7,476,308 Process for multiple stage direct electrowinning of copper

Patent Number/Link:

111111111111111111111111111111111111111111111111111111111111111111111111111

US007476308B2

(12) United States Patent

Marsden et al.

(10) Patent No.:

(45) Date of Patent:

US 7,476,308 B2

*Jan.13,2009

U.S. PATENT DOCUMENTS

(Continued)

FOREIGN PATENT DOCUMENTS

U.S. Cl. 205/580; 205/574; 205/581;

205/584; 205/585; 205/586; 741740; 741743

Field of Classification Search 205/584,

205/586,574,280, 581, 585; 751740, 743

See application file for complete search history.

References Cited

(54) PROCESS FOR MULTIPLE STAGE DIRECT

ELECTROWINNING OF COPPER

(75) Inventors: John O. Marsden, Phoenix, AZ (US);

Robert E. Brewer, Park City, UT (US);

Joanna M. Robertson, Thatcher, AZ

(US); David R. Baughman, Golden, CO

(US); Phillip Thompson, West Valley

City, UT (US); Wayne W. Hazen,

Lakewood, CA (US); Christel M. A.

Bemelmans, Indian Hills, CO (US)

(73) Assignee: Phelps Dodge Corporation, Phoenix,

AZ (US)

(52)

(58)

(56)

3,260,593 A 7/1966 Zimmerleyet al.

( *) Notice: Subject to any disclaimer, the term ofthis

patent is extended or adjusted under 35

U.S.c. 154(b) by 867 days.

0219785

1657-2000

WO 01/00890

12/1958

6/1999

1/2001

OTHER PUBLICATIONS

50 Claims, 3 Drawing Sheets

A system and process for recovering copper from a coppercontaining

ore, concentrate, or other copper-bearing material

to produce high quality cathode copper from a leach solution

without the use of copper solvent/solution extraction techniques

or apparatus. A process for recovering copper from a

copper-containing ore generally includes the steps of providing

a feed stream containing comminuted copper-containing

ore, concentrate, or other copper-bearing material, leaching

the feed stream to yield a copper-containing solution, conditioning

the copper-containing solution through one or more

physical or chemical conditioning steps, and electrowinning

copper directly from the copper-containing solution in multiple

electrowinning stages, without subjecting the coppercontaining

solution to solvent/solution extraction prior to

electrowinning.

PCT International Preliminary Examination Report, PCTIUS01/

23366, Date of Completion of Report: Oct. 23, 2002.

(Continued)

Primary Examiner-Bruce F Bell

(74) Attorney, Agent, or Firm-Snell & Wilmer L.L.P.

(57) ABSTRACT

May 26,2005

(2006.01)

This patent is subject to a tenninal disclaimer.

US 2005/0109163 Al

Appl. No.: 10/976,481

Filed: Oct. 29, 2004

Prior Publication Data

(60)

(63)

(21)

(22)

(65)

Related U.S. Application Data

Continuation-in-part of application No. 101737,420,

filed on Dec. 15,2003, now Pat. No. 6,972,107, which

is a continuation of application No. 10/238,399, filed

on Sep. 9, 2002, now Pat. No. 6,663,689, which is a

continuation of application No. 09/912,921, filed on

Jul. 25, 2001, now Pat. No. 6,451,089, application No.

10/976,481, which is a continuation-in-part of application

No. 101756,574, filed on Jan. 12,2004, now Pat.

No. 7,341,700, which is a continuation of application

No. 09/915,105, filed on Jul. 25, 2001, now Pat. No.

6,676,909.

Provisional application No. 60/517,171, filed on Nov.

3,2003.

(51) Int. Cl.

C2SC 1/12

u.s. PATENT DOCUMENTS

OTHER PUBLICATIONS

PCT International Search Report, PCTIUS02/23454, Mailed:

Jun. 12,2003.

Written Opinion issued by European Patent Office, PCTI

USOl/23468, Mailed: Jul. 17, 2002.

PCT International Preliminary Examination Report, PCTI

USOl/23468, Date of Completion of Report: Dec. 17,2002.

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4,619,814 A

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4,814,007 A

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US 7,476,308 B2

Page 2

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US 7,476,308 B2

Page 3

Fundamental Aspects, Minerals, Metals & Materials Society

pp. 735-757 (Oct. 1993).

Mackiw, V. N., Direct Acid Pressure Leaching o/Chalcocite

Concentrate, JOM 19:2 (Feb. 1967). [Abstract only.].

Opposition To CL 1767-2001 by Anglo American, PLC (with

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no date.

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Australia Conference) (1999).

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to Process Metallurgy, Part II, 218-221 (1979).

Szymanowski, J., Dydroxyoximes and Copper Hydrometallurgy,

(CRC Press), 6 pages, no date.

* cited by examiner

u.s. Patent Jao.13,2009 Sheet 1 of 3 US 7,476,308 B2

101

1010

Cu SEPARATION

ATMOSPHERIC FLASH

111

126

; .

107

122

121

ELECTROLYTE

RECYCLE TANK

ELECTROLYTE

RECYCLE TANK

SECOND STAGE DIRECT

ELECTROWINNING

108

1080

128

125

( Cu )

FIG. 1

u.s. Patent Jao.13,2009 Sheet 2 of 3 US 7,476,308 B2

211

210

209

204

204 i

---------------------------,

--------------- 1

201

ATMOSPHERIC LEACHI

PRESSURE LEACH

ELECTROWINNING

2020

126,1

2030

2070

208

206

203

I \ 205 207 :

~ L I ~ -----------------------

1 1 I ---------------T-----T-----+---------------l 1 I

1 WOO r

FIG. 2

u.s. Patent Jao.13,2009 Sheet 3 of 3 US 7,476,308 B2

CuOREOR

CONCENTRATE

ATMOSPHERICI

PRESSURE LEACH

101

123

1010

Cu SEPARATION 203

1020

1030

LI--.,....---------'

110

---->:1:------

PRESSURE LEACH

104

1040

ATMOSPHERIC FLASH

107

ELECTROLYTE

RECYCLE TANK

1050

~-(---

I 108

__ - ......1

: 1070 FIRST STAGE DIRECT

- - - ~ - - \- - - L...-_E_L_EC_T_R_O_Wr-I_NN_I_N_G__--'

108 120

- - I

~_i _

108 ~ 1060

123

ELECTROLYTE

RECYCLE TANK

121

SECOND STAGE DIRECT

ELECTROWINNING Cu

FIG. 3

US 7,476,308 B2

SUMMARY OF THE INVENTION

purification by solvent/solution extraction-is known. However,

the copper recovered by such so-called direct electrowinning

processes often is too impure for sale or use as is, and

thus, generally must be further refined at an additional cost, or

may be sold at a discount. More specifically, prior art techniques

have shown the ability for direct electrowinning of

copper to produce a relatively low-quality copper product

An effective and efficient method to recover copper from

10 metal-bearing materials, such as, for example, chalcopyrite,

chalcocite, bomite, covellite, digenite, and enargite, that

enables high copper recovery to be achieved at a reduced cost

over conventional processing techniques would be advantageous.

While the way in which the present invention addresses the

deficiencies and disadvantages of the prior art is described in

greater detail hereinbelow, in general, according to various

aspects of the present invention, a process for recovering

copper and other metal values from a copper-containing

material includes obtaining a copper-containing solution

25 from, for example, a pressure leaching system, and then

appropriately conditioning the copper-containing solution for

electrowinning. In an exemplary aspect of the invention, the

composition of the copper-containing solution is similar to

the composition of the electrolyte produced by a solvent/

30 solution extraction circuit, for example, with respect to acid

and copper concentrations. In accordance with various

embodiments of the present invention, however, the coppercontaining

solution is not subjected to solvent/solution

extraction prior to electrowinning.

In accordance with an exemplary embodiment of the

present invention, a process for recovering copper from a

copper-containing material generally includes the steps of: (i)

providing a feed stream containing finely ground coppercontaining

material; (ii) subjecting the copper-containing

40 feed stream to a copper separation stage to produce a coppercontaining

inlet stream; (iii) subjecting the copper-containing

inlet stream to atmospheric leaching or pressure leaching to

yield a copper-containing solution; (iv) conditioning the copper-

containing solution through one or more chemical or

45 physical conditioning steps; (v) electrowinning copper

directly from the copper-containing solution, without subjecting

the copper-containing solution to solvent/solution

extraction; and (vi) recycling all or at least a portion of the

lean electrolyte back to the atmospheric or pressure leaching

50 step. As used herein, the term "pressure leaching" shall refer

to a metal recovery process in which material is contacted

with a liquid (e.g., an acidic solution, water, etc.) and oxygen

under conditions of elevated temperature and pressure (ie.,

above ambient).

In one aspect of an exemplary embodiment of the invention,

one or more processing steps are used to separate copper

from the acid in a recycled portion ofthe lean electrolyte from

the direct electrowinning process, thus enabling the rejection

ofa portion ofthe acid and impurities from the process circuit

60 without rejecting a significant portion of the copper. As discussed

in greater detail hereinbelow, a number of conventional

or hereafter devised processes may be utilized to separate

copper from acid in the feed stream. For example, in

accordance with one aspect of an exemplary embodiment of

65 the invention, a copper precipitation step may be utilized to

precipitate solubilized copper from a lean electrolyte stream

onto the surfaces of solid particles in a copper-containing

FIELD OF INVENTION

CROSS REFERENCE TO RELATED

APPLICATIONS

BACKGROUND OF THE INVENTION

PROCESS FOR MULTIPLE STAGE DIRECT

ELECTROWINNING OF COPPER

Hydrometallurgical treatment of copper-containing materials,

such as copper ores, concentrates, and other copperbearing

materials, has been well established for many years.

Currently, there exist many creative approaches to the hydrometallurgical

treatment ofthese materials; however, common

to almost all of the processes either now known or under

development is the use of solvent/solution extraction and

electrowinning (SX-EW) operations for solution purification

and copper recovery.

The traditional hydrometallurgical process for copper

recovery involves first leaching copper-containing material

with sulfuric acid solution, either atmospherically or under

conditions of elevated temperature and pressure. The resultant

liquid stream-the so-called pregnant leach solution-is

collected and processed in a solvent/solution extraction stage,

in which the leach solution is mixed with an organic solvent

(i.e., an extractant mixed with a suitable diluent, such as

kerosene). The organic phase selectively removes the copper

from the pregnant leach solution. The copper-loaded organic 55

phase is then mixed with an aqueous acid solution, which

strips the copper from the extractant, producing a solution

stream suitable for electrowinning. This resultant solution is

highly concentrated in copper, is relatively pure, and typically

is processed in an electrowinning circuit to yield high quality

copper cathode.

Purification of copper from the pregnant leach solution by

solvent/solution extraction has proven to be a successful

means of providing a concentrated copper solution suitable

for electrowinning of highly pure copper metal. Direct electrowinning

ofcopper-that is, plating ofcopper directly from

the pregnant leach solution without the intervening step of

The present invention relates generally to a process for

recovering copper from a copper-containing ore, concentrate,

or other copper-bearing material, and more specifically, to a

process using super-fine grinding, a copper separation operation,

and pressure leaching to produce cathode copper from a

multiple-stage direct electrowinning process.

This application is a continuation-in-part of U.S. patent

application Ser. No. 101737,420, filed on Dec. 15,2003 now

U.S. Pat. No. 6,972,107, which is a continuation of U.S.

patent application Ser. No. 10/238,399, which was filed on

Sep. 9, 2002 and issued as U.S. Pat. No. 6,663,689 onDec.16,

2003, which is a continuation of U.S. patent application Ser.

No. 09/912,921, which was filed on Jul. 25, 2001 and issued

as U.S. Pat. No. 6,451,089 on Sep. 17,2002, the disclosures

of which are incorporated by reference herein. This applica- 15

tion is also a continuation-in-part of U.S. patent application

Ser. No. 101756,574, filed on Jan. 12,2004 now U.S. Pat. No.

7,341,700, which is a continuation ofU.S. patent application

Ser. No. 09/915,105, which was filed on Jul. 25, 2001 and

issued as U.S. Pat. No. 6,676,909 on Jan. 13, 2004, the dis- 20

closures ofwhich are incorporated by reference herein. This

application further claims priority to U.S. Provisional Application

Ser. No. 60/517,171, filed on Nov. 3, 2003, the disclosure

of which is incorporated by reference herein.

US 7,476,308 B2

3 4

atmospheric leaching operations, such as, for example, heap

leaching, vat leaching, dump or stockpile leaching, pad leaching,

agitated tank leaching, and bacterial leaching operations,

which often require a substantially continuous acid supply.

In accordance with one aspect of an exemplary embodiment

of the present invention, a feed stream containing copper-

containing material is provided for processing. In accordance

with various embodiments of present invention, the

copper-containing material may be an ore, a concentrate, or

any other copper-bearing material from which copper and/or

other metal values may be recovered The copper in the copper-

containing material may be in the form ofcopper oxides,

copper sulfides, and/or other copper minerals, and the coppercontaining

material may include any number of a variety of

other metals, such as, for example, gold, platinum group

metals, silver, zinc, nickel, cobalt, molybdenum, rare earth

metals, rhenium, uranium and mixtures thereof Various

aspects and embodiments ofthe present invention prove especially

advantageous in connection with the recovery of cop-

20 per from copper-bearing sulfide ores, such as, for example,

chalcopytite (CuFeS2 ), chalcocite (Cu2 S), bornite (CusFeS4 ),

covellite (CuS), enargite (Cu3AsS4 ), digenite (Cu9 SS), and/or

mixtures thereof.

The feed stream of copper-containing material can be pro-

25 vided in any number of ways, such that the conditions ofthe

feed stream are suitable for the chosen processing methods.

For example, feed stream conditions such as particle size,

composition, and component concentrations can affect the

overall effectiveness and efficiency of downstream process-

30 ing operations, such as, for example, atmospheric leaching or

pressure leaching.

In accordance with an exemplary aspect of the invention,

the particle size of the copper-containing feed material is

reduced to optimize the processing steps of atmospheric or

35 pressure leaching and subsequent metal recovery processes.

A variety of acceptable techniques and devices for reducing

the particle size of the copper-containing material are currently

available, such as ball mills, tower mills, superfine

grinding mills, attrition mills, stirred mills, horizontal mills

40 and the like, and additional techniques may later be developed

that may achieve the desired result of increasing the surface

area ofthe material to be processed. With regard to one aspect

ofan exemplary embodiment ofthe invention, such a result is

desired because the reaction rate during precipitation and/or

45 leaching may increase as the surface area of the coppercontaining

material increases.

FIG. 1 illustrates an exemplary embodiment of the present

invention wherein copper is the metal to be recovered from a

copper-containing feed material, such as a sulfide ore or con-

50 centrate. In accordance with one aspect of the present invention,

the metal-bearing feed material is prepared for metal

recovery processing by controlled, super-fine grinding. As

used herein, controlled, super-fine grinding refers to any process

by which the particle size ofthe material being processed

55 is reduced such that substantially all ofthe particles are small

enough to react substantially completely during medium temperature

pressure leaching. For example, in accordance with

one aspect ofthe present invention, a particle size distribution

of approximately 98 percent passing about 25 microns is

60 preferable, and more preferably, the copper-containing material

stream has a particle size distribution ofapproximately 98

percent passing from about 10 to about 23 microns, and

optimally from about 13 to about IS microns. These particle

size distributions associated with optimum copper recovery

65 were determined through the use ofa Malvern optical particle

size analyzer. Other methods and apparatus, however, may be

utilized.

BRIEF DESCRIPTION OF THE DRAWING

DETAILED DESCRIPTION OF EXEMPLARY

EMBODIMENTS

The present invention exhibits significant advancements

over prior art processes, especially other so-called "direct

electrowinning" processes, particularly with regard to product

quality and process efficiency. Moreover, existing copper

recovery processes that use a conventional atmospheric or

pressure leaching, solvent/solution extraction, and electrowinning

process sequence may, in many instances, be easily

retrofitted to exploit the many commercial benefits the

present invention provides.

In one aspect of an exemplary embodiment of the invention,

at least a portion of the acid generated during the electrowinning

stage as a copper-containing electrolyte stream is

transported out of the copper recovery process after a separation

step in which substantially all ofthe copper is removed

from the copper-containing electrolyte stream. It is generally

economically advantageous to utilize this generated acid in

some way, rather than to attenuate or dispose of it. Thus, as

discussed in greater detail hereinbelow, the present invention

may find particular utility in combination with conventional

material (e.g., finely ground chalcopyrite) stream in advance

of the pressure leaching step, thereby separating the copper

from the acid solution.

In accordance with various exemplary aspects of the

present invention, by providing for the electrowinning of

copper directly from a copper-containing solution without

first subjecting the copper-containing solution to solvent/solution

extraction, the present invention enables lower-cost

recovery of copper and reduces the expenses associated with

solvent/solution extraction, such as expenses associated with 10

reagents, process apparatus and equipment, and energy

resources. Furthermore, in accordance with one exemplary

aspect ofthe invention, careful control ofthe composition and

the dispersion ofthe copper-containing solution entering the

electrowining circuit enables production ofhigh quality, uni- 15

formly-plated cathode copper. However, in accordance with

still other aspects of the present invention, one or more process

"bleed" streams may be subjected to solvent/solution

extraction, preferably following the electrowinning ofcopper

therefrom.

These and other advantages of a process according to vari0us

aspects and embodiments ofthe present invention will be

apparent to those skilled in the art upon reading and understanding

the following detailed description with reference to

the accompanying figures.

The subject matter of the present invention is particularly

pointed out and distinctly claimed in the concluding portion

of the specification. A more complete understanding of the

present invention, however, may best be obtained by referring

to the detailed description and claims when considered in

connection with the drawing figures, wherein like numerals

denote like elements and wherein:

FIG. 1 illustrates a flow diagram of a copper recovery

process in accordance with an exemplary embodiment ofthe

present invention;

FIG. 2 illustrates a flow diagram of various aspects of a

copper recovery process in accordance with an alternative

embodiment of the present invention; and,

FIG. 3 illustrates a flow diagram of a copper recovery

process in accordance with an alternative embodiment ofthe

present invention

US 7,476,308 B2

5 6

CuFeS2+Cu+2--..,.Fe+2+2CuS

preferably removed from the metal recovery process and

utilized in remote operations, disposed of, or attenuated, the

impurities contained therein are likewise removed from the

metal recovery process and are thus prevented from accumulating

in the process stream. This may be a significant advantage

in that such impurities, particularly metal impurities,

typically have a deleterious effect on the effectiveness and

efficiency ofthe desired metal recovery process. For example,

metal impurities and other impurities in the process stream, if

10 not carefully controlled and/or minimized, can contribute to

diminished physical and/or chemical properties in the cathode

copper producedby electrowinning, and canthus degrade

the copper product and diminish its economic value.

Referring again to FIG. 1, in accordance with one aspect of

15 an exemplary embodiment of the invention, copper-containing

material stream 101 is subjected to a separation step, such

as, for example, a precipitation step, which, in this exemplary

process, serves to precipitate solubilized copper from a

recycled lean electrolyte stream As discussed in detail above,

20 this aspect offers an important advantage in that it enables

recovery of copper from a lean electrolyte stream that otherwise

may have been lost or would have required additional

processing to recover, potentially resulting in significant economic

benefits.

In accordance with one exemplary aspect of an embodiment

ofthe invention, the precipitation step involves coppercontaining

material stream 101 being combined with a lean

electrolyte stream 125 and, optionally, a sulfur dioxide (S02)

stream 109 in a suitable processing vessel. For example, in the

30 embodiment illustrated in FIG. 1, lean electrolyte stream 125

may comprise a recycled acidic copper sulfate stream generated

during an electrowinning operation. Other streams, however,

preferably acidic streams, may also be used. While the

use of such other streams will be described in greater detail

35 hereinbelow, in accordance with various aspects of the

present invention, processing streams, preferably from electrowinning

operations, may be used. For example, in the

embodiments illustrated in FIGS. 1 and 3, multiple stage

electrowining follows pressure leaching. While two such

40 electrowinning stages are illustrated, it will be appreciated

that additional stages may also be utilized in various applications.

However, lean electrolyte from either the first or second

electrowinning stage may be used as the recycled electrolyte

used in copper separation step 1010. Preferably, however, and

45 as is illustrated best in FIG. 3, a stream 123 from the second

electrowinning circuit 1090 is recycled to copper separation

step 1010.

In one aspect of this embodiment of the invention, lean

electrolyte stream 125 has an acid concentration of from

50 about 20 to about 200 grams/liter, preferably from about 70 to

about 180 grams/liter, and most preferably from about 140 to

about 170 grams/liter. In a further aspect ofthis embodiment

of the invention, lean electrolyte stream 125 has a copper

concentration of from about 20 to about 55 grams/liter, pref-

55 erably from about 25 to about 50 grams/liter, and most preferably

from about 30 to about 45 grams/liter. In copper precipitation

stage 1010, copper from lean electrolyte stream 125

precipitates to fonn a desired copper-rich concentrate. Preferably,

precipitation is carried out such that the copper from

60 the lean electrolyte precipitates, at least in part, in the form of

a copper sulfide, such as, for example, CuS. While not wishing

to be bound by any particular theory, the chemical reaction

during this exemplary copper precipitation stepwherein,

for example, the copper-containing material is

65 primarily chalcopyrite-is believed to be as follows:

In accordance with one aspect of an exemplary embodiment

of the invention, satisfactory controlled, super-fine

grinding ofchalcopyrite concentrate with an as-received particle

size of approximately 98 percent passing about 172

microns may be achieved using a super-fine grinding apparatus,

such as, for example, a stirred horizontal shaft mill with

baffles or a vertically stirred mill Without baffles. Such exemplary

apparatus include the Isamill developed jointly by

Mount Isa Mines (MIM), Australia, and Netzsch Feinmahltechnik,

Gennany and the SMD or Detritor mill, manufactured

by Metso Minerals, Finland Preferably, if a horizontal

mill is utilized, the grinding medium would be 1.2/2.4mmor

2.4/4.8 mm Colorado sand, available from Oglebay Norton

Industrial Sands Inc., Colorado Springs, Colo. However, any

grinding medium that enables the desired particle size distribution

to be achieved may be used, the type and size ofwhich

may be dependent upon the application chosen, the product

size desired, grinding apparatus manufacturer's specifications,

and the like. Exemplary media include, for example,

sand, silica, metal beads, ceramic beads, and ceramic balls.

In another aspect of an exemplary embodiment of the

present invention, the comminuted metal-bearing material is

combined with a liquid prior to entering copper separation

stage 1010 (described hereinbelow). Preferably, the liquid

comprises water, but any suitable liquid may be employed, 25

such as, for example, raffinate, pregnant leach solution, or

lean electrolyte. For example, a portion of lean electrolyte

stream 125 from the direct electrowinning process may be

combined with comminuted metal-bearing material to fonn

metal-bearing material stream 10l.

The combination of a liquid with the metal-bearing material

can be accomplished using anyone or more ofa variety of

techniques and apparatus, such as, for example, in-line blending

or using a mixing tank or other suitable vessel. In accordance

with an exemplary aspect of an embodiment of the

invention, the concentration of solid metal-bearing material

in the material stream (i.e., the slurry density) is on the order

ofless than about fifty (50) percent by weight of the stream,

and preferably about forty (40) percent by weight of the

stream. Other slurry densities that are suitable for transport

and subsequent processing may, however, be used.

In accordance with one aspect ofthe present invention, it is

desirable to separate the copper from the acid in a recycled

stream of lean electrolyte from electrowinning, and also to

reduce the amount ofimpurities in the portion ofthe stream to

be subjected to the metal recovery process. In such a separation

process, the acid that is removed from the recycled lean

electrolyte stream may be rejected from the process circuit,

taking with it at least a portion of the solid or soluble impurities

from the copper-containing feed stream and the

recycled lean electrolyte stream Any number ofconventional

or hereafter devised separation processes and techniques may

be useful to achieve the separation ofcopper from acid in the

lean electrolyte stream. For example, separation processes

and/or techniques such as precipitation, low temperature

pressure leaching, acid solvent/solution extraction/ion

exchange, membrane separation, cementation, pressure

reduction, sulfiding, and/or the use of liberator cells may be

useful for this purpose.

The separation aspect of an exemplary embodiment ofthe

invention contributes to providing a resultant acid stream

from copper separation step 1010 that contains a relatively

small fraction of copper, which can be used for leaching, pH

control, and/or other applications. Moreover, utilization of a

separation process in accordance with this aspect of the

invention may advantageously enable removal of certain

impurities. For example, because the resultant acid stream is

US 7,476,308 B2

Other copper minerals and other sulfides react to varying

degrees according to similar reactions, producing copper precipitates

and a weak sulfuric acid by-product In accordance

with an exemplary aspect of the invention, copper separation

stage 1010 is carried out at a slightly elevated temperature,

such as from about 70° C. to about 180° c., preferably from

about 80° C. to about 100° c., and most preferably at a

temperature of about 90° C. Heating, if necessary, can be

effectuated through any conventional means, such as with

steam, electric heating coils, a heat blanket, process fluid heat

exchange, and other ways now known or later developed In

the exemplary process of FIG. 1, steam generated in other

process areas, such as stream 1 19 from flash tank 1040 or

stream 118 from pressure leaching stage 1030, may be

directed to the processing vessel in copper separation stage

1010 to provide the heat desired to enhance the precipitation

process.

The residence time for the copper precipitation process can

vary, depending on factors such as the operating temperature

ofthe processing vessel and the size distribution/surface area

of the composition of the copper-containing material, but

typically ranges from about two (2) minutes to about six (6)

hours. Preferably, conditions are selected such that significant

amounts of copper are precipitated. For example, precipitation

rates on the order of about 98% precipitation of copper

have been achieved in processing vessels maintained at about

90° C. for about 4 hours.

Other parameters to consider when conditioning the copper-

containing material feed stream for processing are (i) the

ratio ofsolid particles in the feed stream to the total volume of

the copper-containing solution feed stream; (ii) the ratio of

copper in solution to copper-containing material; (iii) temperature;

(iv) pressure; (v) viscosity, (vi) slurry density ofthe

feed stream; and (vii) other factors may be suitably addressed

Although these parameters mayor may not be significant to

the overall efficiency ofprocessing operations downstream in

all cases, these parameters can affect equipment size and

material specifications, energy requirements, and other

important aspects ofprocess design. Thus, calculated adjustment

of these stream parameters in advance of complex or

resource-intensive processing stages can positively affect the

economic efficiency ofthe chosen process. Solid-liquid separation

systems, such as, for example, filtration systems,

counter-current decantation (CCD) circuits, thickeners, and

the like are useful in adjusting these parameters and are

widely used in the industry.

In one aspect ofthe embodiment ofthe invention illustrated

in FIG. 1, product stream 102, which generally contains covellite/

chalcopyrite particles and acid, contains acid generated

in pressure leaching stage 1030, first electrowinning stage

1070, and second electrowinning stage 1090, and any acid

generated in copper separation stage 1010 as a result of S02'

In accordance with an exemplary aspect of the invention,

the copper-containing material stream entering the pressure

leaching stage contains from about 10 and about 50 percent

solids by weight, preferably from about 20 to about 40 percent

solids by weight. To adjust the solids concentration of

product stream 102 in accordance with the desired parameters

and to separate the acid-bearing solution from the coppercontaining

solids, in accordance with an exemplary embodiment

of the invention, product stream 102 is sent to a solidliquid

separation circuit 1020. In one aspect of an exemplary

embodiment of the invention, solid-liquid separation circuit

1020 preferably includes a thickener circuit 1021 comprising

at least one thickener that will effectuate solid-liquid separation.

In the illustrated embodiment, the underflow of thickenercircuit

1021 is pressure leaching feed stream 103 and the

overflow is acid stream 110. Preferably, acid stream 110

contains only a negligible amount of copper.

Process effluent acid stream 110 may be utilized, processed,

attenuated, impounded, and/or disposed of in a variety

ofways, the appropriate choice ofwhich is largely dependent

upon economic and regulatory factors. In one aspect of

the illustrated embodiment, the acid stream can be beneficially

used in, for example, a leaching operation, such as an

atmospheric leaching operation, where acid is required to

10 leach copper oxide, copper sulfide, or other metal oxide/

sulfur minerals. Such a leaching operation may be a heap

leach, a vat leach, a tank leach, a pad leach, or any other

similar operation or may be a medium or low-temperature

pressure leaching operation. Acid is consumed in these opera-

15 tions through reaction with acid-consuming constituents in

the ore.

In FIG. 2, acid stream 110 from thickener circuit 1021

(FIG. 1) is sent to an atmospheric pressure leach operation

20 2010. In accordance with one aspect ofan exemplary embodiment

ofthe invention, leach operation 2010 is a conventional

acid-consuming heap leach operation, wherein a copper ore

201 is contacted with acid stream 110 and, optionally, other

process streams, such as raffinate stream 206 from down-

25 stream solvent/solution extraction unit 2020. In the example

of leach operation 2010 as a heap leach operation, the acid

percolates downward through the ore heap, solubilizing the

copper in the copper-containing ore in the form of copper

sulfate, to form a copper-rich pregnant leach solution (PLS)

30 stream 203. In the example of leach operation 2010 as a

pressure leach operation, acid aids in the solubilization of

copper in the feed material to form a PLS stream. PLS stream

203 is sent to a solvent/solution extraction unit, such as solvent/

solution extraction unit 2020 in FIG. 2, to produce a high

35 concentration and relatively pure copper sulfate solution suitable

for electrowinning of copper. In accordance with an

alternative aspect ofthe present invention illustrated in FIG.

2, PLS stream 203 may not be subjected to solvent/solution

extraction, but may instead be blended with other copper-

40 containing process streams, and the resultant stream then sent

to a copper electrowinning circuit. For example, all or a

portion ofPLS stream 203 (broken line) may be blended with

copper-containing solution stream 106 and lean electrolyte

stream 115 in electrolyte recycle tank 1060 (from FIG. 1) to

45 form a resultant product stream suitable for copper electrowinning

in an electrowinning circuit.

Ifeffluent acid stream 110 is not used as an acid-containing

by-product or otherwise utilized, the acid may be attenuated

using, for example, acid-consuming gangue (i.e., mineral

50 processing tailings) or an attenuating agent, such as limestone

or lime. Attenuating with acid-consuming gangue can be

relatively inexpensive, as the attenuating reagent is essentially

free. On the other hand, attenuating with limestone or

lime may be less desirable economically, as both these

55 reagents will incur cost. Nevertheless, should attenuation be

desired, any method for acid attenuation now known or hereafter

devised may be employed.

In accordance with a further aspect ofthis embodiment of

the present invention, as previously briefly mentioned, acid

60 stream 110 advantageously may remove impurities from the

process, for example, the electrowinning process. Such impurities

include, without limitation, iron, aluminum, manganese,

magnesium, sodium, potassium, and other metal ions,

often present as sulfates. In the absence of removal, such

65 impurities may accumulate to deleterious levels, and, as such

negatively impact production efficiencies and product (i.e.,

copper cathode) quality. The presence of such impurities in

US 7,476,308 B2

9 10

2CU2S+502+2H2S04~4CuS04+2H20

2CuS+2H2SO4+02~2Cu+2+2S04+2+2H20+2SC

4CuFeS2+4H2S04+502~4CuS04+2Fe203+8SC+

4H20

Ifdesired, conditions during pressure leaching can be controlled

such that a portion ofthe sulfide sulfur contained in the

feed stream is converted to elemental sulfur instead ofsulfate.

The fraction of chalcopyrite and covellite that fonn sulfur

instead of sulfate are believed to react according to the following

reactions:

Pressure leaching, for example in pressure leaching vessel

1031, preferably occurs in a manner suitably selected to promote

the solubilization of copper using these (or other) processes.

In general, temperature and pressure in the pressure

leaching vessel should be carefully controlled. For example,

in accordance with one aspect of the invention, the temperature

of pressure leaching vessel 1031 is maintained at from

about 100° C. to about 250° c., preferably from about 140° C.

to about 235° C. In accordance with one aspect of one

embodiment of the invention, the temperature of pressure

leaching vessel 1031 is advantageously maintained at from

about 140° C. to about 180° C. or in the range of from about

150° C. to about 175° C. In accordance with anotherembodiment

of the invention, the temperature of pressure leaching

vessel 1031 is advantageously maintained between from

about 200° C. to about 235° C. or in the range of from about

210° C. to about 225° C.

In accordance with one aspect of the present invention,

during pressure leaching in pressure leaching vessel 1031,

sufficient oxygen 112 is injected into the vessel to maintain an

oxygen partial pressure from about 50 to about 250 psig,

preferably from about 75 to about 220 psig, and most preferably

from about 150 to about 200 psig. Furthennore, due to

the nature ofmedium temperature pressure leaching, the total

operating pressure (including oxygen partial pressure and

steam pressure) in the pressure leaching vessel is generally

superatmospheric, preferably from about 100 to about 750

solvent/solution extraction techniques may be used. In an

exemplary embodiment ofthe invention, as illustrated in FIG.

1, pressure leaching feed stream 103 is subjected to a pressure

leaching stage 1030 to yield copper-containing product slurry

104.

In accordance with one aspect of this embodiment of the

present invention, pressure leaching feed stream 103 is transported

to a suitable vessel for pressure leaching, which can be

any vessel suitably designed to contain the process compo-

10 nents at the desired temperature and pressure conditions for

the requisite processing residence time. In an exemplary

embodiment, a pressure leaching vessell 031 is employed for

this purpose. Pressure leaching vessel 1031 is preferably a

horizontal multi-compartment, agitated vessel; however,

15 other vessel configuration and agitation alternatives now

known or hereafter devised may be employed. It should be

appreciated that any pressure leaching vessel that suitably

permits pressure leaching feed stream 103 to be prepared for

copper recovery may be utilized within the scope of the

20 present invention.

Generally, the chemical conversions that occur during

pressure leaching stage 1030 under certain conditions for the

solubilization of the copper in copper-containing materials,

such as chalcopyrite, chalcocite, or covellite are as follows:

acid stream 110 generally does not negatively impact the

aforementioned handling of acid stream 110.

In accordance with one aspect of an exemplary embodiment

of the invention illustrated in FIG. 2, solvent/solution

extraction unit 2020 purifies copper-bearing PLS stream 203

from the heap leach in two unit operations-an extraction

operation, which may have multiple stages, followed by a

stripping operation. In the extraction stage, PLS stream 203 is

contacted with an organic phase consisting of a diluent (e.g.,

kerosene) in which a copper selective extractant reagent (i.e.,

the extractant) is dissolved When the solutions are contacted,

the organic extractant chemically removes the copper from

the PLS, forming an aqueous raffinate stream. The raffinate

and organic streams are subsequently separated in a settler.

After separation of the organic and aqueous phases in the

settler, a portion of the aqueous phase (stream 206) is typically

returned to one or more leaching operations to be

reloaded with copper from the ore in the atmospheric leaching

step 2010 to fonn the PLS. Optionally, a portion ofraffinate

stream 206 may be recycled to copper separation step

1010. The organic stream passes on to the second unit operation

of the solvent/solution extraction process, the stripping

operation In the stripping operation, the organic stream is

contacted with a strongly acidic electrolyte. This acidic solution

"strips" the copper from the extractant, leaving the 25

organic phase substantially depleted of copper. At least a

portion of the loaded strip solution aqueous phase (stream

204) is advanced to an electrowinning plant 2030 as a copper

"rich" solutionAqueous stream 204 is processed in electrowinning

plant 2030 to yield cathode copper 207 and a copper- 30

containing lean electrolyte stream 208, which, in one aspect

of an exemplary embodiment of the invention, may be

recycled in part to solvent/solution extraction unit 2020.

In accordance with one alternative aspect ofthe invention,

aqueous stream 204 may not be subjected to electrowinning 35

immediately after leaving the solvent/solution extraction

unit, but may instead be blended with other copper-containing

process streams, and the resultant stream then sent to an

electrowinning circuit. For example, all or a portion of aqueous

stream 204 (broken line) may be blended with copper- 40

containing solution stream 106 and lean electrolyte stream

115 in electrolyte recycle tank 1060 (from FIG. 1) to fonn a

resultant product stream suitable for electrowinning in an

electrowinning circuit 1070. In such cases the stripping solutions

used in solvent/solution extraction 2020 likely will be 45

comprised of spent electrolyte from electrowinning circuit

1070.

Referring again to FIG. 1, the underflow slurry from thickener

circuit 1021, pressure leaching feed stream 103 in this

preferred embodiment of the invention, has a composition of 50

about 40 to about 60 percent solids by weight, the balance

being a dilute acid solution. The general composition of the

dilute acid solution is dependent upon the ratio of process

water to acid introduced in the thickener circuit.

In a further aspect ofthe present invention, the conditioned 55

copper-containing feed stream preferably is subjected to a

suitable process, such as pressure leaching, to produce product

slurry 104, which comprises a copper-containing solution

106 and a residue 114.

The process may be selected as desired, but, in general, 60

enables production of a copper-containing solution 106 that

exhibits copper and acid concentrations similar to an electrolyte

stream resulting from a solvent/solution extraction circuit-

that is, the copper-containing solution preferably is

suitable for processing in an electrowinning circuit. Any suit- 65

able technique or combination of techniques that yields an

appropriate copper-containing solution without employing

US 7,476,308 B2

psig, more preferably from about 250 to about 400 psig, and

most preferably from about 270 to about 350 psig.

Because pressure leaching of many metal sulfides is a

highly exothermic process and the heat generated is generally

greater than that required to heat pressure leaching feed

stream 103 to the desired operating temperature, cooling liquid

111 is preferably contacted with pressure leaching feed

stream 103 in pressure leaching vessel 1031 during pressure

leaching. Cooling liquid 111 is preferably process water, but

can be any suitable cooling fluid from within the refining 10

process or from an outside source. In an exemplary embodiment

of the invention, a sufficient amount of cooling liquid

111 is added to pressure leaching vessel 1031 to yield a solids

content in the product slurry 104 ranging from about 3 to

about 15 percent solids by weight. In accordance with one 15

aspect of the present invention, and with momentary reference

to FIG. 3, cooling ofthe pressure leaching vessel can be

accomplished by recycling lean electrolyte 123 from one or

more of the subsequent electrowinning stages. For example,

as illustrated in FIG. 3, preferably a lean electrolyte stream 20

108 is directed from the first electrowinning circuit 1070 to

pressure leaching step 1031.

The residence time for pressure leaching generally

depends on a number offactors, including the composition of

the copper-containing feed stream, its particle size, and the 25

operating pressure and temperature of the pressure leaching

vessel. In one aspect of an exemplary embodiment of the

invention, the residence time for the pressure leaching of

chalcopyrite ranges from about 30 to about 180 minutes,

more preferably from about 60 to about 150 minutes, and 30

most preferably on the order of about 80 to about 120 minutes.

In accordance with an exemplary aspect of the present

invention, medium temperature pressure leaching of stream

103 is performed in the presence of a dispersing agent 127. 35

Suitable dispersing agents useful in accordance with this

aspect ofthe present invention include, for example, organic

compounds such as lignin derivatives, such as, for example,

calcium and sodium lignosulfonates, tannin compounds,

such as, for example, quebracho, orthophenylene diamine 40

(OPD), alkyl sulfonates, such as, for example, sodium alkylbenzene

sulfonates, and combinations ofthe above. Dispersing

agent 127 may be any compound that resists degradation

in the temperature range of medium temperature pressure

leaching (i.e., from about 1400 C. to about 1800 C.) long 45

enough to disperse the elemental sulfur produced during the

medium temperature pressure leaching process and that

achieves the desired result of preventing elemental sulfur

from passivating copper values, which may reduce copper

extraction. Dispersing agent 127 may be introduced to the 50

pressure leaching vessel in an amount and/or at a concentration

sufficient to achieve the desired result. In one aspect ofan

exemplary embodiment ofthe invention, favorable results are

achievable during pressure leaching of chalcopyrite using

calcium lignosulfonate in an amount of about 2 to about 20 55

kilograms per tonne, and more preferably in an amount of

about 4 to about 12 kilograms per tonne; and more preferably

in an amount of about 6 to about 10 kilograms per tonne of

chalcopyrite concentrate.

In another aspect of the present invention, the copper- 60

containing solution is conditioned for electrowinning through

one or more chemical and/or physical processing steps. In

much the same way that the copper-containing material feed

stream is conditioned for processing in accordance with

above-described aspects ofthe invention, the copper-contain- 65

ing solution intended to be utilized in the electrowinning

circuit of the present invention is conditioned to adjust the

composition, component concentrations, volume, temperature,

and/or other physical and/or chemical parameters to

desired values. Generally, a properly conditioned coppercontaining

solution will contain a relatively high concentration

of copper in an acid solution and will contain relatively

few impurities. Preferably, the conditions of copper-containing

solution entering the electrowinning circuit are kept at a

constant level to enhance the quality and nniformity of the

cathode copper product.

In an exemplary aspect of the invention, conditioning of a

copper-containing solution for electrowinning begins by

adjusting certain physical parameters of the product slurry

from the previous processing step. In an exemplary embodiment

ofthe invention wherein the previous processing step is

pressure leaching, it is desirable to reduce the temperature

and pressure ofthe product slurry.An exemplary method ofso

adjusting the temperature and pressure characteristics of the

preferred product slurry is atmospheric flashing.

Thus, in accordance with an exemplary aspect of the

embodiment illustrated in FIG. 1, product slurry 104 from

pressure leaching vessel 1031 is flashed in an atmospheric

flash tank 1040 or other suitable atmospheric system to

release pressure and to evaporatively cool the product slurry

104 through the release of steam to form a flashed product

slurry 105. Flashed product slurry 105 preferably has a temperature

ranging from about 900 C. to about 101 0 c., a copper

concentration of from about 40 to about 120 grams/liter, and

an acid concentration of from about 10 to about 60 grams/

liter. In one aspect ofthe invention, however, flashed product

slurry 105 also contains a particulate solid residue containing,

for example, the iron oxide by-product of pressure leaching,

elemental sulfur, precious metals and other components that

are nndesirable for a feed stream to an electrowinning circuit.

Thus, in accordance with the same principles discussed

above, it is desirable to subject the flashed product slurry to a

solid-liquid separation process, such that the liquid portion of

the slurry-the desired copper-containing solution-preferably

is separated from the solid portion of the slurry, which

may be subjected to further processing.

Referring again to FIG. 1, in the illustrated embodiment of

the invention flashed product slurry 105 is directed to a solidliquid

separation stage 1050, such as a CCD circuit 1051. In

an alternative embodiment ofthe invention, solid-liquid separation

stage 1050 may comprise, for example, a thickener or

a filter. A variety of factors, such as the process material

balance, environmental regulations, residue composition,

economic considerations, and the like, may affect the decision

whether to employ a CCD circuit, a thickener, a filter, or

other suitable device in solid-liquid separation stage 1050. In

one aspect of an exemplary embodiment of the invention,

CCD circuit 1051 uses conventional countercurrent washing

ofthe residue stream with wash water 113 to recover leached

copper to the copper-containing solution product and to minimize

the amount of soluble copper advancing to either precious

metal recovery processes or residue disposal. Preferably,

large washratios are used to enhance the effectiveness of

solid-liquid separation stage 1050-that is, relatively large

amounts ofwash water 113 are added to the residue in CCD

circuit 1051. Preferably, the solution portion of the residue

slurry stream is diluted by wash water 113 in CCD circuit

1051 to a copper concentration of from about 5 to about 200

parts per million (ppm) in the solution portion of residue

stream 114. In accordance with one aspect of an exemplary

embodiment of the invention, addition of a chemical reagent

to solid-liquid separation stage 1050 may be desirable to

remove deleterious constituents from the process stream. For

example, a polyethylene oxide may be added to effectuate

US 7,476,308 B2

13 14

Cathode half-reaction: Cu2

++2e---""CUO

2CUS04+2H20~2CuC+2H2S04+02

Turning again to FIG. 1, in an exemplary embodiment the

invention, product stream 107 is directed from electrolyte

recycle tank 1060 to an electrowinning circuit 1070, which

contains one or more conventional electrowinning cells. It

should be understood, however, that any method and/or apparatus

currently known or hereinafter devised suitable for the

electrowinning of copper from acid solution, in accordance

with the above-referenced reactions or otherwise, is within

the scope of the present invention

In accordance with an exemplary aspect of the invention,

electrowinning circuit 1070 yields a cathode copper product

116, optionally, an off gas stream 117, and a relatively large

volume of copper-containing acid, herein designated as lean

electrolyte streams 108 and 115. As discussed above, in the

embodiment illustrated in FIG. 1, lean electrolyte stream 108

may be directed to copper precipitation stage 1010 via lean

electrolyte stream 125 (which, as discussed hereinbelow, may

comprise a portion oflean electrolyte stream 123 from second

electrowinning circuit 1090), and lean electrolyte stream 115

Referring again to FIG. 1, preferably, the copper composition

of product stream 107 is maintained substantially constant.

While product stream 107 may contain a copper concentration

up to the copper solubility limit under the

prevailing conditions, preferably product stream 107 has a

copper concentration ofabout 15 to about 80 grams/liter, and

more preferably ofabout 20 to about 60 grams/liter, and often

above 30 grams/liter. In one aspect of an exemplary embodiment

ofthe invention, control valves are positioned on each of

10 the pipelines feeding lean electrolyte stream 115 and coppercontaining

solution stream 106 to electrolyte recycle tank

1060 to facilitate blending control within the tank

With reference to FIG. 1, copper from the product stream

107 is suitably electrowon to yield a pure, cathode copper

15 product. In accordance with various aspects ofthe invention,

a process is provided wherein, upon proper conditioning of a

copper-containing solution, a high quality, uniformly-plated

cathode copper product 116 may be realized without subjecting

the copper-containing solution to a solvent/solution

20 extraction process prior to entering the electrowinning circuit.

As those skilled in the art are aware, a variety of methods

and apparatus are available for the electrowinning of copper

and other metal values, any ofwhich may be suitable for use

25 in accordance with the present invention, provided the requisite

process parameters for the chosen method or apparatus

are satisfied. For the sake of convenience and a broad understanding

of the present invention, an electrowinning circuit

useful in connection with various embodiments ofthe inven-

30 tion may comprise an electrowinning circuit, constructed and

configured to operate in a conventional manner. The electrowinning

circuit may include electrowinning cells constructed

as elongated rectangular tanks containing suspended

parallel flat cathodes ofcopper alternating with flat anodes of

35 lead alloy, arranged perpendicular to the long axis ofthe tank.

A copper-bearing leach solution may be provided to the tank,

for example at one end, to flow perpendicular to the plane of

the parallel anodes and cathodes, and copper can be deposited

at the cathode and water electrolyzed to form oxygen and

40 protons at the anode with the application of current.

The primary electro chemical reactions for electrowinning

of copper from acid solution are believed to be as follows:

removal of silica by precipitation, or other flocculants and/or

coagulants might be utilized to remove other undesirable

species from the process stream. One such suitable chemical

reagent is POLYOXTM WSR-301, available from Dow

Chemical.

Depending on its composition, residue stream 114 from

solid-liquid separation stage 1050 may be impounded, disposed

of, or subjected to further processing, such as, for

example, precious metal recovery. For example, if residue

stream 114 contains economically significant amounts of

gold, silver, and/or other precious metals, it may be desirable

to recover this gold fraction through a cyanidation process or

other suitable recovery process now known or hereafter

devised. If gold or other precious metals are to be recovered

from residue stream 114 by cyanidation techniques, the content

ofimpurities in the stream, such as elemental sulfur, iron

precipitates, unreacted copper minerals, acid, and soluble

copper and soluble impurities, is preferably minimized Such

materials may promote high reagent consumption in the cyanidation

process and thus increase the expense ofthe precious

metal recovery operation. As mentioned above, it is therefore

preferable to use a large amount ofwash water or other diluent

during the solid-liquid separation process to maintain low

copper and acid levels in the solids-containing residue stream

in an attempt to optimize the conditions for subsequent precious

metal recovery.

As previously noted, careful control ofthe conditions of a

copper-containing solution entering an electrowinning circuit-

especially maintenance ofa substantially constant copper

composition---can enhance the quality of the electrowon

copper by, among other things, enabling even plating of copper

on the cathode and avoidance of surface porosity in the

cathode copper, which degrades the copper product and thus

may diminish its economic value. In accordance with this

aspect of the invention, such process control can be accomplished

using any of a variety of techniques and equipment

configurations, so long as the chosen system and/or method

maintains a sufficiently constant feed stream to the electrowinning

circuit.

Referring again to FIG. 1, in an exemplary aspect of the

invention, copper-containing solution stream circuit 106

from solid-liquid separation stage 1050 is sent to an electrolyte

recycle tank 1060. Electrolyte recycle tank 1060 suitably

facilitates process control for first electrowinning circuit 45

1070, as will be discussed in greater detail below. Coppercontaining

solution stream 106, which generally contains

from about 40 to about 120 grams/liter of copper and from

about 10 to about 60 grams/liter acid, is preferably blended

with a lean electrolyte stream 115 in electrolyte recycle tank 50

1060 at a ratio suitable to yield a product stream 107, the

conditions ofwhich may be controlled to optimize the resultant

product of first electrowinning circuit 1070.

Referring briefly to an alternative embodiment of the

invention illustrated in FIG. 2, an additional lean electrolyte 55

stream 205 may be blended with lean electrolyte stream 115

and copper-containing solution stream 106 in electrolyte

recycle tank 1060 to produce product stream 107 in accordance

with the process control principles discussed in connection

with the embodiment illustrated in FIG. 1. In one 60

aspect ofthis alternative embodiment, lean electrolyte stream

205 preferably has a composition similar to that oflean electrolyte

stream 115. Further, as discussed above, other streams

may be introduced to electrolyte recycle tank 1060 for blending,

such as, for example, PLS stream 203 (FIG. 2) or a 65

portion oflean electrolyte stream 123 from second electrowinning

circuit 1090 (FIG. 3).

US 7,476,308 B2

15 16

The invention claimed is:

1. A method of recovering copper from a metal-bearing

material, comprising the steps of:

(a) providing a feed stream containing copper-containing

material and acid;

(b) separating at least a portion of said copper-containing

material from said acid in said feed stream to yield a

copper-containing feed stream comprising a copperbearing

material;

leaching to yield a product slurry comprising a

metal-bearing solution and a residue;

(d) conditioning the product slurry through one or more

chemical or physical conditioning steps to yield a copper-

containing solution suitable for electrowinning;

(e) electrowinning copper from the copper-containing

solution in a first electrowinning stage to produce copper

cathode and a first stage lean electrolyte stream, without

subjecting the copper-containing solution to solvent/solution

extraction;

(f) electrowinning copper from said first stage lean electrolyte

stream in a second electrowinning stage to produce

copper cathode and a second stage lean electrolyte

stream, without subjecting said first stage lean electrolyte

stream to solvent/solution extraction; and

(g) recycling at least a portion of said first stage lean electrolyte

stream to said pressure leaching step.

2. The method ofclaim 1, wherein said step of providing a

feed stream comprising a metal-bearing material comprises

providing a feed stream comprising a copper-bearing sulfide

ore, concentrate, or precipitate.

3. The method ofclaim 1, wherein said step of providing a

feed stream comprising a metal-bearing material comprises

providing a feed stream comprising at least one of chalcopyrite,

chalcocite, bornite, covellite, digenite, and enargite, or

mixtures or combinations thereof.

tank 1080, electrolyte recycle tank 1060, and/or to copper

precipitation stage 1010. Those skilled in the art will appreciate

the ability to effectively manage stream flow control to

other streams and operations of the invention. Although not

illustrated as such in FIGS. 1 and 3, at least a portion oflean

electrolyte stream 123 may optionally be directed for further

processing in accordance with a process such as that illustrated

in FIG. 2.

The present invention has been described above with ref-

10 erence to a number of exemplary embodiments. It should be

appreciated that the particular embodiments shown and

described herein are illustrative of the invention and its best

mode and are not intended to limit in any way the scope ofthe

invention as set forth in the claims. Those skilled in the art

15 having read this disclosure will recognize that changes and

modifications may be made to the exemplary embodiments

without departing from the scope ofthe present invention. For

example, although reference has been made throughout to

copper, it is intended that the invention also be applicable to

20 the recovery ofother metals from metal-containing materials.

Further, although certain preferred aspects of the invention,

such as techniques and apparatus for conditioning process

streams and for precipitation of copper, for example, are

described herein in tenns of exemplary embodiments, such

25 aspects of the invention may be achieved, through any number

of suitable means now known or hereafter devised.

Accordingly, these and other changes or modifications are

intended to be included within the scope ofthe present invention,

as expressed in the following claims.

is directed to electrolyte recycle tank 1060.As those skilled in

the art are aware, it may be preferable to regulate the flow

amount, flow direction or other aspects ofthe lean electrolyte

streams directed from electrowinning circuit 1070 to further

maximize the efficiency of the described invention.

In accordance with an exemplary aspect of an alternative

preferred embodiment, a portion of lean electrolyte stream

108 is directed to pressure leaching feed stage 1031. Lean

electrolyte stream 108 may exhibit copper concentration sufficient

to combine with pressure leaching feed stream 103 to

further maximize the operational and economic efficiency of

the present invention. In addition, as briefly noted above,

stream 108 may provide suitable cooling liquid to pressure

leaching step 1031.

Again referring to FIG. 3, in an exemplary alternative to an

aspect of the invention, all of copper-containing stream 106

may not be directed to electrolyte recycle tank 1060. To

achieve optimum operational and economic efficiency in

accordance with various embodiments of the present invention,

it may be desirable to direct a portion ofcopper-containing

feed stream 106 to operations other than electrowinning.

As depicted in FIG. 3, a portion of copper-containing stream

106 may be directed to pressure leaching feed stream 103.

Moreover, a portion ofcopper-containing stream 106 may be

directed to precipitation stage 1010.

Referring back again to FIG. 1, electrolyte stream 120 from

first electrowinning circuit 1070-which comprises at least a

portion of the lean electrolyte produced in first electrowinning

circuit 1070 that is not recycled to other process operations-

is subjected to further processing in a second elec- 30

trowinning circuit 1090. In an exemplary aspect of the

embodiment, lean electrolyte stream 120 is sent to electrolyte

recycle tank 1080. Electrolyte recycle tank 1080 suitably

facilitates process control for electrowinning circuit 1090, as

will be discussed in greater detail below. Lean electrolyte 35

stream 120, which generally contains from about 20 to about

40 grams/liter of copper and from about 100 to about 180

grams/liter ofacid, is preferably blended with lean electrolyte

stream 123 from second electrowinning circuit in electrolyte

recycle tank 1080 at a ratio suitable to yield a product stream 40

121, the conditions of which may be chosen to optimize the

resultant product of electrowinning circuit 1090.

With reference to FIG. 1, copper from the product stream

121 is suitably electrowon to yield a pure, cathode copper

product. In accordance with various aspects ofthe invention, 45

a process is provided wherein, upon proper conditioning of a

copper-containing solution, a high quality, unifonnly-plated

cathode copper product 122 may be realized without subjecting

the copper-containing solution to a solvent/solution

extraction process prior to entering the electrowinning cir- 50

cuit.

In furtherance of an exemplary aspect of the embodiment,

second electrowinning circuit 1090 yields a cathode copper

product 122, offgas, and a remainder volume of copper-containing

acid, designated in FIG. 1 as lean electrolyte stream 55

123. In accordance with one exemplary embodiment, at least

a portion oflean electrolyte stream 123 is directed to electrolyte

recycle tank 1080 in an amount suitable to yield a product

stream 121, the conditions of which may be chosen to optimize

the resultant product of second electrowinning circuit 60

1090. Optionally, a portion oflean electrolyte stream 123 may

be recycled to copper separation stage 1010 via stream 125

(which may also comprise a portion of the lean electrolyte

produced in first electrowinning circuit 1070).

In accordance with various exemplary embodiments ofthe 65

invention as illustrated in FIG. 3, lean electrolyte stream 123

is directed optionally, wholly or in part to electrolyte recycle

US 7,476,308 B2

17 18

containing solution with at least a portion of a copper-containing

electrolyte stream to achieve a copper concentration

of from about IS to about 80 grams/liter in said coppercontaining

solution.

19. The method of claim 1, wherein said conditioning step

comprises subjecting at least a portion of said product slurry

to solid-liquid separation, wherein at least a portion of said

metal-bearing solution is separated from said residue.

20. The method of claim 1, wherein said conditioning step

10 further comprises blending at least a portion of said metalbearing

solution with at least a portion of one or more metalbearing

streams to achieve a desired copper concentration in

said metal-bearing solution.

21. The method of claim 1, wherein said conditioning step

15 further comprises blending at least a portion of said metalbearing

solution with at least a portion of one or more metalbearing

streams to achieve a copper concentration of from

about IS to about 80 grams/liter in said metal-bearing solution.

22. The method of claim 1, wherein said conditioning step

comprises subjecting at least a portion of said product slurry

to filtration, wherein at least a portion of said metal-bearing

solution is separated from said residue.

23. The method of claim 1, further comprising the step of

25 using a portion ofsaid second stage lean electrolyte stream in

an atmospheric leaching operation.

24. The method of claim 1, further comprising the step of

recycling a portion of said second stage lean electrolyte

stream to said separating step.

25. A method of recovering copper from a metal-bearing

material, comprising the steps of:

(a) providing a feed stream containing copper-containing

material and acid;

(b) separating at least a portion of said copper-containing

material from said acid in said feed stream to yield a

copper-containing feed stream comprising a copperbearing

material;

leaching to yield a product slurry comprising a

metal-bearing solution and a residue;

(d) conditioning the product slurry through one or more

chemical or physical conditioning steps to yield a copper-

containing solution suitable for electrowinning;

(e) electrowinning copper from the copper-containing

solution in a first electrowinning stage to produce copper

cathode and a first stage lean electrolyte stream, without

subjecting the copper-containing solution to solvent/solution

extraction;

(f) recycling a portion of said first stage lean electrolyte

stream to said pressure leaching step;

(g) electrowinning copper from a portion of said first stage

lean electrolyte stream in a second electrowinning stage

to produce copper cathode and a second stage lean electrolyte

stream, without subjecting said first stage lean

electrolyte stream to solvent/solution extraction;

(h) recycling a portion of said second stage lean electrolyte

stream to said pressure leaching step or said separating

step.

26. The method ofclaim 25, wherein said step ofproviding

60 a feed stream comprising a metal-bearing material comprises

providing a feed stream comprising a copper-bearing sulfide

ore, concentrate, or precipitate.

27. The method ofclaim 25, wherein said step ofproviding

a feed stream comprising a metal-bearing material comprises

65 providing a feed stream comprising at least one of chalcopyrite,

chalcocite, bomite, covellite, digenite, and enargite, or

mixtures or combinations thereof.

4. The method ofclaim 3, wherein said step ofproviding a

feed stream comprising a metal-bearing material comprises

providing a feed stream comprising chalcopyrite.

5. The method ofclaim 1, wherein said step ofproviding a

feed stream comprising a metal-bearing material comprises

providing a feed stream comprising a metal-bearing material

and a solution stream comprising copper and acid.

6. The method ofclaim 1, wherein said step ofproviding a

feed stream comprises subjecting said feed stream to controlled,

super-fine grinding, wherein said controlled, superfine

grinding comprises reducing the particle size ofsaid feed

stream such that substantially all ofthe particles in said feed

stream react substantially completely during pressure leaching.

7. The method of claim 6, wherein said step of subjecting

said feed stream to controlled, super-fine grinding comprises

reducing the particle size of said feed stream to a P98 of less

than about 25 microns.

8. The method of claim 6, wherein said step of subjecting

said feed stream to controlled, super-fine grinding comprises 20

reducing the particle size of said feed stream to a P98 offrom

about 10 to about 23 microns.

9. The method of claim 6, wherein said step of subjecting

said feed stream to controlled, super-fine grinding comprises

reducing the particle size of said feed stream to a P98 offrom

about 13 to about IS microns.

10. The method of claim 1, wherein said separating step

comprises reacting at least a portion ofthe copper in a coppercontaining

electrolyte stream to precipitate at least a portion

ofsaid copper in said copper-containing electrolyte stream as 30

copper sulfide in said feed stream.

11. The method of claim 1, wherein said separating step

comprises reacting at least a portion ofthe copper in a coppercontaining

electrolyte stream in the presence of sulfur dioxide,

whereby at least a portion of said copper in said copper- 35

containing electrolyte stream precipitates as copper sulfide in

said feed stream.

12. The method of claim 1, wherein said leaching step

comprises leaching at least a portion of said copper-containing

feed stream in a pressure leaching vessel.

13. The method of claim 1, wherein said leaching step

comprises leaching at least a portion of said copper-containing

feed stream in a pressure leaching vessel at a temperature

of from about 1400 C. about 1800 C. and at a total operating

pressure of from about 50 psi to about 750 psi.

14. The method of claim 13, wherein said leaching step

further comprises injecting oxygen into the pressure leaching

vessel to maintain an oxygen partial pressure in the pressure

leaching vessel of from about 50 psi to about 250 psi.

15. The method of claim 1, wherein said step of pressure 50

leaching said copper-containing feed stream comprises pressure

leaching said copper-containing feed stream in the presence

of a surfactant selected from the group consisting of

lignin derivatives, orthophenylene diamine, alkyl sulfonates,

and mixtures thereof.

16. The method of claim 1, wherein said step of pressure

leaching said copper-containing feed stream comprises pressure

leaching said copper-containing feed stream in the presence

of calcium lignosulfonate.

17. The method of claim 1, wherein said step of pressure

leaching said copper-containing feed stream comprises pressure

leaching said copper-containing feed stream in the presence

of a surfactant in an amount of from about 2 to about 20

kilograms per tonne of concentrate in the copper-containing

feed stream.

18. The method ofclaim 1, wherein said conditioning step

further comprises blending at least a portion of said copperUS

7,476,308 B2

28. The method ofclaim 27, wherein said step ofproviding

a feed stream comprising a metal-bearing material comprises

providing a feed stream comprising chalcopyrite.

29. The method ofclaim 25, wherein said step ofproviding

a feed stream comprising a metal-bearing material comprises

providing a feed stream comprising a metal-bearing material

and a solution stream comprising copper and acid.

30. The method ofclaim 25, wherein said step ofproviding

a feed stream comprises subjecting said feed stream to controlled,

super-fine grinding, wherein said controlled, superfine

grinding comprises reducing the particle size ofsaid feed

stream such that substantially all ofthe particles in said feed

stream react substantially completely during pressure leaching.

31. The method ofclaim 30, wherein said step ofsubjecting

said feed stream to controlled, super-fine grinding comprises

reducing the particle size of said feed stream to a P98 of less

than about 25 microns.

32. The method ofclaim 30, wherein said step ofsubjecting

said feed stream to controlled, super-fine grinding comprises

reducing the particle size of said feed stream to a P98 offrom

about 10 to about 23 microns.

33. The method ofclaim 30, wherein said step ofsubjecting

said feed stream to controlled, super-fine grinding comprises

reducing the particle size of said feed stream to a P98 offrom

about 13 to about IS microns.

34. The method of claim 25, wherein said separating step

comprises reacting at least a portion ofthe copper in a coppercontaining

electrolyte stream to precipitate at least a portion

ofsaid copper in said copper-containing electrolyte stream as

copper sulfide in said feed stream.

35. The method of claim 25, wherein said separating step

comprises reacting at least a portion ofthe copper in a coppercontaining

electrolyte stream in the presence of sulfur dioxide,

whereby at least a portion of said copper in said coppercontaining

electrolyte stream precipitates as copper sulfide in

said feed stream.

36. The method ofclaim 25, wherein said copper-containing

feed stream from said separating step comprises an acidbearing

solution component and a copper-containing solids

component, and further comprising the step ofsubjecting said

copper-containing feed stream to solid-liquid separation,

whereby at least a portion of the acid-bearing solution component

is removed from said copper-containing feed stream.

37. The method ofclaim 36, further comprising the step of

utilizing at least a portion of the acid-bearing solution component

removed from said copper-containing feed stream in a

leaching operation.

38. The method ofclaim 36, further comprising the step of

utilizing at least a portion of the acid-bearing solution component

removed from said copper-containing feed stream in

an atmospheric leaching operation.

39. The method of claim 25, wherein said leaching step

comprises leaching at least a portion of said copper-containing

feed stream in a pressure leaching vessel at a temperature

of from about 1400 C. about 1800 C. and at a total operating

pressure of from about 50 psi to about 750 psi.

40. The method of claim 39, wherein said leaching step

further comprises injecting oxygen into the pressure leaching

vessel to maintain an oxygen partial pressure in the pressure

leaching vessel of from about 50 psi to about 250 psi.

41. The method of claim 25, wherein said step of pressure

leaching said copper-containing feed stream comprises pressure

leaching said copper-containing feed stream in the pres10

ence of a surfactant selected from the group consisting of

lignin derivatives, orthophenylene diamine, alkyl sulfonates,

and mixtures thereof.

42. The method of claim 25, wherein said step of pressure

leaching said copper-containing feed stream comprises pres15

sure leaching said copper-containing feed stream in the presence

of calcium lignosulfonate.

43. The method of claim 25, wherein said step of pressure

leaching said copper-containing feed stream comprises pressure

leaching said copper-containing feed stream in the pres20

ence ofa surfactant in an amount offrom about 2 to about 20

kilograms per tonne of concentrate in the copper-containing

feed stream.

44. The method ofclaim 25, wherein said conditioning step

further comprises blending at least a portion of said copper-

25 containing solution with at least a portion of a copper-containing

electrolyte stream to achieve a copper concentration

of from about IS to about 80 grams/liter in said coppercontaining

solution.

45. The method ofclaim 25, wherein said conditioning step

30 comprises subjecting at least a portion of said product slurry

to solid-liquid separation, wherein at least a portion of said

metal-bearing solution is separated from said residue.

46. The method ofclaim 45, further comprising the step of

recycling a portion of the metal-bearing solution separated

35 from the residue to said pressure leaching step.

47. The method ofclaim 45, wherein said conditioning step

further comprises blending at least a portion of said metalbearing

solution with at least a portion of one or more metalbearing

streams to achieve a desired copper concentration in

40 said metal-bearing solution.

48. The method ofclaim 45, wherein said conditioning step

further comprises blending at least a portion of said metalbearing

solution with at least a portion of one or more metalbearing

streams to achieve a copper concentration of from

45 about IS to about 80 grams/liter in said metal-bearing solution.

49. The method ofclaim 25, wherein said conditioning step

comprises subjecting at least a portion of said product slurry

to filtration, wherein at least a portion of said metal-bearing

50 solution is separated from said residue.

50. The method ofclaim 25, further comprising the step of

recycling a portion of said product slurry to said pressure

leaching step.

* * * * *