedsignificant nitration of the organic inventory. Since thenthe industry developed the position that ketoxime-basedextractants were the best solution for operations withnitration risk.

Nitrated oximes (ketoximes and aldoximes) form stableCu complexes that prevent the stripping of copper. Oncethe oxime is nitrated, the oxime no longer works as anextractant because that portion of the organic no longertransfers copper.

The nitration mechanism is shown below:

NO3- + H2SO4HNO3+ HSO4- (1)

HNO3+ H2SO4NO2+ + H2O + HSO4- (2)

R1 H OR CH3 ALDOXIME OR KETOXIME

R2 C9H19 OR C12H25 NONYLALDOXIME OR DODECYLALDOXIME

Nitration is certainly a function of the nitrate concentrationin aqueous solutions, but it is also a function of theacidity, temperature, redox potential, interfacial tensionand the reactivity of the aqueous and organic phases.Nitration of oxime compounds leads not only to reducedcopper transference capacity, but also increased phasedisengagement times, reduced interfacial tension, increasedentrainment and hydrolytic degradation.

Given the relevance of the nitration threat in Chile due tohigh nitrate containing ores in some plants and the lackof an available practical solution for the industry, Cytecdeveloped a superior line of modified aldoxime extractants.These products, known commercially as the ACORGANR

series, provide nitration protection without reducing copperproduction capacity.

Examples of the relative performance of ACORGA NRseries extractants and ketoxime-based extractants arediscussed next.

OH N OH N OH NOH OH OH

R2 R2 R2

R1 R1 R1+ NO2+

O2N

H

O2N

+


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Case 1, Plant A

The conditions at Plant A prior to substitution of the ketoxime extractant LIX84I with the modified aldoxime ACORGANR10 are listed below:

TABLE 1: Characterization of the Solutions at Plant A

Element Units PLS Spent

Cu g/L 4.60 36

pH/H2SO4 -/g/L 1.60 180

NO3- ppm 1,890 63

ORP mV 470 500

SimulationsIn order to compare the extraction efficiency of the reagentsLIX84I and ACORGA NR10, the extraction and strippingisotherms were created in the laboratory using real plant

solutions. McCabe Thiele analysis was then used to calculatethe expected recovery for the configuration. The results arepresented in Table 2.

TABLE 2: Results of Simulations with Plant Solutions (23% extractant).

Extractant Efficiency [%] Train A Efficiency [%] Train B

Lix 84I 89.23 77.51

NR10 95.21 87.33

The better extraction kinetics under high copper tenor andlow pH conditions of ACORGA NR10 results in a 6% higher

copper recovery than LIX 84I extractant, which was used inthe plant.

Accelerated Nitration TestsSeveral tests were then carried out in order to evaluate thebehavior of the extractant in a possible nitration scenario.The properties of the evaluated PLS feed (which had

adjusted values of pH and nitrate to make the solution moreaggressive) are shown in Table 3.

This PLS was mixed continuously in a 1:1 ratio at 40Cwith three separate reagents prepared at 25 vol %: LIX84I (ketoxime), LIX 860 (pure aldoxime), ACORGA NR10(modified aldoxime) and Plant Organic (a blend of theregents appointed previously).

TABLE 3: PLS Conditions for the Accelerated Nitration Tests.

Value Units

Cu 2.50 g/L

NO3- 62.0 g/L

FeT 4.70 g/L

Cl- 10.30 g/L

P. Redox 752 mV

T 40 C

pH 1.10

Use of ACORGANR Reagents in the Presence of Nitrate Ions in SX: The State of the Art


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The results presented in Figure 1 show that there was astrongest resistance to nitration when using the ACORGA

NR10 reagent (approx. 50%) compared to LIX84I, LIX860and Plant Organic.

FIGURE 1:

RESULTS OF THE ACCELERATEDNITRATION TESTS BASED ONRESIDUAL COPPER AND NITROXIME

Nitration(%)

ResidualCopper,gplCu

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

0.50

0.45

0.40

0.350.30

0.25

0.20

0.15

0.10

0.05

0

12-09-2012

19-09-2012

26-09-2012

03-10-2012

10-10-2012

17-10-2012

24-10-2012

31-10-2012

07-11-2012

14-11-2012

21-11-2012

28-11-2012

12-09-2012

19-09-2012

26-09-2012

03-10-2012

10-10-2012

17-10-2012

24-10-2012

31-10-2012

07-11-2012

14-11-2012

21-11-2012

28-11-2012

Ketoxime

Unmodified Aldoxime

Plant Organic

NR10


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Case 2, Plant B

The second case shows the laboratory and piloting test tocompare the behavior of the ACORGANR 20 extractantand the reagent currently in use at the plant LIX 84I.

This plant has a complex SX configuration, with twodifferent PLS feeds: the heap leaching solution at 1.8 gpl

Cu and pH 2.0 and the ROM leaching solution at 1.6 gplCu and pH 1.6. The stage efficiency was measured tocompare the performance of LIX 84I and ACORGA NR 20,with both feeds.

FIGURE 2:

STAGE EFFICIENCIES FOR PLS

HEAP AND ROM

As shown in the graph above higher stage efficiencies were achieved with the ACORGA NR reagent.

Accelerated Nitration TestsThe following products were tested, LIX84I, ACORGANR20 and a traditional aldoxime that is not nitrationresistant, unprotected reagent under aggressive nitratingconditions. The evaluation took place over a period of 150

days. The PLS used in this study was modified to be highlynitrating. Impurities were added to a real PLS (chloride,iron, and nitrate) with a pH of 1.0, as shown in Table 5. Theextractants were mixed in a 1:1 ratio, and the solution wassubmerged in a thermostatic bath at a temperature of 40Cwith constant agitation.

TABLE 4: Characterization of the PLS

COMPOSITION MODIFIED PLS

Acidity g/L 5.7

NO3- g/L 58.8

FeT g/L 3.08

Cl- g/L 10.38

It can be clearly seen in Figure 2 that both the ACORGANR20 and LIX 84I extractants had an appropriate resistanceto nitration but the unprotected extractant had significantnitration before 80 days of mixing.

100

90

80

70

60

50

40

Acorga NR 20 HEAP

LIX 84 IC HEAP

Acorga NR 20 ROM

LIX 84 IC ROM

80.1 79.5

90

85.9


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FIGURE 3:

RESULTS OF ACCELERATEDNITRATION TESTS BASED ONRESIDUAL COPPER AND NITROXIME

Pilot Plant EvaluationThe ACORGA NR20 extractant was then evaluated in a 100cm3/min pilot plant utilizing two PLS solutions (Heap andROM). The initial conditions for the pilot study are presentedin Table 5. The configuration of the pilot plant correspondedto that of an industrial plant, and the extractant was added

at 26.30 % for LIX84I and 24.94% for ACORGA NR 20. Theresults of the tests are shown in Table 6.

Table 5: Pilot Plant Test Initial Conditions

HEAP ROM Spent

Cu PLS g/L 1.97 1.63 42

pH / H2SO4 - / g/L 2.08 1.81 175

O/A E - 0.95 0.95

O/A S - 1.24 1.24

The extraction efficiency results clearly show a bettermetallurgical performance for the ACORGA NR20extractant, resulting in a 5.8% increase in copper recoveryfor the Heap and 8.8% increase for the ROM. Bothextraction efficiencies are enhanced using the ACORGANR20 extractant, which is based on a modified aldoxime

that has favourable kinetics for mass transfer as comparedto those for extractants based on ketoxime chemistry. Asa result, a better mixing efficiency near the equilibriumpoint is achieved. In addition, the ACORGAextractanttolerates a wider pH range, maintaining good chemical and

metallurgical performance from pH 1.0 to 2.5.

Table 6: Extraction Efficiency, Pilot Plant Results

Extractant

HEAP ExtractionEfficiency

(%)

ROM ExtractionEfficiency

(%)

Ketoxime 89.44 67.24

ACORGA NR 20 95.28 76.05

In addition, the results for the selectivity of the ACORGANR20 extractant conclusively confirm that the new reagent

improves the plant selectivity by approximately 50%. Theorganic Fe loading for both the Heap and the ROM PLSstreams are shown in Figure 4.

Sample

Nitration(%)

60

50

40

30

20

10

0

0 1 2 3 4 5 6 7 8

Acorga NR 20

Unprotected Reagent

LIX 84IC


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FIGURE 4:

ORGANIC FE COEXTRACTION

AS A FUNCTION OF COPPER LOADINGFOR HEAP AND ROM SOLUTIONS

CONCLUSIONBased on the results of the studies in the laboratory, and inthe pilot plant, the following conclusions can be made:

There is a great increase in the extraction efficiency andtransfer of copper when using the ACORGA NR extractant,

mainly because it provides better performance at low pHand enhanced extraction kinetics, which help improve thestage efficiency.

In all of the cases studied, the ACORGA NR reagentperformed better in terms of copper recovery by at leasttwo percentage points with a maximum difference of 8percentage points.

Cu/Fe selectivity is also increased significantly (50%) byuse of ACORGA NR extractants rather than ketoxime.

The ACORGA NR extractant offers protection for the plantorganic inventory under nitration conditions, ensuring asimilar or better response than the LIX 84Iextractant.



Loaded Organic, %

Loaded Organic, %

Fe+3,ppm

Fe+3,ppm

30

25

20

15

10

5

0

30

25

20

15

10

5

0

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100

Heap-Ketoxime Heap-NR20

ROM-Ketoxime ROM-NR20


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AERO7260 HFP Depressant : Novel, Safe andSustainable Alternative to Traditional HazardousModifiers NaSH, Nokes, Na2S, and Cyanide

Mukund Vasudevan and D.R. Nagaraj

Cytec has developed AERO7260 HFP Depressant, a highly efficient and versatile sulfide mineraldepressant with wide applicability.

Introduction

NaSH/Nokes are commonly used modifiers in Cu-Moseparation systems. However, these materials presenta significant safety and health hazard to humans and apotential environment risk. After listening to the industrysneed for safer alternatives, Cytecs innovation laboratoryin Stamford, CT USA, focused its resources on finding asolution which is described in this article.

Cu-Mo operations typically process ores rich in Cu sulfides(head grade 0.1-2%) and molybdenite (MoS2, head grade0.01- 0.05%) via an operation consisting of a) the bulkflotation circuit, followed by b) Mo circuit as seen inFigure 1.

The bulk flotation circuit is intended to produce a high gradeCu concentrate containing molybdenite values along withminor amounts of pyrite and some non-sulfide gangue. Thisconcentrate is then processed in the Mo circuit to selectively

float MoS2while depressing Cu sulfides and pyrite. Thisselective Cu-Mo separation is accomplished with the use ofdepressants such NaSH, Nokes, and Na2S (and cyanide, insome instances) with NaSH as the most widely used.

FIGURE 1:

A GENERIC FLOW SHEET FOR ACUMO CIRCUIT

Tails

Conc

Cu-Mo ore

Cu ~ 0.5%Mo ~ 0.05%

Roasting SteamCl2, O3, H2O2,etc

Cu Depressants

Bulk CircuitFlotation

Cu-Mo Bulk Concentrate (28% Cu, 1% Mo)

Pre-Treatment (Optional)

Conditioning with Cu Depressant

Mo Rougher

Mo Ro Conc

Mo Circuit

Cu Conc

Mo Cleaner Circuit


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AERO7260 HFP: Novel, Safe and Sustainable Alternative to Traditional Hazardous Modifiers NaSH, Nokes, Na2S, and Cyanide

NaSH, Nokes and Na2S depressants generate significantamounts of a toxic, lethal, and flammable gas, H2S. Cyanide,which is also used as a depressant is both poisonous and hasthe potential to generate HCN, a toxic and flammable gas.

In order to insure the safety of workers, the surroundingcommunities and the environment, Cu-Mo plants requireseveral safety measures including H2S alarms and exhausthoods over flotation cells and other exposed areas. Inaddition, H2S monitors are required on all personnel enteringthese plants and workers must adhere to strict safetyprotocols which involve rigorous training and evacuationprocedures. In spite of these measures, hazards still persist

and the industry is waiting for a safer, economically viabledepressant which will provide the same metallurgicalbenefits.

In response, Cytec has developed AERO7260 HFPDepressant, a highly efficient and versatile sulfide mineraldepressant with wide applicability as a selective depressantfor Cu sulfides and pyrite and a safer alternative to NaSH,Na2S, and Nokes reagent.

The following sections discuss in greater detail the issueswith conventional depressants and benefits and application

guidelines for AERO7260 HFP in Cu-Mo separation.

Problems with Current/Conventional Depressant TechnologyNaSH has been the main Cu sulfide depressant used inCu-Mo separations for many decades. However, due tothe danger of generation of high concentrations of toxic,flammable, hazardous, and lethal H2S gas, NaSH posessignificant issues in plant operations and poses a threat tothe local environment. Transportation of 20 to 40 tonsper day of 40% solution of NaSH present shipping and

logistics issues both in urban and remote areas. Metallurgicalperformance with NaSH is also not robust, for instance,plants can observe large performance swings with changes

in ore mineralogy, and often pyrite depression with NaSH isinadequate even at very large dosages, creating a significantchallenge in flotation operations.

In the absence of a robust and economically viablealternative, NaSH (Na2S and Nokes in some plants)continues to be used extensively in Cu-Mo operationsglobally despite the hazards and all the safety concerns

associated with it. AERO7260 HFP is Cytecs innovativesolution to this challenging issue.

Advantages of AERO7260 HFP Depression Efficiency

AERO7260 HFP is a highly efficient depressant for Cusulfides and pyrite which effectively replaces 50 to 90% ofNaSH depending on the process conditions.

Dosage-PerformanceAERO7260 HFP requires only 10% to 20% of the dosageof NaSH, providing similar metallurgical performance.

Stability and Ease of Handling

Stable and chemically inert reagent in storage,transportation, and under process conditions

Does not release H2S or other toxic gases, and isnon-hazardous

Classified as non-hazardous to the environment

No downstream or upstream effects to mineralprocessing

Easy-to-handle aqueous solution

Completely miscible in water

pH

AERO

7260 HFP is effective in a wide pH range (6 to 12).

Staged AdditionAERO7260 HFP is long lasting reagent eliminating thenecessity of staged addition down the bank in scavengersand cleaner cells as with NaSH.

Bulk Concentrate PretreatmentEliminates pretreatment of bulk Cu-Mo concentrate withsteam, acid and CO2conditioning, attrition conditioning, etc.


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Applicability and Other Advantages

Eliminates the need for N2 or covered cells.

Does not require extended conditioning time.

Does not contain any phosphorous or arsenic, so issuitable in many MoS2operations.

Clearly, with such advantages, AERO7260 HFP offers asignificant technological step forward in minimizing humanand environmental hazards in Cu-Mo separations.

Proven Performance of AERO7260 HFP Lab and Plant DataThe cumulative Cu and Mo recoveries from the concentratefrom a North American mine are shown in Figure 2. For

this concentrate sample, 7.5 kg/T of NaSH was required toprovide efficient Cu depression (Cu recovery ~ 10%) and

Mo recovery of greater than 95%. AERO7260 HFP at 0.5kg/T replaced approximately 65% of the NaSH dosage and

provided comparable Cu depression.

FIGURE 2:

CUMULATIVE CU AND MO RECOVERYFROM A CUMO NORTH AMERICANCONCENTRATE

100

80

60

40

20

0

NaSH 7.5 kg/T NaSH 7.5 kg/T + 7260 0.52 kg/T

Recovery(%)

Cu Mo


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FIGURE 3:

CUMULATIVE CU AND MO RECOVERYFROM A CUMO ASIAN CONCENTRATE

In Figure 3, the Cu and Mo recoveries for a Cu-Moconcentrate from an Asian mine are shown. Efficient Cudepression was achieved only when 44 kg/T of Na2S wasused. Under these conditions, Cu recovery was about 20%

and Mo recovery was about 80%. The effect of 1.2 kg/TAERO7260 HFP helped achieve even better Cu depressionand Mo selectivity with only half the dosage of Na2S.

90

80

70

60

50

40

30

20

10

0

Na2S 44 kg /T Na2S 22 kg /T, AERO 7260 HFP 1.2 kg/T

80.9

19.8

81.3

11.8

Recovery(%)

Mo Cu


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FIGURE 4:

2NDCLEANER CIRCUIT

LAB DATA OF CU, MO AND FEA RECOVERY ANDB GRADE

Clearly, the benefits of adding AERO7260 HFP are observed by the improved metallurgical performance and substantiallyreduced dosage of NaSH.

Figures 4A and B show Cu, Mo, and Fe recoveries andgrades for lab data using AERO7260 HFP on another NorthAmerican mine Cu-Mo cleaner concentrate. In terms ofCu depression, this concentrate required about 11 kg/T ofNaSH; however the Fe depression was not efficient at thisdosage. For efficient Cu and Fe depression, a higher dosage

of 55 kg/T NaSH was required. The addition of 0.25 kg/T ofAERO7260 HFP plus 11 kg/T of NaSH significantly enhancedboth Cu and Fe depression and Mo selectivity. This suggeststhat AERO7260 HFP is highly effective in the depression ofboth Cu and Fe and enables mine operations to significantlyreduce NaSH consumption, in this case by over 80%.

100

90

80

70

60

50

40

30

20

10

0

50

40

30

20

10

0

Cu Mo Fe

Cu Mo Fe

36.9

0.2

36.9

0.2

Mo Concentrate

Mo Concentrate

Recovery(%)

Grade(%)

NaSH 55 kg/T

NaSH 11 kg/T

NaSH 11 kg/T + 0.25 kg/T 7260

33

0.2

99.2

49.2

99

45.4

98.8

50.7

68.4

3.2

92

4.2

47.2

2.4

A

B


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Figure 5 provides the average Mo assay in the scavenger tailsfrom another Cu-Mo plant. The overall objective in this plantwas to significantly reduce or eliminate Nokes (1400 g/T)usage in its Mo circuit, while maintaining Mo recovery

(Mo < 0.2% in scavenger tails). With only about 100 to 200g/T of AERO7260 HFP, a significant volume of Nokes wasreplaced, while the key specifications were maintained.

FIGURE 5:

PLANT DATA FOR MO INSCAVENGER TAILS AS A FUNCTIONOF NOKES DOSAGES USED

Figure 6 shows the plant data when using AERO

7260 HFPin an on/off cycle on 3 consecutive days. The plot shows thepercentage difference in Cu, Mo and Fe grades in the cleanercircuit with and without AERO7260 HFP on any given day.In the off-cycle, only NaSH was being used to control therespective grades in order to meet production specifications.With NaSH only, both Mo and Cu specifications wereachieved while Fe was above the specifications, i.e. sufficient

pyrite depression was not achieved. With the addition ofAERO7260 HFP (on-cycle), all the specifications wereachieved in addition to reducing the NaSH consumptionby over 60%. Further, it was observed that Mo grades weresignificantly better in the on-cycle. This clearly suggests thebenefits of AERO7260 HFP in such operations. Moreover,through optimization, the NaSH dosage could be reduced by80%, by adding only about 2 kg/T of AERO7260 HFP.

.40

.35

.30

.25

.20

.15

.10

.05

0

Nokes Standard 50% Reduction 75% Reduction 100% Reduction

AverageMoinScav

Tail(%)


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FIGURE 6:

THREE CONSECUTIVE DAYS OF PLANTDATA USING AERO7260 HFP IN AN

ON/OFF CYCLE IN THE CLEANERCIRCUIT. THE % DIFFERENCE IN FE, CU,AND MO GRADES BETWEEN CONTROLOFF CYCLE AND WITH AERO7260 HFPON CYCLE IS SHOWN

General Guidelines for Application The typical dosages to test AERO7260 HFP is around

250-1500 g/T, and needs to be adjusted depending onthe ore mineralogy and other process conditions. Higher

dosages may be evaluated as needed. Optimization shouldbe based upon Cu and pyrite depression, Mo selectivity,and economics.

The performance of AERO7260 HFP is best when air isused. Note: N2can be used, however the performanceadvantages and benefits of AERO7260 HFP may not befully realized.

Pretreatments are not required with AERO7260 HFP.

AERO7260 HFP should be added along with NaSH(or Nokes/Na2S).

Recommended conditioning times are 5 to 15 minutes.Longer conditioning times, e.g. 30 min or longer are notrequired.

AERO7260 HFP can be added in the roughers, scavengeror cleaner stage, as needed. Usually, if the dosages areoptimized, stage addition is not required.

AERO7260 HFP can be added as-is, or may be diluted asneeded.

Other Applications for AERO7260 HFPAERO7260 HFP is an excellent depressant for a variety ofsulfide minerals, selectivity being dictated by dosage ofAERO7260 HFP and process conditions. Products based onAERO7260 HFP have a wide range of applications including:

a) Rejection of gangue from sulfide concentrates:Depression of all sulfide minerals while floating NonSulfide Gangue E.g. Ni-talc separation.

b) Depression of penalty/toxic elements in Cu and complexsulfide ores.

c) Enhancement of selectivity in Cu-Pb, Pb-Zn, Cu-Znseparations.

d) Depression of iron sulfides in Cu-pyrite and Zn-pyriteseparations.

e) Depression of Cu sulfides and pyrite in Cu-Mo,Cu-graphite, Cu-F, Cu-Talc separations.

20

0

-20

-40

-60

-80

-100Day 1 Day 2 Day 3

%DifferencebetweencontrolandwithAERO7260HFP(%)

Fe Cu Mo


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ConclusionAERO7260 HFP is a novel, safer, versatile and highlyeffective Cu sulfide and pyrite depressant with broadapplicability. This paper focuses on the application andbenefits of using AERO7260 HFP in Cu-Mo separations.The examples discussed in the paper include both lab andplant data which highlight the effectiveness of AERO7260

HFP in depressing Cu sulfides and pyrite and improving theselectivity with respect to Mo. In addition to enhancedselectively, dosages of hazardous reagents such as NaSH,Nokes, and Na2S could be reduced by 60%-80% withrelatively small dosage of AERO7260 HFP (0.5 to 2 kg/T).

References

D. R. Nagaraj, S. S. Wang, P. V. Avotins and E. Dowling, Structure-activity relationships for copper depressants, Trans. IMM, Sect C:Vol 95, 1986, pp. 17-26.

D.R. Nagaraj, C.I. Basilio, R.-H. Yoon and C. Torres, The Mechanism

of Sulfide Depression with Functionalized Synthetic Polymers, Proc.Symp. Electrochemistry in Mineral and Metals Processing, TheElectrochemical Society, Princeton, Proceedings Vol 92-17, 1992,

pp 108-128.

Chander, S. 1988. Inorganic depressants for sulfide minerals.Chapter 14 in Reagents in Mineral Technology. Edited by P.

Somasundaran and B.M. Moudgil. New York: Marcel Dekker.





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The mining industry is currently facing significantsustainability challenges in terms of dealing with difficult-to-process low-grade resources. These ores are typicallycharacterized by complex mineralogy and the presence ofsignificant amounts of penalty gangue sulfide minerals andtoxic elements. Among them, pyrite is a common challengein many operations.

Three chemical strategies for dealing with gangue sulfidesand penalty elements include:

a) selective flotation of value minerals while rejectingpenalty minerals throughout the entire circuit;

b) rejecting penalty minerals in an appropriate part of thecircuit using selective depressants; and

c) using a combination of selective collectors anddepressants in appropriate parts of the circuit.

New products and application technologies have beendeveloped in recent years for implementing these strategiesas dictated by the particular needs of a given plant.However, in recognition of the growing interest in meetingsustainability challenges, Cytec has been focused on the

creation of greener products (collectors, modifiers andfrothers) and processes using the FLOTATON MATRX 100approach.

Chemicals today play a critical role, not just in flotation, butin almost all areas of mineral processing. They will play aneven greater role in tackling the challenges and achieving thegoals of sustainable mineral processing, particularly in theareas of water efficiency and water resource management;waste reduction and remediation; minimizing environmentalimpact, safety and health risks (meeting and exceeding therequirements of regulations); energy efficiency; and dealingwith difficult-to-process, low-grade mineral resources andreserves. Together, these challenges are often termed greenerprocessing. There is also a growing desire to develop greenerchemicals, a major challenge in itself.

Different strategies for dealing with difficult-to-processlow-grade resources in a sustainable manner are evaluatedin order to determine the most efficient alternatives. Thediscussion includes an overview of recent developments atCytec using case studies in which the application of selectivecollectors and polymeric modifiers, including the newer,

greener chemistries, are demonstrated.

Rejection of Pyrite: Challenges and SustainableChemical Solutions

Mario Palominos* and Carmina Quintanar

In recognition of the growing interest in meeting sustainability challenges, Cytec has beenfocused on the creation of greener products (collectors, modifiers and frothers) and processesusing the FLOTATON MATRX 100approach.

Abstract


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IntroductionIn earlier years, pyrite content and other sulphide gangueswere less of a problem in the mineral processing of copper,lead, zinc and other elements, mainly due to the lowercontent of this mineralogical species, the high content of thevaluable minerals and the lower ecological sensitivity to gasemissions (principally SO2) coming from the smelter.

The first goal was to achieve higher selectivity, which wasachieved through the development of dithiophosphatealternatives to the well-known xanthates (introduced

to the market in 1923). Subsequently, it was found thatthionocarbamates (and most commonly the isopropylethyl derivative, IPETC), generally have a higher selectivitythan the above-mentioned chemistries. A third stage in thedevelopment of selective collectors focused on xanthateesters and dithiocarbamates1.

In parallel, the use of high pH2to depress pyrite wasimplemented (particularly as a cleaning step). Lime (CaO)was the depressant agent, and was used as a slurry (Ca(OH)2in preference to caustic soda (NaOH) or soda ash (Na2CO3).Hence, the solution used was based on flotation at high

pH (10-11) using a selective collector in the rougher stageand a very high pH (> 11) in the cleaning step. The solutionwas acceptable for the processing conditions at that time.However, the use of lime negatively affected the recovery ofvaluable secondary elements (e.g., molybdenum and gold).Currently, use of seawater is an additional limiting factor forthe application of lime.

A second alternative, employed now for several years, isbased on the use of depressants for iron sulphides (mainlypyrite and pyrrhotite). Sodium cyanide yields some goodresults; however, secure handling and environmental issues

make its use unattractive. Thus, sulphoxy depressants havebeen increasingly applied in recent years.

A factor not always considered is the degree of activationof the pyrite, mainly by copper ions from altered or oxidizedminerals. When pyrite is unactivated, it is possible to obtaingood results using lime, sodium cyanide or sulphoxy species(such as sodium or ammonium sulphite or metabisulphite3).

When pyrite is activated, however, lime is much lesseffective, cyanide has its safety, health and environmental(SHE) issues and the sulphoxy species have to be used athigh dosages. Furthermore, the degree of association ofpyrite, particularly in conjunction with valuable species(copper, molybdenum, gold, lead, zinc etc.) must beconsidered. Selectivity should be for liberated pyrite in orderto prevent the loss of any valuable species associated withthe pyrite.

Alternatives to inorganic depressants have also beenutilized, including organic products from natural sources4,5,6(including quebracho, tannins and their derivatives) andethylene diamine tetraacetic acid. In recent years, polymericdepressants have been developed that work effectivelyfor both active and non-activated pyrites. These productsare actually hydrophilic copolymers containing chemicalfunctionality that is able to adhere selectively to ironsulphide species and lead to their depression. Importantly,polymeric depressants do not have the toxicity problemsassociated with the inorganic depressants, and they may beused at significantly lower doses.

The need to process ores with higher iron sulphide content,the generally lower grades of valuable elements and thegrowing importance of secondary elements (molybdenum,gold, etc.), are driving greater interest in the use of selectivecollectors. In recent years, more selective reagents havebeen developed for the rougher stage in order to achieveselective flotation with high efficiency at this point, and thusminimise the use of depressants in the cleaning step. Thecompounds of interest have included structurally modifieddithiocarbamates and thionocarbamates. These collectorshave the advantage of being selective against liberated

pyrite, but effective for the valuable elements associatedwith pyrite, such as copper, molybdenum, and others,thereby avoiding the loss of these valuable species related tothe non-flotation of associated particles (middlings).

Rejection of Pyrite: Challenges and Sustainable Chemical Solutions


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MethodologyMineral ore samples from South America were used to evaluate the application of selective collectors and polymericdepressants. The feed grades of the ores are listed in Table 1.

TABLE 1: Feed Grades of the Mineral Ores Used in the Evaluation of Selective Collectors.

Ore Copper content, % Iron content, % Molybdenum content, ppm

Ore-1 0.74 2.1 98

Ore-2 0.33 4.73 107

Ore-3 1.05 4.40 300

Experimental ProcedureLaboratory flotation tests were conducted to simulate 1) justthe Rougher stage and 2) the different stages of the plant(open cycle test). The flotation products were collected andanalysed for copper, iron and molybdenum using atomicabsorption analysis. These mass balance results allowed the

calculation of the metallurgical balance, and therefore themetallurgical recoveries, for each test. The conditions for thelaboratory tests with the different mineral ores are describedin Table 2.

TABLE 2: Laboratory Test Conditions for Each of the Ores

Conditions Ore-1 Ore-2 Ore-3

Machine Agitair L500 Denver Wemco

pH 10.5 9.5 9.5

% Solids 34 34 30

Flotation time (min) 10 15 12

Grinding 30% + 100#Ty 20% + 100 #Ty 20% +65#Ty

Note that with Ore-3, when the standard collector was used,typical conditions for the cleaning stage were used (lime wasadded) and the pH was 11.5. However, lime was not added in

the cleaning stage for the other collectors tested with Ore-3(final pH=8.7).

Results and DiscussionThe study with Ore-1 demonstrated the difference inthe selectivity for iron for the different types of selectivecollectors: dithiophosphate (DTP),

isopropyl ethylthionocarbamate (IPETC) and a structurallymodified thionocarbamate (SMTC).



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The difference in the performance of DTP and IPETC, asdescribed above in the Introduction, can be readily seenin Figure 1. IPETC, one of the first selective collectors toreplace the xanthates, provides good recoveries and betterselectivity. Importantly, though, it can also be seen inFigure 1 that the structurally modified thionocarbamateAEROXD-5002 promoter, which represents a new family

of collectors developed by Cytec, is clearly advantageous interms of its selectivity for copper minerals against pyrite (asrepresented by the Fe assay).

A complementary study was then conducted with a secondore (Ore-2) with different mineralogical characteristics.Again, a series of selective collectors was evaluated,including the structurally modified thionocarbamate AERO9950 promoter, which provided the highest selectivityagainst iron and also the best copper recovery among thetested chemicals. The results of this study are presented in

Figure 2, while the different collectors and their dosage levelsused in the test are listed in Table 3. Collector-1 refers tothe main collector that was added to the grind. Collector-2,when used, refers to a secondary collector added in theconditioning stage prior to initiation of flotation.

FIGURE 2:

EVALUATION OFSELECTIVE VERSUS NONSELECTIVECOLLECTORS USING ORE 2

FIGURE 1:

SELECTIVITY COMPARISON FORCOPPER MINERALS VS. PYRITE FOR

3 COLLECTOR TYPES

Fe Recovery

CuRecovery

CuRec(%)

94

92

90

88

86

84

82

80

88.5

88

87.5

87

86.5

86

15 20 25 30 35 40 45 50 55 60

14.0 17.5 22.0 22.1 19.5 29.0 Fe Rec (%)

6.8 5.8 6.8 6.5 6.8 6.4 Mass Pull (weight %)

1 2 3 4 5 std Test

DT IPET SMTC


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It can be seen in the figure that similar copper rougher

recoveries were obtained for all three of the collectors,while in the rougher stage, the xanthate and AERO9950promoter had similar molybdenum recoveries and theAERO9955 promoter provided a greater recovery. The ironrecoveries in the rougher stage were significantly different,however. The xanthate had a high recovery (approximately80%), followed by the AERO 9955 promoter (with a valuenear 65%), but the AERO 9950 promoter was the mostselective (rougher Fe recovery of approximately 40%).

The overall recovery of iron for the xanthate was calculated

to be 30% based on analysis of the final concentrateafter the two cleaning steps and considering the classicalcleaning at high pH. AERO 9955 promoter, meanwhile, hadan overall iron recovery of close to 20%, while that of AERO9950 promoter (the most efficient in the rougher stage)was approximately 15%. With these values, the gradesobtained for the final concentrate in terms of the coppercontent were determined and are indicated in Figure 3.With both AERO 9950 promoter and AERO 9955 promoter,

FIGURE 3:

COMPARATIVE STUDY BETWEEN ANONSELECTIVE COLLECTOR SIPXAND TWO SELECTIVE COLLECTORS

TABLE 3: Reagent Scheme for the Study Using Ore-2.

N Collector-1[M] Collector-2 [C]

1 AP-9950; 20 g/t

2 XD-5002; 10 g/t

3 AP-9950; 15 g/t MX-945; 5 g/t

4 MX-8522; 15 g/t MX-945; 5 g/t

5 MX-7017; 15 g/t MX-945; 5 g/t

STD PAX; 20 g/t

[M]: Grind mill; [C]: Conditioning

The third study included a cleaning stage (evaluated in anopen cycle test). As indicated in the Experimental section,for the standard collector, the cleaning stage was conducted

at pH 11.5, the regular condition for depression when lime isused. For the evaluated alternatives, however, lime was notadded in the cleaning stage, so that comparisons could bemade with results obtained for the subsequent study usingdepressants (see below).

The selective collectors evaluated with Ore-3 included AERO

9950 promoter (structurally modified thionocarbamate)and AERO9955 promoter (a mix of thionocarbamate anddithiocarbamate). Their performance was compared tothat of the non-selective collector SIPX (sodium isopropylxanthate), for which the standard conditions were used.

The following figure (Figure 3) shows both the rougher andglobal recoveries (considering an open cycle test with twocleaning stages and a scavenger stage) conducted on Ore-3.

Cu Fe Mo100

90

80

70

60

50

40

30

20

10

0

Rougher Final Rougher Final Rougher Final

ST AP- AP-

Recovery(%)

Cu-FC Grade =


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FIGURE 4:

INORGANIC AND ORGANICDEPRESSANTS FOR PYRITEUSING ORE3

MBS and the polymeric depressant developed by Cytec,AERO7260 HFP depressant, were evaluated under similarconditions (pH = 8.5). The standard test used only limeas the depressant and was conducted at pH = 11.5. All

three depressants were added at the regrind mill stage.Importantly, as can be seen in Figure 4, neither the standardor the alternative depressants reached the values necessaryfor commercial concentrate grades (Cu > 25%).

The addition of the depressant in the rougher stageto simulate the effect of the selective collector wasalso evaluated. However, low depression of iron wasobserved. The most significant effect was that copper and

molybdenum species were depressed at high levels.

the final copper concentrates reached or exceeded therequirements for commercial grade material. In addition,due to the lower pH, there was limited loss during recovery

of the by-product molybdenum (Mo) in the cleaning stageas compared to the reduction in the Mo recovery using thestandard collector (SIPX).

Comparative Study with Different Pyrite DepressantsFigure 4 shows the results using different depressants, suchas lime (for the standard condition), sodium metabisulphite(MBS), which is currently used, particularly when seawateris used for the processing, and new polymeric organicdepressants. The ore used in this work was the same as that

used to evaluate the selective collectors (Ore-3). In thisstudy, the standard collector (xanthate) was used in all ofthe tests so that the effect of the different depressants couldbe evaluated in the cleaning stage.

Rougher Final Rougher Final Rougher Final Rougher Final

ST Coll-STD /A-7260; 50

Coll-STD /A-7260; 100

Coll-STD /MBS-Na; 300

Cu Fe Mo100

90

80

70

60

50

40

30

20

10

0

Recovery(%)

Cu-FC Grade =


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ConclusionThe results presented above demonstrate that there arenew alternatives available on the market that are even moreselective than the classic collectors commonly used forpyrite and other sulphide mineral gangue and can addressthe increasing levels of these contaminants that are presentin todays mineral deposits.

In addition, it was also shown that it is more efficient touse highly selective collectors in the roughing stage, ratherthan to use collectors with low or medium selectivity inconjunction with depressants. In the latter case, high dosesare typically required, particularly when using organicdepressants, which were found to be inefficient and havethe potential to negatively affect the recovery of both themain sulphide product and secondary products, such asmolybdenum and gold.

References

1. Klimpel R. Richard, A discussion of traditional and new reagentChemistries for a Flotation of Sulphide Minerals. Chapter 7,

Reagents for Better Metallurgy, Society for Mining Metallurgyand Exploration Inc., Littleton, Colorado USA, 1964.

2. Yuqiong Li, Jianhua Chen, Duan Kang, Jin Guo, Depression ofPyrite in alkaline medium and subsequent activation by copper,

Minerals Engineering 26 (2012) 64-69.

3. G.I. Dvila-Pulido, A. Uribe-salas, R. Espinosaa-Gomez,

International Journal of Mineral Processing, 101 (2011) 71-74.

4. Pedro E. Sarquis, Adriana Moyano, Mercedes Gonzalez, VanesaBazn, Organic Depressant Reagent Effect on pyrite in CopperMinerals Flotation, 8th International Mineral Processing Seminar

(Procemin 2011), 109-116.

5. Maximiliano Zanin, Saeed Farrokhpay, Depression of Pyrite inPorphyry Copper Flotation, 8th International Mineral ProcessingSeminar (Procemin 2011), 135-143.

6. Jianhua Chen, Yuqiong Li,Ye Chen , Cu-S Flotation Separation

via the combination of Sodium Humate and Lime in a low pH

Medium, Minerals Engineering, 24 (2011), 58-63.




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MAX HTBayer Sodalite Scale Inhibitor:A Green Solution to Energy Consumption

Morris Lewellyn, Alan Rothenberg, Calvin Franz, Frank Ballentine, Frank Kula, Luis Soliz, Qi Dai, andScott Moffatt

As the premier advanced chemicals partner for the Alumina industry, Cytec specializes inproducing products with the breadth and depth to advance all stages in the Bayer Process. Ourproduct innovations have transformed the industrys expectations regarding their technology

suppliers and our strategy is to continue to develop solutions that will provide step changes inthe industry. Our MAX HTscale inhibitor, a revolutionary product that eliminates sodalite scalefrom heat exchangers, recently received the 2012 Environmental Protection Agencys PresidentialGreen Chemistry award.

The award recognizes companies that have pioneeredsustainable technologies that incorporate the principles ofgreen chemistry.

MAX HT was developed to reduce or eliminate scaling fromthe evaporator and digester heaters in the Bayer process.

This product has been successfully applied in 20 Bayerprocess plants worldwide, resulting in the significant benefitsof increased heat transfer, reduced energy consumption andreduced acid waste from reduced heater cleanings. Based

on trial data from a number of plants, the estimated annualsavings per ton of alumina produced are 0.26-1.3 Gj energy,resulting in 13-92 kg reduction in CO2emissions, and0.9-2.7 kg reduction in acid waste.* When these savings areapplied to the total alumina production from the 20 plants,this leads to an estimated realized annual savings of 11-56

million Gj energy, 0.54-3.9 billion kg CO2emissions, and38-116 million kg of acid waste reduction.

* The range reflects the wide variety in the operation of Bayer plants aroundthe world.

IntroductionCytec has developed a line of polymers for use as scaleinhibitors in evaporator and digester heaters used in theBayer process [1-8]. These products provide benefits byreducing or eliminating the scale formation in the heatersresulting in significantly higher heat transfer, reducing

energy consumption and waste. These products have beensuccessfully applied in a number of plants utilizing theBayer process throughout the world [9-11]. This technologyis also being assessed for sodalite scale elimination in theevaporation process for the treatment of other types ofsubstrate [12].

The scale deposited in these heaters is sodiumaluminosilicate sodalite or DSP (desilication product).

This is a result of the silica that is present in bauxite ores assilicates, primarily clay minerals, that dissolves quickly undertypical Bayer alumina digestion conditions. The Bayer liquorremains supersaturated in silica and this supersaturationis greatest after the alumina precipitation step, i.e. in the

spent liquor. As the alumina-depleted liquor is reheated,the rate of silica precipitation in the form of sodaliteincreases markedly with increasing temperature due to fasterkinetics[13]. This precipitation occurs as scaling on the insideof the heat exchange tubes and a significant loss of heattransfer occurs, leading to increased energy consumption,increased caustic losses, reduced liquor flows, reducedthroughput, reduced evaporation, and reduced production.


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Without MAX HT, the method used to manage the sodalitescale problem is to clean out the system whenever the heatexchanger performance drops below a certain level, typicallyabout half the original heat transfer rate. This cleaning isgenerally accomplished with the use of a 5-10% sulfuricacid solution to dissolve the scale. The used acid constitutesa waste stream requiring disposal. In addition to the acidcleaning, much of the inter-stage piping is cleaned usingmechanical means, such as jackhammers, to remove the scale.

The use of MAX HT is one way to make the Bayer processgreener in terms of energy use and waste generation. MAX

HT is commercial at twenty different plants across the globe,and under evaluation at a number of other plants. Many ofthese are double stream plants where the scale inhibitor canbe used on both evaporator and digester heaters, but thereare a number of single stream plants that find benefits from

just treating the evaporator heaters.

Cytec performed plant trials to research energy savings. SeeFigures 4 & 5. For detail on the results of the trials please goto www.cytec.com. The results of the trials show potentialenergy and waste savings which was the basis for theawarding Cytec the 2012 U.S. EPA (Environmental ProtectionAgency) Presidential Green Chemistry Challenge Award forMAX HT.

DIRTY AND CLEAN HEAT EXCHANGERS FROM OPERATING

WITHOUT AND WITH MAX HT ANTISCALANT AFTER 160 HRS.OF CONTINUOUS OPERATION, CORRESPONDING TO THE

HEAT TRANSFER CURVES IN FIGS. 4 AND 5, RESPECTIVELY.

MAX HTBayer Sodalite Scale Inhibitor: A Green Solution to Energy Consumption

FIGURE 4:

TYPICAL HEAT TRANSFER DECAYDURING 160 HRS. WITHOUT MAX HT

Without Antiscalant With Antiscalant

2700

2500

2300

2100

1900

1700

1500

1300

1100

900

700

5000 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160

y = -8.325x + 1981.8

Hours


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Benefits of MAX HTMAX HT sodalite scale inhibitor has been used successfullyin a number of Bayer process plants. Typically, the on-streamtime for a heater is increased from some 8-10 days to

45-60 days for digestion and 20-30 days to >150 days forevaporators. This ability to maintain a high heat transfer overa much longer life cycle between cleanings has resulted in anumber of benefits. These benefits are summarized below:

1. Increased evaporation when used in the evaporatorheaters. This leads to reduced caustic consumption andimproved mud washing in the washer circuit becausemore water is available for efficient washing of the redmud and gibbsite crystals. The annual realized reductionof caustic is estimated to be 79,000-198,000 tons of 50%caustic.

2. Increased production. This is a result of an increasedaverage flow due to being able to maintain theoutlet temperature without having to reduce flow toaccommodate a lower heat transfer rate.

3. Reduced energy consumption realized per annum.Savings in the range of 4.4-22.0 million tons of steamhave been realized, which translates to 11-56 million Gjenergy, or 0.54-3.9 billion kg CO2.

4. Less direct steam to the digester when used in thedigester heaters. By being able to maintain the maximumlive steam heater outlet temperature, the need to add

steam by direct injection in the digesters is reduced oreliminated, resulting in less extraneous dilution whichimpacts soda recovery and therefore caustic consumption.This also allows more mass in the digester in terms ofliquor and bauxite leading to higher production.

5. Reduced digester and evaporator heaters cleaning andmaintenance. This leads to a reduction in cost for theacid, labor, tube changes, etc. There is also less exposureof the workers to the associated hazards. The realizedannual reduction in hazardous acid waste is 38-116million kg. The number of cleaning cycles can be reduced

from a range of 20-50 per year per heater train to lessthan 10 per heater train.

6. Steadier plant operation.

FIGURE 5:

CONSTANT HEAT TRANSFERCOEFFICIENT RESULTING FROMTHE USE OF MAX HT

2300

2100

1900

1700

1500

1300

1100

900

700

5001 11 21 31 41 51 61 71 81 91 101 111 121 131 141 151 161

y = -0.4267x + 1744.1

Hours


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The value of the MAX HT technology is to reduce energyusage by 0.26-1.3 Gj, reduce CO2emissions by 13-92 kg, andreduce waste generation by 0.9-2.7 kg per ton of aluminaproduced. There are about 73 operating Bayer plantsthroughout the world, ranging in production capacity of

0.2 to 6 million tons of alumina annually, with the majoritybeing in the 1.5 to 3 million tons capacity. The estimatedannual environmental benefit for the 20 commercializedplants is shown in Table 6 along with the estimated globalannual potential benefit based on 2011 figures.

TABLE 6. POTENTIAL AND REALIZED BENEFITS OF MAX HT TECHNOLOGY

Energy (Gj) CO2Reduction (Kg) Waste Reduction (Kg)

Savings per ton of alumina produced 0.26 1.3 13 92 0.9 2.7

Realized savings (20 commercial plants) 11 56 million 0.54 3.9 billion 38 116 million

Potential savings (All 73 plants) 25 128 million 1.3 8.9 billion 86 263 million

Conclusion1. MAX HT provides estimated annual savings per ton of

alumina produced of 0.26-1.3 Gj energy, resulting in 13-92kg reduction in CO2emissions and 0.9-2.7 kg reduction inacid waste.

2. This more efficient use of energy results in increased

evaporation in the evaporator heaters, leading to reducedcaustic consumption and more efficient use of water.

3. The use of MAX HT leads to increased production dueto an increase in average flow and reduced direct steaminjection.

4. The use of MAX HT also results in reduced cleaning ofdigester and evaporator heaters resulting in reduced

exposure of workers to the hazards and reduced acidwaste.

References

1. D. Spitzer, A. Rothenberg, H. Heitner, and F. Kula, Method ofpreventing or reducing aluminosilicate scale in a Bayer process,

U.S. patent 6,814,873B2 (2004).

2. D. Spitzer, A. Rothenberg, H. Heitner, and F. Kula, Method and

compositions for preventing or reducing aluminosilicate scale inalkaline industrial processes, U.S. patent 7,390,415B2 (2008).

3. H. Heitner, Silane substituted polyethylene oxide reagents and

method of using for preventing or reducing aluminosilicate scalein industrial processes, U.S. patent 7,674,385B2 (2010).

4. H. Heitner and D. Spitzer, Hydrophobically modified polyaminescale inhibitors, U.S. patent 7,999,065B2 (2011).

5. D. Spitzer, A. Rothenberg, H. Heitner, F. Kula, M. Lewellyn, O.Chamberlain, Q. Dai, and C. Franz, Reagents for the eliminationof sodalite scaling, Light Metals, 2005, 183-188.

6. D. Spitzer, A. Rothenberg, H. Heitner, F. Kula, M. Lewellyn, O.Chamberlain, Q. Dai, and C. Franz, A real solution to sodalitescaling problems, Proceedings of the 7th International Alumina

Quality Workshop, 2005, 153-157.

7. D. Spitzer, O. Chamberlain, C. Franz, M. Lewellyn, and Q. Dai,

MAX HT Sodalite Scale Inhibitor: Plant experience and impact

on the process, Light Metals, 2008, 57-62.

8. M. Lewellyn, A. Patel, D. Spitzer, C. Franz, F. Ballentine, Q. Dai,O. Chamberlain, F. Kula, and H. Chen, MAX HT Sodalite ScaleInhibitor: Plant experience with first and second generation

products, Proceedings of the 8th International Alumina qualityWorkshop, 2008, 121-124.



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9. A. Oliveira, J. Dutra, J. Batista, J. Lima, R. Diniz, and E. Repetto,Performance appraisal of evaporation system with scale

inhibitor application in Alunorte plant, Light Metals, 2008,133-136.

10. L. Riffaud, P. James, E. Allen, and J. Murray, Evaluationof sodalite scaling inhibitor A users perspective (Paper

presented at the International Symposium on Aluminum: FromRaw Materials to Applications Combining Light Metals 2006

and the 17th International ICSOBA Symposium, Montreal,Quebec, Canada, 1-4 October 2006), Bauxite & Aluminasession, paper 29.7.

11. M. Kiriazis, J. Gill, and D. Stegink, Evaluation of MAX HT

atQueensland Alumina LTD, Proceedings of the 9th InternationalAlumina Quality Workshop, 2012, 88-92.

12. L.N. Oji, T.L. Fellinger, D.T. Hobbs, H.P. Badheka, W.R. Wilmarth,M. Taylor, E.A. Kamenetsky, and M. Islam, Studies of potential

inhibitors of sodium aluminosilicate scales in high-level wasteevaporation, Separation Science and Technology, 43 (2008),

2917-2928.

13. J. Addai-Mensah, Fundamentals of sodium aluminosilicate

crystallization during process heat exchange, (Paper presentedat the World congress of Chemical Engineering, 7th, Glasgow,

United Kingdom, 10-14 July 2005), 86781/1-86781/10.

14. L. Perez, Mechanism of calcium phosphate scale formation and

inhibition in cooling systems, Calcium Phosphates in Biological

and Industrial Systems, ed. Z. Amjad (Boston, Kluwer, 1998),395-415.





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Performance Evaluation of CYFLOCULTRAHX-5300 A New HXPAM Red Mud FlocculantApplied in CBA (Companhia Brasileira de Aluminio)

Luis Soliz, Renata Vinhas, Emiliano Repetto, Paulo Prado, Haunn-Lin T.Chen, Roberto Seno Junior,Andre Arantes, Rodrigo Santos, and Rodrigo Moreno

In the late 1980s, Cytec Industries Inc. developed a series of hydroxamated polyacrylamideproducts (HXPAM) to be used as high performance flocculants for treating red mud in the

Alumina Bayer Process1,2,3. This product family, known as CYFLOCHX Series, has since becomethe most widely used flocculant on red mud settlers in the industry.

IntroductionThe applications of several flocculants from CYFLOCHX00 and 000 series have been evaluated in a variety ofalumina plants worldwide. Since then, the alumina industryhas realized a number of significant benefits from the use ofCYFLOC HX flocculants.

After years of producing HXPAM emulsions, CYTECIndustries Inc. has developed a family of new hydroxamatedpolyacrylamide products5 CYFLOC ULTRA HXPAMS.CYFLOC ULTRA HX-5300 was the first of a new series.

The replacement of CYFLOC ULTRA HX-5300 by CYFLOCULTRA HX-6000 series HX-6100, HX-6200, HX-6300,and HX-6400 was due to further improvements in themanufacturing process. The new series will be available inthe market in the near future.

This paper describes the relative performance of CYFLOCULTRA HX-5300 versus CYFLOC HX-3000 in the CBAalumina plant.

Background CBA Bauxites CharacterizationThere are two types of bauxites processed in CBA: Zona daMata and Pocos de Caldas. Both bauxites are commonlyblended and added into the process in different ratiosaccording to the production plan.

The Pocos de Caldas ore has shown to be more difficult to

process than Zona da Mata ore due to the higher contentof reactive silica as well as the lower amounts of iron and

available alumina content. Operational adjustments arerequired in order to control instabilities in the clarificationstage when the blend contains more than 40% Pocos deCaldas bauxite. These instabilities include: difficulties in redmud settling, and a loss of compaction in the vessel, whichleads to reduced throughput and consequently reducedproduction.

Benchmarking of CYFLOC ULTRA HX-5300 PerformanceIn December of 2011, settling tests were conducted at CBAin order to determine the performance of CYFLOC ULTRAHX-5300 relative to the CYFLOC HX-3000 sample applied inthe process used on the settlers and first washer at the time.

Samples of settler feed slurry were collected and tested inCBAs laboratory. According to the process data, the blendof Zona da Mata and Pocos de Caldas bauxite at the time oftesting was 71% and 29% respectively.


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Figure 1 indicates that the manufacturing and laboratorysamples of CYFLOCULTRA HX-5300 provided a significantimprovement in the red mud settling rate and overflowclarity. Approximately 238 g/T of CYFLOC HX-3000was required in order to deliver a settling rate of 10 m/h.Conversely, the same settling rate was achieved withapproximately 194 g/T of CYFLOC ULTRA HX-5300. Findingsfrom these tests showed that the dosage of flocculantwas reduced by approximately 18% when CYFLOC ULTRAHX-5300 was applied versus CYFLOC HX-3000.

Similar to settling rate performance, samples of CYFLOCULTRA HX-5300 also outperformed CYFLOC HX-3000in clarity, as indicated in Figure 2. At a dosage of 225 g/T,CYFLOC ULTRA HX-5300 delivered supernatant clarityof approximately 80mg/L versus 140 mg/L when CYFLOCHX-3000 was applied. After positive results were achievedin the laboratory a plant trial was recommended in order toverify the product performance in the plant.

Performance Evaluation of CYFLOCULTRA HX-5300 A New HXPAM Red Mud FlocculantApplied in CBA(Companhia Brasileira de Aluminio)

FIGURE 1:

SETTLING RATE VERSUS TOTAL DOSEOF FLOCCULANT

FIGURE 2:

SUPERNATANT SOLIDS VERSUS TOTALDOSE OF FLOCCULANT

Total Dose (g/T)

Total Dose (g/T)

SettlingRate(m/h)

OverflowSolids(mg/L)

30

25

20

15

10

5

0

600

500

400

300

200

100

0

100 150 200 250 300 350 400

100 150 200 250 300 350 400

CYFLOCHX-3000

CYFLOCUltra HX-5300 (Lab. Lot)

CYFLOCUltra HX-5300 (Manuf. Lot)

CYFLOCHX-3000

CYFLOCUltra HX-5300 (Lab. Lot)

CYFLOCUltra HX-5300 (Manuf. Lot)


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Plant Application of CYFLOCULTRA HX-5300In February 2012, a plant trial was conducted at CBAfor a period of ten days. The purpose of the trial was todemonstrate that it is possible to control the settler stagewith the application of CYFLOC ULTRA HX-5300 whileachieving a dose reduction of approximately 18% versusCYFLOC HX-3000. Based on historical data of two previousmonths, the success criteria of the trial was to maintainprocess conditions similar to the prior conditions whenCYFLOC HX-3000 was applied. These conditions included:

Maintain the overflow (O/F) solids equal to or less than,80 mg/L

Maintain underflow (U/F) density equal to or higher than,1450 g/L

Maintain the interphase level at approximately 4.5 meters

Maintain U/F density equal to or higher than 1450 g/L

Do not negatively impact filtration operation (carry overmeasurements)

The plant trial was carried out on the TD1 settler accordingto the diagram below:

Results and DiscussionDuring the trial the target of Pocos de Caldas bauxite contentwas 38% in the blend. However due to logistic issues, thereal content of Pocos bauxite in the blend varied from 27%to 45%. That wide range of Pocos de Caldas bauxite charge

was an interesting aspect to be evaluated. Even when theamount to Pocos bauxite increased from 27% to 45%, itwas possible to control the settler stage with the CYFLOCULTRA HX-5300 application. This observation suggestedthat CYFLOC ULTRA HX-5300 has significant potential toallow for flexibility in bauxite savings. However, a longer termevaluation is required to confirm this hypothesis.

Figure 4 contains sixty days of overflow clarity data froma period prior to the trial as well as overflow clarity datathat was collected during the ten day trial period. Thedata indicates that the overflow clarity was maintained at

approximately 75mg/L in the TD 1 settler when CYFLOCUltra HX-5300 was applied. The mean and the standarddeviation in both periods were very similar. Over the last fewdays of the trial the data suggested that the overflow clarityincreased to approximately 100 mg/L. This deterioration isattributed to inefficient dispersion of the flocculant in thevessel caused by a reduction of the feed rate.


FIGURE 3:

CBAS CLARIFICATION FLOW DIAGRAM

Overflow

Flocculant

Settler Feed Slurry Filtrate(KM)

Flocculant

Red MudResidue

Mud Settler TD 1 Mud Washer Mud Washer Mud Washer Mud Washer


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Specifically, the CBA measurement of the interphase level istaken from the top of the settler. The data from the periodprior to the trial indicated that the interphase level

was approximately 4.2 meters. Figure 5 illustrates that theinterphase level remained stable and in some cases slightlyimproved to 4.6 meters when the new flocculant was applied.

FIGURE 4:

OVERFLOW CLARITY CHART

FIGURE 5:

INTERPHASE LEVEL CHART

Date

Date

Date

Date

IndividualValue

IndividualValue

MovingRange

MovingRange

5

4

3

120

100

80

60

40

1.5

1.0

0.5

0

40

30

20

10

0

UCL = 5.483

X = 4.567

LCL = 3.651

UCL = 98.72

X = 75.41

LCL = 52.09

UCL = 1.125

MR = 0.344

LCL = 0

UCL = 28.65

MR = 8.77

LCL = 0

1/12/11 8/12/11 15/12/11 22/12/1129/12/11 5/1/12 12/1/12 19/1/12 26/1/12 2/2/12 9/2/12

1/12/11 8/12/11 15/12/11 25/12/11 1/1/12 8/1/12 15/1/12 22/1/12 29/1/12 5/2/12

1/12/11 8/12/11 15/12/11 25/12/11 1/1/12 8/1/12 15/1/12 22/1/12 29/1/12 5/2/12

1/12/11 8/12/11 15/12/11 22/12/1129/12/11 5/1/12 12/1/12 19/1/12 26/1/12 2/2/12 9/2/12

HX-3000 ULTRA HX-5300





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Similar to the overflow clarity and interphase level, theunderflow density also remained stable during the trial.Figure 6 depicts the mud density data prior to the trial and

during the trial. The mean density prior to the trial andduring the trial was approximately 1515 g/L and 1521 g/L,respectively.

FIGURE 6:

UNDERFLOW DENSITY CHART

The Filtration Rate parameter was also monitored. Figure 7showed that the filtration rate remained stable during thetrial. CYFLOCUltra HX-5300 delivered a filtration rate ofapproximately 0.97 m3/m2/h versus 0.94 m3/m2/h whenCYFLOC HX-3000 was applied.

The carry over was also monitored to ensure that noflocculant was carried over to the filters. No problems orissues were reported from the security filtration stage.

Date

Date

IndividualValue

MovingRange

1600

1550

1500

1450

100

75

50

25

0

UCL = 1607.0

X = 1521.1

LCL = 1435.2

UCL = 105.5

MR = 32.3

LCL = 0

1/12/11 8/12/11 15/12/11 22/12/1129/12/11 5/1/12 12/1/12 19/1/12 26/1/12 2/2/12 9/2/12

1/12/11 8/12/11 15/12/11 22/12/11 29/12/115/1/12 12/1/12 19/1/12 26/1/12 2/2/12 9/2/12




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Figure 8 illustrates the flocculant dosage usage in the plantboth prior to and during the trial. Statistical evaluation

indicated that CYFLOCHX-3000 dosage was approximately252 g/T of mud, while CYFLOC Ultra HX-5300 was 208 g/T.

This represented a dosage reduction of approximately 18%when CYFLOC Ultra HX-5300 was applied as opposed to

CYFLOC HX-3000, even during the time period in which45% Pocos de Caldas bauxite was added the process.

FIGURE 7:

FILTRATION RATE CHART

Date

Date

IndividualValue

MovingRange

1.1

1.0

0.9

0.8

.20

.15

.10

.05

0

UCL = 1.0704

X = 0.969

LCL = 0.8676

UCL = 0.1246

MR = 0.0381

LCL = 0

1/12/11 8/12/11 15/12/11 22/12/1129/12/11 5/1/12 12/1/12 19/1/12 26/1/12 2/2/12 9/2/12

1/12/11 8/12/11 15/12/11 22/12/11 29/12/115/1/12 12/1/12 19/1/12 26/1/12 2/2/12 9/2/12




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Conclusion

1. The test indicated that CYFLOCULTRA HX-5300 hadequivalent settler performance as compared to CYFLOCHX-3000.

2. It was possible to control the settler stage while applyingCYFLOC ULTRA HX-5300, even when the process had theaddition of 45% Pocos de Caldas bauxite.

3. There were no problems or issues reported by the securityfiltration stage during the trial.

4. It was possible to reduce flocculant dosage byapproximately 18% with the application of CYFLOCULTRA HX-5300 relative to CYFLOC HX-3000.

References1. Spitzer, D. P. and Yen, W. S., US 4,767,540 (1988)

2. Rothenberg, A. S., Spitzer, D. P., Lewellyn, M.E., and Heitner, H.

I. New reagents for alumina processing, Light Metals, (1989), pp91-96.

3. Spitzer, D. P., Rothenberg, A. S., Heitner, H. I., Lewellyn, M.E.,Laviolette, L. H., Foster, T., and Avotins, P. V., Development ofnew Bayer process flocculants, Light Metals,

cytec solutions 2013

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