Day A. Mining chemicals hand book

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Flotation of sulfide ores

109

AAEERROOFFLLOOAATT 224422 pprroommootteerr

– This is the ammonium salt of

AEROFLOAT 31 promoter. It is water soluble, but should be made

up at minimum 10% strength to avoid precipitation of the second-

ary collector. Widely used for flotation of Pb from Pb/Zn ores and

Cu/Pb from Cu/Pb/Zn ores. Improves Ag recovery from these ores.

AAEERROO 77331100 pprroommootteerr

– This is similar to AEROFLOAT 241 promoter

but with a higher activity.

Comments

•

AAEERROOFFLLOOAATT 2255

and

3311

promoters have considerable frothing

properties, much more so than their ammonium salts,

AAEERROOFFLLOOAATT 224411

and

224422

promoters

• In alkaline circuit, the aryl AEROFLOAT promoters have a much

lower tendency than xanthates to float pyrite, pyrrhotite, and

unactivated sphalerite.

• Unlike xanthates, the aryl AEROFLOAT promoters are stable in

acid circuit; however, lose their selectivity against iron sulfides.

Consequently,

AAEERROOFFLLOOAATT 2255

and

3311

promoters can be used as

strong, non-selective sulfide promoters for bulk flotation in

acid circuit.

•

AAEERROOFFLLOOAATT 2255

and

3311

promoters should be added to the pulp

full strength. Because they are in the free acid form, pre-mixing

with water or

AAEERROOFFLLOOAATT 224411

224422

promoters, or any other

aqueous product could release toxic H

S gas. This precaution

does not apply to the addition of these reagents to pulps in the

amounts normally used for flotation.

Physical characteristics

AEROFLOAT Viscosity (cps)

promoters Color S.G. 25°C**

25 Dk. Brown --- Blk. 1.19 100-200

31 Dk. Brown --- Blk. 1.19 250-500

241* Dk. Brown --- Blk. 1.13 300-800

242* Dk. Brown --- Blk. 1.13 300-600

7310 Yellow --- Brown 1.14 80-100

**Water Soluble -- Solution strength of AEROFLOAT 242 promoter should never be

less than 10%.

**Brookfield Model LVF No.2 spindle, 30rpm

Mining Chemicals Handbook

110

A.2 Monothiophosphates

AERO 5688 promoter is a novel collector based on monothiophos-

phate chemistry. In commercial use at a number of operating

locations around the world, AERO 5688 promoter is particularly

effective for selective flotation of precious metals in alkaline circuits

(pH > 7.0). It is also effective in the flotation of sulfide minerals and

precious metals in acid circuits. In moderately alkaline circuits

(pH 7-10), it can be used for selective flotation of copper sulfide

minerals and precious metals from ores in which the presence of

highly activated iron sulfide minerals precludes the use of other

sulfide collectors; in fact with respect to iron sulfides, AERO 5688

promoter is one of the most selective of the available sulfide

collectors in alkaline circuits.

Typical properties AERO 5688 promoter

Appearance Clear amber to red liquid

Specific Gravity, @ 20°C (68°F) 1.20

pH >13

Viscosity, Brookfield LVT,

cps @ 20°C (68°F) 15-35

Spindle#2 @ 60 rpm

Freezing Point

Crystallization begins, °C (°F) 2 (36)

Pourable Slurry forms, °C (°F) -10 (14)

Product Solidifies, °C (°F) -16 (3)

Freeze-thaw Stability Good

Conductivity (µmhos) 23.6-24

Solubility in Water Infinite

Comments/Primarily used in the flotation of:

• Base metal sulfides, gold/silver and PGMs from ores in acid

circuit (pH 3-7).

• Selective gold/silver and copper sulfides flotation in mildly

alkaline circuits (pH 7-10).

• Used in conjunction with traditional sulfide collectors to improve

precious metals recovery in alkaline circuits.

• Flotation of cement copper in LPF process.

• In acid circuits, dosage requirements for

AAEERROO 55668888

promoter

are significantly lower than those for the more traditional sulfide

collectors. Experience also indicates that these collectors improve

flotation kinetics, especially of slow floating gold particles.

• Dosage rates are usually in the range of 5 to 50 g/t for base metal

sulfide ores and up to 100 g/t for precious metal ores.

•

AAEERROO 55668888

promoter can be fed directly to the circuit, or can be

diluted with water to any strength. For ease of metering, it is often

diluted to 5-10 % strength.

•

AAEERROO 55668888

promoter exhibits some frothing properties.

A.3 Formulated P-based product

AERO 8985 promoter is a formulated product that is used for Cu-Au

Ores, where it provides optimum recovery of both Cu and Au by

combining the advantages of dithiophosphates and monothiophos-

phates.

B. Alkyl AEROFLOAT and AERO promoters

B.1 Dithiophosphates

Sodium

AAEERROOFFLLOOAATT

promoter – (R=ethyl). Used mainly for selec-

tive flotation of Cu from Cu/Zn ores where Zn minerals tend to

float readily; for flotation of activated Zn sulfides where selectivity

against iron sulfides presents a problem. Very selective against iron

sulfides.

AAEERROOFFLLOOAATT 220088 pprroommootteerr

– (R=ethyl + sec. Butyl). Selective col-

lector for copper ores. Excellent collector for native Au, Ag and Cu.

AAEERROOFFLLOOAATT 221111 pprroommootteerr

– (R=isopropyl). Selective collector for

Cu and activated Zn minerals. Stronger collector than Sodium

AEROFLOAT promoter.

AAEERROOFFLLOOAATT 223388 pprroommootteerr

– (R=sec. Butyl). Widely used in Cu

flotation and for increasing by-product Au recovery. Combines good

collecting power with good selectivity against iron sulfides.

AAEERROO 33447777 pprroommootteerr

– (R= isobutyl). A strong, but selective collector

for Cu, Ni and activated Zn minerals. Improves recoveries of

precious metals, particularly those of the platinum group metals.

Flotation of sulfide ores

111

Dialkyl Dithiophosphate Dialkyl Monothiophosphate

Mining Chemicals Handbook

112

AAEERROO 33550011 pprroommootteerr

– (R=isoamyl). Used for flotation of Cu and

activated Zn minerals, especially for coarse middlings. Applications

are similar to those of AERO 3477 promoter, but tends to generate

more froth.

AAEERROO 55443300 pprroommootteerr

– (R=isobutyl). A "low-frothing" version of

AERO 3477 promoter. Used when maximum froth control is desired.

AAEERROO 55447744 pprroommootteerr

– (R=isoamyl). A "low-frothing" version of

AERO 3501 promoter. Also used when maximum froth control is

desired.

Physical properties

AEROFLOAT promoters Sodium 208 211 238

Appearance Colorless to yellow liquids

pH 13.0 - 13.7

sp.gr., 30°C 1.20 1.15 1.15 1.12

Viscosity (cps)

0°C 22 25 31 45

30°C 6 7 8 12

Boiling Point, °C 103 103 103 103

Crystallization Starts, °C -4 -12 -10 -12

Pourable Slurry Forms, °C -9 -15 -10 -13

Solidification, °C -13 -29 -20 -26

Freeze-Thaw Stability Good

Physical properties

AERO promoters 3477 3501 5430 5474

Appearance Colorless to yellow liquids

pH 13.0 - 13.7

sp.gr., 30°C 1.12 1.08 1.07 1.05

Viscosity (cps)

0°C 41 38 2000 2200

30°C 11 10 750 550

Boiling Point, °C 103 103 107 107

Crystallization Starts, °C 2 4 <-20 <-20

Pourable Slurry Forms, °C -13 -4 - -

Solidification, °C -25 -9 - -

Freeze-Thaw Stability Good

Flotation of sulfide ores

113

Comments

• The alkyl AERO and AEROFLOAT promoters are more selective

against iron sulfides in alkaline circuit than the corresponding

xanthates.

•

SSooddiiuumm AAEERROOFFLLOOAATT

and

AAEERROOFFLLOOAATT 220088,, 221111

and

223388

have

minimal effect upon froth generation.

•

SSooddiiuumm AAEERROOFFLLOOAATT

and

AAEERROOFFLLOOAATT 220088,, 221111

and

223388

are

poor collectors for galena, making them the ideal choice for

selective flotation of Cu from Pb.

• For many ores, the alkyl AERO and AEROFLOAT promoters are

used as the principal collector, in conjunction with a xanthate as

a secondary or scavenger collector. The longer chain ones are,

however, often used as the sole collector to insure maximum

selectivity.

B.2 Monothiophosphates

AERO 6697 promoter is a novel collector based on monothiophos-

phate chemistry, similar to AERO 5688 promoter in many of its

collector properties. AERO 6697 promoter is in commercial use at a

number of operating locations around the world. The choice between

AERO 5688 and AERO 6697 promoters depends on the mineralogy/

ore type, gangue mineralization, and frothing characteristics. On any

particular ore, both products should be tested. For a description of

typical applications, refer to Section on AERO 5688 promoters.

Physical properties

AERO 6697 promoter

Appearance Clear yellow to amber liquid

Specific Gravity, @ 20°C (68°F) 1.14

pH >13

Viscosity, Brookfield LVT,

cps @ 20°C (68°F) 15-35

Spindle#2 @ 60 rpm

Freezing Point

Crystallization begins, °C (°F) 2 (36)

Pourable Slurry forms, °C (°F) -10 (14)

Product Solidifies, °C (°F) -16 (3)

Freeze-thaw Stability Good

Solubility in Water Infinite

B.3 Formulated P-based product

AERO 7249 promoter is a formulated product that is used extensively

in many Cu-Au plants, where it provides optimum recovery of both

Cu and Au by combining the advantages of dithiophosphates and

monothiophosphates, and provides excellent selectivity against iron

sulfides.

C. Dialkyl dithiophosphinates

AEROPHINE 3418A

AEROPHINE 3418A promoter is a unique, P-based sulfide collector.

It was originally developed for the flotation of copper and activated

zinc minerals. It has since been found to be an invaluable (and often

irreplaceable) collector in the beneficiation of complex, polymetallic,

and massive sulfide ores. On these ores it provides very selective

separations. It is highly effective for galena and precious metals,

especially silver. Its main attributes are strong collecting power but

with excellent selectivity against iron sulfide minerals, unactivated

sphalerite and penalty elements. On many ores, the dosage required

may be considerably lower than that needed for traditionally-used

non-selective collectors such as xanthates. Other characteristics

include:

• Low frothing contribution, even on ores containing clay minerals.

• Fast kinetics.

• Good collection of coarse middling particles.

• Excellent collector for precious metals, PGM, galena, and copper

sulfides from complex, polymetallic or massive sulfide ores.

AERO 6931 and Reagents S-4604 and S-7583 promoters

These collectors were developed recently as lower-cost versions of

AEROPHINE 3418A promoter. Comparative testing should always

be conducted, to ensure that metallurgical results are equivalent to

those obtained with AEROPHINE 3418A promoter.

Mining Chemicals Handbook

114

Flotation of sulfide ores

115

6.1.4 The 400 series of AERO promoters

AAEERROO 440000 pprroommootteerr

– Used mainly for flotation of gold-bearing

pyrite in acid and neutral circuits.

AAEERROO 440044 pprroommootteerr

– Widely used for the flotation of tarnished

and secondary Cu minerals, tarnished Pb and Zn minerals, and

precious metals in alkaline circuit. Excellent collector for pyrite and

auriferous pyrite in acid and neutral circuits.

AAEERROO 440077 pprroommootteerr

– A stronger collector than AERO 404 promoter.

May substantially replace xanthates in many applications, while

being more selective against iron sulfides in alkaline circuit.

Useful for treating a wide range of precious and base-metal ores,

particularly those of Cu, Ni and Zn. Excellent for bulk flotation of

poly-metallic ores and pyritic gold ores in acid circuits.

AAEERROO 441122 pprroommootteerr

– A stronger collector than AERO 407 promoter

with substantially the same applications.

Physical properties

AERO promoters Aerofloat pro400 404 407 412

Appearance Colorless to Yellow Liquid

Boiling Point, °C 103 104 103 103

Freezing Point, ºC N/A -2 -7 9

pH >12 11.5 - 13.0

sp.gr., 25°C 1.26 1.15 1.17 1.16

Viscosity (cps)

0°C N/A 21 20 –

30°C N/A 6 6 7

Solubility Completely Water Soluble

Comments

• Generally stronger collectors than the corresponding alkyl AERO

and AEROFLOAT promoters, but still more selective than xan-

thates against iron sulfides in alkaline circuit. Use of xanthate as a

secondary collector is sometimes helpful in providing maximum

recovery.

Mercaptobenzothiazole Dithiophosphate

N/A= Not Applicable

• Compared to alkyl dithiophosphates, longer conditioning times

or addition to grinding mill is sometimes beneficial.

• Although originally developed mainly for the flotation of tarnished

Pb ores, the 400 series of AERO promoters are now widely used

in the flotation of most base-metal and precious metal ores. For

the flotation of "oxide" Cu, Pb and Zn minerals, pre-sulfidization

is usually required.

6.1.5 Nitrogen-based collectors

A. Dialkyl thionocarbamates

AERO 3894 promoter

This oily collector was originally developed for, and is still used in,

the selective flotation of copper ores in alkaline circuits. However,

due to its high selectivity, it generally requires the conjoint use of

a xanthate to insure maximum recovery of middling (composite)

particles. Being water-insoluble, addition to the grinding circuit is

often beneficial.

B. The Functionalized Thionocarbamates

In view of the limitations of the dialkyl thionocarbamates mentioned

above, Cytec in the mid 1980’s developed a series of funtionalized

thionocarbamates with the intention of producing collectors that

combine the selectivity of the dialkyl thionocarbamates and the

collecting power of xanthates. The other objective was to develop

collectors which would allow selective flotation of copper ores

containing iron sulfides under mildly alkaline conditions (pH 8-10)

Dialkyl Thionocarbamate

Alkyl Alkoxycarbonyl Thionocarbamate

Mining Chemicals Handbook

116

in contrast to the higher pH values required to depress pyrite when

using xanthate and other collectors. Essentially this was achieved by

the incorporation in the collector molecule of an O-containing

(ethoxycarbonyl) functional group, thereby augmenting the role of

the S functional group. The introduction of this second functional

group lowers the pKa of the molecule by several orders of magni-

tude compared to that of dialkyl thionocarbamates. This allows the

collector to be effective at lower pH values. (for further discussion,

see Section 5) Further, the second functional group provides for the

formation of more favorable and stronger metal complexes and,

therefore, stronger adsorption. This has been demonstrated by

sequential adsorption studies. For example, AERO 5415 and AERO

5460 promoters have been shown to replace previously adsorbed

dialkyl thionocarbamate from the mineral surface but, on the other

hand, dialkyl thionocarbamate does not replace previously adsorbed

AERO 5415 or AERO 5460 promoters. They are especially effective

for copper-rich minerals such as chalcocite, digenite, covellite and

bornite. They are poor galena collectors, as all thionocarbamates are.

AERO 5415, AERO 5460 promoters

These two collectors are structurally similar, but AERO 5460 promoter

being the higher homologue is the more powerful of the two and,

therefore, especially suitable for the recovery of coarse middlings

particles, whilst being only slightly less selective. Both of these

collectors are now in wide commercial use (both as-is or as compo-

nents of customized formulations) for the flotation of Cu, Cu-Mo

and Cu-Au ores. In most cases, the dosage required of these collectors

is lower than that for the traditional collectors, in addition to pro-

viding considerable savings in lime costs.

Comments

• Being insoluble in water, addition to the grinding circuit or a

conditioning step ahead of flotation may be beneficial. However, in

many cases

AAEERROO 55441155

and

AAEERROO 55446600

promoters are more

readily dispersible than the dialkyl thionocarbamates and allyl

alkyl thionocarbamates (depending upon pH and other condi-

tions). Consequently, in many cases, addition to the head of flota-

tion is possible and indeed may be preferable. The best point of

addition should be determined by laboratory and plant testing.

• Because of their high collecting power in moderately alkaline

circuits, and their high selectivity against iron sulfide minerals,

Flotation of sulfide ores

117

the preferred rougher flotation pH for these collectors is usually

in the range of 8 to 10, compared to the typical range of 10 to 12

required with other collectors. Similarly, in the cleaner circuits,

the pH required is lower than that necessary with other collectors.

• Operating in the lower pH range not only provides a considerable

reduction in lime costs but, on ores containing significant amounts

of clay and other slimes, also reduces pulp viscosity. This usually

enhances flotation efficiency or permits operating the circuit at

higher % solids.

• It has been well established in practice that the use of

AAEERROO 55441155

and

55446600

promoters generally enhances the recovery of precious

metals.

• They are stable hydrolytically in a wide pH range.

C. Allyl Alkyl Thionocarbamates

AERO 5100 promoter

AERO 5100 promoter is a modified version of IPETC, with incorpo-

ration of an allyl group attached to the nitrogen, which increases its

collecting power but retains its known selectivity against iron sulfide

minerals. Due to its very low solubility in water, it sometimes has a

flattening effect on the froth, especially if overdosed. The optimum

point of addition – to the grind, to a conditioner, or staged-addition

– should always be determined by experiment. If a flat, dry froth is

still a problem, the conjoint use of a small amount (10% to 20% of

the AERO 5100 dosage) of a short-chain dithiophosphate such as

Sodium AEROFLOAT or AEROFLOAT 208 promoter, is often helpful.

The principal uses of AERO 5100 promoter are in the flotation of

copper, activated zinc, and precious metals. It is an extremely poor

collector for galena and is therefore an excellent choice for floating

ores which contain only nuisance amounts of lead, or for selective

flotation of copper in Cu-Pb-Zn ores.

Allyl Alkyl Thionocarbamate

Mining Chemicals Handbook

118