8,003,064 Controlled copper leach recovery circuit

Patent Number/Link:

111111111111111111111111111111111111111111111111111111111111111111111111111

US008003064B2

(12) United States Patent

Savage et al.

(10) Patent No.:

(45) Date of Patent:

US 8,003,064 B2

Aug. 23, 2011

( *) Notice:

(54) CONTROLLED COPPER LEACH RECOVERY

CIRCUIT

(75) Inventors: Barbara J. Savage, Silver City, NM

(US); David G. Meadows, Phoenix, AZ

(US); Wayne W. Hazen, Lakewood, CO

(US)

(73) Assignee: Freeport-McMoran Corporation,

Phoenix, AZ (US)

Subject to any disclaimer, the term ofthis

patent is extended or adjusted under 35

U.S.c. 154(b) by 936 days.

(21) Appl. No.: 11/856,605

6,107,523 A

6,177,055 Bl

6,242,625 Bl

6,350,354 Bl

6,395,062 B2

6,432,167 Bl

6,596,053 B2

6,599,414 Bl

6,702,872 Bl

6,726,887 Bl

6,733,688 Bl

7,166,144 B2

7,169,371 B2

7,214,256 B2

7,309,474 B2

7,390,468 B2

2005/0031512 Al

2006/0088458 Al

2006/0117908 Al

8/2000 Virnig et al.

112001 Virnig et al.

6/2001 Kordosky

2/2002 Neuman et al.

5/2002 Olafson et al.

8/2002 Virnig et al.

7/2003 Virnig et al.

3/2004 Virnig et al.

4/2004 Sugarman

5/2004 Sugarman et al.

112007 Hein et al.

112007 Jones

5/2007 Kordosky et al.

12/2007 Soderstrom

6/2008 Pekkala et al.

2/2005 Kordosky et al.

4/2006 Kordosky et al.

6/2006 Virnig et al.

US 2009/0074639 Al

(22) Filed:

(65)

Sep. 17, 2007

Prior Publication Data

Mar. 19,2009

FOREIGN PATENT DOCUMENTS

W00015857 3/2000

WO 2006/041695 4/2006

OTHER PUBLICATIONS

Primary Examiner - Steven Bos

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

International Search Report and Written Opinion from corresponding

PCT Application No. PCTIUS2008/075037 dated Dec. 10,2008.

International Preliminary Report on Patentability for corresponding

Int'I Application No. PCTIUS08/075037 dated Apr. 1,2010.

(51) Int. Cl.

C21B 15/00 (2006.01)

(52) U.S. Cl. 423/24; 205/560; 205/568; 205/580;

205/589; 205/604; 75/722

(58) Field of Classification Search 423/24;

205/560,568,580, 589, 604; 75/722

See application file for complete search history.

(57) ABSTRACT

(56) References Cited

U.S. PATENT DOCUMENTS

1,841,437 A 111932 Greenawalt

4,582,689 A 4/1986 Kordosky

4,666,512 A 5/1987 Hansen et al.

4,957,714 A 9/1990 Olafson et al.

5,470,552 A 1111995 Kordosky et al.

5,632,963 A 5/1997 Schwab et aI.

5,908,605 A 6/1999 Virnig et aI.

5,919,674 A 7/1999 Tunley

5,976,218 A 1111999 Virnig et aI.

The present invention relates generally to a process for controlled

leaching and sequential recovery oftwo or more metals

from metal-bearing materials. In one exemplary embodiment,

recovery of metals from a leached metal-bearing

material is controlled and improved by providing a high grade

pregnant leach solution ("HGPLS") and a low grade pregnant

leach solution ("LGPLS") to a single solution extraction plant

comprising at least two solution extractor units, at least two

stripping units, and, optionally, at least one wash stage.

25 Claims, 4 Drawing Sheets

u.s. Patent Aug. 23, 2011 Sheet 1 of 4

100

US 8,003,064 B2

PREPARATION OF METAL 250

BEARING MATERIAL

REACTIVE PROCESSING STEP

CONDITIONING STEP

202

203

104 ~105

SOLUTION EXTRACTION STEP 252

PRIMARY METAL RECOVERY

106 107

SECONDARY METAL RECOVERY

207

FIG. 1

u.s. Patent Aug. 23, 2011 Sheet 2 of 4 US 8,003,064 B2

305

304

SOLUTION EXTRACTION PLANT

300

100

CONTROLLED GRINDING

(OPTIONAL)

101 302

LEACHING

102

FLASHING (OPTIONAL)

103

200

285

202

3031---------"---~f_---.L!~

204

307

ADDITIONAL EXEMPLARY

LEACHING PROCESSES

FIG.2A

276

205

ELECTROLYTE RECYCLE TANK

108

253

ELECTROWINNING

208

FIG. 28

402

7Jl

•

~=~

104

High grade

Pregnant Leach I )

Solution . I HIGH GRADE SOLUTION I ) •

FIG. 3

rFJ =('

(..'D...

(.H

o....

,j;o,.

(.H

........

rJl

QO -==w -=0'1

~=N

401

210

--.2. 277

1-----·------------, )

STRIPPING UNIT (OPTIONAL): Rich •

I I

L. - - - - - - - - - - - - - - - - - - - Electrolyte

400

306

105 305

Wash water

Lean

Electrolyte

Low grade

Pregnant Leach I )~

Solution . I LOW GRADE SOLUTION I. •

EXTRACTION UNIT

STRIPPING UNIT

Rich

Electrolyte

212

r------------------~,

I .1 ORGANIC WASH (OPTIONAL) : •

~ - - - - - - - - - - - - - - - - - - - I Reject Water

High grade

Pregnant Leach

Solution

High grade

raffinate

Low grade

Pregnant Leach

Solution

Low grade

raffinate

Lean

Electrolyte

Rich

Electrolyte

7J).

•

~=~

V 104 --./304 --./105 --../282 V 306 --./277

......,...209 Additional ......,...213 V 211 Additional '-./214 '-./210 V210

High Grade Serial Low Grade Serial

Solution Solution Solution Solution Stripping Unit Stripping Unit

Extractor Unit Extractor Unit ~ Extractor Unit ~O Extractor Unit (High Grade) (Low Grade) ~1

402

~ Loaded Organic

FIG. 4

(.H

........

rFJ =('

(..'D...

,j;o,.

o....

,j;o,.

rJl

QO -==w -=0'1

~=N

US 8,003,064 B2

SUMMARY OF THE INVENTION

However, under these current leaching and solution extraction

processes, large concentrations of soluble metal and

metal precipitate can be lost in the metal-depleted, acidcontaining

aqueous phase raffinate solutions. These losses

lead to inefficiencies and low overall process yields. Additionally,

these high metal concentrations in the raffinate make

recovery ofsecondary metals costly and possibly impractical.

Accordingly, a process circuit for controlling the concentration

of metal, especially copper, in the raffinate solution

10 which is the feed for the subsequent recovery of secondary

metals without negatively affecting the primary metal recovery

circuit would be advantageous.

FIELD OF INVENTION

CONTROLLED COPPER LEACH RECOVERY

CIRCUIT

The present invention relates generally to a process for

controlled leaching and sequential recovery of two or more

metals from metal-bearing materials. In one exemplary

embodiment, recovery of metals from a leached metal-bearing

material is controlled and improved by providing a high

grade pregnant leach solution ("HGPLS") and a low grade

pregnant leach solution ("LGPLS") to a single solution

extraction plant comprising at least two solution extractor

units, at least two stripping units, and, optionally, at least one 15

wash stage.

BRIEF DESCRIPTION OF THE DRAWING

A more complete understanding of the present invention,

however, may best be obtained by referring to the detailed

description when considered in counection with the drawing

figures, wherein like numerals denote like elements and

wherein:

FIG. 1 illustrates a flow diagram of a general metal recovery

process in accordance with the present invention;

FIG. 2A illustrates a flow diagram of an alternate preparation

process in accordance with the present invention;

FIG. 2B illustrates a flow diagram of an exemplary

embodiment of a metal recovery process in accordance with

the present invention;

FIG. 3 illustrates a solution extraction process in accordance

with the present invention; and

The present invention relates generally to a process for

controlled leaching and sequential recovery of two or more

metals from metal-bearing materials. In one exemplary

20 embodiment, recovery of metals from a leached metal-bearing

material is controlled and improved by providing a high

grade pregnant leach solution ("HGPLS") and a low grade

pregnant leach solution ("LGPLS") to a single solution

extraction plant comprising at least two solution extractor

25 units, at least two stripping units, and, optionally, at least one

wash stage.

For example, in accordance with the various exemplary

embodiments of the present invention, the present process

comprises (a) providing a HGPLS to a solution extractor unit

30 within a single solution extraction plant, (b) producing a high

grade raffinate and a metal-loaded organic solution by contacting

the HGPLS with a partially loaded organic solution in

the solution extractor, (c) providing a LGPLS to a different

solution extractor unit within the same solution extraction

35 plant, and (d) producing a low grade raffinate and the partially

loaded organic solution by contacting the LGPLS with a

barren organic flow containing a metal-specific extraction

reagent. Furthermore, in accordance with the various

embodiments of the present invention, the flow rate and

40 reagent concentration ofthe barren organic flow containing a

metal-specific extraction reagent can be altered based on the

incoming metal material quality to maintain a constant concentration

of metal in the low grade raffinate, allowing for

efficient secondary metal recovery, including but not limited

45 to cobalt recovery. In accordance with an exemplary embodiment

of the present invention, the concentration of metal in

the LGPLS may be adjusted by blending a portion of the

LGPLS with the high grade pregnant leach solution so that the

quantity of metal entering the low grade extraction circuit

50 remains substantially constant.

BACKGROUND OF THE INVENTION

Hydrometallurgical treatment of metal-bearing materials,

such as metal ores, metal-bearing concentrates, and other

metal-bearing substances, has been well established for many

years. Moreover, leaching of metal-bearing materials is a

fundamental process utilized to extract metals from metalbearing

materials. In general, the first step in this process is

contacting the metal-bearing material with an aqueous solution

containing a leaching agent or agents which extracts the

metal or metals from the metal-bearing material into solution.

For example, in copper leaching operations, especially copper

from copper minerals, such as chalcopyrite, chalcocite,

covellite, malachite, pseudomalachite, azurite, chrysocolla,

and cuprite, sulfuric acid in an aqueous solution is contacted

with copper-bearing ore. During the leaching process, acid in

the leach solution may be consumed and various soluble

components are dissolved thereby increasing the metal content

of the aqueous solution. Other ions, such as iron may

participate in the leaching of various minerals as these ions

participate in dissolution reactions.

The aqueous leach solution containing the leached metal

can then be treated via a known process referred to as solution

extraction wherein the aqueous leach solution is contacted

with an organic solution comprising a metal-specific extraction

reagent, for example, an aldoxime and/or ketoxime or a

mixture thereof. The metal-specific extraction reagent

extracts the metal from the aqueous phase into the organic

phase. Moreover, during the solution extraction process for

copper and certain other metals, a leaching agent may be

regenerated in the aqueous phase. In the case where sulfuric

acid is the leaching agent, sulfuric acid is regenerated in the

aqueous phase when copper is extracted into the organic

phase by the extraction reagent. Iron ions, which should not

be extracted by the metal-specific extraction reagent, should

be recycled to the leaching step to the maximum extent possible.

In a standard agitation leaching process for copper, fol- 55

lowed by solution extraction, the leach solution is diluted to a

lesser or greater extent with acidified water in conjunction

with the solid-liquid separation process needed to provide a

clarified leach liquor and solid discharge. The diluted clarified

leach solution then undergoes solution extraction 60

wherein copper is removed from, and the sulfuric acid concentration

is increased in, the aqueous phase.A portion ofthis

copper-depleted, acid-containing aqueous phase, now called

the raffinate, may be recycled back to the leaching process,

recycled to the front of the solid-liquid separation process, 65

and/or forwarded to secondary metal extraction processes,

including but not limited to cobalt recovery.

US 8,003,064 B2

3 4

mation, as well as chemical and/or physical conditioning in

preparation step 250 before metal extraction.

Referring again to FIG. 1, in an exemplary embodiment of

the present invention, after metal-bearing material 100 has

been suitably prepared in preparation step 250 for metal

recovery processing, it may be forwarded to a reactive processing

step 202, for example, metal extraction. The reactive

processing step 202 may be any suitable process or reaction

that puts a metal in the metal-bearing material 100 in a con-

10 dition such that it may be subjected to later metal recovery

processing. For example, exemplary suitable processes

include reactive processes that tend to liberate the desired

metal value or values in the metal bearing material 100 from

the metal-bearing material 100. In accordance with a pre-

IS ferred embodiment of the present invention, as described in

greater detail below, reactive processing step 202 may comprise

a leaching process.

In one aspect of an exemplary embodiment of the present

invention, conditioning ofa metal-bearing solution after reac-

20 tive process step 202 begins by adjusting certain physical

parameters in conditioning step 203. For example, as discussed

in some detail herein below, after reactive processing

202 metal-bearing material 100 may undergo reagent additions,

flashing processes, one ormore solid-liquid phase sepa-

25 ration steps including use of filtration systems, counter-current

decantation (CCD) circuits, thickeners, clarifiers, or any

other suitable device for solid-liquid separation, in conditioning

step 203 to prepare the metal solubilized therein for recovery.

Further, referring again to FIG. 1, in an exemplary embodiment

of the present invention, after metal-bearing material

100 has been suitably conditioned in conditioning step(s) 203

it may be forwarded to solution extraction step 252. In accordance

with further aspects ofthis exemplary embodiment, the

35 conditioning step(s) 203 produces a high grade pregnant

leach solution ("HGPLS") 104, comprising high concentrations

of dissolved metal values, and a low grade pregnant

leach solution ("LGPLS") 105, comprising a lower concentration

of dissolved metal values than found in the HGPLS

40 104. In another exemplary embodiment, as discussed in some

detail herein below, the HGPLS 104 and LGPLS 105 may be

produced by separate reactive processing steps and/or separate

conditioning steps.

Regardless ofthe reactive step which produces the HGPLS

45 104 and LGPLS 105, in an exemplary embodiment of the

present invention, at least one HGPLS 104 stream and at least

one LGPLS 105 stream is forwarded to solution extraction

step 252. In accordance with an exemplary embodiment of

the present invention, solution extraction step 204 comprises

50 only one solution extraction plant. For example, in accordance

with an exemplary embodiment of the present invention,

solution extraction plant 204 may comprise multiple

interconnected solution extraction trains within a single solution

extraction plant 204. Generally, in accordance with the

55 various embodiments of the present invention, the single

solution extraction plant 204 is housed in one facility. It

should be understood that this disclosure teaches, inter alia,

efficient and controllable metal solution extraction from more

than two separate pregnant leach solution ("PLS") feed

60 streams containing two or more recoverable metal values in a

single solution extraction plant and that any number of PLS

streams are contemplated herein.

In contrast, the prior art teaches only multiple plant solution

extraction for more than one PLS feed stream. It should

65 be understood that any multiple plant solution extraction

design requires roughly twice the equipment and capital cost

in reference to a single solution extraction plant.

DETAILED DESCRIPTION OF EXEMPLARY

EMBODIMENTS

FIG. 4 illustrates one solution extraction plant for processing

multiple leach solution streams in accordance with an

exemplary embodiment of the present invention.

The detailed description ofexemplary embodiments ofthe

invention herein shows various exemplary embodiments and

the best modes, known to the inventors at this time. These

exemplary embodiments and modes are described in sufficient

detail to enable those skilled in the art to practice the

invention and are not intended to limit the scope, applicability,

or configuration of the invention in any way. Rather, the

following disclosure is intended to teach both the implementation

of the exemplary embodiments and modes and any

equivalent modes or embodiments that are known or obvious

to those of reasonable skill in the art. Additionally, all

included figures are non-limiting illustrations of the exemplary

embodiments and modes, which similarly avail themselves

to any equivalent modes or embodiments that are

known or obvious to those of reasonable skill in the art.

Various embodiments ofthe present invention exhibit significant

advancements over prior art processes, particularly

with regard to metal recovery and process efficiency. Moreover,

existing copper recovery processes that utilize a reactive

process for metal recovery/solution extraction/electrowinning

process sequence may, in many instances, be easily

retrofitted to exploit the many commercial benefits the 30

present invention provides.

Referring to FIG. 1, in accordance with various aspects of

the present invention, a metal-bearing material 100 is provided

for processing. Metal-bearing material 100 may be an

ore, a concentrate, or any other material from which copper

and/or other metal values may be recovered. Metal values

such as, for example, copper, gold, silver, zinc, platinum

group metals, nickel, cobalt, molybdenum, rhenium, uranium,

rare earth metals, and the like, may be recovered from

metal-bearing materials in accordance with various embodiments

of the present invention. The various aspects and

embodiments of the present invention, however, prove especially

advantageous in connection with the recovery of copper

from copper-bearing materials, such as, for example, ores

and/or concentrates containing chalcopyrite (CuFeS2), chalcocite

(Cu2S), bornite (CusFeS4), and covellite (CuS), malachite

(CU2C03 (OH)2)' pseudomalachite (CuS[(OH)2P04]2)'

azurite (CU3(C03MOH)2), chrysocolla ((Cu,Al)2H2Si20s

(OH)4.nH20), cuprite (Cu20), brochanite (CuS04.3Cu

(OH)2), atacamite (Cu2[OH3 Cl]) and other copper-bearing

minerals or materials and mixtures thereof. Thus, metal-bearing

material 100 preferably is a copper ore or concentrate

containing at least one other metal value.

Metal-bearing material 100 may be prepared in preparation

step 250 for metal recovery processing in any manner that

enables the conditions ofmetal-bearing material 100 -such

as, for example, composition and component concentration

-to be suitable for the chosen reactive processing method, as

such conditions may affect the overall effectiveness and efficiency

of metal recovery operations. Desired composition

and component concentration parameters can be achieved

through a variety of chemical and/or physical processing

stages, the choice of which will depend upon the operating

parameters ofthe chosen processing scheme, equipment cost

and material specifications. For example, as discussed in

some detail herein below, metal-bearing material 100 may

undergo combination, flotation, blending, and/or slurry forUS

8,003,064 B2

5 6

(2)

(1)

4CuFeS2+1702+4H20~2Fe203+4Cu2++8H++

8soi-

Thus, in accordance with one aspect of the present invention,

in order to maintain preferable leaching temperature, a

cooling liquid 301 may be introduced into the leaching vessel

At lower temperatures, acid is generally consumed and

elemental sulfur is fonned according to the following reaction:

plated herein and the subject matter of that patent is hereby

incorporated by reference. Preferably, a uniform particle size

distribution is achieved. Additionally, process water 300 is

preferably added to metal-bearing material stream 100 to

bring the percent solids to the optimal pulp density specified

for the controlled grinding unit 200. It should be understood

that a variety ofacceptable techniques and devices for reducing

the particle size of the copper-bearing material are currently

available, such as ball mills, tower mills, grinding

10 mills, attrition mills, stirred mills, horizontal mills and the

like, and additional techniques may later be developed that

may achieve the desired result ofreducing the particle size of

the copper-bearing material to be transported.

Referring again to both FIG. 1 and FIG. 2B, in an exem-

15 plary embodiment ofthe present invention, after metal-bearing

material 100 has been suitably prepared for metal recovery

processing, optionally by controlled grinding 200, and

other physical and/or chemical conditioning processes,

including but not limited to a thickening process, it may be

20 combined with any number ofliquid feed stream, represented

by numerical reference 307, to fonn a metal-bearing inlet

stream 101. Preferably, in an exemplary embodiment of the

present invention, the liquid feed stream 307 comprises process

water, but any suitable liquid may be employed, such as,

25 for example, recycled raffinate, pregnant leach solution, lean

electrolyte, and/or other recycled streams from the metal

recovery processes, including but not limited to secondary

metal, such as cobalt or iron, recovery process streams.

Further, in an exemplary embodiment ofthe present inven-

30 tion, metal-bearing inlet stream 101 is subjected to a reactive

processing step 202 (FIG. 1), for example, metal extraction.

The reactive processing step 202 (FIG. 1) may be any suitable

process or reaction that puts a metal in metal-bearing material

100 in a condition such that it may be subjected to later metal

35 recovery processing. In accordance with one embodiment of

the present invention, reactive processing step 202 (FIG. 1)

comprises a leaching step 201 (FIG. 2B). Furthennore, in an

exemplary embodiment ofthe present invention, the leaching

process may comprise any leaching process suitable for

40 extracting the metal in metal-bearing material 100 into an

aqueous leach solution 102. In accordance with one aspect of

the present invention, the leach step 201 comprises atmospheric

leaching, pressure leaching, whole ore leaching, agitation

leaching, heap leaching, stockpile leaching, pad leach-

45 ing, thin-layer leaching and/or vat leaching, at either ambient

or elevated temperatures. Preferably, pressure leaching 201 is

a pressure leaching process operating at a temperature in the

range of about 1400 C. to about 2500 C. and more preferably

in the range of about 1500 C. to about 2200 C.

In accordance with an aspect of the present invention, the

optimum temperature range selected for operation will tend

to maximize the extraction of copper and other metals, minimize

acid consumption, and thereby minimize make-up acid

requirements. That is, at higher temperatures, sulfide sulfur

55 generally is converted to sulfate according to the following

reaction:

Moreover, in accordance with an exemplary embodiment

of the present invention, single solution extraction plant 204

comprises at least two solution extractor units, at least two

stripping units, and, optionally, at least one wash stage, which

are housed in the same facility. It should be understood that

this disclosure teaches, inter alia, any number of solution

extractor units, any number ofstripping units, and, optionally,

any number ofwash stages for processing any number ofPLS

streams are contemplated herein.

Generally, as will be described in greater detail below, in

accordance with an exemplary embodiment of the present

invention, LGPLS 105 is subjected to a solution extractor

unit, wherein a barren organic flow containing a metal-specific

extraction reagent extracts at least one metal value from

the LGPLS 105 into the organic phase to fonn a partially

loaded organic solution and a low grade raffinate 107. Additionally,

in accordance with an exemplary embodiment ofthe

present invention, HGPLS 104 is subjected to a different

solution extractor unit within the same solution extraction

plant 204, wherein the partially loaded organic solution further

extracts at least one metal value from the HGPLS 104

into the organic phase to form a metal-loaded organic solution,

rich electrolyte, 106, preferably containing a high concentration

ofprimary metal values, and a high grade raffinate.

Further, referring again to FIG. 1, in an exemplary embodiment

of the present invention, after solution extraction step

252, the resulting metal-loaded solution 106 may be forwarded

to primary metal recovery, illustrated as step 206. In

accordance with various aspects ofthe present invention primary

metal recovery step 206 may be any metal recovery

process, for example, electrowinning, sulphidation, precipitation,

ion exchange or any other process suitable for recovery

of metals, may be utilized. In an exemplary embodiment of

the present invention metals to be recovered in primary metal

recovery step 206 may include copper, silver, platinum group

metals, molybdenum, zinc, nickel, cobalt, uranium, rhenium,

rare earth metals, and the like. In a preferred exemplary

embodiment of the present invention, primary recovery step

preferably comprises an electrowinning circuit suitably

designed to carry out any electrowinning process capable of

producing a metal cathode product 208.

Similarly, referring again to FIG. 1, in an exemplary

embodiment ofthe present invention, after solution extraction

step 252, the resulting low grade raffinate 107 may be forwarded

to one or more secondary metal recovery steps 207. In

an exemplary embodiment of the present invention, additional

electrowinning circuits may be employed in the secondary

metal recovery step 207. Moreover, in an exemplary

embodiment of the present invention, the secondary metal

recovery step 207 may comprise any metal recovery process, 50

for example, electrowinning, sulphidation, precipitation, ion

exchange, cyanidation, or any other process suitable for

recovery of secondary metals. Preferably, as discussed in

some detail herein below, in an exemplary embodiment ofthe

present invention, precipitation processes are used, thus making

it advantageous to have low concentrations of primary

metals in the low grade raffinate. Additionally, in an exemplary

embodiment ofthe present invention, secondary metals

to be recovered in secondary metal recovery step 207 may

include, silver, platinum group metals, molybdenum, zinc, 60

nickel, cobalt, uranium, rhenium, rare earth metals, and the

like.

Now with reference to FIG. 1 and FIG. 2B, in accordance

with one aspect ofthe present invention, metal-bearing material

100 may optionally be prepared in a preparation step 250 65

comprising controlled grinding 200. More precisely, U.S. Pat.

No. 6,676,909 describing controlled grinding is contemUS

8,003,064 B2

7 8

concentrations, solids content, volume, temperature, pressure,

and/or other physical and/or chemical parameters to

desired values and thus to form a suitable metal-bearing solution.

Generally, a properly conditioned metal-bearing solution

will contain a relatively high concentration of soluble

metal, for example, copper sulfate, in an acid solution and

preferably will contain few impurities. Moreover, the conditions

of the metal-bearing solution preferably are kept substantially

constant to enhance the quality and uniformity of

the copper product ultimately recovered. conditioning steps

203 (FIG. 1). In one exemplary embodiment, the product

stream 102 from leaching step 201 may be conditioned to

adjust the composition, component concentrations, solids

content, volume, temperature, pressure, and/or other physical

and/or chemical parameters to desired values and thus to form

a suitable metal-bearing solution. Generally, a properly conditioned

metal-bearing solution will contain a relatively high

concentration of soluble metal, for example, copper sulfate,

in an acid solution and preferably will contain few impurities.

20 Moreover, the conditions of the metal-bearing solution preferably

are kept substantially constant to enhance the quality

and uniformity of the copper product ultimately recovered.

In one aspect of an exemplary embodiment of the present

invention, conditioning of a metal-bearing solution for metal

recovery begins by adjusting certain physical parameters of

the product slurry 102 from the leaching step 201. Optionally,

in an exemplary aspect of this embodiment of the invention,

wherein the leaching step 201 is pressure leaching, it is desirable

to reduce the temperature and pressure of the product

slurry, in some instances to approximately ambient conditions.

An exemplary method of so adjusting the temperature

and pressure characteristics of the product slurry is flashing

251 (FIG. 2B). In one aspect ofan exemplary embodiment of

the present invention, flashing step 251 (FIG. 2B) comprises

atmospheric flashing. Further, flashed gases, solids, solutions,

and steam may optionally be suitably treated, for

example, by use of a Venturi scrubber wherein water may be

recovered and hazardous materials may be prevented from

entering the environment.

In accordance with further aspects of this exemplary

embodiment, either the slurry product 102 directly from the

leach process 201 or the flashed product slurry 103, if subjected

to a flashing step 202 (FIG. 2B), may be further conditioned

in preparation for later metal-value recovery steps.

For example, one or more solid-liquid phase separation steps

285 (FIG. 2B) may be used to separate solubilized metal

solution from solid particles. This may be accomplished in

any conventional manner, including use of filtration systems,

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

and the like. 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, a clarifier, or any other suitable device in a solid-liquid

separation apparatus. In one aspect ofan exemplary embodiment

of the invention, one or more solid-liquid phase separation

steps 285 (FIG. 2B) may be carried out with a conventional

CCD utilizing conventional countercurrent washing of

the residue stream to recover leached metal values to one or

more solution products and to minimize the amount of

soluble metal values advancing with the solid residue to further

metal recovery processes or storage.

In accordance with further aspects of this exemplary

embodiment, as exemplified in FIG. 2B, the solid-liquid

phase separation step 285 produces a high grade pregnant

leach solution ("HGPLS") 104, comprising high concentrations

of dissolved metal values, and a low grade pregnant

201 during leaching. In accordance with one aspect of this

embodiment ofthe present invention, a cooling liquid 301 is

preferably contacted with the feed stream in leaching vessel

201 during leaching. Cooling liquid 301 may comprise makeup

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

process or from an outside source, such as recycled liquid

phase from the product slurry or a mixture of cooling fluids.

Cooling liquid may be introduced into leaching vessel 201

through the same inlet as metal-bearing inlet stream 101, or in

any manner that effectuates cooling of metal-bearing inlet 10

stream 101. The amount ofcooling liquid added during leaching

may vary according to the pulp density of the metalbearing

inlet stream 101, as well as other parameters of the

leaching process. In an exemplary aspect ofthis embodiment

of the invention, a sufficient amount of cooling liquid 301 is 15

added to leaching vessel 201 to yield a solids content in

product slurry 102 on the order ofless than about 50% solids

by weight, more preferably ranging from about 3 to about

35% solids by weight, and most preferably ranging from

about 10% to about 20% solids by weight.

Moreover, in accordance with one aspect of the present

invention, leaching step 201 may occur in any pressure leaching

vessel suitably designed to contain the pressure leaching

mixture at the desired temperature and pressure conditions

for the requisite pressure leaching residence time. In accor- 25

dance with one aspect of an exemplary embodiment of the

invention, the pressure leaching vessel used in leaching step

201 is an agitated, multi-compartment pressure leaching vessel.

However, it should be appreciated that any pressure leaching

vessel that suitably permits metal-bearing material 100 to 30

be prepared for metal recovery may be utilized within the

scope of the present invention.

During leaching step 201, copper and/or other metal values

may be solubilized or otherwise liberated in preparation for

later recovery processes. Any substance that assists in solu- 35

bilizing the metal value, and thus releasing the metal value

from a metal-bearing material, may be used. For example,

where copper is the metal being recovered, an acid, such as

sulfuric acid, may be contacted with the copper-bearing material

such that the copper may be solubilized for later recovery 40

steps. However, it should be appreciated that any suitable

method of solubilizing metal values in preparation for later

metal recovery steps may be utilized within the scope ofthis

invention.

In accordance with one aspect of the present invention, 45

during pressure leaching in leaching vessel 201, sufficient

oxygen 302 is injected into the vessel to maintain an oxygen

partial pressure from about 50 to about 200 psi, preferably

from about 75 to about 750 psi and most preferably from

about 100 to about 400 psi Furthermore, due to the nature of 50

medium temperature pressure leaching, the total operating

pressure in leaching vessel 201 is generally superatmospheric.

The residence time for the pressure leaching process can

vary, depending on factors such as, for example, the charac- 55

teristics of the copper-bearing material and the operating

pressure and temperature of the pressure leaching vessel. In

one aspect ofan exemplary embodiment ofthe invention, the

residence time for the pressure leaching ranges from about 30

to about 180 minutes, more preferably from about 60 to about 60

120 minutes.

Subsequent to metal-bearing material 100 undergoing

leaching step 201, the metal values that have been made

available by the leaching process undergo one or more of

various conditioning steps 203 (FIG. 1). In one exemplary 65

embodiment, the product stream 102 from leaching step 201

may be conditioned to adjust the composition, component

US 8,003,064 B2

leach solution ("LGPLS") 105, comprising a lower concentration

of dissolved metal values than found in the HGPLS

104. Preferably, in accordance with further aspects of this

exemplary embodiment, large wash ratios are utilized in the

solid-liquid phase separation steps 285-that is, relatively

large amounts of wash water are added to either the slurry

product 102 or, if after the product slurry has been subjected

to a flashing step 202, the flashed product slurry 103. This

wash water collects the remaining dissolved metal values and

thus becomes the LGPLS 105.

As further discussed herein below, the separated solids

may further be subjected to later processing steps, including

other metal recovery, such as, for example, recovery of gold,

silver, platinum group metals, molybdenum, zinc, nickel,

cobalt, uranium, rhenium, rare earth metals, and the like, by

sulphidation, cyanidation, or other techniques. Alternatively,

the separated solids may be subject to impoundment or disposal.

The liquid separated from a solid-liquid phase separation

step 285 may also undergo a series of conditioning steps to

prepare the metal solubilized therein for recovery. For

example, the separated liquid may undergo various reagent

additions to put the metal in a state such that the metal is

susceptible to conventional metal recovery techniques. Further,

subsequent conditioning and/or processing steps may be

undertaken such that recovery rates are as efficient as possible.

Referring to FIG. 1 and FIG. 2B, in accordance with an

exemplary embodiment of the present invention, after any

desired conditioning steps 203 (FIG. 1), for example, addition

of diluting solution 303, the HGPLS 104 and LGPLS 105

may be forwarded to the desired metal recovery step. The

copper recovery step may include any suitable conditioning

and/or copper recovery method or methods, for example,

electrowinning, precipitation, solution extraction (sometimes

referred to as solvent extraction or liquid ion exchange), ion

exchange, and/or ion flotation, and preferably results in a

relatively pure copper product. Additionally, in accordance

with an exemplary embodiment of the present invention,

diluting solution 303 may be any suitable liquid, for example,

water or atmospheric leach effluent solution, that sufficiently

reduces the copper and acid concentrations to desired levels

to provide desirable equilibrium conditions for solution

extraction 252. In accordance with an exemplary embodiment

of the present invention, sufficient amount of diluting

solution 303 is added to yield an acid concentration ranging

from about 2 to about 25 grams/liter, and more preferably

from about 4 to about 7 grams/liter and a pH preferably

ranging from about pH 1.5 to about pH 2.5 and more preferably

from about pH 1.8 to about pH 2.2, and optimally in the

range ofabout pH 2.0. TheHGPLS 104 andLGPLS 105 may

thereafter be processed, such as for example in accordance

with metal extraction by solution extraction 204.

In many instances, due to variation in incoming metal tenor

in the metal-bearing material 100, it is advantageous to mix

one or more leach solutions prior to solution extraction. As

discussed briefly above, it is sometimes necessary to process

two or more separate leach solution streams from multiple

leach processes at one time. For example, ifan operation has

both a heap leach operation and a pressure or agitated leach

operation, then the heap leach solution, equivalent to the

LGPLS 105, may need to be processed with a more concentrated

pregnant leach solution, HGPLS 104. In this instance,

with reference to FIG. 2A and FIG. 2B and in accordance with

an exemplary embodiment of the present invention, it is not

required that the HGPLS 104 and LGPLS 105 are produced

from the same leaching step 201, flashing step 202, and/or

solid-liquid phase separation step 285. Stated another way,

with reference to FIG. 2A and FIG. 2B and in accordance with

an exemplary embodiment ofthe present invention, either the

HGPLS 104 or the LGPLS 105 can be produced by one or

more reactive processing steps 202. Additionally, with reference

to FIG. 2A and FIG. 2B and in accordance with an

exemplary embodiment of the present invention, multiple

controlled grinding steps 200, flashing steps 202, and/or

solid-liquid phase separation steps 285 can be utilized to

10 produce either the HGPLS 104 or the LGPLS 105.

As mentioned above, the metal tenor in the metal-bearing

material 100 can vary greatly over the course of operating a

metal recovery plant. Due to this variation, both primary and

secondary metal recovery processes can evidence losses in

15 efficiency and overall processing yields. One reason for these

losses is the inability to control and tune the metal tenor in the

raffinate from solution extraction of the LGPLS extraction,

low grade raffinate. For example, low grade raffinate is preferably

subjected to a selective precipitation process wherein

20 all metal ions except for those of the secondary metal to be

recovered, for example cobalt, are eliminated from the process

stream by precipitating them as solids. The precipitated

primary metal solids may be recycled to the reactive step.

These precipitated solids may have a high probability of

25 being rendered unrecoverable depending on the precipitating

mechanism employed. In the instance where there is high

primary metal tenor in the low grade raffinate, the amount of

precipitated primary metal solids recycled to the reactive step

may increase. This increase in precipitated metal solids may

30 lead to process inefficiencies due to high circulating loads in

process steps 202 and 204 (FIG. 2B).

Similarly, the inability to control and tune the metal tenor

in the low grade raffinate directly affects the costs associated

with the secondary metal recovery processes. For instance,

35 low metal tenors in the low grade raffinate require less reagent

to effect precipitation (operating cost savings), thus smaller

equipment can be used to recycle the copper precipitate (capital

cost savings).

The present metal recovery process with single extraction

40 plant advantageously allows for control and tuning ofthe low

grade raffinate. Moreover, the solution extraction process

204, described in detail below, preferably, allows for control

and tuning of the low grade raffinate by adjustment of the

barren organic flow rate and/or adjustment of the reagent

45 content and/or adjustment of the flow of the feed material

and/or adjusting the metal content by blending or dilution,

and/or any combinations thereof. It should be understood that

any of these parameters or others may be advantageously

adjusted or controlled as may be desired to suitably adjust the

50 copper flux to the reactive process. Additionally, in accordance

with an exemplary embodiment, the overall efficiency

of the reactive process may be influenced by blending the

primary metal solids precipitated from the low grade raffinate

with high grade raffinate prior to recycling to the reactive

55 process step.

By making any ofthese adjustments to control and tune the

metal tenor in the low grade raffinate, the low grade raffinate

should preferably contain very limited amounts of the primary

metal and allows for efficient secondary metal process-

60 ing. Additionally, the metal recovery process and solution

extraction plant described below, allows plant operators to

maintain a substantially controlled metal concentration in

both the LGPLS stream and the low grade raffinate stream.

Generally, in accordance with exemplary embodiments of

65 the present invention, the controllable process within solution

extraction plant 204 comprises (a) providing a HGPLS to a

solution extractor unit within a single solution extraction

US 8,003,064 B2

plant, (b) producing high grade raffinate and a metal-loaded

organic solution by contacting the high grade leach solution

with a partially loaded organic solution in the solution extractor,

unit within the same solution extraction plant, and (d) producing

a low grade raffinate and the partially loaded organic

solution by contacting the LGPLS with a barren organic flow

containing a metal-specific extraction reagent.

As discussed above, in accordance with the various

embodiments ofthe present invention, the flow rate and concentration

of the barren organic flow containing a metalspecific

extraction reagent can be altered based on the incoming

metal ore quality to maintain a constant concentration of

metal in the low grade raffinate, allowing for efficient secondary

processing of other metals, including but not limited to

cobalt recovery. Because both the HGPLS and LGPLS

streams are treated in one facility, the metal content of the

LGPLS may be controlled and held constant by adjusting

LGPLS rate according to grade, with the excess being

blended with the HGPLS.

In this regard, solution extraction plant 204 of FIG. 2 is

described in greater detail in FIG. 3. In accordance with an

exemplary embodiment of the present invention, with reference

to FIG. 3, the HGPLS 104 is provided to a high grade

solution extractor unit 209 and the LGPLS 105 is provided to

a low grade solution extractor unit 211. In accordance with

this exemplary embodiment ofthe present invention, HGPLS

104 has a greater concentration ofmetal than the LGPLS 105.

In accordance with this exemplary embodiment ofthe present

invention, the LGPLS 105 has a concentration of metal

greater than about 20% of the concentration of metal in the

HGPLS 104. Preferably, in accordance with this exemplary

embodiment of the present invention, the LGPLS 105 has a

concentration ofmetal greater than about 40% ofthe concentration

ofmetal in the HGPLS 104. Most preferably, in accordance

with this exemplary embodiment ofthe present invention,

the LGPLS 105 has a concentration ofmetal greater than

about 50% of the concentration of metal in the HGPLS 104.

As discussed briefly above, in accordance with exemplary

embodiments of the present invention, the LGPLS 105 is

contacted with a barren organic flow containing a metalspecific

extraction reagent 401, for example, an aldoxime

and/or ketoxime. The barren organic flow containing a metalspecific

extraction reagent 401 extracts at least one primary

metal value from the aqueous phase of the LGPLS 105 into

the organic phase. In accordance with exemplary embodiments

of the present invention, the metal-specific extraction

reagent is supplied by external feed 305. More specifically, in

accordance with another exemplary embodiment of the

present invention, the LGPLS 105 is contacted with the barren

organic flow 401 in low grade solution extractor unit 211.

It should be understood that the solution extractor unit 211 is

only an exemplary reference andmay comprise multiple solution

extractor units.

Further, in accordance with this exemplary embodiment of

the present invention, upon extraction of the at least one

primary metal value from the aqueous phase of the LGPLS

105, a low grade raffinate 281 and a partially loaded organic

solution 400 are produced. In accordance with this exemplary

embodiment ofthe present invention, low grade raffinate 281

is an aqueous stream containing at least one secondary metal

values and containing very low primary metal tenor, thus the

low grade raffinate is suitable for secondary metal recovery

207 as discussed above with reference to FIG. 1 and further

exemplified in FIG. 2B.

Secondly, in accordance with this exemplary embodiment

ofthe present invention, the partially loaded organic solution

400 may be contacted with the HGPLS 104 to produce a

metal-loaded organic solution 402 and a high grade raffinate

304. Similarly, with reference to FIG. 3 and in accordance

with exemplary embodiments of the present invention, the

HGPLS 104 is contacted with the partially loaded organic

solution 400 in high grade solution extractor unit 209. As will

be discussed in detail below, in accordance with exemplary

embodiments of the present invention, metal-loaded organic

solution 402 is forwarded to at least one stripping unit 210 for

10 recovery of at least one metal value. It should be understood

that the solution extractor unit 209 is only an exemplary

reference and may comprise multiple solution extractor units.

As discussed previously, it is desirable to produce a metalloaded

organic solution 402 with high metal tenor, which is

15 suitably conditioned for metal recovery by stripping and electrowinning.

Additionally, it is desirable to produce a low

grade raffinate 281, which contains very low primary metal

tenor and is suitable for secondary metal extraction. In order

to accomplish this, with reference to FIG. 3 and in accordance

20 with exemplary embodiments of the present invention, the

barren organic flow rate may be varied in correlation to the

grade of the incoming metal-bearing material and may be

produced in one or more stripping units 210. Additionally, in

accordance with exemplary embodiments of the present

25 invention, any metal-specific extraction reagent may be supplied

by external feed 305 to the stripping units 210 or any

time prior to contacting the LGPLS 105. In accordance with

exemplary embodiments ofthe present invention, the concentration

of the metal-specific extraction reagent 305 may be

30 varied in correlation to the grade of the incoming metalbearing

material.

With reference to FIG. 3 and in accordance with exemplary

embodiments of the present invention, the partially loaded

organic solution 400 may be subjected to an optional strip-

35 ping unit 210 prior to contacting the HGPLS 104. This intermediate

optional stripping unit 210 may increase the extraction

effectiveness of the organic solution 400, thereby

allowing for a lower reagent concentration without sacrificing

metal extraction efficiency. It should be understood that this

40 disclosure teaches, inter alia, any number of solution extractor

units and any number of stripping units in any configuration.

As mentioned above, in accordance with exemplary

embodiments of the present invention, the metal-loaded

45 organic solution 402, preferably containing a high metal

tenor, is subjected to stripping unit 210 and at least one metal

value is stripped from the metal-loaded organic solution 402.

In accordance with exemplary embodiments of the present

invention, at least one metal value is stripped from the metal-

50 loaded organic solution 402 by using any fluid suitable for

stripping metal values from a metal-loaded organic solution,

preferably lean electrolyte 306 recycled from an electrowinning

circuit 216 (FIG. 2B). Optionally, in accordance with

exemplary embodiments ofthe present invention, the metal-

55 loaded organic solution 402 is subjected to a wash stage 212

prior to being stripped in stripping unit 210.

High grade raffinate 304 from solution extraction plant 204

(FIG. 2B) may be used beneficially in a number of ways. For

example, all or a portion of high grade raffinate 304 maybe

60 recycled to any leaching step 201 for temperature control or

may be used in atmospheric leaching, pressure leaching,

whole ore leaching, agitation leaching, heap leaching, stockpile

leaching, pad leaching, thin-layer leaching, vat leaching,

and/or may be used for a combination thereof at either ambi-

65 ent or elevated temperatures. The use of high grade raffinate

304 in heap leaching operations may be beneficial because

the acid and ferric iron values contained in raffinate 304 can

US 8,003,064 B2

13 14

depicted in FIG. 4, low grade solution extractor unit 211 is

separated from the high grade solution series solution extractor

unit 209 by at least one serial solution extractor unit 213.

Additionally, the low grade solution extractor unit 211 is

separated from the stripping unit 210 by at least on serial

solution extractor unit 204.

More precisely, with reference to FIG. 4 and the exemplary

embodiment, the low grade solution extractor unit 211 and

solution extractor unit 214 are in a series configuration. Addi-

10 tionally, the high grade solution extractor unit 209 and solution

extractor unit 213 are in a series configuration. Moreover,

it should be understood that it is not the number of solution

extraction units employed, but the sequence in which they are

configured, thus any number of solution extraction units can

15 be employed and are contemplated herein. Further, as illustrated

by FIG. 3, the high grade extractor units may optionally

be separated from the low grade extractor units by an intermediate

strip unit 210 (FIG. 3), if solution chemistry and

process kinetics make it advantageous to do so. Additionally,

20 an organic wash stage 212 (FIG. 3) may be added prior to

stripping if necessitated by solution chemistry.

Returning to FIG. 2B, in accordance with the various

embodiments ofthe present invention, metal-bearing solution

stream, or rich electrolyte, 276 from solution extraction plant

25 204 may be sent to an electrolyte recycle tank 205. The

electrolyte recycle tank may suitably facilitate process control

for an electrowinning circuit 216, as will be discussed in

greater detail below. Metal-bearing solution stream 276,

which can contain from about 25 to about 75 grams/liter of

30 copper and from about 145 to about 180 grams/liter acid, is

preferably blended with a lean electrolyte 306 (i.e., electrolyte

that has already been through the metal recovery phase

and has had a portion of its dissolved copper removed) and

makeup fluid 215, such as, for example, water, in the electro-

35 Iyte recycle tank 205 at a ratio suitable to yield a product

stream 108, the conditions of which may be chosen to optimize

the resultant product of electrowinning step 216.

In accordance with the various embodiments ofthe present

invention, the metal composition of product stream 108 is

40 maintained substantially constant at a value from about 20 to

about 60 grams/liter, more preferably at a value from about 30

to about 50 grams/liter. Metal values from the product stream

108 are removed during electrowinning circuit 216 to yield a

pure, cathode metal product 217. As mentioned above, in

45 accordance with the various embodiments of the present

invention, electrowinning circuit 216 produces pure, cathode

metal product 217 and lean electrolyte 306, which can be

recycled to the electrolyte recycle tank 205, the solution

extraction plant 204, and/or the leaching step 201.

It should be appreciated that in accordance with the various

aspects of the invention, a process wherein, upon proper

conditioning of the copper-bearing solution, a high quality,

uniformly-plated cathode copper product may be realized

without subjecting the copper-bearing solution to solution

55 extraction prior to entering the electrowinning circuit is

within the scope of the present invention. As previously

noted, careful control ofthe conditions ofthe copper-bearing

solution entering an electrowinning circuit-especially

maintenance of a substantially constant copper composition

60 in the stream---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

diminishes its economic value. In accordance with this aspect

65 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 maintain

act to optimize the potential for leaching oxide and/or sulfide

ores that commonly dominate agitation leaching, heap leaching,

stockpile leaching, pad leaching, thin-layer leaching and/

or vat leaching operations. That is, the ferric and acid concentrations

of raffinate 304 may be used to optimize the Eh

and pH ofheap leaching operations. It should be appreciated

that the properties of high grade raffinate 304, such as component

concentrations, may be adjusted in accordance with

the desired use ofhigh grade raffinate 304.

Additionally, in accordance with the various embodiments

ofthe present invention, low grade raffinate 107 from solution

extraction plant 204 (FIG. 2B) may be sent to secondary

metal processing 207 (FIG. 1) for other secondary metals,

including, but not limited to silver, platinum group metals,

molybdenum, zinc, nickel, cobalt, uranium, rhenium, rare

earth and actinide metals. As mentioned above, preferred

embodiments of the present invention advantageously provide

for maintenance of a constant metal tenor in both the

high grade and low grade raffinate. This direct control facilitates

a known and substantially controlled metal precipitate

recycle, increasing operating efficiency, potential limiting

metal losses, and reducing recycle equipment size and subsequent

capital costs. Therefore, in accordance with the various

embodiments of the present invention, the flow rate and

concentration of the organic flow containing a metal-specific

extraction reagent 401 can be altered based on the incoming

metal-bearing ore quality to maintain a constant concentration

(tenor) ofmetal in the low grade raffinate 281. To effectuate

such direct control either the metal concentration and/or

flow rate of any organic and/or aqueous flow in the process

may be controlled, thus enabling extraction to take place

under tightly controlled conditions. Specifically, the amount

of high grade raffinate which is recycled to a leach step may

be controlled. This ability to maintain the metal tenor of the

low grade raffinate 107 allows for the efficient recovery of

cobalt or other secondary metal values at any given metallic

ore quality by removing a majority of primary metals, which

would interfere with the recovery of other secondary metal,

from the low grade raffinate 107.

With reference to FIG. 3, the present invention allows the

extraction circuit for the primary metal value to be tuned and

optimized, both in terms of metallurgical performance and

capital and operating costs. There is a trade off between

achieving optimum metallurgical performance and minimizing

the capital costs of the operating facility. The decisions

made regarding this trade off are based on the performance

and cost ofthe metal-specific extraction reagent employed as

well as the chemistry ofthe pregnant leach solution streams to

be treated. For example, the use ofa metal-specific extraction

reagent with exhibits rapid extraction kinetics may minimize 50

the number of sequential extractors needed to achieve a satisfactory

level of metal recovery. The presence of iron, manganese,

or chloride in the pregnant leach solution streams

may require the use of a wash stage prior to stripping. The

number and placement of stripping units is decided based on

the stripping kinetics of the extraction reagent as well as its

maximum metal loading capacity. Accordingly, various configurations

are within the scope of the present invention.

Moreover, in accordance with this exemplary embodiment

ofthe present invention, multiple solution extractor units can

be utilized in any configuration, preferably series or parallel

configurations, within the same solution extraction plant 204.

More specifically, the high grade solution extractor unit 209 is

suitably connected in parallel to the low grade solution

extractor unit 211 by a common organic flow containing a

metal-specific extraction reagent. For example, in accordance

with an exemplary embodiment of the present invention, as

US 8,003,064 B2

15 16

8. The process of claim 1, wherein said low grade raffinate

is subjected to secondary extraction processing.

9. The process of claim 8, wherein the low grade raffinate

comprises a secondary metal selected from the group consisting

ofgold, silver, platinum group metals, molybdenum, zinc,

nickel, cobalt, uranium, rhenium, rare earth metals, and

actinide metals.

10. A controlled copper leach and recovery process comprising:

providing a high grade pregnant leach solution to a first

solution extractor unit;

producing a high grade raffinate and a metal-loaded

organic solution by contacting said high grade pregnant

leach solution with a partially loaded organic solution;

providing a low grade pregnant leach solution to a second

solution extractor unit,

wherein said high grade pregnant leach solution has a

greater concentration ofmetal than said low grade pregnant

leach solution and wherein said first solution

extractor unit and said second solution extractor unit are

in the same solution extraction plant;

producing a low grade raffinate and said partially loaded

organic solution by contacting said low grade pregnant

leach solution with a barren organic flow; and

producing said barren organic flow by stripping at least one

metal value from said metal-loaded organic solution in

at least one stripping unit within said solution extraction

plant.

11. The process of claim 10, further comprising adding a

metal-specific extraction reagent to said barren organic flow

35 prior to contacting with said low grade pregnant leach solution.

12. The process ofclaim 10, wherein said high grade pregnant

leach solution is generated from at least one of an atmospheric

leaching process, a pressure leaching process, an

agitation leaching process, a heap leaching process, a stockpile

leaching process, a pad leaching process, a thin-layer

leaching process, and a vat leaching process.

13. The process of claim 10, wherein said high grade raffinate

is recycled to at least one of a atmospheric leaching

process, a pressure leaching process, an agitation leaching

process, a heap leaching process, a stockpile leaching process,

a pad leaching process, a thin-layer leaching process,

and a vat leaching process.

14. The process of claim 10, wherein said low grade raffinate

is subjected to secondary extraction processing.

15. The process of claim 14, wherein the low grade raffinate

comprises a secondary metal selected from the group

consisting of silver, platinum group metals, molybdenum,

55 zinc, nickel, cobalt, uranium, rhenium, rare earth metals, and

actinide metals.

16. The process ofclaim 10, wherein said concentration of

metal in said high grade pregnant leach solution is greater

than about 20% of the concentration of metal in said low

grade pregnant leach solution.

17. The process of claim 10, wherein said first solution

extraction unit is connected to said second solution extraction

unit in parallel.

18. The process ofclaim 10, wherein at least one stripping

unit is positioned between said first solution extractor unit and

said second solution extractor unit.

What is claimed is:

1. A controlled copper leach and recovery process com- 25

prising:

subjecting a metal-bearing material to a reactive process to

liberate at least one metal value from said metal-bearing

material;

obtaining a product slurry from said reactive process, 30

wherein at least two metal values are present in said

product slurry;

producing a high grade pregnant leach solution and a low

grade pregnant leach solution by subjecting said product

slurry to a solid-liquid separation process;

providing said high grade pregnant leach solution to a

solution extraction plant comprising at least two solution

extractors and at least two stripping units;

producing a high grade raffinate and a metal-loaded solution

by contacting said high grade pregnant leach solu- 40

tion with a partially loaded organic solution in said solution

extraction plant;

providing said low grade pregnant leach solution to said

solution extraction plant, wherein said low grade pregnant

leach solution comprises a lower metal concentra- 45

tion than said high grade pregnant leach solution; and

producing a low grade raffinate and said partially loaded

organic solution by contacting said low grade pregnant

leach solution with a barren organic flow for extracting

said at least one metal value.

2. The process of claim 1, wherein said reactive process

comprises a leaching process.

3. The process ofclaim 1, wherein at least one metal value

is stripped from said metal-loaded solution in at least one

stripping unit.

4. The process ofclaim 3, wherein said barren organic flow

is produced by stripping said at least one metal value in at

least one stripping unit.

5. The process of claim 4, wherein said partially loaded

organic solution is subjected to at least one stripping unit prior 60

to contacting said high grade pregnant leach solution.

6. The process ofclaim 2, wherein said high grade raffinate

is recycled to a leaching process.

7. The process of claim 1, wherein the concentration of

metal in low grade raffinate is held substantially constant by 65

varying the flow rate of said barren organic flow or reagent

concentration.

a sufficiently constant feed stream to the electrowinning circuit.

As those skilled in the art are aware, a variety ofmethods

and apparatus are available for the electrowinning of copper

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

in accordance with the present invention, provided the requisite

process parameters for the chosen method or apparatus

are satisfied.

It is believed that the disclosure set forth above encompasses

at least one distinct invention with independent utility.

While the invention has been disclosed in the exemplary 10

forms, the specific embodiments thereof as disclosed and

illustrated herein are not to be considered in a limiting sense

as numerous variations are possible. The subject matter ofthe

inventions includes all novel and non-obvious combinations 15

and sub combinations ofthe various elements, features, functions

and/or properties disclosed herein.

The method and system described herein may be implemented

to recover copper and other metals in a controlled

manner. Other advantages and features ofthe present systems 20

and methods may be appreciated from the disclosure herein

and the implementation ofthe method and system.

US 8,003,064 B2

19. The process of claim 10, wherein at least one solution

extractor unit separates said first solution extractor unit from

said second solution extractor unit.

20. The process of claim 10, further comprising stripping

said metal-loaded organic solution in at least one stripping

unit to produce a metal-rich solution and a barren organic

solution.

21. The process of claim 20, further comprising sending

said metal-rich solution to an electrowinning process.

22. The process of claim 20, further comprising washing

said metal-loaded organic solution in at least one wash stage

prior to said stripping step.

23. The process of claim 10, wherein the concentration of

metal in low grade raffinate is held substantially constant by

varying the flow rate of said barren organic flow.

24. The process of claim 10, wherein the concentration of

metal in said low grade raffinate is controlled by altering the

flow rate of at least one of said high grade pregnant leach

solution and said low grade pregnant leach solution.

25. The process ofclaim 10, wherein said at least one metal

value is stripped from metal-loaded solution by at least one of

10 a lean electrolyte from an electrowinning process and a sulfuric

acid solution.

* * * * *