Low pH Pyrite Flotation Collector Development Program 1

Cytec SolutionsFor Solvent Extraction, Mineral Processing and Alumina Processing

Low pH Pyrite Flotation Collector Development Program1

As we head into 2012, we are all facing another exciting year and it is

clear that the pace of change in our world is continuing to accelerate.

This requires us all to be more agile and flexible in our approach. At

Cytec, we have continued on our strategic path of market needs driven

technology innovation that allows us to “Deliver Technology Beyond

our Customers’ Imagination”. When reviewing the feedback from

our recent customer survey, I was pleased to see that we are meeting

and in many cases exceeding your expectations in bringing innovative

solutions. We remain convinced that the development and deployment

of technology solutions to long term industry challenges is a source of

value for both us and our customers.

The Flotation Matrix 100® and Minchem modeling tools are particularly relevant in the fast

changing environment as they minimize the need for test work through careful experimental

design and high quality data interpretation. In combination with our excellent capabilities in

chemical design and optimization, it is possible for Cytec to continue to bring timely innovation

to our customers even though the pace has quickened. Another key lever in cutting time to

market is collaboration and as many of you know from personal experience this is remains key in

our success.

Over the last 18 months we have brought to market ACORGA® NR, ACORGA® OR, ACORGA®

OPT® 5540, EZ reagents for Electrostatic Separation, and the XR series of collectors as full or

partial NaSH replacement and we are seeing strong interest in all of these products. We have also

made significant progress on several other new product innovations that will be launched in 2012

including a scale control product, ACORGA CB™ for metal extraction processes. We have also

extended our geographic reach by establishing commercial presence in Peru and Serbia.

To address the growing demand for our Phosphine based chemistries including AEROPHINE®

and CYANEX® technologies, we have recently announcement plans to significantly expand

capacity at our manufacturing plant in Canada. This is a sign of our continued commitment to

the mining industry and ensuring we meet future demands.

I trust that you will find the latest edition of Cytec Solutions interesting and a source of

inspiration. Whether your interest is in Mineral Processing, Alumina Chemicals or Metal

Extraction Products there is something here for you.

Thank you for your valued business,

Martin Court

Vice President, In Process Separation

Letter from the Vice President

Low pH Pyrite Flotation Collector Development Program 11

Copper Solvent Extraction: Behavior of Iron and Manganese in Electrowinning Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The Impact of PLS Viscosity on Solvent Extraction . . . . . . . . . . . . . . . . . . . . . . . .

Low pH Pyrite Flotation Collector Development Program . . . . . . . . . . . . . . . . .

Use of AEROPHINE® 3418A Promoter for Sulfide Minerals Flotation . . . . . . . . .

New Flocculants for Improved Processing of High Silica Bauxite . . . . . . . . . . . .

The Inhibition of Vishnevite Scale in Chinese Refineries Using MAX HT® 550 Scale Inhibitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3

8

12

16

24

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Table of Contents

Solvent Extractions

Mineral Processing

Alumina Processing

Cytec Mining Chemicals Business Segments2

Solvent Extraction

Almost 40 years in the solvent extraction (SX)

business has translated into extensive experience

and successes in solving difficult problems and in

introducing many patented formulations.

Cytec offers two extraction product families:

hydroxyoxime extractants under the

trademark ACORGA® extraction reagents and

organophosphorus derivatives under the trademark

CYANEX® solvent extraction reagents.

Mineral Processing

Cytec's new reagent technologies are changing the

face of the mineral processing industry. Precision

targeting of chemistries yields increased recoveries,

productivity and safety. Using Cytec products,

customers have been able to attain an entirely new

level of profitability.

Recovering maximum value from mineral ore

is our primary goal. To that end, Cytec has

brought advanced tools to precious and base

metals operations for solving increasingly difficult

problems. Cytec employs specialty collectors and

reagents, dewatering aids and antiscalants. These

include highly selective reagents and modifiers

to provide plants with enhanced kinetics,

productivity and throughput. Other advanced

tools include modeling software and statistical

process analysis and design tools, as well as

proprietary laboratory and field tests - many of

which have become industry standards.

Alumina Processing

Cytec continues to provide the alumina industry

with value-adding, efficiency-enhancing

technology for all stages in Bayer Process alumina

production. Cytec's technological innovations

for alumina processing began with programs

for the solid-liquid separation processes and the

introduction of synthetic polyacrylate flocculants

to replace starch and have continued with a

constant stream of new products.

Subsequent development of copolymers for the

CCD circuit provided significant improvements

in refinery economics and red mud disposal.

Cytec pioneered the release of hydroxamic

acid flocculants, a quantum leap in flocculant

technology for the clarification circuit, providing

improved economics, liquor filtration rates and

reduced settler scaling.

The development of MAX HT® socialite scale

inhibitor, a revolutionary product that eliminates

sodalite scale from heat exchangers throughout

the Bayer Process, is another testament to Cytec’s

commitment to provide technologically advanced

chemistry that brings real value and contributes to

the sustainability of the alumina industry.

All of Cytec's initiatives in alumina are supported

by a global team of field engineers - and a

vertically integrated supply chain - to support

today's programs and technologies with an eye to

future industry needs.

www.cytec.com

3Copper Solvent Extraction: Behavior of Iron and Manganese in Electrowinning Solutions

Troy Bednarski, Matthew Soderstrom - Tempe, AZ

Introduction

An important part of the electrowinning process

is managing the iron and manganese in the

electrolyte solution. The primary benefits of

controlling these are better current efficiency

and cathode quality. An electrowinning study

utilizing a Hull Cell was conducted to identify

the behavior and affects of iron and manganese in

the electrolyte during electrowinning. The Hull

Cell is a test electrowinning cell commonly used

in the electroplating industry to test the affects

of various additives. The cell is a trapezoidal

container which positions a single cathode at an

angle to an anode so the plating occurs at different

current densities as a function of distance down

the cell. The cell may be fitted with a paddle

to vary the agitation in the bath. The plating is

achieved on a batch basis so it is not necessarily

representative of commercial cells but these tests

effectively simulate the relative behavior of iron

and manganese within the electrolyte.

Iron Behavior

Ferric iron in the electrolyte is reduced at the

cathode thus consuming energy; the resulting

ferrous iron is then oxidized back to ferric iron

at the anode in a constant cycle. This oxidation-

reduction cycle reduces the current efficiency as

some of the electrons are no longer available for

copper reduction.

The affect of ferric iron on current efficiency

was investigated at various iron concentrations

and various current densities. The solution

composition and Hull Cell test conditions are

given below:

Solution conditions:

Synthetic electrolyte: 45 gpl copper, 155 gpl

sulfuric acid

Ferric iron (0, 1, 2, 3, 5, and 10 gpl)

Hull Cell conditions:

40 Degrees C

Lead anode

Copper cathode blank

Current density (18.3, 27.4 and 36.3 amp/ft2)

Rectifier amps ( 1, 1.5 and 2 amps)

Plating time (3hrs 22 min, 2hrs 15 min, and

1hr 41 min)

Solution agitation provided with a paddle

Table 1 shows the ferrous ion concentration

and ORP (oxidation reduction potential) of the

electrolyte following the electrowinning process

(with a set agitation rate). Although the initial

electrolyte was made up with ferric sulfate, as

shown, a significant portion of the iron was

reduced at the cathode back to the ferrous state

resulting in a reduction in the ORP value.

4Copper Solvent Extraction: Behavior of Iron and Manganese in Electrowinning Solutionscontinued

Table 1

Percent Ferrous Iron and Oxidation-Reduction Potential

+3

01235

9.5

+2

04138413938

ORP (mV)

605506502502500498

ORP (mV)

560483489489488495

ORP (mV)

615506504500498501

+2

02933313438

+2

04243383940

ORP (mV)

570625645660675690

36.6 amp/ft227.4 amp/ft218.3 amp/ft2Initial solution

ORP measured using a Ag/AgCl reference electrode with 4 M KCl filling solution

Under the test conditions, approximately 30- 40% of the ferric iron was reduced to ferrous iron during

electrowinning. Since the reduction of ferric to ferrous consumes an electron which is no longer available

to reduce Cu+2. Any increase in the electrolyte ferric iron concentration will result in a decrease in current

efficiency. Under these conditions, the decrease in current efficiency was also dependent on the current

density as shown in Figure 1. As the current density was increased, the current efficiency also increased for

a given total iron concentration.

Figure 1

Iron Concentration vs. Current Efficiency

Iron concentration vs current efficiency

60

65

70

75

80

85

90

95

100

0 2 4 6 8 10

Initial Ferric Iron Concentration (gpl)

Cu

rren

t ef

fici

ency

%

18.3 amp/ft2

27.4 amp/ft2

36.6 amp/ft2

Amps/ft2 calculated based on total cathode area (not taking into account diagonal configuration)

5Copper Solvent Extraction: Behavior of Iron and Manganese in Electrowinning Solutions

continued

Iron/Manganese Behavior

Although iron is a consumer of energy, its

presence is beneficial to ensure that any

manganese, present as Mn+2 does not oxidize

to higher oxidative states (Mn+4 or Mn+7). The

oxidation of manganese to MnO happens at the

anode surface. The MnO can flake off of the

anode surface deteriorating the anode quality.

This leads to accumulation of lead on the bottom

of the cell or increases the likelihood of lead

becoming trapped within the cathode affecting

product quality. Further oxidation of Mn

(especially if the permanganate ion is formed)

will oxidize the organic in the stripping stage of

the solvent extraction process. The oxidation of

the organic will affect both physical and chemical

performance of the extractant thereby negatively

impacting the SX process.

The historic rule of thumb to control these issues

has been to maintain a total Fe to Mn ratio of

10/1 in the electrolyte to prevent the formation of

manganese in higher valence states. At this ratio it

is assumed ~ ½ of the iron will be present in the

ferrous state. The reduction half-reaction shows

that 5 ferrous ions are needed to reduce Mn+7 to

Mn+2 as shown in the following balanced half-

reaction equation:

5Fe +2 + MnO4

- + 8H + 5Fe +3 + Mn +2 + 4H2O

Although a 10:1 ratio of iron to manganese

is often recommended, there are a number of

operations which operate at significantly lower

ratios without generating a high ORP value. While

operations with ratios significantly over 10:1 may

still generate Mn at higher valence states if the

total iron concentration is not high enough.

Synthetic electrolyte solutions containing 45 gpl

copper, 165 gpl sulfuric acid were generated with

the following Fe/Mn ratios.

30/1 (0.3 gpl Fe and 0.01 gpl Mn)

10/1 (1 gpl Fe and 0.1 gpl Mn)

4/1 (1 gpl Fe and 0.25 gpl Mn)

These solutions were tested in the Hull Cell with

(Table 2) and without (Table 3) agitation at a

temperature of 40 degrees C at a current density

of 27.4 amp/ft2.

The results show that the permanganate ion was

formed with the 4.3/1 Fe/Mn ratio, even with

ferrous iron present in the starting rich solution.

The presence of ferrous iron in the electrolyte did

delay the formation of Mn+7 by the oxidation/

reduction reaction. When ferrous was present in

the starting solution it took 30 minutes to achieve

an ORP value greater that 1100 mV. At a Fe/Mn

ratio of 9.6/1 or greater no permanganate was

formed. There was very little ferrous iron present

in the ending solution when utilizing the 9.6/1

ratio. This indicates that the ferric iron was

reduced to ferrous iron then oxidized back to

ferric due to reduction of higher valence state Mn

that would have been generated at the anode. This

was not the case at a Fe/Mn ratio of 30/1. There

was ferrous iron present in the ending solutions in

the range of 30-40%, similar to the results of

Table 1 when manganese was not present in the

starting solution.

Copper Solvent Extraction: Behavior of Iron and Manganese in Electrowinning Solutionscontinued

6

Table 2

Electrowinning with Cell Agitation

(1) @ 5 min, (2) @ 30 min

Rich Electrolyte Solution Lean Electrolyte Solution

4.3

4.3

9.6

29

32

ORP

(mV)

648

458

648

615

422

+3

(gpl)

0.98

0.98

0.9

0.21

0.21

+2

(gpl)

–

–

0.06

0.08

0.11

+2

(%)

–

–

6.3

28

34

ORP

1115(1)

1118(2)

583

503

505

+2

(gpl)

0

0.53

0

0

0.32

+3

(gpl)

0.98

0.45

0.96

0.29

0

Table 3

Electrowinning without Cell Agitation

+3

(gpl)

0.96(1)

0.29

+2

(gpl)

0

0

+3

(gpl)

0.93

0.2

+2

(%)

3.1

31

ORP

(mV)

587

545

+2

(gpl)

0.03

0.09

ORP

(mV)

642

627

9.6

29

Rich Electrolyte Solution Lean Electrolyte Solution

7Copper Solvent Extraction: Behavior of Iron and Manganese in Electrowinning Solutions

continued

Permanganate ion was generated even at a

9.6/1 Fe/Mn ratio when the cell was operated

without agitation, ORP = 1155 at 5 min. During

this test the cell agitation was turned on and

the permanganate slowly started to reduce, as

evidenced by a reduction of the ORP value and a

diminishing of the electrolyte color from purple

back to the original blue. At a Fe/Mn ratio of

29/1 cell agitation did not appear to influence the

formation of the permanganate ion, apparently

sufficient iron was present in the ferrous state.

Conclusion

Iron and manganese are typically present

in copper PLS and can be transferred to the

electrolyte by physical means (entrainment) and

chemical transfer (ferric iron only). The transfer

of iron to the electrolyte will reduce the current

efficiency. This reduction will depend on the iron

concentration in the electrolyte, the cell agitation

dynamics, and the current density.

When manganese is present in the electrolyte

it is important to monitor the ORP and insure

the electrolyte returning to SX will not cause

oxidation. This is typically achieved by having

ferrous iron present in the tankhouse (rule

of thumb 10/1 total iron/manganese ratio)

to prevent the oxidation of Mn to higher

oxidation states. At high oxidation states Mn

can affect organic quality, cathode quality and

cause maintenance and anode stability issues.

Limiting the transfer of Mn to the electrolyte

by controlling physical (A in O) entrainment

is the key to minimizing potential issues.

The Impact of PLS Viscosity on Solvent Extraction8

Figure 1

Impurities Balance Scheme

Heap

PLS Pond

EW

SX RaffinatePond

Copper Cathode

H2SO4 with Impurities

Raffinate withImpurities

Cu and Impurities

ImpuritiesConcentrate

Until Equilibriumis Reached

Cu

H2SO4 Addition

Figure 1 shows the impurities balance scheme.

Eventually an equilibrium is reached when the

dissolving of impurities in the heap is in balance

with the precipitation of impurities.

Aluminum and magnesium are two of the common

impurities which tend to build-up within the PLS

contributing to higher viscosities.

Figure 2 shows aluminum and magnesium

concentrations in the PLS from Chilean operations.

Figure 2 Al, Mg in PLS for Chilean operations

Concentration of Aluminium and Magnesium in PLSChilean Plants

0

2

4

6

8

10

12

14

16

18

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

SX PlantsAl Mg

Con

cent

ratio

n (g

pl)

Alexis Soto

Introduction

In commercial scale solvent extraction, the impact

of impurities in a PLS (pregnant leach solution)

is frequently underestimated. Additionally, when

impurities are considered, the focus tends to be on

iron, chloride or nitrate depending on the origin

of the ore

However, the accumulation of some other

impurities like aluminum and magnesium

can increase the PLS viscosities. Under these

conditions poor physical behaviors may occur,

including increased entrainment and/or reduced

stage efficiency.

The typical PLS viscosity in Chilean solvent

extraction operations is between 1.0 and 3.0 cPs.

However approximately 20% of operations have

viscosities significantly higher than 3.0 cPs.

Studies were conducted to evaluate impact of PLS

viscosity on Cu extraction stage efficiency and

phase disengagement.

PLS Impurities and Viscosity Data

During the leaching process a number of elements

other than copper also leach. Depending on the

water balance and solubility limits, the build-up of

these impurities can vary greatly.

As shown, Al and Mg have the greatest impact

while iron addition had limited affect on viscosity.

Stage Efficiency

To assess the impact of PLS viscosity on mixer

efficiency kinetics curves were generated for

various aqueous solutions. Each aqueous solution

was prepared by diluting a real leach liquor sample

(one with a high content of impurities) with

water and then adjusting Cu and pH to the same

original values. These solutions were mixed with a

20 Vol % ACORGA® M5640 solution at a mixer

speed of 600 rpm, under organic continuity at

room temperature. The copper transfer rate data

was used to estimate stage efficiency assuming

three stage mixing, each with one minute

retention time. The results of this analysis are

shown in Table 1.

Table 1

Aqueous Viscosity and Calculated Stage Efficiency

Dilution, %0255075

Aqueous Viscosities, cP

7.84.22.81.7

Efficiency, %91.694.195.698.3

As shown, the stage efficiency would be expected

to vary from 91.6% to 98.3% dependent on the

aqueous viscosity.

9The Impact of PLS Viscosity

on Solvent Extractioncontinued

Figure 3 shows PLS viscosity data for a number of

the operations.

Figure 3

Viscosities in PLS for Chilean Operations

Chilean Plants

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

SX Plants

Visc

osity

, cP

Pregnant Leach Solution Viscosity

Synthetic solutions were prepared containing Cu,

Cu/Fe, Cu/Fe/Al, Cu/Fe/Mg and Cu/Fe/Al/Mg.

These solutions contained Cu=6 gpl, Fe=10 gpl,

Al=15 gpl and Mg=15 gpl. The pH of each solution

was adjusted with sulfuric acid to 2.35 and the

viscosity of each was measured and compared to

the solution containing all four metals.

Figure 4 shows the percentage contribution of

each element/combination to the total viscosity.

Figure 4 Impact of Cu, Fe, Al and Mg on Viscosity

0

10

20

30

40

50

60

70

80

90

100

Cu Cu/Fe Cu/Fe/Al Cu/Fe/Mg Cu/Fe/Al/Mg

Impact of Impurities on PLS ViscositySynthetic solution, Cu 6 gpl, Fe, 10 gpl, Al 15 gpl, Mg 15 gpl

Co

ntr

ibu

tio

n o

n v

isco

sity

, %

10

The impact of stage efficiency on copper recovery

was modeled for a 2E+1S circuit. The results are

shown in the Figure 5 below.

Figure 5

Stage Efficiency vs. Cu Recovery

70

75

80

85

90

95

100

70 75 80 85 90 95 100

Extract Stage Efficiency %

2E+1S M5640 20 Vol%, PLS=7 gpl Cu, pH 2, LE=38 gpl Cu, 190 gpl

Stage Efficiency vs. Copper Recovery

As shown the improvement in stage efficiency

from 91% to 98% could lead to a 5% higher

copper recovery under the conditions tested.

Phase Disengagement (PD)

Phase disengagement tests, under both organic

and aqueous continuity, were completed using

the adjusted PLS solutions. The results are shown

in Figure 6.

Figure 6

Phase Disengagement Times Versus PLS Viscosity

0

50

100

150

200

250

300

350

400

450

PLS 1 (7.81 cP) PLS 2 (4.21 cP) PLS 3 (2.80 cP) PLS 4 (1.69 cP)

Time (sec)

Org. Cont. Aq. Cont.

Phase Disengagement Time

The Impact of PLS Viscosity on Solvent Extraction continued

As shown PLS viscosity has a direct impact on

phase disengagement time, this effect is especially

apparent under aqueous continuity.

The physical behavior was studied more in depth

in a piloting run.

Piloting Studies

A pilot trial was run in a 2E+1S configuration

utilizing 100 ml/min flow rates. The PLS was

adjusted with 0%, 25% and 50% dilution (Cu

and pH adjusted to original values).

Table 2

Piloting Conditions

Circuit ConfigurationRun Time per Test

Mixer Retention Time

Viscosity of PLS 1Viscosity of PLS 2Viscosity of PLS 3

hourm3 2

sec20 Vol%

cPcPcP

2 + 116

1.541.75184

M56407.814.212.79

Figure 7 Pilot Plant Pictures

11The Impact of PLS Viscosity

on Solvent Extractioncontinued

Figure 8

Pilot Plant Pictures

Table 3 shows the piloting results for each aqueous

solution. The high PLS viscosity resulted in

significantly larger dispersion bands, and higher A

in O entrainment verses the diluted PLS feeds.

Table 3

Piloting Results

Test

Viscosity of PLS

Units

cP

°C

°C

sec

mm

ppm

Test 1

7.81

0.81

25.6

42.7

91

17.8

71.3

Test 2

4.21

0.86

24.9

43

84

2.8

24.2

Test 3

2.79

0.91

25.1

43

73

1

5.2

Conclusions and Recommendations

In the Latin American region, PLS viscosities

under 3 cPs are common, however there are

a number of operations with viscosity values

significantly higher due to the build-up of

impurities (primarily Al and Mg).

High aqueous solution viscosity may result in:

Increased dispersion band depths

Increased A in O entrainment

Longer phase disengagement times,

particularly under aqueous continuity

Reduced stage efficiency

Decreased copper transfer and recovery

Increased cost to operate

The viscosity of the PLS should be monitored

continuously due to potential impacts on SX

performance. This is especially important for plant

start-up and until a steady state is reached.

Experimental Test Procedures

Table 1

Flotation and Condition Times

Unit Operation

Conditioning 1

Conditioning 2

Time, (min)

2

6

2

6

Fresh plant pulp was taken every day from the

flotation circuit feed, and diluted to 30% using

plant process dilution water (pH 1-2) in a 20 liter

pail. The pail was agitated using a Denver flotation

machine so a 2.5 kg representative sample of

pulp could be cut for flotation testing. Flotation

was done using a Denver flotation machine

operating at 1200 RPM's, using a 2.2 liter Denver

flotation cell. Flotation times can be seen in

Table 1. Collector and frother were added to the

conditioning stages as required using a micro

syringe (neat) or a plastic syringe as a 1% solution.

The air valve was opened full during flotation. A

thirty second induction time was allotted in order

to build froth. Four scrapes (once around the

cell) were pulled from the flotation cell every 10

seconds. Both concentrates were collected in one

pan. The concentrate and tail were filtered, dried,

and assayed for copper, sulfur and iron.

Results

Test results are reported in groups by day since

plant pulp was used for testing. At least one

standard test using AERO 8045 promoter was run

each day in order to set a benchmark for the set.

Low pH Pyrite Flotation Collector Development Program

Peter Riccio

12

Introduction

At an established Cytec customer site, low pyrite

recovery has been an ongoing problem in the

flotation circuit since plant commissioning in late

2004. Sulfur recovery as an indirect measure of

pyrite was improved from 40% to 65% in mid-

2005 when on site laboratory work confirmed

that AERO® 8045 promoter was a more effective

collector than AERO 407 promoter. However,

sulfur recoveries above 65% could never be

achieved. The customer requested the Ian Wark

Research Institute[1] to complete a surface analysis

study using Scanning Electron Microscopy, X-ray

Photoelectron Spectroscopy, and Time-of-Flight

Secondary Ion Mass Spectroscopy to determine if

clay coated pyrite played a role. It was concluded

that the pyrite losses to the tail are made up of

a combination of coarse (+ 100um) liberated

particles and finer (-200um) particles that have

been coated by clay fines. The majority of the

losses appear to be due to the former. A series of

diagnostic tests performed in the Cytec Stamford,

CT research facility using synthetic plant water

showed that AERO 8045 was complexing with

metal ions in solution in the harsh, slimy, low

pH, environment. The complexed collector was

unable to make pyrite hydrophobic, and float. The

laboratory screening results showed that AERO

3302, AERO 9863, and AERO XD102 would not

complex with ferric, ferrous, or copper in solution,

and therefore recover more sulfur (as pyrite).

Theses chemistries were then sent to the customer’s

site for laboratory flotation testing.

Objective

The objective was to formulate a flotation collector

in the laboratory that will recover pyrite under

harsh operating conditions, and increase sulfur

recovery above 75%.

13Low pH Pyrite Flotation Collector

Development Program continued

Tests CY-1 to CY-4 Alternative Collector Testing

In the first block of tests, the objective was to

determine which collector chemistries could be an

effective replacement for AERO 8045, and also

to determine the effective dosage (see Table 2).

AERO 8045 was tested at a high dose (168g/t)

so as to achieve the highest sulfur recovery. A

typical sulfur recovery of almost 63% was achieved

using AERO 8045. AERO 3302 was tested at less

than half the dosage of AERO 8045 (53g/t) and

recovered 81% of the total sulfur. Almost 90%

sulfur recovery was achieved when 82g/t of AERO

3302 promoter was used. Increasing the dose to

124g/t did not increase sulfur recovery. AERO

3302 was identified as a potential formulation

component. A subsequent experimental design the

following day was developed and completed using

AERO 3302 as the formulation base.

CY-6 to CY-14 Baseline Development and Collector Blends

The objective of second experimental design was

to develop a statistically significant AERO 8045

baseline recovery using replicate testing. AERO

3302 formulations were also tested for comparison.

Table 2AERO 3302 Dosage Study, Sulfur Recoveries

Test No

CY-1

CY-4

CY-2

CY-3

Collector

AERO 8045

AERO 3302

AERO 3302

AERO 3302

Collector Dose, g/t

168

53

82

124

Recovery,% S

62.61

81.39

89.97

89.08

Grade, % S

22.50

30.00

28.10

27.30

Calc Head, % S

9.92

10.87

11.24

10.45

Several replicates of AERO 8045 under the same

conditions were randomly completed over the

course of the day to determine baseline data

and test reproducibility. All gave similar results,

recovering approximately 70% of the sulfur,

41% to 45% of the iron, and 65% to 67% of the

copper (see Table 3).

The optimum dosage for AERO 3302 promoter

is approximately 62g/t where 86% of the total

sulfur was recovered. Increasing the dose to

126g/t did not significantly increase recovery.

This is consistent with the previous day's work.

This trend was also reflected in both iron and

copper recoveries. All metal recoveries were

substantially higher as compared to the AERO

8045 standard. The best metallurgy was achieved

using 81g/t AERO MX3048 promoter, which

is a formulated collector containing AERO

3302 and AERO XD102. AERO XD102 was

identified in the screening phase, and being

robust in the harsh flotation environment.

AERO MX3048 recovering 90% of the total

sulfur, 62.7% iron. The performance of the other

formulations tested, AERO 9863 and Reagent

S-10291 were inferior to AERO MX3048. AERO

MX3048 was chosen for an industrial plant

trial and renamed AERO MX3048 promoter.

14Low pH Pyrite Flotation Collector Development Programcontinued

Industrial Plant Trial Using AERO

MX3048 Promoter

A plant trial quantity of AERO MX3048

promoter was purchased by the customer as

the product proved to be very effective under

controlled laboratory conditions.

The full plant trial ran for 7 days. Sulfur recovery

ranged from 43% sulfur to 73% sulfur. The

scavenger tail grade was lower than the previous

day and ranged between 2.4% sulfur to 2.9%

sulfur. Sulfur Head grade ranged from 3.5% sulfur

to 6.1% sulfur. The final concentrate grade was

not affected with the increase in recovery. Frother

was turned off the fourth day of the trial which

was a significant cost savings. The froth was richly

mineralized in both the rougher and cleaner

concentrate. The final concentrate storage tank

was full, (>92%) and the pyrite filter press needed

to be operated so that the extra pyrite could be

stored on a stock pile for use at a later date. This is

the first time since commissioning that circuit has

performed well, even though the sulfur feed grade

was relatively low (2% sulfur).

Test No

CY-7

CY-9

CY-13

CY-12

CY-8

CY-10

CY-14

CY-6

CY-11

Product

AERO 8045

AERO 8045

AERO 8045

AERO MX3048

AERO 9863

S-10291

AERO 3302

AERO 3302

AERO 3302

Collector Dose, g/t

141

138

143

81

83

84

62

86

126

Recovery, % S

70.31

70.84

69.22

90.14

67.51

80.79

86.60

87.43

86.27

Grade, % S

20.57

19.68

18.98

23.62

25.51

27.61

24.16

26.61

21.33

Calc Head, % S

8.74

9.04

9.07

10.14

8.93

9.93

9.17

9.63

9.50

Recovery, % Fe

41.40

42.39

45.42

62.67

35.27

49.65

55.75

54.05

60.29

Recovery, % Cu

67.05

66.74

65.83

79.72

55.90

71.98

75.47

74.42

76.22

Table 3

Dosage and Blend Study

Half hourly spot samples of the head, tail and final

concentrate were collected as a cross-check with

the plant samples. The sulfur grades in the final

tail were quite similar between the plant and spot

samples, reading between 2.2% to 3.2% sulfur.

Conclusions

The AERO MX3048 promoter trial proved that

the product was successful in reducing sulfur in

the final tails in a low pH, and high dissolved

metal ion pulp. The product also improved total

sulfur recovery without the loss of sulfur grade.

In addition, the frother requirements dropped

substantially.

There was a significant decline in the tail

profile from surveys with the use of AERO

MX3048. Previous tail profile shows minimal

change in tail grade across the rougher/

scavenger cells.

Minimal change in final grade was noticed

with the increase in recovery.

15

Further reduction in tail could be achieved

by operating at higher pulp levels in all the

rougher and scavenger cells.

The use of stage dosing across all rougher

and scavenger cells, except for the last cell,

especially with the new promoter proved to be

beneficial in reducing recovery.

There is a step change reduction in the tail

grade for sulfur from the addition of the

new promoter and also through operating

adjustments made to the float circuit.

The feed grade was low towards the end,

hovering at 6% sulfur. However that did not

affect the performance of the float plant as it

normally would. Both concentrate tank level

and density were high.

The final concentrate grade remained very

consistent at above 50% sulfur with various

head grade and recoveries.

AERO MX3048 promoter trial proved that

the promoter was successful in reducing the

tail grade step wise, thereby improving the

overall sulfur recovery.

Further trials involving stage dosing will be

beneficial in reducing further the tail grade

and improve sulfur recovery.

Further adjustments and fine tuning on the

operating conditions of the float circuit (i.e.

froth level, pull rates and density, and possibly

desliming) is likely to improve sulfur recovery.

Addition of frother was stopped after the

fourth day of the trial. AERO MX3048

appears to provide some frothing

characteristics.

Low pH Pyrite Flotation Collector Development Program

continued

References

1. Bassell, Chris, Kawashima, Nobuyuki, Lewis,

Andrew, Newell, Ray, Ian Wark Research

Institute"Surface Analysis and pyrite flotation"

Report to Lane

Xang Minerals (Laos), April 2006.

16Use of AEROPHINE® 3418A Promoterfor Sulfide Minerals Flotation

Phillip Mingione

AEROPHINE® 3418A is a unique sulfide mineral

promoter produced by Cytec, based on phosphine

(PH3) chemistry. It has proven effective as a

collector for the sulfide minerals of copper and

particularly lead (galena), as well as for secondary

gold and silver values. AEROPHINE 3418A has

widest application as a Cu and/or Pb collector

for complex ores of Cu-Zn and Pb-Zn, which

frequently have significant quantities of associated

precious metal values. Advantages shown in

the use of AEROPHINE 3418A are improved

selectivities against Zn- and Fe-sulfides, increased

precious metals recoveries, reduced total collector

consumptions for Cu and/or Pb flotation, and

increased flotation kinetics leading to higher

recoveries of these values. Operating plant, pilot

plant and laboratory test data from treating

different ores are presented, demonstrating the

advantages in use and preferred application of

AEROPHINE 3418A.

Introduction

Cytec operates the only phosphine and

phosphine derivatives plant in North America,

located in Niagara Falls, Ontario. Specialty

chemicals manufactured at this facility are used

in many diverse applications, including solvent

extraction reagents. A unique phosphine-based

sulfide mineral promoter, AEROPHINE 3418A,

is also produced in this facility.

The origins of AEROPHINE 3418A promoter

date back to the 1960's, when it was established

that sulfide mineral collectors based on

phosphine chemistry demonstrated efficacy. This

new collector chemistry was found to provide

flotation performance differing significantly

from those of more traditional thiol collector

chemistries such as xanthates, dithiophosphates,

mercaptobenzothiazoles, thionocarbamates

and those with xanthogen groups. Some of

the advantages ultimately demonstrated by

AEROPHINE 3418A promoter compared to these

traditional collectors include:

Improved selectivities and recoveries in base

metals flotation, particularly with complex

polymetallic ores.

Increased recoveries of precious metals

associated with base metal ores.

Greater selectivity against iron-sulfide gangue

minerals.

Rapid flotation kinetics.

Decreased collector consumption.

A further advantage observed in operating

plants, but difficult to quantify, is very stable

flotation circuit operation. This characteristic of

AEROPHINE 3418A facilitates the optimization

of circuit performance, particularly by computer

control, and enables treatment of variable feeds

with predictability.

Application Ore Types

AEROPHINE 3418A has found widest

application in flotation of copper- and lead-sulfide

minerals, particularly where these are found in

complex sulfide ores containing sphalerite zinc

mineralization, and ores with high levels of pyrite

and/or pyrrhotite. These ore types frequently

contain secondary gold and/or silver values,

the recovery of which can have a significant

economic impact on the profitability of an

operating plant whose primary products are base

metal concentrates. AEROPHINE 3418A has a

particular affinity toward silver and silver-sulfides.

It is also in use to treat porphyry copper ores

where copper is the only base metal recovered,

and has been used as collector for the recovery of

Ag-jarosites. Test work has given indications that

17Use of AEROPHINE® 3418A Promoter

for Sulfide Minerals Flotationcontinued

nickel-bearing sulfide minerals are also

amenable to treatment using AEROPHINE

3418A as collector.

Laboratory testing in the zinc flotation stage

with some ores has given indications that

AEROPHINE 3418A may be effective as an

activated sphalerite collector. The results when

using AEROPHINE 3418A promoter as an

activated sphalerite collector, generally have not

as frequently shown the advantages more typically

seen of its application to copper, lead and precious

metals flotation stages. The reasons for this are not

clear, but are thought in part to be related to the

stoichiometry of Fe within the sphalerite crystal

lattice. Nevertheless, use of AEROPHINE 3418A

in a zinc flotation circuit should not be discounted.

Application and Evaluation Techniques

There are two basic tenets to follow for proper

evaluation of the potential metallurgical benefits

AEROPHINE 3418A may provide: 1) use staged

additions of AEROPHINE 3418A for optimum

selectivity and control, and 2) use AEROPHINE

3418A as the sole collector. Adherence to these two

tenets is strongly recommended.

AEROPHINE 3418A can be a very powerful

collector. For initial evaluations on ore presently

being treated,the first addition of AEROPHINE

3418A promoter should be made at approximately

50% of the dosage of the current collector dosage

in use. The concentrate from this flotation stage

should be kept for assay, separate from any

subsequent concentrates produced. The preferred

first addition point for AEROPHINE 3418A is to

a 0.5-3 minute conditioning stage before flotation.

Determining the effects of AEROPHINE 3418A

addition to grinding can be reserved for later stages

of the investigation.

If a visual assessment of this first flotation stage

is favorable, a second addition of AEROPHINE

3418A should be made at about 25% of the

currently used collector dosage. The concentrate

from this second flotation stage should be kept

separate from the first. If a visual assessment

seems to indicate more collector is required, a

third flotation stage should be carried out in a

like manner to the second stage, keeping this

concentrate separate from the others.

If, on the other hand, the first flotation stage

appears to be non-selective and pulls too much

weight, another test should be made with an initial

AEROPHINE 3418A promoter dosage no more

than 20-25% that of the normal collector dosage.

Subsequent flotation stage collector additions can

then be made with AEROPHINE 3418A dosages

10-15% that of the standard collector dosage.

If AEROPHINE 3418A is suited to treating the

ore under evaluation, its flotation performance will

generally be characterized by a heavily mineralized

froth and fast flotation kinetics. If too much

AEROPHINE 3418A is added to the head of

flotation, the froth may be so heavily mineralized

that it will collapse on itself and be difficult to

remove from the flotation cell. If more frother

is used to help move the froth off the cell, it is

possible to encounter an overfrothing condition

further along the rougher/scavenger flotation

stages. Staged additions of AEROPHINE 3418A

alleviate these conditions.

AEROPHINE 3418A generally displays little

or no frothing properties. At times this has

required an increase in frother dosage when using

AEROPHINE 3418A as a collector, compared to

the frother dosage required with a collector having

frothing properties. This has proven advantageous

in some plants, as it tends to separate the function

of collector from that of the frother. Optimum

18Use of AEROPHINE® 3418A Promoterfor Sulfide Minerals Flotationcontinued

circuit frothing control can then be more readily

achieved by frother dosage alone, without

complications of additional frothing contributed

by the collector. Alcohol frothers, such as MIBC,

are generally preferred for best results, although

a number of plants using AEROPHINE 3418A

as a collector utilize a glycol-based frother. Staged

addition of frother, with AEROPHINE 3418A

as a collector, is widely practiced. This same

practice generally applies to laboratory testing.

Having assay results in hand from the flotation

experiments conducted, the metallurgical data

will require evaluation. Particularly when dealing

with Cu-Zn or Pb-Zn ores, very frequently

containing Au and/or Ag values, certain

evaluation techniques tend to best establish and

highlight the performance characteristics of

AEROPHINE 3418A.

Take as an example, a Pb-Ag-Zn ore where a

majority of recoverable Ag reports to the Pb

concentrate. Assume that AEROPHINE 3418A

is being evaluated as the Pb circuit collector for

comparison to some standard collector normally

used to treat this ore. The widely used technique

of graphing the cumulative concentrate grades

(%Pb) vs. cumulative Pb recoveries provided by

the different collector systems tested is always a

good basis for initial comparisons. Very often the

use of AEROPHINE 3418A will demonstrate an

advantage at this level of evaluation,compared to

other collectors.

Since the example ore contains three different

metals of economic importance, and since the

distribution of these metals within the concentrates

produced has an impact on the overall economic

return, evaluation of flotation test data should be

carried out further.

In this instance, it would be very informative to

plot Ag recovery to the Pb concentrate vs. Pb

recovery,and Zn recovery to the Pb concentrate vs.

Pb recovery. This will help provide a clear picture

of where Ag and Zn are reporting in relation to

some comparative unit recovery of the primary

metal being recovered. Under such evaluation,

the use of AEROPHINE 3418A promoter

frequently has demonstrated a greater recovery

of Ag and/or greater rejection of Zn at some

established level of Pb recovery, when compared

to the same level of Pb recovery provided by a

different collector system.

Of course, the mineralogical associations of the

metals in question will have a large influence on

the attainable metallurgical results, i.e., a selective

increase in Ag recovery or decrease in Zn recovery

at comparable Pb recoveries. If, for example,

additional Ag recovery can only be obtained as

Ag associated with sphalerite or pyrite, it will not

be possible to demonstrate a selective increase in

Ag recovery to the Pb concentrate through the

use of different collectors. Increased selectivities

against sphalerite or pyrite may actually result in a

decrease in Ag recovery to Pb concentrate; this in

spite of equal or improved Pb recoveries or grades

when using AEROPHINE 3418A promoter as

the Pb circuit collector. If this situation exists,

it is suggested that Ag recoveries be compared

to the sum of Pb plus Zn recoveries, plus Fe

recoveries if found to be significantly influential.

In this manner, a Pb collector which undesirably

recovers sphalerite and pyrite, thereby seeming to

produce higher Ag recoveries to Pb concentrate,

may be shown as not offering any real advantage

compared to the more elective collector. The

plant's metallurgical objectives would define what

constitutes an advantage.

Figure 1 demonstrates data evaluation from the

use of AEROPHINE 3418A as the Pb collector

applied to a Pb-Zn ore,compared to usage of

the standard sodium isopropyl xanthate (SIPX)

collector. In this example Zn recovery to the Pb

19Use of AEROPHINE® 3418A Promoter

for Sulfide Minerals Flotationcontinued

concentrate is compared to the Pb recovery. It

can be seen that the use of 35 g/t AEROPHINE

3418A could reject an additional 2% of the Zn,

compared to the usage of the standard 45 g/t

SIPX collector, when the data are evaluated at the

final Pb recovery produced by SIPX. This offers

the distinct advantage of sending more Zn to the

Zn circuit for recovery. At the same time, there is

indication that the use of AEROPHINE 3418A

can provide additional Pb recovery. When this data

was originally evaluated as % Pb concentrate grade

vs. Pb recovery, an advantage was noted for the

use of AEROPHINE 3418A, as well. The greater

metallurgical advantage of improved Zn rejection

was not, however, readily apparent until the data

were evaluated as described.

Figure 1

Polymetallic Ore Data Evaluation

94

92

90

88

86

84

82

80

78

Pb %

Rec

ove

ry

Zn % Recovery to Pb Conc.14 16 18 20 22 24 26 28

35g/t AEROPHINE 3418A45g/t SIPX

The second tenet to follow when evaluating the

performance of AEROPHINE 3418A is to test it

completely on its own. This advice is based upon

applying AEROPHINE 3418A to a wide variety

of ores principally for Cu and Pb flotation. If

AEROPHINE 3418A is suited to treating an ore,

the preponderance of data in hand indicates it

will perform best generally when used as the sole

collector in the circuit to which it is being applied.

The conjunctive use of AEROPHINE 3418A

promoter with differing collectors may have

undesirable effects on the flotation performance

provided by AEROPHINE 3418A.

Every "rule" has its exceptions, however, and there

are a number of plants presently treating Cu-Zn

ores, using AEROPHINE 3418A promoter and

a dithiophosphate in the Cu flotation circuit.

Generally there are significant precious metals

values and secondary copper mineralization

associated with chalcopyrite at these plants.

The use of a dithiophosphate as a secondary

collector with AEROPHINE 3418A promoter

in these Cu flotation circuits has been shown to

offer a metallurgical advantage. It has first been

necessary to establish the flotation performance

of AEROPHINE 3418A as the sole collector,

so as to eliminate any undesirable effects which

a secondary collector potentially may exert on

the flotation system. In these circumstances the

conjunctive use of AEROPHINE 3418A promoter

with a dithiophosphate collector has been shown

to be an acceptable collector combination, without

negative impact on the resulting metallurgy.

Other thiol type collectors may demonstrate

suitability as secondary collectors with

AEROPHINE 3418A, as well.

The conjunctive use of xanthates with

AEROPHINE 3418A promoter, for Cu or Pb

flotation, is very strongly discouraged. There

is overwhelming data to show that such joint

reagent usage diminishes the benefits provided

by the AEROPHINE 3418A. The resulting

metallurgy from the conjunctive use of xanthates

20Use of AEROPHINE® 3418A Promoterfor Sulfide Minerals Flotationcontinued

and AEROPHINE 3418A will trend toward that

provided by xanthates used alone or, in some cases,

inferior metallurgy. Particularly where xanthate is

already in use for Cu or Pb flotation, the urge to

initially evaluate AEROPHINE 3418A as a partial

replacement for the xanthate should be resisted.

In these circumstances, proper assessment of the

metallurgical benefits which AEROPHINE 3418A

is capable of providing can only be made when

AEROPHINE 3418A is tested as the sole collector.

An example of the antagonistic effect of xanthate,

used conjunctively with AEROPHINE 3418A,

is shown in Figure 2. This is an example of Pb

flotation on a Pb-Zn ore. Collector dosages used

were 60 g/t. From Figure 2 it can be seen that

AEROPHINE 3418A promoter used on its own

provided superior selectivity against Zn compared

to the use of xanthate. When a combined dosage

of 75% AEROPHINE 3418A and 25% xanthate

was used, the resulting selectivity against Zn was

about the same as with xanthate used alone. Note

also that total Pb recovery is lower than with

either AEROPHINE 3418A or xanthate used on

their own.

Another example of xanthate antagonism of the

performance of AEROPHINE 3418A is given in

Table 1. These are plant operating data from trial

periods of AEROPHINE 3418A in a plant treating

a porphyry copper ore. The standard plant collector

was sodium isopropyl xanthate (SIPX). The data

given are each one week averages under the reagent

conditions indicated.

At the initial introduction of AEROPHINE 3418A

promoter into the flotation circuit, a conservative

approach was taken where the AEROPHINE

3418A replaced 33% of the normal SIPX dosage.

From the data in Table 1 it can be seen this

collector combination performed no better than

when SIPX was used alone. Subsequently the SIPX

Figure 2

Xanthate Antagonism Pb/Zn Ore – Pb Flotation

94

92

90

88

86

84

82

80

78

76

74

72

Pb %

Rec

ove

ry

Zn % Recovery to Pb Conc.18 20 22 24 26 28 30 32 34 36 38 40 42

Xanthate75:25 AEROPHINE 3418A/Xanthate

AEROPHINE 3418A

Table 1

Xanthate Antagonism AEROPHINE 3418A

Performance

Assays-% CuRelative Dosage

1.84

2.17

1.94

2.07

SIPX

1.00

0.67

0.50

0

Conc.

2702

2408

28.7

27.1

AEROPHINE3418A

0

0.33

0.50

0.43

0.20

0.24

0.21

0.19

% Rec.

89.79

89.81

89.83

91.46

and AEROPHINE 3418A dosages were equalized,

without any significant benefit resulting. When the

use of SIPX was eliminated, and AEROPHINE

3418A promoter was used as the sole collector

at 43%of the normal SIPX dosage rate, a

significant improvement in metallurgy was noted.

AEROPHINE 3418A has since been adopted as

21Use of AEROPHINE® 3418A Promoter

for Sulfide Minerals Flotationcontinued

the collector at this plant, used without any other

collector type. The dosage of AEROPHINE 3418A

has ultimately been optimized at 10% of the

former xanthate consumption.

In plant applications it may be possible to use a

low xanthate dosage toward the end of Cu or Pb

flotation, where little or no xanthate would be

recycled to the head of rougher flotation. This

possibility can exist where it is desired to recover

principally iron-sulfide minerals, bearing precious

metals or small amounts of the primary metal,

into a low grade scavenger concentrate. The only

area of application where the use of xanthate with

AEROPHINE 3418A can be recommended is for

activated sphalerite flotation. AEROPHINE 3418A

generally has not demonstrated advantages in use

as the sole collector for sphalerite as frequently

as it has for the flotation of copper minerals and

galena. As mentioned previously, this is thought

to be due to the stoichiometry of Fe within the

sphalerite crystal lattice. Use of a xanthate with

AEROPHINE 3418A in Zn flotation has given

promising results with some ores.

A peculiar characteristic of AEROPHINE 3418A

promoter, seen only in laboratory flotation

investigations, is its tendency to sometimes

produce better selectivities with increasing dosages.

This phenomenon has been noted with a number

of ores by different investigators. The reasons for

the occurrence of this phenomenon in laboratory

flotation are not known, but it is noteworthy that

it has not been observed in actual plant application.

There has, in fact, been a general tendency for

effective plant dosages of AEROPHINE 3418A

promoter to be lower than what may have been

indicated in laboratory investigations.

Figure 3 demonstrates increased selectivity against

Zn with increased AEROPHINE 3418A dosage,

when applied to laboratory Pb flotation on a Pb-

Zn ore.

Figures 3, 4 & 5

Laboratory Dosage Selectivity Phenomenon

Pb/Zn Ore – Pb Flotation97

96

95

94

93

92

91

90

89

88

87

Cu

% R

eco

very

18 20 22 24 26 28 30 32

Zn % Recovery to Cu Conc.

60g/t AEROPHINE 3418A

42g/t AEROPHINE 3418A

Pyrrhotitic Cu Ore

35g/t AEROPHINE 3418A40g/t AEROPHINE 3418A

30g/t AEROPHINE 3418A

Cu

% R

eco

very

90

85

80

75

70

65

60

55

50

% Cu Conc. Grade8 10 12 14 16 18 20

Cu/Zn Ore – Cu Flotation97

96

95

94

93

92

91

90

89

88

87

Cu

% R

eco

very

10 12 14 16 18 20 22 24 26 28 30 32 34

Zn % Recovery to Cu Conc.

10g/t AEROPHINE 3418A

7.5g/t AEROPHINE 3418A

22Use of AEROPHINE® 3418A Promoterfor Sulfide Minerals Flotationcontinued

Figure 4 demonstrates increasing selectivities

with increasing AEROPHINE 3418A dosages

when used for laboratory copper flotation. In

this example, the ore is a massive sulfide with

pyrrhotitegangue. The improved grades at higher

AEROPHINE 3418A dosages are due to increased

selectivity against the pyrrhotite.

Figure 5 shows the phenomenon when

AEROPHINE 3418A was applied to laboratory

copper flotation on a Cu-Zn ore. The increased

selectivity against Zn is evident at the higher

AEROPHINE 3418A dosage.

As stated previously, this peculiar trait of

AEROPHINE 3418A promoter to sometimes

demonstrate better selectivity when used at higher

dosages seems limited to laboratory testing only.

The information is provided solely for the purpose

of preparing the flotation investigator, should he or

she encounter this phenomenon in a laboratory

test program.

Advantages in Use

The following example highlights the advantages

which the use of AEROPHINE 3418A can provide.

Example

A laboratory flotation investigation was carried

out on a massive sulfide ore containing 0.67%

Cu and 0.7 g/t Au. The principal gangue sulfide

mineral was pyrrhotite which carried about half

the Au values.

Using a coarse feed granulometry of 50% minus

200 mesh, comparative testing of a variety of

different collectors established AEROPHINE

3418A promoter as providing the best combination

Figure 6

Increased Au Recovery in Cu Flotation

Au

% R

eco

very

40

38

36

34

32

30

28

26

24

22

20

18

16

70 72 74 76 78 80 82 84 86 88 90 92

Cu % Recovery

30g/t AEROPHINE 3418A

50g/t AEROPHINE 3418A

Figure 7

Selectivity in Cu Flotation

4 5 6 7 8 9 10 11 12 13

Cu

% R

eco

very

% Cu Conc. Grade

92

90

88

86

84

82

80

78

76

74

72

70

30g/t AEROPHINE 3418A

50g/t SIPX

23Use of AEROPHINE® 3418A Promoter

for Sulfide Minerals Flotationcontinued

of Cu and Au recoveries, and selectivity against

pyrrhotite. These benefits are illustrated in Figures

6 and 7.

Figure 6 compares Cu vs. Au recoveries for a

test made using 30 g/t AEROPHINE 3418A

and another made using 50g/t SIPX, both

with a flotation pH 10.1. Both tests produced

Cu recoveries of 90-91%. The test made with

AEROPHINE 3418A, however, recovered

significantly more Au per unit of Cu recovery than

did the test with SIPX. The use of AEROPHINE

3418A promoter also demonstrated improved

concentrate grades, illustrated in Figure 7,

compared to those produced by SIPX. This

was principally due to better selectivity against

pyrrhotite.

Since a large portion of Au contained in the ore is

associated with the pyrrhotite, yet AEROPHINE

3418A promoter was shown to be more selective

against pyrrhotite than SIPX, the increased Au

recovery produced by AEROPHINE 3418A is

attributed to improved recovery of some portion of

Au existing in a liberated state.

Conclusions

AEROPHINE 3418A is a unique sulfide mineral

promoter, based on phosphine chemistry. It has

found widest application for flotation of copper-

sulfides and galena, particularly where these are

found in complex polymetallic ores containing

sphalerite, and ores with high levels of pyrite and/

or pyrrhotite. Use of AEROPHINE 3418A has

demonstrated improved recoveries of base metals

and associated precious metals, with excellent

selectivity characteristics against iron-sulfide

gangue minerals and depressed sphalerite. Other

advantages seen in use are rapid flotation kinetics,

and decreased collector consumption compared

to more traditional thiol type collectors. The

unique flotation performance characteristics of

AEROPHINE 3418A can best be realized when

AEROPHINE 3418A is evaluated according to

recommended application techniques.

24New Flocculants for Improved Processing of High Silica Bauxite

Qi Dai, Matt Davis Ruzi Zhang

Introduction

An important element in the production of

alumina from bauxite is an effective solid-liquid

separation in gravity thickeners to generate sodium

aluminate liquor containing low amounts of

suspended solids. This process relies heavily on

synthetic flocculants that are introduced to the

slurry feed to enhance the aggregation of red mud

particles and accelerate the settling of the red mud.

Over the years, new reagents have been developed

to improve this separation, which include the high

molecular weight polyacrylates and hydroxamated

polyacrylamides that are routinely used today[1, 2].

Despite their widespread utility, these flocculants

are not always able to deal with the settling

problems brought on by the decreasing quality

of bauxite. One such example is with increasing

reactive silica levels in the bauxite. In the Bayer

process, silica and silicate minerals (mainly

kaolinite) react with caustic liquor to form sodalite

or DSP (desilication products) particles having

the general formula 3(Na2 2

O3 2

0-2H2 2

X, where X is an anionic species

such as OH-, Cl-, CO2

3- or SO4

2- [3]. The 2-step

reaction is thought to proceed according to the

following chemical reactions[3, 4]:

3 Al2Si

2O

5(OH)

4 + 18 NaOH

6 Na2SiO

3 + 6 NaAl(OH)

4 + 3 H

2O (1)

6 Na2SiO

3 + 6 NaAl(OH)

4 + Na

2X

Na6[Al

6Si

6O

24 2X + 12 NaOH + 6 H

2O (2)

Additional species can accompany DSP in the

mud depending upon factors such as liquor

chemistry and impurity mineral phases present

in the bauxite. These phases include calcium

aluminosilicates, calcium silicates, titanium

dioxide and calcium titanate. The presence of fine

particles of DSP and these other phases can have

a negative impact on overflow clarity, overflow

filtration, mud settling and compaction[5, 6]

which cannot be overcome by using conventional

flocculants and often result in flow cuts. Therefore

Cytec Industries has responded to the need for

further improvements in flocculant technology

to meet the challenges put forth by the industry’s

increased utilization of low quality bauxite ores.

This paper highlights a new family of polymers

incorporating silane functionality that show

improved flocculation of suspended silicate

and titanate solids in the Bayer process[7].

The development of these reagents and the

corresponding performance on slurries generated

from processing high silica gibbsitic bauxite has

been discussed elsewhere[8]. This publication

represents an extension of this technology

to settler and washer applications at plants

processing high silica diasporic bauxite (with

and without sweetening with gibbsitic bauxite),

a subject particularly applicable to the alumina

industry in China. Data from laboratory settling

experiments demonstrating the performance

of these polymers on slurry from representative

Bayer refineries are presented.

Experimental

The performance of the new flocculant was tested

on red mud slurries collected on-site at a number

of alumina refineries. The data from static cylinder

tests were used to compare results obtained from

the use of the new silane-containing polymers to

those using only a polyacrylate flocculant.

On-site evaluation of new reagents at several

refineries was conducted by obtaining thickener

feed and transferring to 500 ml graduated

cylinders to conduct laboratory settling tests.

25New Flocculants for Improved

Processing of High Silica Bauxitecontinued

For experiments evaluating the performance in

the washers, appropriate ratios of overflow and

underflow were combined to yield representative

slurries. To account for variation between batches,

measurement of slurry solids and liquor analysis

were performed on at least two cylinders per batch.

In all experiments, the polyacrylate flocculant

was added to the slurry using a single addition,

followed by 5 gentle mixing strokes of a

perforated plunger. In experiments evaluating the

developmental product CYFLOC™ SA settling

aid (one of the new flocculants), the polymer

was dosed prior to the standard addition of the

polyacrylate as described above. A polyacrylate

flocculant dose was chosen to achieve settling

rates representative of the plant, which were

calculated by timing the descent of the mud

interface, and these experiments were treated as

the control. After flocculant addition and mixing

were complete, the cylinders were left in a water

bath for a fixed time, after which the supernatant

clarity was measured gravimetrically by filtering an

aliquot of the overflow liquor. When this was not

possible, overflow clarity was determined with a

turbidimeter.

Results and Discussion

The dose response of CYFLOC SA was

investigated on settler feed slurry at a Bayer

refinery that was processing diasporic bauxite with

an average reactive silica level of 13% and A/S

(alumina to silica) ratio = 5. The dosage of the new

polymer was varied between 0 and 408 g/T which

was added in combination with a fixed dosage of

polyacrylate flocculant (522 g/T). Mud solids were

measured to be 98 g/L. Because it was not possible

to measure supernatant solids gravimetrically, the

performance of the new polymer was assessed by

measuring the turbidity of the supernatant. The

settling rate results, along with the supernatant

turbidity on the secondary axis, are displayed

in Figure 1.

Figure 1

Settling Rate (diamonds) and Supernatant Turbidity

(triangles) Data As a Function of CYFLOC SA

Dose When Dosed to Slurry Obtained While

Processing Diasporic Bauxite. In all experiments, the

polyacrylate dose was held constant at 522 g/ton.

0

50

100

150

200

250

300

350

0

2

4

6

8

10

0 75 150 225 300 375 450

Sup

ernatan

t Turb

idity (N

TU)

Sett

ling

Rat

e (m

/hr)

CYFLOC SA Dose (g/ton)

Settling RateTurbidity

As seen in Figure 1, increasing the dose of

CYFLOC SA results in a doubling in settling

rate. This large improvement in settling rate is

not accompanied with a significant change in the

supernatant turbidity.

The dose response of the same reagent, CYFLOC

SA, was investigated on plant slurry collected

from another Bayer refinery that was processing

diasporic bauxite while sweetening with 10%

gibbsitic bauxite. The dosage of the polymer was

varied between 0 and 481 g/ton which was added

in combination with a fixed dosage of polyacrylate

(154 g/ton). The settling rate and supernatant

clarity results are displayed in Figure 2.

26New Flocculants for Improved Processing of High Silica Bauxitecontinued

Figure 2

Settling Rate (diamonds) and Supernatant Turbidity

(triangles) Data As a Function of CYFLOC SA

Dose When Dosed to Slurry Obtained While

Processing Diasporic Bauxite and Sweetening with

10% Gibbsitic Bauxite. In all experiments, the

polyacrylate dose was held constant at 154 g/ton.

0

1

2

3

4

5

0

4

8

12

16

0 100 200 300 400 500

O/F C

larity (g/L)

Sett

lin

g R

ate

(m/h

r)

CYFLOC SA Dose (g/ton)

Settling RateClarity

From the data in Figure 2, it is clear that addition

of the new polymer to red mud slurries results

in improved supernatant clarity compared to the

addition of conventional flocculants alone. This

improvement in clarity was also accompanied by

an improvement in settling rate, with observed

increases up to 80%. These results illustrate the

applicability of this reagent to improve the settling

performance of slurry when the plant is processing

high silica diasporic bauxite and practicing

sweetening with gibbsitic bauxite.

During the course of our evaluations at Bayer

refineries, we also observed that improved

performance in the mud washing circuit could

be realized by the addition of CYFLOC SA. The

dose response of the new polymer was established

on feed to the 2nd washer of a Bayer refinery

processing high silica diasporic bauxite. The

dosage of the polymer was varied between 0 and

111 g/ton which was added in combination with

a fixed dosage of polyacrylate (120 g/ton). The

settling rate and supernatant turbidity results are

displayed in Figure 3.

Figure 3

Settling Rate (diamonds) and Supernatant Turbidity

(triangles) Data As a Function of CYFLOC SA Dose

When Dosed to Slurry Feed from the 2nd Washer.

In all experiments, the polyacrylate dose was held

constant at 120 g/ton.

0

50

100

150

200

250

0

2

4

6

8

10

0 50 100 150

Sup

ernatan

t Turb

idity (N

TU)

Sett

lin

g R

ate

(m/h

r)

CYFLOC SA Dose (g/ton)

Settling RateTurbidity

From the settling test data in Figure 3, it is

apparent that CYFLOC SA can significantly

improve flocculation performance in washers,

resulting in faster settling rates and lower overflow

solids. The data from these experiments show

a settling rate more than double that which is

obtained by the addition of polyacrylate alone.

This is accompanied by a large reduction in the

supernatant turbidity.

In the mining industry, the dual polymer

program is widely used, in which a low molecular

weight polymer is added first followed by a

high molecular weight polymer. The role of the

low molecular weight polymer (often referred

to as coagulant) is to form small mud particle

aggregates which can subsequently be flocculated

by the high molecular weight flocculant more

efficiently than the case of single polymer

program. There is also a variety of choice of the

low molecular weight polymer; cationic, anionic,

inorganic and organic[9]. However, in the Bayer

process, flocculation of red mud is almost solely

achieved by high molecular weight polymers with

occasional cases involving lime and dextran as

27New Flocculants for Improved

Processing of High Silica Bauxitecontinued

flocculation aids. Attempts have been made in the

past to find or develop coagulant type of polymers

to aid red mud flocculation without much success.

This new polymer is the first of this kind that has

shown significant improvement in this area.

Conclusions

1. Laboratory results conducted with plant slurry

demonstrate the effectiveness of new silane-

containing polymers for improved flocculation

of muds generated from processing high silica

diasporic bauxite.

2. A 2-3 time improvement in settling rate was

observed on multiple substrates obtained

from different plants when CYFLOC SA was

added in combination with a conventional

polyacrylate flocculant.

3. In most cases, this settling rate improvement

was also accompanied by a significant

improvement in overflow clarity by capturing

particles that would normally report to the

settler overflow.

4. CYFLOC SA was also shown to be effective at

improving flocculation efficiency in the mud

washing circuit.

References

1. Rothenberg, A.S., Spitzer, D.P., Lewellyn,

M.E., and Heitner, H.I., New reagents for

alumina processing, Light Metals, (1989),

pp. 91-96

2. Ryles, R.G., and Avotins, P.V., "Superfloc®

HX*, a new technology for the alumina

industry" (4th International Alumina Quality

Workshop, Darwin, Northern Territory,

1996), pp. 206-216.

3. Whittington, B.I., Fletcher, B.L., and Talbot,

C., The effect of reaction conditions on the

composition of desilication product (DSP)

formed under simulated Bayer conditions,

Hydrometallurgy, Vol. 49, (1998), pp. 1-22.

4. Smith, P., The processing of high silica

bauxites -- Review of existing and potential

processes, Hydrometallurgy, Vol. 98, (2009),

pp. 162-176.

5. Peiwang, L., Zhijian, L., Yucai, L., Hailong,

C., Fengling, W., and Hong, W., The

influence of the predesilication temperature

of bauxite slurry on the sedimentation of red

mud and the utilization of which in alumina

production, Light Metals, (1994), pp. 133-

136.

6. Li, S.-M., Ge, L.-Y., and Zeng, X.-Q., The

simulation experiment about silica to the

settling of red mud separation process, Ziran

Kexueban, Vol. 36, No. 3 (2007), pp. 18-20.

7. Dai, Q., Spitzer, D., Heitner, H.I., and Chen,

H.-L.T., Use of silicon-containing polymers

to improve red mud flocculation in the Bayer

process, US Patent Application 2008/0257827

A1, (2008).

8. Davis, M., Dai, Q., Chen, H.-L.T., and

Taylor, M., New Polymers for Improved

Flocculation of High DSP-Containing Muds,

Light Metals, (2010), pp. 57-61.

9. Heitner, H.I., Foster, T., and Panzer, H.P.,

"Mining Applications" (Encyclopedia of

Polymer Science and Engineering, 2nd Ed.,

Vol. 9, 1987), p. 824.

The Inhibition of Vishnevite Scale in Chinese Refineries Using MAX HT® 550 Scale Inhibitor28

Qi Dai, John Carr, Frank Kula, Jerome O’Keefe

Introduction

Silica present in bauxite dissolves under Bayer

alumina digestion conditions and subsequently

precipitates as a sodium aluminosilicate,

“desilication product” (DSP). This precipitation

occurs as scaling on the inside of the heat exchange

tubes and causes significant loss of heat transfer.

The impact of scale and options for dealing with

the scaling problem is well documented[1,2]. The

current method to clean the heater tubes is a

combination of acid and mechanical cleaning that

is unsatisfactory from an economical, safety, and

efficiency perspective[3].

In 2004, Cytec developed the MAX HT®

technology to prevent the aluminosilicate

scale growth in refinery evaporators and heat

exchangers[4]. Since then MAX HT has successfully

eliminated the formation of sodalite scale under

various process conditions[2,3,5,6]. This technology

was originally limited to double stream refineries,

becoming ineffective at high solids (single stream)

and low solids conditions. A second generation

product, MAX HT® 550, was developed that was

shown to work more robustly at low solid levels

encountered in some double stream refineries[7, 8].

The effectiveness of MAX HT is influenced

by the type of scale (mineralogy) formed at a

particular refinery. Development work focused on

inhibiting sodalite scale that is prevalent in many

Bayer plants. When scale other than sodalite is

predominant, MAX HT technology may have

reduced effectiveness requiring increased dosages

to inhibit scale formation. The tendency and type

of aluminosilicate scale to form in a particular

refinery will depend on a wide variety of factors,

related primarily to the type of bauxite and process

conditions. Table 1 shows some characteristics of

the scales in various regions of the world. Chinese

refineries have been shown to form vishnevite type

scale instead of sodalite or cancrinite commonly

found in other regions. This difference originates

from the type of the bauxite and impurity minerals

associated with it. Most vishnevite scale is found

in Chinese refineries which process domestic

diasporic bauxite. Some Chinese refineries process

imported gibbsitic bauxite, and evaporator scale in

those refineries is exclusively sodalite (not shown

in Table 1).

Performance testing of MAX HT in China began

with the first generation product in diasporic and

gibbsitic bauxite refineries. Standard laboratory

tests showed that the product performed well in

both refineries, achieving complete inhibition

of sodium aluminsilicate at expected dosages

(typically 15-40 ppm). The test work continued

after the development of the second generation

MAX HT. More recently, we discovered that

the second generation product is not only

more solids tolerant but also more effective in

inhibiting vishnevite scale than the first generation

product. This paper presents the laboratory

results simulating the formation and inhibition of

vishnevite scale using both first generation MAX

HT and second generation (MAX HT 550) scale

inhibitors.

Vishnevite Scale

Chemically, sodium aluminosilicate scale is usually

either sodalite or cancrinite, with cancrinite the

predominant scale in higher temperature plants.

Vishnevite forms a solid solution series with

cancrinite in which the main substitution is

between CO3 and SO

4. K+ incorporation may

also occur.

29The Inhibition of Vishnevite Scale in Chinese

Refineries Using MAX HT® 550 Scale Inhibitorcontinued

Cancrinite (Na, Ca)7-8

(Al6Si

6O

24)

(CO3, SO

4, Cl)

1.2-2.0 1-5H

2O

Vishnevite (Na,Ca,K)6-7

(Al6Si

6O

24)

(SO4, CO

3, Cl)

1.0-1.5 1-5H

2O

Sodalite Na8(Al

6Si

6O

24) Cl

Structurally, sodalite has a roughly spherical unit

cell of ca. 9Å and is isometric (cubic). Vishnevite

and cancrinite have rod like structures and unit

cells of ca. 12.7 X 5.15 Å and are both hexagonal.

All have very open structures and, as a result, low

densities that probably contribute to their ability

to lower heat exchanger efficiency.

Vishnevite scale is a unique type of aluminosilicate

scale commonly found in evaporators in Chinese

refineries processing domestic bauxite. While

the chemistry of all evaporator scales is sodium

aluminosilicate, vishnevite scale contains markedly

more SO3 and K

2O than sodalite and cancrinite

scales (Table 1).

Domestic Chinese bauxite is predominantly

diasporic, and has high amounts of clay minerals

including kaolinite, illite and pyrophyllite[9,10]. The

preference of forming vishnevite scale over sodalite

and cancrinite is due to the impurity minerals in

Chinese bauxite, especially illite and pyrite. As

described above, vishnevite forms when K

substitutes some Na and SO4- is incorporated as

anions in the crystal. Illite is the source of K+, and

pyrite is the source of SO4-. The presence of SO

4-

can promote the formation of vishnevite[11].

Table 1

Scales from Various Bayer Refineries in Different Regions

Plant

A

B

C

D

E

G

H

Region/ Country

Europe

Scale from

--

Scale

Vishnevite

Vishnevite

Vishnevite

--

SO3

3.8

1.4

1.5

11

4.4

--

1.7

--

7.8

6

4

4.56

4.06

K2O

0.5

0.4

0.7

0.2

0.7

--

0.04

--

10

16

7

3.17

2.15

CaO

0.05

0.1

0.3

0.1

0.2

--

0.04

--

0.05

3.5

1

0.26

1.14

Wt% in scale

*Chinese refineries processing diasporic bauxite

30The Inhibition of Vishnevite Scale in Chinese Refineries Using MAX HT® 550 Scale Inhibitorcontinued

Figure 1 below shows initial synthetic attempts

at forming vishnevite scale in the laboratory by

altering various liquor/digestion conditions.

Figure 1

XRD Spectrum of an Initial Attempt at Making

Vishnevite Scale in the Laboratory

0

500

1000

1500

2000

2500

01-071-5356> Sodalite - Na8(Al6Si6O24)

01-070-8054> Quartz- - SiO2

01-086-1155> Anatase - Ti0.784O2

10 20 30 40 50 60 70

Two-Theta (deg)

I(C

ou

nts

)

[S20085-101C.raw] carbonate scale - 1ds1ss0.3mmrs

Figures 2 and 3 show the effect of incorporating

increasing amounts of potassium hydroxide in the

synthetic liquor. Vishnevite scale was successfully

formed followed by a phase that had higher degree

of potassium cation substitution.

Figure 2

X-ray Diffraction Spectrum of a Laboratory

Prepared Vishnevite Scale with 25% NaOH

Replaced with KOH in the Liquor

10 20 30 40 50 60 700

500

1000

1500

2000

2500

3000

3500

Inte

nsi

ty(C

ou

nts

)

[S20146-6-14raw.raw]

00-046-1333> Vishnevite - Na8Al6Si6O24(SO4)-2H2O

Two-Theta (deg)

Methodology

Details of the laboratory scale inhibition test

can be found in[1,2]. The same method is used in

both the Cytec R&D laboratories and in alumina

refinery laboratories. In the Cytec laboratories,

tests are performed primarily in synthetic

Bayer liquors containing 0.8 g/L SiO2, 45 g/L

Al2O

3, 160 g/L NaOH, 40 g/L Na

2CO

3 and

20 g/L Na2SO

4. The composition was designed

to promote reasonable amount of sodalite

precipitation in the liquor in 16 hours. To

generate vishnevite solids, the formulation was

modified by substituting 50% NaOH replacement

with KOH (on a molar basis). Increasing Na2SO

4

above 20 g/L did not seem to promote the

formation of vishnevite.

The test method allows for a large number of tests

to be done rapidly with results that have proven

to be predictive of performance. The amount

of precipitated solids in each test is used as a

measure of inhibition performance; the less the

precipitation, the better the performance.

Analytical Characterization

The major mineral phases associated with

synthetically prepared and Bayer plant scales were

determined by x-ray diffraction (XRD) using a

Rigaku Multiflex spectrometer. Elemental data

were obtained via x-ray fluorescence (XRF) using

a Rigaku ZSX Primus II wavelength dispersive

spectrometer. Vibrational spectroscopy was

conducted at an outside laboratory with a Kaiser

Holoprobe dispersive Raman spectrometer using

785nm laser excitation to confirm the presence of

vishnevite scale in synthetically prepared samples.

31The Inhibition of Vishnevite Scale in Chinese

Refineries Using MAX HT® 550 Scale Inhibitorcontinued

Figure 3

X-ray Diffraction Spectrum of a Laboratory

Prepared Vishnevite Scale with 50% NaOH

Replaced with KOH in the Liquor

10 20 30 40 50 60 70x103

5.0

10.0

15.0

20.0

25.0

30.0

Inte

nsi

ty(C

ou

nts

)

[S20146-65B.raw] scale from KOH - 1ds1ss0.3mmrs

01-078-2203> Vishnevite - K0.5Na0.76(SiAlO4)(SO4)0.13(H2O)0.33

Two-Theta (deg)

Raman analysis was also performed for the

synthetic sample to confirm the presence of

vishnevite scale. Although the sample produced

a high fluorescence background masking some of

the characteristic bands, the most intense band for

vishnevite is observable at 995 cm-1 (Figure 4).

Figure 4

Raman Spectrum for Synthetically Made Scale

Showing Main Vibration at 995 cm-1.

500000

450000

400000

995 45

9

350000

300000

250000

200000

150000

100000

50000

1150 1100 1050 1000 950 900 850 800 750 700

wavenumbers

650 600 550 500 450 400 350 300 250

0

Results

Synthetic Liquors

Figure 5 compares the rate of sodalite

precipitation to that of vishnevite without

MAX HT addition. Vishnevite is formed by

replacing 50% of the NaOH with KOH (on

a molar basis). Vishnevite precipitates out at a

much slower rate than sodalite during the first

eight hours. Data from all other tests show

that at the end of the test (16 hours), the final

amount of precipitation reaches the same level

of 0.22±0.01g/120 mL. This provides an equal

basis to evaluate MAX HT performance when

comparing sodalite and vishnevite inhibition.

Figure 5

Rate of Sodalite vs. Vishnevite Precipitation

without MAX HT

Dose (ppm)

Prec

ipit

atio

n (g

/120

mL)

0

0.00

0.05

0.10

0.15

0.20

2 4 6 8 10

Vishnevite (50% NaOH replacement)

Sodalite (0% NaOH replacement)

Performance of the first generation MAX HT at

various NaOH replacement levels are shown in

Figure 6. Results are plotted as percentage of DSP

precipitation vs. blanks, i.e., no inhibitor added;

100% would mean no effect of the inhibitor,

while 0% means complete scale inhibition. As

the inhibitor dose increases, the precipitation

decreases to zero. There is, however, a slight trend

of increasing precipitation as NaOH replacement

increases to 50%, a condition favoring vishnevite

32The Inhibition of Vishnevite Scale in Chinese Refineries Using MAX HT® 550 Scale Inhibitorcontinued

formation. In contrast, MAX HT 550 displays

the opposite trend (Figure 7) with significantly

improved inhibition at higher NaOH replacement

by KOH.

Figure 6

Performance of First Generation MAX HT

Dose (ppm)

Pre

cip

itati

on

(%

of

bla

nk)

0

0

20

40

60

80

100

5 10 15 20

25% NaOH replacement50% NaOH replacement

No NaOH replacement

Figure 7

Performance of First Generation MAX HT 550

Dose (ppm)

Pre

cip

ita

tio

n (

% o

f b

lan

k)

0

0

20

40

60

80

100

1 2 3 4 5 6

25% NaOH replacement

50% NaOH replacement

0% NaOH replacement

Figure 8 compares the two generations of MAX

HT in vishnevite inhibition tests using liquors

with 25% and 50% NaOH replacement by KOH.

The results show that MAX HT 550 is superior

to the first generation in terms of vishnevite

inhibition. It can also be observed from Figures

6 and 8 that the first generation MAX HT,

although effective on both types aluminosilicate

scales, requires higher dosages to inhibit vishnevite

formation than sodalite formation (No NaOH

replacement).

Figure 8

Comparison of First Generation MAX HT and

MAX HT 550

Dose (ppm)

Prec

ipit

atio

n (

% o

f b

lan

k)

0

0

20

40

60

80

100

5 10 15 20 25

MAX HT 550 25% NaOHreplacementMAX HT 50% NaOHreplacementMAX HT 550 50% NaOHreplacement

MAX HT 25% NaOHreplacement

Plant Liquors

MAX HT was also tested in laboratories at a

number of refineries where evaporator scales

are identified as vishnevite. Two comparative

examples are displayed in Figures 9 and 10.

One example was performed using feed liquor

to the 1st Effect of the evaporator at Refinery K

(Figure 9) and the other example was performed

using spent liquor of Refinery L (Figure 10).

Consistent with previous test work, MAX HT

550 demonstrates superior vishnevite inhibition

relative to the first generation product.

One should not expect that the difference in

dosages required of the two generation

products will be the same as those required in

a plant. The important point from the results

33The Inhibition of Vishnevite Scale in Chinese

Refineries Using MAX HT® 550 Scale Inhibitorcontinued

presented here is that it is possible to eliminate

sodalite and vishnevite precipitation with MAX

HT 550 at much lower doses than with the first

generation product.

Figure 9

MAX HT Performance in Laboratory Tests Using

Feed Liquor to the 1st Effect of the Evaporator at

Refinery K

Dose (ppm)

Pre

cip

itati

on

(%

of

bla

nk)

0

0

20

40

60

80

100

5 10 15 20 25 30

MAX HT 550

MAX HT Gen.1

Figures 10

MAX HT Performance in Tests Using Spent Liquor

at Refinery L

Dose (ppm)

Pre

cip

ita

tio

n (

% o

f b

lan

k)

0

0

20

40

60

80

100

5 10 15 20 25 30

MAX HT 550

MAX HT Gen.1

Commercial discussions surrounding the efficacy

of MAX HT 550 are currently underway

throughout China with multiple customers.

Conclusions

1. MAX HT 550, the second generation of

aluminosilicate scale inhibitor effectively

inhibits scale and is far superior in terms

of vishnevite scale inhibition to the first

generation product.

2. The performance advantage of the second

generation over the first generation has been

proven in both synthetic liquors and real

plant liquors.

3. Chinese bauxites are predominantly diasporic

and contain potassium bearing silicate

clays. The presence of potassium in Bayer

liquor causes the formation of ‘vishnevite’; a

potassium aluminosilicate scale in evaporators.

4. Sodalite is the common aluminosilicate scale

in low temperature double stream plants,

while vishnevite occurs principally in Chinese

high temperature plants that process domestic

Chinese diasporitic bauxite.

5. X-ray diffraction and Raman spectroscopy of

synthetic scale samples showed the successful

formation of vishnevite.

6. In the laboratory, synthetic liquor for sodalite

precipitation can be modified to form

vishnevite by replacing NaOH in the liquor

by KOH.

34The Inhibition of Vishnevite Scale in Chinese Refineries Using MAX HT® 550 Scale Inhibitorcontinued

References

1. Spitzer, D., Rothenberg, A., Heitner, H.,

Kula, F., Lewellyn, M., Chamberlain, O., Dai,

Q. and Franz, C., Reagents for the elimination

of sodalite scaling, Light Metals (2005), pp

183-188.

2. Spitzer, D., Rothenberg, A., Heitner, H.,

Kula, F., Lewellyn, M., Chamberlain, O.,

Dai, Q. and Franz, C., A real solution to

sodalite scaling problems, Proceedings of the

7th International Alumina Quality workshop

(2005), pp 153-157.

3. Oliveira, A., Dutra, J., Batista, J., Lima,

J., Diniz, R. and Repetto, E., Performance

appraisal of evaporation system with scale

inhibitor application in Alunorte plant, Light

Metals (2008), pp 133-136.

4. Spitzer, D., Rothenberg, A., Heitner, H. and

Kula, F., Method of preventing or reducing

aluminosilicate scale in a Bayer process, U.S.

patent 6,814,873 (2004).

5. Spitzer, D., Chamberlain, O., Franz, C.,

Lewellyn, M. and Dai, Q., MAX HT™

sodalite scale inhibitor: Plant experience and

impact on the process, Light Metals (2008),

pp 57-62.

6. Riffaud, J.P., James, P.D., Allen, E. and

Murray, J.P., Evaluation of sodalite scaling

inhibitor – A user’s perspective, International

Symposium on Alumimum: From Raw

Materials to Applications – Combining Light

Metals 2006 and the 17th International

ICSOBA Symposium, Montreal, Canada,

Oct. 1-4, 2006, Bauxite and Alumina Session,

paper 29.7.

7. Spitzer, D., Rothenberg, A., Heitner, H. and

Kula, F., Polymers for preventing or reducing

aluminosilicate scale in a bayer process, U.S.

patent 7,442,755 (2008).

8. Lewellyn, M., Patel, A., Spitzer, D., Franz,

C., Ballentine, F., Dai, Q., Chamberlain,

O., Kula, F. and Chen, H., MAX HT 500:

A second generation sodalite scale inhibitor,

Proceedings of the 8th International Alumina

Quality workshop (2008), pp 121-124.

9. Gu, S., Chinese bauxite and its influences on

alumina production in China, Light Metals

(2008), pp 79-83.

10. Li, W., Liu, J., Liu, Z. and Wang, Y., The

most important sustainable development

issues of Chinese alumina industry, Light

Metals (2008), pp 191-195.

11. Bi, S. (Ed.), Process of alumina production,

Chemical Industry Press, Beijing, China

(2007), p.69 (Chinese).

12. W. Deer, R. Howie, J. Zussman, Rock

Forming Minerals, Vol. 4, Longman, Green

and Co. LTD, Ppp 289-295,

310-315

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