6,451,089 Process for direct electrowinning of copper

Patent Number/Link:

111111111111111111111111111111111111111111111111111111111111111111111111111

US006451089Bl

(12) United States Patent

Marsden et al.

(10) Patent No.:

(45) Date of Patent:

US 6,451,089 Bl

Sep.17,2002

(54) PROCESS FOR DIRECT ELECTROWINNING FOREIGN PATENT DOCUMENTS

OF COPPER

AU 0219785 * 12/1958

Notice:

L.W. Beckstead, et aI., "Acid Ferric Sulfate Leaching of

Attritor-Ground Chalcopyrite Concentrate," vol. 11, Extractive

Metallurgy of Copper, Ch. 31, pp. 611-32, Published by

American Institute of Mining, Metallurgical, and Petroleum

Engineers, Inc. 1976.*

Evans, et aI., "International Symposium of Hydrometallurgy,"

Mar. 1, 1973, 2 pages.

Duyesteyn, et aI., "The Escondida Process for Copper Concentrates,"

1998, No Month.

King, et aI., "The Total Pressure Oxidation of Copper

Concentrates," 1993, No Month.

King, l.A., "Autoclaving of Copper Concentrates," paper

from COPPER 95, vol. III: Electrorefining and Hydrometallurgy

of Copper, International Conference held in Santiago,

Chile, Nov. 1995.

Mackis, V. N., "Direct Acid Pressure Leaching of Chalcocite

Concentrate," vol. 19, No.2, Feb. 1967.

(List continued on next page.)

Primary Examiner-Roy King

Assistant Examiner-Tima McGuthry-Banks

(74) Attorney, Agent, or Firm---8nell & Wilmer

(75)

(73)

( * )

(21)

(22)

(51)

(52)

(58)

(56)

Inventors: John O. Marsden, Phoenix; Robert E.

Brewer, Safford; Joanna M.

Robertson, Thatcher, all of AZ (US);

David R. Baughman, Golden, CO

(US); Philip Thompson, West Valley

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

Lakewood; Christel M. A. Bemelmans,

Indian Hills, both of CO (US)

Assignee: Phelps Dodge Corporation, Phoenix,

AZ (US)

Subject to any disclaimer, the term of this

patent is extended or adjusted under 35

U.S.c. 154(b) by 0 days.

Appl. No.: 09/912,921

Filed: Jul. 25, 2001

Int. CI? . ... ... ..... ... ... .... C22B 3/06

U.S. Cl. 75/744; 205/367; 423/34

Field of Search 75/744; 205/367;

423/34

References Cited (57)

OTHER PUBLICATIONS

ABSTRACT

U.S. PATENT DOCUMENTS

3,260,593 A 7/1966 Zimmerley et al.

3,528,784 A 9/1970 Green

3,637,371 A 1/1972 Mackiw et al.

3,656,888 A 4/1972 Barry et al.

3,669,651 A 6/1972 Spedden et al.

3,868,440 A 2/1975 Lindblad et al.

3,896,208 A 7/1975 Dubeck et al.

3,917,519 A * 11/1975 Fisher et al. 205/584

3,949,051 A * 4/1976 Pawlek et al. 241/16

3,958,985 A 5/1976 Anderson

3,961,028 A 6/1976 Parker et al.

3,962,402 A 6/1976 Touro

3,985,553 A 10/1976 Kunda et al.

3,991,159 A 11/1976 Queneau et al.

4,017,309 A 4/1977 Johnson

(List continued on next page.)

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 extraction techniques or

apparatus. A process for recovering copper from a coppercontaining

ore generally includes the steps of providing a

feed stream containing communicated 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 conditional steps, and electowinning

copper directly from the copper-containing solution,

without subjecting the copper-containing solution to solvent

extraction.

23 Claims, 2 Drawing Sheets

US 6,451,089 Bl

Page 2

U.S. PATENT DOCUMENTS

4,020,106 A

4,028,462 A

4,029,733 A

4,039,405 A

4,039,406 A

4,046,851 A

4,069,119 A

4,091,070 A

4,093,526 A *

4,120,935 A

4,150,976 A

4,157,912 A

4,165,362 A

4,256,553 A

4,266,972 A

4,272,341 A

4,338,168 A

4,405,569 A

4,415,540 A

4,442,072 A

4,507,268 A

4,571,264 A

4,619,814 A

4,775,413 A

4,814,007 A

4,875,935 A

4,880,607 A

4,892,715 A

4,895,597 A

4,971,662 A

4,992,200 A

5,028,259 A

5,059,403 A

5,073,354 A

5,176,802 A

5,223,024 A

5,232,491 A *

5,316,567 A *

5,356,457 A

5,670,035 A

5,698,170 A

5,730,776 A *

4/1977

6/1977

8/1977

9/1977

1/1978

5/1978

6/1978

10/1978

4/1979

6/1979

8/1979

3/1981

5/1981

6/1981

7/1982

9/1983

11/1983

4/1984

3/1985

2/1986

10/1986

10/1988

3/1989

10/1989

11/1989

1/1990

11/1990

2/1991

7/1991

10/1991

12/1991

1/1993

6/1993

8/1993

5/1994

10/1994

9/1997

12/1997

3/1998

Ackerley et al.

Domic et al.

Faugeras et al.

Wong

Stanley et al.

Subramanian et al.

Wong

Riggs et al.

Blanco et al. 205/584

Fountain et al.

Dain

Weir et al.

Reynolds

Beczek et al.

Redondo-Abad et al.

Lamb

Stanley et al.

Dienstbach

Wilkomirsky et al.

Baglin et al.

Kordosky et al.

Weier et al.

Salter et al.

Horton et al.

Lin et al.

Gross et al.

Horton et al.

Horton

Lin et al.

Sawyer et al.

Lin et al.

Chen

Fuller et al.

Duyvesteyn et al.

Jones

Corrans et al. 423/27

Jones 423/24

Alvarez et al.

Virnig et al.

King

Collins et al. 423/27

5,770,170 A 6/1998 Collins et al.

5,849,172 A 12/1998 Allen et al.

5,895,633 A 4/1999 King

5,902,474 A 5/1999 Jones

5,917,116 A 6/1999 Johnson et al.

5,989,311 A 11/1999 Han et al.

OTHER PUBLICATIONS

Hirsch, H. E., "Leaching of Metal Sulphides," Patents, UK,

No. 1,598,454, 7 pages, No Month.

Chimielewski, T., "Pressure Leaching of a Sulphide Copper

Concentrate with Simultaneous Regeneration of the Leaching

Agent," Hydrometallurgy, vol. 13, No.1, 1984, pp.

63-72, No Month.

Dannenberg, R. 0., "Recovery of Cobalt and Copper From

Complex Sulfide Concentrates," Government Report, 20

pages, Report No. BM RI 9138, U.S. Dept. of the Interior,

1987, No Month.

Berezowsky, R.M.G.S., "The Commercial Status of Pressure

Leaching Technology," JOM, vol. 43, No.2, 1991, pp.

9-15, No Month.

Hacki, R. P, "Effect of Sulfur-Dispersing Surfactants on the

Oxygen Pressure Leaching of Chalcopyrite," paper from

COPPER 95, vol. III, pp. 559-577, Met Soc of CIM, Nov.

1995.

Hackl, R.P, "Passivation of Chalcopyrite During Oxidative

Leaching in Sulfate Media," Hydrometallurgy, vol. 39,

1995, pp. 25-48.

Jim A. King, et aI., paper entitled: "The Total Pressure

Oxidation of Copper Concentrates," vol. 1, Fundamental

Aspects, 1993, No Month.

Dreisinger, D. B., "Total Pressure Oxidation of EI Indio Ore

and Concentrate," COPPER 1999, Fourth International Conference,

Phoenix, Arizona, USA, Oct. 1999.

Richmond, G. D., "The Commissioning and Operation of a

Copper Sulphide Pressure Oxidation Leach Process at Mt.

Gordon," Alta Copper 1999: Copper Sulphides Symposium

& Copper Hydrometallurgy Forum, Gold Coast, Queensland,

Australia Conference, 1999, No Month.

* cited by examiner

u.s. Patent Sep.17,2002 Sheet 1 of 2 US 6,451,089 Bl

108 1010 r101

Cu SEPARATION

109

102

THICKENER

1 1021

1020f:I

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

110

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

103

PRESSURE LEACHING

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

1030 f :- - - - - - - - - - - - - - - - - - - - - - - - - - - - -

118

104

119

1040

FLASH

105

------------1 114

113

\ : 1051

I CCD

1050 f :- - - - - - - - - - - - - - - - - - - - - - - - - - - - -

106

1060

ELECTROLYTE RECYCLE TANK

108 1070

107

ELECTROWINNING

116

FIG. 1

u.s. Patent Sep.17,2002 Sheet 2 of 2 US 6,451,089 Bl

SUBGRADE ORE

201

EVAP.

ELECTROWINNING

208

206

203

204

204 I

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

205 207 1

~_ - - - - - - - - - - - - - - - - - - - - - - - - - - - 1

1 I

2030

: 203

:_-~--------------------

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

I 2020

~~----------------------

ELECTROLYTE

RECYCLE TANK

107 115

1070

ELECTROWINNING

116

FIG. 2

US 6,451,089 B1

An effective and efficient method to recover copper from

copper-containing materials, especially copper from copper

sulfides such as chalcopyrite and chalcocite, that enables

high copper recovery to be achieved at a reduced cost over

5 conventional processing techniques would be advantageous.

SUMMARY OF THE INVENTION

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 coppercontaining

material includes obtaining a copper-containing

solution from, for example, a pressure leaching system, and

15 then appropriately conditioning the copper-containing solution

for electrowinning. In a preferred aspect of the

invention, the composition of the copper-containing solution

is similar to the composition of the electrolyte produced by

a solvent extraction circuit, for example, with respect to acid

20 and copper concentrations. In accordance with the various

embodiments of the present invention, however, the coppercontaining

solution is not subjected to solvent extraction.

In accordance with an exemplary embodiment of the

25 present invention, a process for recovering copper from a

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

providing a feed stream containing copper-containing material;

(ii) subjecting the copper-containing feed stream to

atmospheric leaching or pressure leaching to yield a copper-

30 containing solution; (iii) conditioning the copper-containing

solution through one or more chemical or physical conditioning

steps; and (iv) electrowinning copper directly from

the copper-containing solution, without subjecting the

copper-containing solution to solvent extraction. As used

35 herein, the term "pressure leaching" shall refer to a metal

recovery process in which material is contacted with an

acidic solution and oxygen under conditions of elevated

temperature and pressure.

In one aspect of a preferred embodiment of the invention,

40 one or more processing steps are used in order to separate

copper from the acid in a recycled portion of the lean

electrolyte from the direct electrowinning process, thus

enabling the rejection of a portion of the acid component

from the process circuit without rejecting a significant

45 portion 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 the invention, a copper pre-

50 cipitation step may be utilized to precipitate solubilized

copper from a lean electrolyte stream onto the surfaces of

solid particles in a copper-containing material stream in

advance of the pressure leaching step, thus separating the

copper from the acid solution.

In an aspect of another embodiment of the invention, a

recycle circuit is used intermediate to the leaching and

electrowinning steps to facilitate control of the composition

of copper-containing solution entering the electrowinning

stage, and to thus enhance the quality of the copper recov-

60 ered therefrom.

In accordance with various preferred 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

65 extraction, the present invention enables lower-cost recovery

of copper and eliminates the expenses associated with

solvent extraction, such as specialized reagents, process

BACKGROUND OF THE INVENTION

PROCESS FOR DIRECT ELECTROWINNING

OF COPPER

FIELD OF THE INVENTION

Hydrometallurgical treatment of copper containing

materials, such as copper ores, concentrates, and other

copper-bearing materials, has been well established for

many years. Currently, there exist many creative approaches

to the hydrometallurgical treatment of these materials;

however, common to almost all of the processes either now

known or under development is the use of solvent extraction

and electrowinning (SX-EW) for solution purification and

copper recovery. Although SX-EW is not without its

drawbacks, the proven success in the copper SX-EW field

has made this approach standard for production of high

quality copper products.

The traditional hydrometallurgical process for copper

recovery involves first leaching copper-containing material

with an acidic solution, either atmospherically or under

conditions of elevated temperature and pressure. The resultant

process stream-the so-called pregnant leach solutionis

recovered, and in a solvent extraction (or solution

extraction, as it is sometimes called) stage, is mixed with an

organic solvent (i.e., an extractant), which selectively

removes the copper from the pregnant leach solution. The

copper-loaded extractant 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 stream is highly concentrated and relatively

pure, and typically is processed into high quality

copper cathode in an electrowinning circuit.

In general, electrowinning of copper consists of the electrolytic

deposition (sometimes called "plating") of copper

onto a cathode and the evolution of oxygen at an anode. In

a simple design of an exemplary electrowinning unit, a set

of cathodes and anodes are set in a reaction chamber

containing the copper-containing electrolyte. When the unit

is energized, copper ions are reduced onto the cathode (i.e.,

plated). Plating of copper typically occurs on copper starter

sheets or stainless steel blanks. Anodes are quasi-inert in the

electrolyte and provide a surface for oxygen evolution. The

copper plates produced by the electrowinning unit can be in

excess of 99.99 percent pure.

Purification of copper from the pregnant leach solution by

solvent extraction has proven to be a successful means of 55

providing a concentrated copper solution suitable for electrowinning

of highly pure copper metal. Direct electrowinning

of copper-that is, plating of copper directly from the

pregnant leach solution without the intervening step of

purification by solvent 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.

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 for producing cathode copper

without the use of solvent/solution extraction, ion exchange

of copper, or related processes to refine and concentrate the 10

copper-bearing solution.

US 6,451,089 B1

apparatus and equipment, and energy resources.

Furthermore, in accordance with one preferred aspect of the

invention, careful control of the composition of the coppercontaining

solution entering the electrowinning circuit

enables production of high quality, uniformly-plated cathode

copper.

These and other advantages of a process according to

various aspects of the 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.

BRIEF DESCRIPTION OF IRE DRAWING

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 of the

present invention; and

FIG. 2 illustrates a flow diagram of a copper recovery

process in accordance with an alternative embodiment of the

present invention.

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 utilize a conventional atmospheric

or pressure leaching/solvent extraction/electrowinning process

sequence may, in many instances, be easily retrofitted

to exploit the many commercial benefits the present invention

provides.

In one aspect of a preferred embodiment of the invention,

the relatively large amount of 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 of the

copper is removed from the acid stream. It is generally

economically advantageous to utilize this generated acid

stream in some way, rather than to neutralize or dispose of

it. Thus, as discussed in greater detail hereinbelow, the

present invention may find particular utility in combination

with conventional 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 one aspect of an exemplary embodiment of the present

invention, a feed stream containing copper-containing material

is provided for processing. In accordance with the

various embodiments of present invention, the coppercontaining

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 of copper

oxides, copper sulfides or other copper minerals, and the

copper-containing 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 of the present invention prove

especially advantageous in connection with the recovery of

copper from copper sulfide ores, such as, for example,

5 chalcopyrite (CuFeS2 ), chalcocite (Cu2 S), bornite

(CusFeS4), and covellite (CuS).

The feed stream of copper-containing material can be

provided in any number of ways, such that the conditions of

the feed stream are suitable for the chosen processing

10 methods. For example, feed stream conditions such as

particle size, composition, and component concentrations

can affect the overall effectiveness and efficiency of downstream

processing operations, such as, for example, atmospheric

leaching or pressure leaching.

15 In accordance with a preferred aspect of the invention, the

particle size of the copper-containing feed material is

reduced to facilitate fluid transport and to optimize the

processing steps of atmospheric or pressure leaching and

subsequent metal recovery processes. A variety of acceptable

techniques and devices for reducing the particle size of

20 the copper-containing material are currently available, such

as ball mills, tower mills, ultrafine grinding mills, attrition

mills, stirred mills, horizontal mills and the like, and additional

techniques may later be developed that may achieve

the desired result of increasing the surface area of the

25 material to be processed. With regard to one aspect of a

preferred embodiment of the invention, such a result is

desired because the reaction rate during leaching generally

increases as the surface area of the copper-containing material

increases, such that increasing the fineness of the

30 copper-containing material before subjecting the material

stream to pressure leaching generally will allow for more

moderate temperature and pressure conditions to be

employed within the pressure leaching vessel, and may

reduce the residence time of the oxidation reaction during

35 pressure leaching.

FIG. 1 illustrates an exemplary embodiment of the present

invention wherein copper is the metal to be recovered from

a copper-containing material, such as a sulfide ore. In

preparation for froth flotation, the copper-containing mate-

40 rial feed stream is ground to a particle size suitable to

liberate mineral-bearing particles from gangue materials. In

one aspect of a preferred embodiment, copper-containing

material is communicated using, for example, a ball mill,

and subjected to conventional flotation techniques and prac-

45 tices. In one aspect of the present invention, the coppercontaining

material has a PSO of less than about 250

microns, preferably a PSO from about 75 to about 150

microns, with the optimal size depending on flotation and

liberation characteristics. The product from flotation prefer-

50 ably has a PSO of less than about 150 microns, and more

preferably a PSO on the order of from about 5 to about 75

microns. Other particle sizes and distributions that facilitate

fluid transport and subsequent processing may, however, be

utilized.

55 In another aspect of a preferred embodiment of the

present invention, the communicated copper-containing

material is combined with a liquid to form a coppercontaining

material stream 101. Preferably, the liquid comprises

water, but any suitable liquid may be employed, such

60 as, for example, raffinate, pregnant leach solution, or lean

electrolyte. For example, a portion of lean electrolyte stream

108 from the direct electrowinning process may be combined

with communicated copper-containing material to

form copper-containing material stream 101 (not shown in

65 FIG. 1).

The combination of the liquid with the copper-containing

material can be accomplished using anyone or more of a

US 6,451,089 B1

5 6

CuFeS2+Cu+2~Fe+2+2CuS (possible side reaction)

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 a preferred aspect of the invention, copper

separation stage 1010 is 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 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 119 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 of the processing vessel and the

composition of the copper-containing material, but typically

ranges from about thirty (30) minutes to about 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

the fraction of solid particles in the feed stream and the total

volume of the feed stream. Thus, these or other parameters,

such as, for example, temperature, pressure, viscosity,

density, composition, and the like, may be suitably

addressed. Although these parameters mayor may not be

significant to the overall efficiency of processing operations

downstream in all cases, these parameters can affect equipment

size and material specifications, energy requirements,

and other important aspects of process design. Thus, calculated

adjustment of these stream parameters in advance of

example, in the embodiment illustrated in FIG. 1, lean

electrolyte stream 108 may comprise a recycled acidic

copper sulfate stream generated during an electrowinning

operation. Other streams, however, preferably copper-rich

5 streams, may also be used. In one aspect of this embodiment

of the invention, lean electrolyte stream 108 has an acid

concentration of from about 20 to about 200 gramslliter,

preferably from about 30 to about 150 gramslliter, and most

preferably from about 50 to about 120 gramslliter. In a

10 further aspect of this embodiment of the invention, lean

electrolyte stream 108 has a copper concentration of from

about 20 to about 55 grams/liter, preferably from about 25

to about 50 gramslliter, and most preferably from about 30

to about 45 gramslliter. In copper precipitation stage 1010,

15 copper from lean electrolyte stream 108 precipitates to form

a desired copper-rich concentrate. Preferably, precipitation

is carried out such that the copper from the lean electrolyte

precipitates, at least in part, onto the surface of unreacted

copper-containing material particles within stream 101 in

20 the form of copper sulfides, such as, for example, eus.

While not wishing to be bound by any particular theory, the

chemical reaction during this exemplary copper precipitation

step-wherein, for example, the copper-containing

material is primarily chalcopyrite-is believed to be as

25 follows:

variety of techniques and apparatus, such as, for example,

in-line blending or using a mixing tank or other suitable

vessel. In accordance with a preferred aspect of this

embodiment, the material stream is concentrated with the

copper-containing material being on the order less than

about 50 percent by weight of the stream, and preferably

about 40 percent by weight of the stream. Other concentrations

that are suitable for transport and subsequent processing

may, however, be used.

In accordance with one aspect of the present invention, it

is desirable to separate the copper in a recycled stream of

lean electrolyte from electrowinning from the acid, and also

to reduce the amount of contaminants in the portion of the

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 metal

contaminants and other soluble impurities from the coppercontaining

feed stream and the recycled lean electrolyte

stream. Any number of conventional or hereafter devised

separation processes and techniques may be useful to

achieve the separation of copper from acid in the feed

stream. For example, separation processes and/or techniques

such as precipitation, low temperature pressure leaching,

acid solvent 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 a preferred embodiment of the

invention contributes to providing a resultant acid stream

that contains a relatively small fraction of copper, which can 30

be used for leaching, pH control, or other applications.

Moreover, utilization of a separation process in accordance

with this aspect of the invention may be particularly advantageous

in that it may enable contaminants from the unrefined

copper-containing material stream to be removed from 35

the copper-containing material stream and incorporated into

the resultant acid stream. Because the resultant acid stream

is preferably removed from the metal recovery process

altogether and utilized in remote operations, disposed of, or

neutralized, the contaminants contained therein are likewise 40

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 contaminants,

particularly metal contaminants, typically have a deleterious

effect on the effectiveness and efficiency of the desired metal 45

recovery process. For example, metal contaminants and

other impurities in the process stream, if not carefully

controlled and/or minimized, can contribute to diminished

physical and/or chemical properties in the cathode copper

produced by electrowinning, and can thus degrade the 50

copper product and diminish its economic value.

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

of a preferred embodiment of the invention, coppercontaining

material stream 101 is subjected to a separation,

such as, for example, a precipitation step, which, in this 55

exemplary process, serves to precipitate solubilized copper

from a recycled lean electrolyte stream onto the surfaces of

solid particles in the copper-containing material stream. As

discussed in detail above, this aspect offers an important

advantage in that it enables recovery of copper from a lean 60

electrolyte stream that otherwise may have been lost or

would have required additional processing to recover, potentially

resulting in significant economic benefits.

In this preferred aspect of the invention, the precipitation

step involves the copper-containing material stream being 65

combined with a sulfur dioxide (S02) stream 109 and a lean

electrolyte stream 108 in a suitable processing vessel. For

US 6,451,089 B1

7 8

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

a resultant product stream suitable for electrowinning in an

electrowinning circuit.

In accordance with a further aspect of this embodiment of

5 the present invention, as previously briefly mentioned, acid

stream 110 advantageously may remove impurities from the

process, for example the electrowinning process. Such

impurities include, without limitation, iron, aluminum,

magnesium, sodium, potassium and the like, often present as

10 sulfates. In the absence of removal, such impurities may

accumulate to deleterious levels, and, as such negatively

impact production efficiencies and product (e.g. copper

cathode) quality. The presence of such impurities in acid

stream 110 generally does not negatively impact the afore-

15 mentioned handling of acid stream 110.

In accordance with one aspect of a preferred embodiment

of the invention illustrated in FIG. 2, solvent extraction unit

2020 purifies copper-bearing PLS stream 203 from the heap

leach in two unit operations-an extraction operation, which

20 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 in which a copper

selective reagent (i.e., the extractant) is dissolved. When the

solutions are contacted, the organic extractant chemically

25 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

30 more leaching operations to be reloaded with copper from

the ore in the atmospheric leach to form the PLS. The

organic stream passes on to the second unit operation of the

solvent extraction process, the stripping operation. In the

stripping operation, the organic stream is contacted with a

35 strongly acidic electrolyte. This acidic solution "strips" the

copper from the extractant, leaving the 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" solution.

40 Aqueous stream 204 is processed in electrowinning plant

2030 to yield cathode copper 207 and a copper-containing

lean electrolyte stream 208, which, in one aspect of a

preferred embodiment of the invention, may be recycled in

part to solvent extraction unit 2020.

In accordance with one alternative aspect of the invention,

aqueous stream 204 may not be subjected to electrowinning

immediately after leaving the solvent extraction unit, but

may instead be blended with other copper-containing process

streams, and the resultant stream then sent to an

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

aqueous stream 204 (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

form a resultant product stream suitable for electrowinning

55 in an electrowinning circuit 1070. In such cases the stripping

solutions used in solvent extraction 2020 likely will be

comprised of spent electrolyte from electrowinning circuit

1070.

If efiluent acid stream 110 is not used as a by-product

60 reagent or otherwise utilized, the acid may be neutralized

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

processing tailings) or a neutralizing agent, such as limestone

or lime. Neutralizing with acid-consuming gangue can

be relatively inexpensive, as the neutralizing reagent is

65 essentially free. On the other hand, neutralizing with limestone

or lime may be less desirable economically, as both

these reagents will incur cost. Nevertheless, should neutralcomplex

or resource-intensive processing stages can positively

affect the economic efficiency of the 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 of the embodiment of the invention illustrated

in FIG. 1, product stream 102, which generally

contains covellite/chalcopyrite particles and acid, contains a

large fraction of acid generated in pressure leaching stage

1030 and electrowinning stage 1070, and the acid generated

in copper separation stage 1010.

In accordance with a preferred 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, in accordance with an exemplary embodiment

of the invention, product stream 102 is sent to a solid-liquid

separation circuit 1020. In one aspect of a preferred embodiment

of the invention, solid-liquid separation circuit 1020

preferably includes a wash thickener circuit 1021 comprising

multiple thickener stages arranged in a counter-current

decantation (CCD) configuration that effectuate separation

of a substantial amount of the acid in the product stream

from the copper-containing solid particles therein. In the

illustrated embodiment, the underflow of thickener circuit

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 efiluent acid stream 110 may be utilized,

processed, neutralized, impounded, and/or disposed of in a

variety of ways, the appropriate choice of which 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, an atmospheric leaching

operation, where acid is required to leach copper oxide or

sulfide minerals. Such a leaching operation may be a heap

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

similar operation. Acid is consumed in these operations

through reaction with acid-consuming constituents in the

ore.

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

(FIG. 1) is sent to a conventional atmospheric leach opera- 45

tion 2010. In accordance with one aspect of a preferred

embodiment of the invention, atmospheric leach operation

2010 is a conventional acid-consuming heap leach

operation, wherein a subgrade ore 201 is contacted with acid

stream 110 and, optionally, other process streams, such as

raffinate stream 206 from downstream solvent extraction

unit 2020. In heap leach operation 2010, 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) stream

203. In conventional atmospheric leach operations, PLS

stream 203 is sent to a solvent extraction unit, such as

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

concentration and relatively pure copper sulfate solution

suitable for electrowinning. In accordance with an alternative

aspect of the present invention illustrated in FIG. 2, PLS

stream 203 may not be subjected to solvent extraction, 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 PLS

stream 203 (broken line) may be blended with coppercontaining

solution stream 106 and lean electrolyte stream

US 6,451,089 B1

ization be desired, any method for acid neutralization now

known or hereafter devised may be employed.

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

thickener circuit 1021, pressure leaching feed stream 103 in

this preferred embodiment of the invention, has a composition

of 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 (i.e.,

the wash ratio).

In a further aspect of the present invention, the conditioned

copper-containing feed stream preferably is subjected

to a suitable process, such as pressure leaching, to produce

a product slurry 104, which comprises a copper-containing

solution and a residue 114. The process may be selected as

desired, but, in general, enables production of a coppercontaining

solution that exhibits copper and acid concentrations

similar to an electrolyte stream resulting from a solvent

extraction circuit-that is, the copper-containing solution

preferably is suitable for processing in an electrowinning

circuit. Any suitable technique or combination of techniques

that yields an appropriate copper-containing solution without

employing solvent extraction techniques may be used. In

a preferred embodiment of the invention, as illustrated in

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

pressure leaching stage 1030 to yield a 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 contain the process

components at the desired temperature and pressure conditions

for the requisite processing residence time. In a preferred

embodiment, a pressure leaching vessel 1031 is

employed for this purpose. Pressure leaching vessel 1031 is

preferably a multi-compartment, agitated vessel.

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:

If desired, conditions during pressure leaching can be

controlled such that a portion of the sulfide sulfur contained

in the feed stream is converted to elemental sulfur instead of

sulfate. The fraction of chalcopyrite and covellite that form

sulfur instead of sulfate are believed to react according to the

following equations:

2CuS+2H2S04+02~2Cu+2+2S04-2+2H20+2S0

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 main-

tained 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

another embodiment of the invention, the temperature of

pressure leaching vessel 1031 is advantageously maintained

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

of from about 210° C. to about 225° C. Furthermore, the

total operating pressure in pressure leaching vessel 1031 is

necessarily superatmospheric, ranging from about 50 to

about 750 psi. In accordance with one aspect of one embodi-

10 ment of the invention, the pressure is advantageously in the

range of between from about 200 to about 450 psi, and more

preferably from about 250 to about 400 psi. In accordance

with another embodiment of the invention, the pressure is

advantageously maintained between from about 400 or

15 about 500 to about 700 psi.

During pressure leaching, it is generally desirable to inject

oxygen into the pressure leaching vessel. In one aspect of a

preferred embodiment of the invention, during pressure

leaching in pressure leaching vessel 1031, sufficient oxygen

20 112 is injected into the vessel to maintain an oxygen partial

pressure in pressure leaching vessel 1031 of from about 50

to about 200 psi, preferably from about 75 to about 150 psi,

and most preferably from about 100 to about 125 psi.

Because pressure leaching of many metal sulfides is a

25 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

30 pressure leaching. Cooling liquid 111 is preferably process

water, but can be any suitable cooling fluid from within the

refining process or from an outside source. In a preferred

embodiment of the invention, a sufficient amount of cooling

liquid 111 is added to pressure leaching vessel 1031 to yield

35 a solids content in the product slurry 104 ranging from about

3 to about 15 percent solids by weight.

The residence time for pressure leaching generally

depends on a number of factors, including the composition

of the copper-containing feed stream and the operating

40 pressure and temperature of the pressure leaching vessel. In

one aspect of the invention, the residence time for pressure

leaching ranges from about thirty minutes to about three

hours.

In another aspect of the present invention, the copper-

45 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 of the invention, the

50 copper-containing 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 condi-

55 tioned copper-containing solution will contain a relatively

high concentration of copper in an acid solution and will

contain few impurities. Preferably, the conditions of coppercontaining

solution entering the electrowinning circuit are

kept at a constant level to enhance the quality and uniformity

60 of the cathode copper product.

In a preferred 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 a preferred embodi-

65 ment of the invention wherein the previous processing step

is pressure leaching, it is desirable to reduce the temperature

and pressure of the product slurry. A preferred method of so

US 6,451,089 B1

adjusting the temperature and pressure characteristics of the

preferred product slurry is atmospheric flashing.

Thus, in accordance with a preferred aspect of the

embodiment illustrated in FIG. 1, product slurry 104 from

pressure leaching vessel 1031 is flashed in an atmospheric 5

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 90° C. to about 101°C., a 10

copper concentration of from about 40 to about 75 grams/

liter, and an acid concentration of from about 20 to about

100 gramslliter. In one aspect of the invention, however,

flashed product slurry 105 also contains a particulate solid

residue containing, for example, the iron oxide by-product

of pressure leaching, other by-products, precious metals and 15

other components that are undesirable 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 20

copper-containing solution-is separated from the solid portion

of the slurry-the undesired residue.

Referring again to FIG. 1, in the illustrated embodiment

of the invention flashed product slurry 105 is directed to a

solid-liquid separation stage 1050, such as a CCD circuit 25

1051. In an alternative embodiment of the invention, solidliquid

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 30

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 a preferred embodiment

of the invention, CCD circuit 1051 uses conventional

countercurrent washing of the residue stream with wash 35

water 113 to recover leached copper to the coppercontaining

solution product and to minimize the amount of

soluble copper advancing to either precious metal recovery

processes or residue disposal. Preferably, large wash ratios

are utilized to enhance the effectiveness of solid-liquid 40

separation stage 1050 -that is, relatively large amounts of

wash 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 45

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

114.

Depending on its composition, residue stream 114 from

liquid/solid separation stage 1050 may be impounded, disposed

of, or subjected to further processing, such as, for 50

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. If gold or other precious 55

metals are to be recovered from residue stream 114 by

cyanidation techniques, the content of contaminants in the

stream, such as elemental sulfur, amorphous iron

precipitates, and unreacted copper minerals, is preferably

minimized. Such materials may promote high reagent con- 60

sumption in the cyanidation process and thus increase the

expense of the precious metal recovery operation. As mentioned

above, it is therefore preferable to use a large amount

of wash water or other diluent during the solid-liquid

separation process to maintain low copper and acid levels in 65

the solids-containing residue stream in an attempt to optimize

the conditions for subsequent precious metal recovery.

As previously noted, careful control of the conditions of

a copper-containing solution entering an electrowinning

circuit---especially maintenance of a 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 a preferred aspect of the

invention, copper-containing solution stream 106 from

solid-liquid separation stage 1050 is sent to an electrolyte

recycle tank 1060. Electrolyte recycle tank 1060 suitably

facilitates process control for electrowinning circuit 1070, as

will be discussed in greater detail below. Copper-containing

solution stream 106, which generally contains from about 40

to about 70 gramslliter of copper and from about 15 to about

100 grams/liter acid, is preferably blended with a lean

electrolyte stream 115 in electrolyte recycle tank 1060 at a

ratio suitable to yield a product stream 107, the conditions

of which may be chosen to optimize the resultant product of

electrowinning circuit 1070.

Referring briefly to an alternative embodiment of the

invention illustrated in FIG. 2, an additional lean electrolyte

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

aspect of this alternative embodiment, lean electrolyte

stream 205 preferably has a composition similar to that of

lean 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).

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 level under the

prevailing conditions, preferably product stream 107 has a

copper concentration of about 20 to about 80 gramslliter, and

more preferably of about 30 to about 60 gramslliter, and

often above 40 gramslliter. In one aspect of an exemplary

embodiment of the invention, control valves are positioned

on each of the pipelines feeding lean electrolyte stream 115

and copper-containing 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

product. In accordance with the various aspects of the

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 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 of which may be suitable for use

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

US 6,451,089 B1

13 14

What is claimed is:

1. A method for recovering copper from a coppercontaining

material, consisting essentially of:

providing a feed stream comprising comminuted coppercontaining

material;

reacting at least a portion of said feed stream with at least

a portion of a copper-containing lean electrolyte steam

in an acidic environment to yield a precipitation product

stream comprising a solid copper-bearing precipitate;

subjecting said precipitation product stream to solidliquid

separation to yield a solution stream comprising

acid and an inlet stream comprising copper-containing

material and the remaining acid;

optionally, conditioning at least a portion of said inlet

steam to alter at least one physical parameter selected

from the group consisting of: temperature, pressure,

volume, solids content, composition, and density;

subjecting at least a portion of said inlet stream to pressure

leaching to yield a product slurry comprising a coppercontaining

solution and a residue;

optionally, reducing the temperature and pressure of said

product slurry in a flash tank;

separating at least a portion of said copper-containing

solution from said residue using a physical separation

technique;

optionally, blending at least a portion of said coppercontaining

solution with at least a portion of one or

more copper-containing streams to yield a coppercontaining

product stream having a desired copper

concentration;

electrowinning copper from said copper-containing solution

or said copper-containing product stream to yield

cathode copper and a copper-containing lean electrolyte

stream;

optionally, recycling at least a portion of said coppercontaining

lean electrolyte stream from said electrowinning

step to said reacting step;

optionally, recycling at least a portion of said coppercontaining

lean electrolyte stream from said electrowinning

step to said blending step.

2. The method of claim 1, wherein said step of providing

a feed stream comprising communicated copper-containing

45 material comprises providing a feed stream comprising

communicated copper sulfide ore or concentrate.

3. The method of claim 1, wherein said step of providing

a feed stream comprising communicated copper-containing

material comprises providing a feed stream comprising

50 communicated chalcopyrite.

4. The method of claim 1, wherein said reacting step

comprises reacting at least a portion of said copper in said

copper-containing lean electrolyte stream in the presence of

sulfur dioxide, whereby at least a portion of said copper in

55 said copper-containing lean electrolyte stream precipitates

as copper sulfide onto at least a portion of the coppercontaining

material in said feed stream.

5. The method of claim 1, wherein said step of subjecting

at least a portion of said inlet stream to pressure leaching

60 comprises subjecting at least a portion of said inlet stream to

pressure leaching in a pressure leaching vessel al a temperature

of from about 100 to about 2500 C. and at a pressure of

from about 50 to about 750 psi.

6. The method of claim 5, wherein said leaching step

65 further comprises injecting oxygen into the pressure leaching

vessel to maintain an oxygen partial pressure in the

pressure leaching vessel of from about 50 to about 200 psi.

Cathode half-reaction: eu2++2e---..,..Cu°

broad understanding of the present invention, an electrowinning

circuit useful in connection with various embodiments

of the invention may comprise an electrowinning

circuit, constructed and configured to operate in a conventional

manner. The electrowinning circuit may include elec- 5

trowinning cells constructed as elongated rectangular tanks

containing suspended parallel flat cathodes of copper alternating

with flat anodes of lead alloy, arranged perpendicular

to the long axis of the tank. A copper-bearing leach solution

may be provided to the tank, for example at one end, to flow 10

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 protons at the anode

with the application of current. As with conventional electrowinning

cells, the rate at which direct current can be 15

passed through the cell is effectively limited by the rate at

which copper ions can pass from the solution to the cathode

surface. This rate, called the limiting current density, is a

function of factors such as copper concentration, diffusion

coefficient of copper, cell configuration, and level of agita- 20

tion of the aqueous solution.

The general chemical process for electrowinning of copper

from acid solution is believed to be as follows:

Turning again to FIG. 1, in a preferred embodiment the 30

invention, product stream 107 is directed from electrolyte

recycle tank 1060 to an electrowinning circuit 1070, which

contains one or more conventional electrowinning cells.

In accordance with a preferred aspect of the invention,

electrowinning circuit 1070 yields a cathode copper product 35

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

illustrated embodiment of the invention, lean electrolyte

streams 108 and 115 are directed to copper precipitation 40

stage 1010 and electrolyte recycle tank 1060, respectively.

Lean electrolyte streams 108 and 115 generally have a lower

copper concentration than product stream 107, but typically

have a copper concentration of less than about 40 grams/

liter.

The present invention has been described above with

reference 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 of

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

art having read this disclosure will recognize that changes

and modifications may be made to the exemplary embodiments

without departing from the scope of the present

invention. For example, although reference has been made

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

applicable to the recovery of other metals from metalcontaining

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 terms of exemplary

embodiments, such 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

of the present invention, as expressed in the following

claims.

US 6,451,089 B1

7. The method of claim 1, wherein said blending step

comprises blending at least a portion of said coppercontaining

solution with at least a portion of one or more

copper-containing streams to achieve a copper concentration

of from about 20 to about 75 gramslliter in said copper- 5

containing solution.

8. The method of claim 1, wherein said blending step

comprises blending at least a portion of said coppercontaining

solution with at least a portion of a coppercontaining

electrolyte stream to achieve a copper concen- 10

tration of from about 20 to about 75 grams/liter in said

copper-containing solution.

9. A method for recovering copper from a coppercontaining

material, comprising the steps of:

(a) providing a feed stream comprising a copper- 15

containing material, wherein said copper-containing

material comprises a at least one of a copper sulfide ore,

a copper sulfide concentrate, or other copper-bearing

material;

(b) reacting at least a portion of said feed stream with at 20

least a portion of a copper-containing electrolyte stream

in an acidic environment to yield an inlet stream

comprising a solid copper precipitate and acid;

stream using a solid-liquid separation device;

(d) leaching at least a portion of said inlet stream in an

oxidizing environment at a temperature of from about

100 to about 2500 C. and a pressure of from about 50

to about 750 psi to yield a product slurry comprising a 30

copper-containing solution and a residue;

(e) conditioning said product slurry without the use of

solvent extraction techniques to yield a coppercontaining

product stream suitable for electrowinning,

wherein said conditioning step comprises separating at 35

least a portion of said copper-containing solution from

said residue using a solid-liquid separation technique

and blending at least a portion of said coppercontaining

solution with at least a portion of a coppercontaining

electrolyte stream at a blending ratio suit- 40

able to yield a copper-containing product stream having

a copper concentration of from about 20 to about 75

grams/liter;

(f) electrowinning copper from said copper-containing

product stream to produce cathode copper and a 45

copper-containing lean electrolyte stream.

10. The method of claim 9 further comprising the step of:

(g) recycling at least a portion of said copper-containing

lean electrolyte stream produced in electrowinning step

(f) to reacting step (b). 50

11. The method of claim 9 further comprising the step of:

(g) recycling at least a portion of said copper-containing

lean electrolyte stream produced in electrowinning step

(f) to blending step (e). 55

12. The method of claim 9 further comprising the steps of:

(g) recycling at least a portion of said copper-containing

lean electrolyte stream produced in electrowinning step

(f) to reacting step (b); and

(h) recycling at least a portion of said copper-containing 60

lean electrolyte stream produced in electrowinning step

(f) to blending step (e).

13. The method of claim 9, wherein said step of providing

a feed stream comprising copper-containing material comprises

providing a feed stream comprising copper sulfide ore 65

or concentrate having a P80 of from about 5 to about 75

microns, and wherein said leaching step comprises leaching

at least a portion of said inlet stream in an oxidizing

environment at a temperature of from about 140 to about

1800 C. and at a pressure of from about 200 to about 450 psi.

14. The method of claim 9, wherein said step of providing

a feed stream comprising copper-containing material comprises

providing a feed stream comprising copper sulfide ore

or concentrate having a P80 of from about 5 to about 75

microns, and wherein said leaching step comprises leaching

at least a portion of said inlet stream in an oxidizing

environment at a temperature of from about 200 to about

2350 C. and at a pressure of from about 400 to about 700 psi.

15. The method of claim 9, wherein said reacting step

comprises reacting at least a portion of the copper from said

copper-containing lean electrolyte stream with sulfur

dioxide, whereby at least a portion of said copper in said

copper-containing lean electrolyte stream precipitates as

copper sulfide onto at least a portion of the coppercontaining

material in said feed stream.

16. The method of claim 9, wherein said conditioning step

further comprises controlling the copper concentration of

said copper-containing product stream such that the copper

concentration of said copper-containing product stream

entering said electrowinning circuit is maintained at a level

of about 40 grams/liter.

17. The method of claim 9, wherein said step of reducing

the amount of acid in said inlet stream further comprises

reducing the impurities in said inlet stream.

18. A method for recovering copper from a coppercontaining

material, comprising:

providing a feed stream comprising comminuted coppercontaining

material;

reacting at least a portion of said feed stream with at least

a portion of a copper-containing lean electrolyte stream

in an acidic environment to yield a precipitation product

stream comprising a solid copper-bearing precipitate;

subjecting at least a portion of said precipitation product

stream to pressure leaching to yield a coppercontaining

solution and a residue;

electrowinning copper from said copper-containing solution

to yield cathode copper and a copper-containing

lean electrolyte strewn.

19. The method of claim 18, wherein said step of providing

a feed stream comprising comminuted coppercontaining

material comprises providing a feed stream comprising

comminuted copper sulfide ore or concentrate.

20. The method of claim 18, wherein said step of providing

a feed stream comprising comminuted coppercontaining

material comprises providing a feed stream comprising

comminuted chalcopyrite.

21. The method of claim 18, wherein said step of subjecting

at least a portion of said inlet stream to pressure

leaching comprises subjecting at least a portion of said inlet

stream to pressure leaching in a pressure leaching vessel at

a temperature of from about 100 to about 2500 C. and at a

pressure of from about 50 to about 750 psi.

22. The method of claim 21, 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 to about 200 psi.

23. The method of claim 18, further comprising the step

of recycling at least a portion of said copper-containing lean

electrolyte stream from said electrowinning step to said

reacting step.

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