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US007462272B2
(12) United States Patent
Marsden et al.
(10) Patent No.:
(45) Date of Patent:
US 7,462,272 B2
*Dec. 9, 2008
peT-International Search Report, Mailing Date: Apr. 24, 2006.
(Continued)
(Continued)
OTHER PUBLICATIONS
U.S. PATENT DOCUMENTS
111978 Emmett, Jr. et al.
4/1997 Young et al.
9/2002 Marsden et al. 75/744
12/2003 Marsden et al. 75/744
112004 Marsden et al. 423/28
12/2005 Marsden et al. 266/171
4/2002 Marsden et al. 423/28
References Cited
4,066,520 A
5,622,615 A
6,451,089 Bl *
6,663,689 B2 *
6,676,909 B2 *
6,972,107 B2 *
2002/0044899 Al *
(54) PROCESS FOR MULTIPLE STAGE DIRECT (56)
ELECTROWINNING OF COPPER
(75) Inventors: John O. Marsden, Phoenix, AZ (US);
Robert E. Brewer, deceased, late of
Park City UT (US); by Susan R.
Brewer, legal representative, Park City,
UT (US); Joanna M. Robertson,
Thatcher, AZ (US); David R.
Baughman, Golden, CO (US); Philip
Thompson, West Valley City, UT (US);
Wayne W. Hazen, Lakewood, CO (US);
Christel M. A. Bemelmans, Indian
Hills, CO (US)
(73) Assignee: Phelps Dodge Corporation, Phoenix,
AZ (US)
Primary Examiner-Bruce F Bell
(74) Attorney, Agent, or Firm-Snell & Wilmer L.L.P.
( *) Notice: Subject to any disclaimer, the term ofthis
patent is extended or adjusted under 35
U.S.c. 154(b) by 222 days.
This patent is subject to a tenninal disclaimer.
(57) ABSTRACT
Appl. No.: 11/163,761
Filed: Oct. 28, 2005
Prior Publication Data
Related U.S. Application Data
Provisional application No. 60/623,199, filed on Oct.
29,2004.
Int. Cl.
C2SC 1/12 (2006.01)
U.S. Cl. 205/580; 205/574; 205/581;
205/584; 205/585; 205/586
Field of Classification Search 205/574,
205/580,584,586,581,585
See application file for complete search history.
(21)
(22)
(65)
(60)
(51)
(52)
(58)
US 2006/0144716 Al luI. 6, 2006
A system and process for recovering copper from a coppercontaining
ore, concentrate, or other copper-bearing material
to produce high quality cathode copper from a leach solution
without the use of copper solvent/solution extraction techniques
or apparatus. A process for recovering copper from a
copper-containing ore generally includes the steps of providing
a feed stream containing comminuted copper-containing
ore, concentrate, or other copper-bearing material, leaching
the feed stream to yield a copper-containing solution, conditioning
the copper-containing solution through one or more
physical or chemical conditioning steps, and electrowinning
copper directly from the copper-containing solution in multiple
electrowinning stages, without subjecting the coppercontaining
solution to solvent/solution extraction prior to
electrowinning.
19 Claims, 3 Drawing Sheets
125 ........
US 7,462,272 B2
Page 2
u.s. PATENT DOCUMENTS
OTHER PUBLICATIONS
peT-Written Opinion of the International Searching Authority,
Mailing Date: Apr. 24, 2006.
* cited by examiner
2003/0019330 Al *
2004/0130076 Al *
2004/0146438 Al *
2005/0109163 Al *
2005/0126923 Al *
2005/0269209 Al *
2006/0016684 Al *
112003 Marsden et al. 75/631
7/2004 Marsden et al. 266/101
7/2004 Marsden et al. 423/27
5/2005 Marsden et al. 75/740
6/2005 Marsden et al. 205/580
12/2005 Sandoval et al. 205/586
112006 Marsden et al. 204/237
2006/0016696 Al *
2006/0016697 Al *
2006/0144717 Al *
112006 Stevens et al. 205/586
112006 Gilbert et al. 205/586
7/2006 Marsden et al. 205/584
u.s. Patent Dec. 9,2008 Sheet 1 of 3 US 7,462,272 B2
101
1010 Cu SEPARATION
(OPTIONAL)
111
118
1031 104
~----------------------l
I I
->,--'---------"4'1 PRESSURE LEACHING I+--T---
1040
ATMOSPHERIC FLASH
---------------,
107
ELECTROLYTE
RECYCLE TANK
128
- - - .....
+- - - - -k----.---------j
125
108
FIRST STAGE DIRECT
ELECTROWINNING
120
122 123
126
116
ELECTROLYTE
RECYCLE TANK
SECOND STAGE DIRECT
ELECTROWINNING
1080
FIG. 1
u.s. Patent Dec. 9,2008 Sheet 2 of 3 US 7,462,272 B2
201 202
ATMOSPHERIC LEACH!
PRESSURE LEACH
203
1
126~
110
208
2020 206
204 204
---------------------~-----I
ELECTROWINNJNG
2030 1
I
I
203 I
~ 205 207 : -------------------- ~ . J
1 1 1
- - - - - - - - - - - - - - - -1- - - - - - r- - - - - - t- - - - - - - - - - - - - - - - 1
I 1 I
I I
I I
I I
I I
1 I
: 206 209 211:
I I
I 2070 I
I I
I I
I I
I 212 I
: 210 :
I 1
~------------------------------------- I
FIG. 2
u.s. Patent Dec. 9,2008 Sheet 3 of 3
Gu ORE OR
CONCENTRATE
US 7,462,272 B2
123
1 1
ATMOSPHERICI
PRESSURE LEACH
1h V 101 I
\
1010 -.......... Cu SEPARATION 203
(OPTIONAL)
V102
1020
S---- l \ V103 110
1030
PRESSURE LEACH
---~------
1
1 /104 1
I
1 1040
1 ATMOSPHERIC FLASH
1
1 ~105 Ir
I
-.......... 1 1050 ________ S I L
I \ I ","- - - - 1 - - r 114
I.c- _1- - - - - - - - - - - - - - - -V 106
108 ~ 1060
1 '~ ELECTROLYTE
tL -1- --.... RECYCLE TANK
I
- r 108 /107 - - - ......
1
J 1070,,- I FIRST STAGE DIRECT J
~----'<---'\--- ELECTROW~NNING / Cu
108 L/120 116
123
\ 1080-.......... ELECTROLYTE
RECYCLE TAN K
123
~121
;2 \ 1090, SECOND STAGE DIRECT J Cu ) ElECTROWINNING \
FIG. 3
US 7,462,272 B2
1
PROCESS FOR MULTIPLE STAGE DIRECT
ELECTROWINNING OF COPPER
2
SUMMARY OF 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 copper-containing
material includes obtaining a copper-containing solution
from, for example, a pressure leaching system, and then
10 appropriately conditioning the copper-containing solution for
electrowinning. In an exemplary aspect of the invention, the
composition of the copper-containing solution is similar to
the composition of the electrolyte produced by a solvent/
solution extraction circuit, for example, with respect to acid
15 and copper concentrations. In accordance with various
embodiments of the present invention, however, the coppercontaining
solution is not subjected to solvent/solution
extraction prior to electrowinning.
In accordance with an exemplary embodiment of the
20 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) optionally, subjecting the copper-containing feed
stream to a copper separation stage; (iii) subjecting the cop-
25 per-containing feed stream to atmospheric leaching or pressure
leaching to yield a copper-containing solution; (iv) conditioning
the copper-containing solution through one or more
chemical or physical conditioning steps; (v) electrowinning
copper directly from the copper-containing solution, without
30 subjecting the copper-containing solution to solvent/solution
extraction; (vi) optionally, treating at least a portion ofa lean
electrolyte stream from the electrowinning step in a solvent/
solution extraction and electrowinning operation; and (vii)
recycling at least a portion ofthe lean electrolyte stream to the
35 atmospheric or pressure leaching step to provide some or all
ofthe acid requirement of the leaching operation.
In accordance with another exemplary embodiment ofthe
present invention, a process for recovering copper from a
copper-containing material generally includes the steps of: (i)
40 providing a feed stream containing copper-containing material;
(ii) optionally, subjecting the copper-containing feed
stream to a copper separation stage; (iii) subjecting the copper-
containing feed stream to atmospheric leaching or pressure
leaching to yield a copper-containing solution; (iv) con-
45 ditioning the copper-containing solution through one or more
chemical or physical conditioning steps; (v) electrowinning
copper directly from the copper-containing solution, without
subjecting the copper-containing solution to solvent/solution
extraction; (vi) optionally, treating at least a portion ofa lean
50 electrolyte stream from the electrowinning step in a solvent/
solution extraction and electrowinning operation; and (vii)
recycling at least a portion ofthe lean electrolyte stream to the
atmospheric or pressure leaching step to provide some or all
of the acid requirement of the leaching operation. As used
55 herein, the term "pressure leaching" shall refer to a metal
recovery process in which material is contacted with a liquid
(e.g., an acidic solution, water, etc.) and oxygen under conditions
of elevated temperature and pressure (i.e., above
ambient).
In one optional aspect of an exemplary embodiment ofthe
invention, one or more processing steps are used to separate
copper from the acid in a recycled portion of the lean electrolyte
from the direct electrowinning process, thus rejecting
a portion of the acid and impurities from the process circuit
65 without rejecting a significant portion of the copper. As discussed
in greater detail hereinbelow, a number of conventional
or hereafter devised processes may be utilized to sepa-
FIELD OF INVENTION
BACKGROUND OF INVENTION
CROSS-REFERENCE TO RELATED
APPLICATIONS
This application claims priority from U.S. Provisional
Patent Application Ser. No. 60/623,199; entitled "Process for
Multiple Stage Direct Electrowinning of Copper" filed Oct.
29,2004.
The present invention relates generally to a process for
recovering copper from a copper-containing ore, concentrate,
or other copper-bearing material, and more specifically, to a
process using super-fine grinding, a copper separation operation,
and pressure leaching to produce cathode copper from a
multiple-stage direct electrowinning process.
Hydrometallurgical treatment of copper-containing materials,
such as copper ores, concentrates, and other copperbearing
materials, has been well established for many years.
Currently, there exist many creative approaches to the hydrometallurgical
treatment ofthese materials; however, common
to almost all of the processes either now known or under
development is the use of solvent/solution extraction and
electrowinning (SX-EW) operations for solution purification
and copper recovery.
The traditional hydrometallurgical process for copper
recovery involves first leaching copper-containing material
with sulfuric acid solution, either atmospherically or under
conditions of elevated temperature and pressure. The resultant
liquid stream-the so-called pregnant leach solution-is
collected and processed in a solvent/solution extraction stage,
in which the leach solution is mixed with an organic solvent
(i.e., an extractant mixed with a suitable diluent, such as
kerosene). The organic phase selectively removes the copper
from the pregnant leach solution. The copper-loaded organic
phase is then mixed with an aqueous acid solution, which
strips the copper from the extractant, producing a solution
stream suitable for electrowinning. This resultant solution is
highly concentrated in copper, is relatively pure, and typically
is processed in an electrowinning circuit to yield high quality
copper cathode.
Purification of copper from the pregnant leach solution by
solvent/solution extraction has proven to be a successful
means of providing a concentrated copper solution suitable
for electrowinning of highly pure copper metal. Direct electrowinning
ofcopper-that is, plating ofcopper directly from
the pregnant leach solution without the intervening step of
purification by solvent/solution extraction-is known. However,
the copper recovered by such so-called direct electrowinning
processes often is too impure for sale or use as is, and
thus, generally must be further refined at an additional cost, or
may be sold at a discount. More specifically, prior art techniques
have shown the ability for direct electrowinning of 60
copper to produce a relatively low-quality copper product.
An effective and efficient method to recover copper from
metal-bearing materials, such as, for example, chalcopyrite,
chalcocite, bornite, covellite, digenite, and enargite, that
enables high copper recovery to be achieved at a reduced cost
over conventional processing techniques would be advantageous.
US 7,462,272 B2
3 4
In accordance with an exemplary aspect of the invention,
the particle size of the copper-containing feed material is
reduced to optimize the processing steps of atmospheric or
pressure leaching and subsequent metal recovery processes.
A variety of acceptable techniques and devices for reducing
the particle size of the copper-containing material are currently
available, such as ball mills, tower mills, superfine
grinding mills, attrition mills, stirred mills, horizontal mills
and the like, and additional techniques may later be developed
that may achieve the desired result of increasing the surface
area ofthe material to be processed. With regard to one aspect
ofan exemplary embodiment ofthe invention, such a result is
copper is removed from the copper-containing electrolyte
stream. It is generally economically advantageous to utilize
this generated acid in some way, rather than to attenuate or
dispose ofit. Thus, as discussed in greater detail hereinbelow,
embodiments of the present invention incorporating these
optional aspects 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
10 leaching operations, which often require a substantially continuous
acid supply.
In accordance with one aspect of an exemplary embodiment
of the present invention, a feed stream containing copper-
containing material is provided for processing. In accor-
15 dance with various embodiments of present invention, the
copper-containing material may be an ore, a concentrate, or
any other copper-bearing material from which copper and/or
other metal values may be recovered. The copper in the copper-
containing material may be in the form ofcopper oxides,
20 copper sulfides, and/or other copper minerals, and the coppercontaining
material may include any number of a variety of
other metals, such as, for example, gold, platinum group
metals, silver, zinc, nickel, cobalt, molybdenum, rare earth
metals, rhenium, uranium and mixtures thereof. Various
25 aspects and embodiments ofthe present invention prove especially
advantageous in connection with the recovery of copper
from copper-bearing sulfide ores, such as, for example,
chalcopyrite (CuFeS2 ), chalcocite (Cu2 S), bornite
(CusFeS4 ), covellite (CuS), enargite (Cu3AsS4 ), digenite
30 (Cu9 SS ), and/or mixtures thereof.
In accordance with an exemplary embodiment of the
present invention, copper is the metal to be recovered from a
metal-bearing material, such as a copper sulfide concentrate.
35 One aspect of this exemplary embodiment involves use of a
copper sulfide concentrate produced by froth flotation. In
preparation for froth flotation, the metal-bearing material
feed stream is ground to a particle size suitable to liberate
mineral-bearing particles from gangue materials. However,
40 as noted above, other concentrates may also be utilized.
Metal-bearing material 101 may be prepared for metal
recovery processing in any manner that enables the conditions
of metal-bearing material 101 to be suitable for the
chosen processing method, as such conditions may affect the
45 overall effectiveness and efficiency ofprocessing operations.
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
50 pressure leaching. 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 specifi-
55 cations.
DETAILED DESCRIPTION
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention exhibits significant advancements
over prior art processes, especially other so-called "direct
electrowinning" processes, particularly with regard to product
quality and process efficiency. Moreover, existing copper
recovery processes that use a conventional atmospheric or
pressure leaching, solvent/solution extraction, and electrowinning
process sequence may, in many instances, be easily 60
retrofitted to exploit the many commercial benefits the
present invention provides.
In one optional aspect ofan exemplary embodiment ofthe
invention, at least a portion of the acid generated during the
electrowinning stage as a copper-containing electrolyte 65
stream is transported out ofthe copper recovery process after
an optional separation step in which substantially all of the
rate copper from acid in the feed stream. For example, in
accordance with one aspect of an exemplary embodiment of
the invention, a copper precipitation step may be utilized to
precipitate solubilized copper from a lean electrolyte stream
onto the surfaces of solid particles in a copper-containing
material (e.g., finely ground chalcopyrite) stream in advance
of the pressure leaching step, thereby separating the copper
from the acid solution.
In accordance with various exemplary aspects of the
present invention, by providing for the electrowinning of
copper directly from a copper-containing solution without
first subjecting the copper-containing solution to solvent/solution
extraction, the present invention enables lower-cost
recovery of copper and reduces the expenses associated with
solvent/solution extraction, such as expenses associated with
reagents, process apparatus and equipment, and energy
resources. Furthermore, in accordance with one exemplary
aspect ofthe invention, careful control ofthe composition and
the dispersion ofthe copper-containing solution entering the
electrowinning circuit enables production of high quality,
uniformly-plated cathode copper. However, in accordance
with still other aspects of the present invention, one or more
process "bleed" streams may be subjected to solvent/solution
extraction or treatment in one or more liberator cells or other
similar processes, preferably following the electrowinning of
copper therefrom.
These and other advantages of a process according to vari0us
aspects and embodiments ofthe present invention will be
apparent to those skilled in the art upon reading and understanding
the following detailed description with reference to
the accompanying figures.
The subject matter of the present invention is particularly
pointed out and distinctly claimed in the concluding portion
of the specification. A more complete understanding of the
present invention, however, may best be obtained by referring
to the detailed description when considered in connection
with the drawing figures, wherein like numerals denote like
elements and wherein:
FIG. 1 illustrates a flow diagram of a copper recovery
process in accordance with an exemplary embodiment ofthe
present invention;
FIG. 2 illustrates a flow diagram of various aspects of a
copper recovery process in accordance with an alternative
embodiment of the present invention; and,
FIG. 3 illustrates a flow diagram of a copper recovery
process in accordance with an alternative embodiment ofthe
present invention.
US 7,462,272 B2
5 6
tively small fraction of copper, which can be used for leaching,
pH control, and/or other applications. Moreover, utilization
of a separation process may advantageously enable
removal of certain impurities. For example, because the
resultant acid stream is preferably removed from the metal
recovery process and utilized in remote operations, disposed
of, or attenuated, the impurities contained therein are likewise
removed from the metal recovery process and are thus prevented
from accumulating in the process stream. This may be
10 a significant advantage in that such impurities, particularly
metal impurities, typically have a deleterious effect on the
effectiveness and efficiency of the desired metal recovery
process. For example, metal impurities and other impurities
in the process stream, ifnot carefully controlled and/or mini-
15 mized, can contribute to diminished physical and/or chemical
properties in the cathode copper produced by electrowinning,
and can thus degrade the copper product and diminish its
economic value.
Referring again to FIG. 1, in accordance with one optional
20 aspect ofan exemplary embodiment ofthe invention, coppercontaining
material stream 101 is subjected to a separation
step, such as, for example, a precipitation step, which, in this
exemplary process, serves to precipitate solubilized copper
from a recycled lean electrolyte stream. As discussed in detail
25 above, this aspect offers an important advantage in that it
enables recovery ofcopper from a lean electrolyte stream that
otherwise may have been lost or would have required additional
processing to recover, potentially resulting in significant
economic benefits.
In accordance with an exemplary embodiment ofthe invention,
an optional precipitation step involves copper-containing
material stream 101 being combined with a lean electrolyte
stream 125 and, optionally, a sulfur dioxide (S02) stream
109 in a suitable processing vessel. For example, in the
35 embodiment illustrated in FIG. 1, lean electrolyte stream 125
may comprise a recycled acidic copper sulfate stream generated
during an electrowinning operation. Other streams, however,
preferably acidic streams, may also be used. While the
use of such other streams will be described in greater detail
40 hereinbelow, in accordance with various aspects of the
present invention, processing streams, preferably from electrowinning
operations, may be used. For example, in the
embodiments illustrated in FIGS. 1 and 3, multiple stage
electrowinning follows pressure leaching. While two such
45 electrowinning stages are illustrated, it will be appreciated
that additional stages may also be utilized in various applications.
However, lean electrolyte from either the first or second
electrowinning stage may be used as the recycled electrolyte
used in optional copper separation step 1010. Preferably,
50 however, and as is illustrated best in FIG. 3, a stream 123 from
the second electrowinning circuit 1090 is recycled to copper
separation step 1010.
In one aspect of an embodiment of the invention, lean
electrolyte stream 125 has an acid concentration of from
55 about 20 to about 200 grams/liter, preferably from about 70 to
about 180 grams/liter, and most preferably from about 140 to
about 170 grams/liter. In a further aspect ofthis embodiment
of the invention, lean electrolyte stream 125 has a copper
concentration of from about 20 to about 55 grams/liter, pref-
60 erably from about 25 to about 50 grams/liter, and most preferably
from about 30 to about 45 grams/liter. If utilized, in
copper precipitation stage 1010, copper from lean electrolyte
stream 125 precipitates to form a desired copper-rich concentrate.
Preferably, when used, precipitation is carried out such
65 that the copper from the lean electrolyte precipitates, at least
in part, in the form of a copper sulfide, such as, for example,
CuS. While not wishing to be bound by any particular theory,
desired because the reaction rate during precipitation and/or
leaching may increase as the surface area of the coppercontaining
material increases.
In accordance with one aspect of an exemplary embodiment
of the invention, satisfactory grinding of chalcopyrite
concentrate with an as-received particle size of approximately
98 percent passing about 172 microns may be
achieved using a grinding apparatus such as, for example, a
stirred horizontal shaft mill with baffles or a vertically stirred
mill without baffles. Exemplary apparatus include the Isamill
developed jointly by Mount Isa Mines (MIM), Australia, and
Netzsch Feinmahitechnik, Gennany and the SMD or Detritor
mill, manufactured by Metso Minerals, Finland. Preferably, if
a horizontal mill is utilized, the grinding medium would be
1.2/2.4 mm or 2.4/4.8 mm Colorado sand, available from
Oglebay Norton Industrial Sands Inc., Colorado Springs,
Colo. However, any grinding medium that enables the desired
particle size distribution to be achieved may be used, the type
and size of which may be dependent upon the application
chosen, the product size desired, grinding apparatus manufacturer's
specifications, and the like. Exemplary media
include, for example, sand, silica, metal beads, ceramic
beads, and ceramic balls.
In another optional aspect ofan exemplary embodiment of
the present invention, all or part ofthe metal-bearing material
feed stream may be combined with a liquid prior to entering
optional copper separation stage 1010 (described hereinbelow)
or copper leaching stage 1030. Preferably, the liquid
comprises water, but any suitable liquid may be employed,
such as, for example, raffinate, pregnant leach solution, or 30
lean electrolyte. For example, a portion of lean electrolyte
stream 125 from the direct electrowinning process may be
combined with metal-bearing material to fonn metal-bearing
material feed stream 10l.
The optional combination of a liquid with the metal-bearing
material can be accomplished using anyone or more of a
variety of techniques and apparatus, such as, for example,
in-line blending or using a mixing tank or other suitable
vessel. In accordance with an exemplary aspect ofan embodiment
ofthe invention, the concentration of solid metal-bearing
material in the material stream (i.e., the slurry density) is
on the order ofless than about fifty (50) percent by weight of
the stream, and preferably about forty (40) percent by weight
of the stream. Other slurry densities that are suitable for
transport and subsequent processing may, however, be used.
In accordance with another optional aspect of an exemplary
embodiment ofthe present invention, at least a portion
of the copper in a recycled stream of lean electrolyte from
electrowinning is separated from the acid in the stream,
thereby reducing the amount of impurities 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 solid or
soluble impurities from the copper-containing feed stream
and the recycled lean electrolyte stream. Any number ofconventional
or hereafter devised separation processes and techniques
may be useful to achieve the separation ofcopper from
acid in the lean electrolyte stream. For example, separation
processes and/or techniques such as precipitation, low temperature
pressure leaching, acid solvent/solution extraction!
ion exchange, membrane separation, cementation, pressure
reduction, sulfiding, and/or the use of liberator cells may be
useful for this purpose.
The optional separation aspect of an exemplary embodiment
ofthe invention contributes to providing a resultant acid
stream from copper separation step 1010 that contains a relaUS
7,462,272 B2
8
ment of the invention, product stream 102 is sent to a solidliquid
separation circuit 1020. In one aspect of an exemplary
embodiment of the invention, solid-liquid separation circuit
1020 preferably includes a thickener circuit 1021 comprising
at least one thickener that will effectuate solid-liquid separation.
In the illustrated embodiment, the underflow of 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 effluent acid stream 110 may be utilized, processed,
attenuated, impounded, and/or disposed of in a variety
ofways, the appropriate choice ofwhich is largely dependent
upon economic and regulatory factors. In one aspect of
the illustrated embodiment, the acid stream can be benefi-
15 cially used in, for example, a leaching operation, such as an
atmospheric leaching operation, where acid is required to
leach copper oxide, copper sulfide, or other metal oxide/
sulfur minerals. Such a leaching operation may be a heap
leach, a vat leach, a tank leach, a pad leach, or any other
20 similar operation or may be a medium or low-temperature
pressure leaching 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
25 (FIG. 1) is sent to an atmospheric pressure leach operation
2010. In accordance with one aspect ofan exemplary embodiment
ofthe invention, leach operation 2010 is a conventional
acid-consuming heap leach operation, wherein a copper ore
201 is contacted with acid stream 110 and, optionally, other
30 process streams, such as raffinate stream 206 from downstream
solvent/solution extraction unit 2020. In the example
of leach operation 2010 as a heap leach operation, the acid
percolates downward through the ore heap, solubilizing the
copper in the copper-containing ore in the form of copper
35 sulfate, to form a copper-rich pregnant leach solution (PLS)
stream 203. In the example of leach operation 2010 as a
pressure leach operation, acid aids in the solubilization of
copper in the feed material to form a PLS stream. PLS stream
203 is sent to a solvent/solution extraction unit, such as sol-
40 vent/solution extraction unit 2020 in FIG. 2, to produce a high
concentration and relatively pure copper sulfate solution suitable
for electrowinning of copper. In accordance with an
alternative aspect ofthe present invention illustrated in FIG.
2, PLS stream 203 may not be subjected to solvent/solution
45 extraction, but may instead be blended with other coppercontaining
process streams, and the resultant stream then sent
to a copper electrowinning circuit. For example, all or a
portion ofPLS stream 203 (broken line) may be blended with
copper-containing solution stream 106 and lean electrolyte
50 stream 115 in electrolyte recycle tank 1060 (from FIG. 1) to
form a resultant product stream suitable for copper electrowinning
in an electrowinning circuit.
Ifeffluent acid stream 110 is not used as an acid-containing
by-product or otherwise utilized, the acid may be attenuated
55 using, for example, acid-consuming gangue (i.e., mineral
processing tailings) or an attenuating agent, such as limestone
or lime. Attenuating with acid-consuming gangue can be
relatively inexpensive, as the attenuating reagent is essentially
free. On the other hand, attenuating with limestone or
60 lime may be less desirable economically, as both these
reagents will incur cost. Nevertheless, should attenuation be
desired, any method for acid attenuation now known or hereafter
devised may be employed.
In accordance with a further aspect ofthis embodiment of
65 the present invention, as previously briefly mentioned, acid
stream 110 advantageously may remove impurities from the
process, for example, the electrowinning process. Such impu-
CuFeS2+Cu+2---.,.Fe+2+2CuS
7
the chemical reaction during this exemplary copper precipitation
step-wherein, for example, the copper-containing
material is primarily chalcopyrite-is believed to be as follows:
Other copper minerals and other sulfides react to varying
degrees according to similar reactions, producing copper precipitates
and a weak sulfuric acid by-product. In accordance
with an optional aspect of the invention, copper separation 10
stage 1010 is carried out at a slightly elevated temperature,
such as from about 70° C. to about 180° c., preferably from
about 80° C. to about 100° c., and most preferably at a
temperature of about 90° C. Heating, if necessary, can be
effectuated through any conventional means, such as with
steam, electric heating coils, a heat blanket, process fluid heat
exchange, and other ways now known or later developed. In
the exemplary process of FIG. 1, steam generated in other
process areas, such as stream 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 optional copper separation process
can vary, depending on factors such as the operating
temperature ofthe processing vessel and the size distribution!
surface area of the composition of the copper-containing
material, but typically ranges from about two (2) minutes to
about six (6) hours. Preferably, conditions are selected such
that significant amounts of copper are precipitated. For
example, precipitation rates on the order of about 98% precipitation
ofcopper have been achieved in processing vessels
maintained at about 90° C. for about 4 hours.
Other parameters to consider when conditioning the copper-
containing material feed stream for processing are (i) the
ratio ofsolid particles in the feed stream to the total volume of
the copper-containing solution feed stream; (ii) the ratio of
copper in solution to copper-containing material; (iii) temperature;
(iv) pressure; (v) viscosity; (vi) slurry density ofthe
feed stream; and (vii) other factors may be suitably addressed.
Although these parameters mayor may not be significant to
the overall efficiency ofprocessing operations downstream in
all cases, these parameters can affect equipment size and
material specifications, energy requirements, and other
important aspects ofprocess design. Thus, calculated adjustment
of these stream parameters in advance of complex or
resource-intensive processing stages can positively affect the
economic efficiency ofthe chosen process. Solid-liquid separation
systems, such as, for example, filtration systems,
counter-current decantation (CCD) circuits, thickeners, and
the like are useful in adjusting these parameters and are
widely used in the industry.
In one aspect ofthe embodiment ofthe invention illustrated
in FIG. 1, product stream 102, which generally contains covellite/
chalcopyrite particles and acid, contains acid generated
in pressure leaching stage 1030, first electrowinning stage
1070, and second electrowinning stage 1090, and any acid
generated in optional copper separation stage 1010 as a result
ofS02 ·
In accordance with an exemplary aspect of the invention,
the copper-containing material stream entering the pressure
leaching stage contains from about 10 and about 50 percent
solids by weight, preferably from about 20 to about 40 percent
solids by weight. To adjust the solids concentration of
product stream 102 in accordance with the desired parameters
and to separate the acid-bearing solution from the coppercontaining
solids, in accordance with an exemplary embodiUS
7,462,272 B2
9 10
2CU2S+502+2H2S04~4CuS04+2H20
2CuS+2H2SO4+02~2Cu+2+2S04-2+2H20+2SC
4CuFeS2+4H2S04+502~4CuS04+2Fe203+8SC+
4H20
Ifdesired, conditions during pressure leaching can be controlled
such that a portion ofthe sulfide sulfur contained in the
feed stream is converted to elemental sulfur instead ofsulfate.
The fraction of chalcopyrite and covellite that fonn sulfur
instead of sulfate are believed to react according to the following
reactions:
Pressure leaching, for example in pressure leaching vessel
1031, preferably occurs in a manner suitably selected to promote
the solubilization of copper using these (or other) processes.
In general, temperature and pressure in the pressure
leaching vessel should be carefully controlled. For example,
in accordance with one aspect of the invention, the temperature
of pressure leaching vessel 1031 is maintained at from
about 100° C. to about 250° c., preferably from about 140° C.
to about 235° C. In accordance with one aspect of one
embodiment of the invention, the temperature of pressure
leaching vessel 1031 is advantageously maintained at from
about 140° C. to about 180° C. or in the range of from about
150° C. to about 175° C. In accordance with anotherembodiment
of the invention, the temperature of pressure leaching
60 vessel 1031 is advantageously maintained between from
about 200° C. to about 235° C. or in the range of from about
210° C. to about 225° C.
In accordance with one aspect of the present invention,
during pressure leaching in pressure leaching vessel 1031,
sufficient oxygen 112 is injected into the vessel to maintain an
oxygen partial pressure from about 50 to about 250 psig,
preferably from about 75 to about 220 psig, and most prefertions
similar to an electrolyte stream resulting from a solvent/
solution extraction circuit-that is, the copper-containing
solution preferably is suitable for processing in an electrowinning
circuit. Any suitable technique or combination oftechniques
that yields an appropriate copper-containing solution
without employing solvent/solution extraction techniques
may be used. In an exemplary embodiment of the invention,
as illustrated in FIG. 1, pressure leaching feed stream 103 is
subjected to a pressure leaching stage 1030 to yield copper-
10 containing product slurry 104.
In accordance with one aspect of this embodiment of the
present invention, pressure leaching feed stream 103 is transported
to a suitable vessel for pressure leaching, which can be
any vessel suitably designed to contain the process compo-
15 nents at the desired temperature and pressure conditions for
the requisite processing residence time. In an exemplary
embodiment, a pressure leaching vessell 031 is employed for
this purpose. Pressure leaching vessel 1031 is preferably a
horizontal multi-compartment, agitated vessel; however,
20 other vessel configuration and agitation alternatives now
known or hereafter devised may be employed. It should be
appreciated that any pressure leaching vessel that suitably
permits pressure leaching feed stream 103 to be prepared for
copper recovery may be utilized within the scope of the
25 present invention.
Generally, the chemical conversions that occur during
pressure leaching stage 1030 under certain conditions for the
solubilization of the copper in copper-containing materials,
such as chalcopyrite, chalcocite, or covellite are as follows:
rities include, without limitation, iron, aluminum, manganese,
magnesium, sodium, potassium, and other metal ions,
often present as sulfates. In the absence of removal, such
impurities may accumulate to deleterious levels, and, as such
negatively impact production efficiencies and product (i.e.,
copper cathode) quality. The presence of such impurities in
acid stream 110 generally does not negatively impact the
aforementioned handling of acid stream 110.
In accordance with one aspect of an exemplary embodiment
of the invention illustrated in FIG. 2, solvent/solution
extraction unit 2020 purifies copper-bearing PLS stream 203
from the heap leach in two unit operations-an extraction
operation, which may have multiple stages, followed by a
stripping operation. In the extraction stage, PLS stream 203 is
contacted with an organic phase consisting of a diluent (e.g.,
kerosene) in which a copper selective extractant reagent (i.e.,
the extractant) is dissolved. When the solutions are contacted,
the organic extractant chemically removes the copper from
the PLS, forming an aqueous raffinate stream. The raffinate
and organic streams are subsequently separated in a settler.
After separation of the organic and aqueous phases in the
settler, a portion of the aqueous phase (stream 206) is typically
returned to one or more leaching operations to be
reloaded with copper from the ore in the atmospheric leaching
step 2010 to fonn the PLS. Optionally, a portion ofraffinate
stream 206 may be recycled to copper separation step
1010. The organic stream passes on to the second unit operation
of the solvent/solution extraction process, the stripping
operation. In the stripping operation, the organic stream is
contacted with a strongly acidic electrolyte. This acidic solu- 30
tion "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. Aqueous stream 204 is processed in electrow- 35
inning plant 2030 to yield cathode copper 207 and a coppercontaining
lean electrolyte stream 208, which, in one aspect
of an exemplary embodiment of the invention, may be
recycled in part to solvent/solution extraction unit 2020.
In accordance with one alternative aspect ofthe invention, 40
aqueous stream 204 may not be subjected to electrowinning
immediately after leaving the solvent/solution extraction
unit, but may instead be blended with other copper-containing
process streams, and the resultant stream then sent to an
electrowinning circuit. For example, all or a portion of aque- 45
ous stream 204 (broken line) may be blended with coppercontaining
solution stream 106 and lean electrolyte stream
115 in electrolyte recycle tank 1060 (from FIG. 1) to fonn a
resultant product stream suitable for electrowinning in an
electrowinning circuit 1070. In such cases the stripping solu- 50
tions used in solvent/solution extraction 2020 likely will be
comprised of spent electrolyte from electrowinning circuit
1070.
Referring again to FIG. 1, the underflow slurry from thickener
circuit 1021, pressure leaching feed stream 103 in this 55
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.
In a further aspect ofthe present invention, the conditioned
copper-containing feed stream preferably is subjected to a
suitable process, such as pressure leaching, to produce product
slurry 104, which comprises a copper-containing solution
106 and a residue 114. The process may be selected as 65
desired, but, in general, enables production of a copper-containing
solution 106 that exhibits copper and acid concentraUS
7,462,272 B2
11 12
much the same way that the copper-containing material feed
stream is conditioned for processing in accordance with
above-described aspects ofthe invention, the copper-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 conditioned coppercontaining
solution will contain a relatively high concentra-
10 tion of copper in an acid solution and will contain relatively
few impurities. Preferably, the conditions of copper-containing
solution entering the electrowinning circuit are kept at a
constant level to enhance the quality and nniformity of the
cathode copper product.
In an exemplary aspect of the invention, conditioning of a
copper-containing solution for electrowinning begins by
adjusting certain physical parameters of the product slurry
from the previous processing step. In an exemplary embodiment
ofthe invention wherein the previous processing step is
20 pressure leaching, it is desirable to reduce the temperature
and pressure ofthe product slurry.An exemplary method ofso
adjusting the temperature and pressure characteristics of the
preferred product slurry is atmospheric flashing.
Thus, in accordance with an exemplary aspect of the
25 embodiment illustrated in FIG. 1, product slurry 104 from
pressure leaching vessel 1031 is flashed in an atmospheric
flash tank 1040 or other suitable atmospheric system to
release pressure and to evaporatively cool the product slurry
104 through the release of steam to form a flashed product
30 slurry 105. Flashed product slurry 105 preferably has a temperature
ranging from about 900 C. to about 101 0 c., a copper
concentration of from about 40 to about 120 grams/liter, and
an acid concentration of from about 10 to about 60 grams/
liter. In one aspect ofthe invention, however, flashed product
35 slurry 105 also contains a particulate solid residue containing,
for example, the iron oxide by-product of pressure leaching,
elemental sulfur, precious metals and other components that
are nndesirable for a feed stream to an electrowinning circuit.
Thus, in accordance with the same principles discussed
40 above, it is desirable to subject the flashed product slurry to a
solid-liquid separation process, such that the liquid portion of
the slurry-the desired copper-containing solution-preferably
is separated from the solid portion of the slurry, which
may be subjected to further processing.
Referring again to FIG. 1, in the illustrated embodiment of
the invention flashed product slurry 105 is directed to a solidliquid
separation stage 1050, such as a CCD circuit 1051. In
an alternative embodiment ofthe invention, solid-liquid separation
stage 1050 may comprise, for example, a thickener or
50 a filter. A variety of factors, such as the process material
balance, environmental regulations, residue composition,
economic considerations, and the like, may affect the decision
whether to employ a CCD circuit, a thickener, a filter, or
other suitable device in solid-liquid separation stage 1050. In
55 one aspect of an exemplary embodiment of the invention,
CCD circuit 1051 uses conventional countercurrent washing
ofthe residue stream with wash water 113 to recover leached
copper to the copper-containing solution product and to minimize
the amount of soluble copper advancing to either pre-
60 cious metal recovery processes or residue disposal. Preferably,
large washratios are used to enhance the effectiveness of
solid-liquid separation stage 1050-that is, relatively large
amounts ofwash water 113 are added to the residue in CCD
circuit 1051. Preferably, the solution portion of the residue
65 slurry stream is diluted by wash water 113 in CCD circuit
1051 to a copper concentration of from about 5 to about 200
parts per million (ppm) in the solution portion of residue
ably from about ISO to about 200 psig. Furthermore, due to
the nature ofmedium temperature pressure leaching, the total
operating pressure (including oxygen partial pressure and
steam pressure) in the pressure leaching vessel is generally
superatmospheric, preferably from about 100 to about 750
psig, more preferably from about 250 to about 400 psig, and
most preferably from about 270 to about 350 psig.
Because pressure leaching of many metal sulfides is a
highly exothermic process and the heat generated is generally
greater than that required to heat pressure leaching feed
stream 103 to the desired operating temperature, cooling liquid
111 is preferably contacted with pressure leaching feed
stream 103 in pressure leaching vessel 1031 during pressure
leaching. Cooling liquid 111 is preferably process water, but
can be any suitable cooling fluid from within the refining 15
process or from an outside source. In an exemplary embodiment
of the invention, a sufficient amount of cooling liquid
111 is added to pressure leaching vessel 1031 to yield a solids
content in the product slurry 104 ranging from about 3 to
about IS percent solids by weight. In accordance with one
aspect of the present invention, and with momentary reference
to FIG. 3, cooling ofthe pressure leaching vessel can be
accomplished by recycling lean electrolyte 123 from one or
more of the subsequent electrowinning stages. For example,
as illustrated in FIG. 3, preferably a lean electrolyte stream
108 is directed from the first electrowinning circuit 1070 to
pressure leaching step 1031.
The residence time for pressure leaching generally
depends on a number offactors, including the composition of
the copper-containing feed stream, its particle size, and the
operating pressure and temperature of the pressure leaching
vessel. In one aspect of an exemplary embodiment of the
invention, the residence time for the pressure leaching of
chalcopyrite ranges from about 30 to about 180 minutes,
more preferably from about 60 to about ISO minutes, and
most preferably on the order of about 80 to about 120 minutes.
In accordance with an exemplary aspect of the present
invention, medium temperature pressure leaching of stream
103 is performed in the presence of a dispersing agent 127.
Suitable dispersing agents useful in accordance with this
aspect ofthe present invention include, for example, organic
compounds such as lignin derivatives, such as, for example,
calcium and sodium lignosulfonates, tannin compounds,
such as, for example, quebracho, orthophenylene diamine 45
(OPD), alkyl sulfonates, such as, for example, sodium alkyIbenzene
sulfonates, and combinations ofthe above. Dispersing
agent 127 may be any compound that resists degradation
in the temperature range of medium temperature pressure
leaching (i.e., from about 1400 C. to about 1800 C.) long
enough to disperse the elemental sulfur produced during the
medium temperature pressure leaching process and that
achieves the desired result of preventing elemental sulfur
from passivating copper values, which may reduce copper
extraction. Dispersing agent 127 may be introduced to the
pressure leaching vessel in an amount and/or at a concentration
sufficient to achieve the desired result. In one aspect ofan
exemplary embodiment ofthe invention, favorable results are
achievable during pressure leaching of chalcopyrite using
calcium lignosulfonate in an amount of about 2 to about 20
kilograms per tonne, and more preferably in an amount of
about 4 to about 12 kilograms per tonne; and more preferably
in an amount of about 6 to about 10 kilograms per tonne of
chalcopyrite concentrate.
In another aspect of the present invention, the coppercontaining
solution is conditioned for electrowinning through
one or more chemical and/or physical processing steps. In
US 7,462,272 B2
13 14
Cathode half-reaction: Cu2++2e---""CUO
2CUS04+2H2°--<>2Cu'+2H2S04+02
Anode half-reaction: 2H20--<>4H++02+4e-
Turning again to FIG. 1, in an exemplary embodiment the
invention, product stream 107 is directed from electrolyte
recycle tank 1060 to an electrowinning circuit 1070, which
contains one or more conventional electrowinning cells. It
should be understood, however, that any method and/or apparatus
currently known or hereinafter devised suitable for the
electrowinning of copper from acid solution, in accordance
with the above-referenced reactions or otherwise, is within
the scope of the present invention.
In accordance with an exemplary aspect of the invention,
electrowinning circuit 1070 yields a cathode copper product
116, optionally, an off gas stream 117, and a relatively large
volume of copper-containing acid, herein designated as lean
electrolyte streams 108 and 115. As discussed above, in the
embodiment illustrated in FIG. 1, lean electrolyte stream 108
may be introduced to electrolyte recycle tank 1060 for blending,
such as, for example, PLS stream 203 (FIG. 2) or a
portion oflean electrolyte stream 123 from second electrowinning
circuit 1090 (FIG. 3).
Referring again to FIG. 1, preferably, the copper composition
of product stream 107 is maintained substantially constant.
While product stream 107 may contain a copper concentration
up to the copper solubility limit under the
prevailing conditions, preferably product stream 107 has a
10 copper concentration ofabout 15 to about 80 grams/liter, and
more preferably ofabout 20 to about 60 grams/liter, and often
above 30 grams/liter. In one aspect of an exemplary embodiment
ofthe invention, control valves are positioned on each of
the pipelines feeding lean electrolyte stream 115 and copper-
15 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 various aspects ofthe invention,
20 a process is provided wherein, upon proper conditioning of a
copper-containing solution, a high quality, uniformly-plated
cathode copper product 116 may be realized without subjecting
the copper-containing solution to a solvent/solution
extraction process prior to entering the electrowinning cir-
25 cuit.
As those skilled in the art are aware, a variety of methods
and apparatus are available for the electrowinning of copper
and other metal values, any ofwhich may be suitable for use
in accordance with the present invention, provided the requi-
30 site process parameters for the chosen method or apparatus
are satisfied. For the sake of convenience and a broad understanding
of the present invention, an electrowinning circuit
useful in connection with various embodiments ofthe invention
may comprise an electrowinning circuit, constructed and
35 configured to operate in a conventional manner. The electrowinning
circuit may include electrowinning cells constructed
as elongated rectangular tanks containing suspended
parallel flat cathodes ofcopper alternating with flat anodes of
lead alloy, arranged perpendicular to the long axis ofthe tank.
40 A copper-bearing leach solution may be provided to the tank,
for example at one end, to flow perpendicular to the plane of
the parallel anodes and cathodes, and copper can be deposited
at the cathode and water electrolyzed to form oxygen and
protons at the anode with the application of current.
The primary electro chemical reactions for electrowinning
of copper from acid solution are believed to be as follows:
stream 114. In accordance with one aspect of an exemplary
embodiment ofthe invention, addition of a chemical reagent
to solid-liquid separation stage 1050 may be desirable to
remove deleterious constituents from the process stream. For
example, a polyethylene oxide may be added to effectuate
removal of silica by precipitation, or other flocculants and/or
coagulants might be utilized to remove other undesirable
species from the process stream. One such suitable chemical
reagent is POLYOXTM WSR-301, available from Dow
Chemical.
Depending on its composition, residue stream 114 from
solid-liquid separation stage 1050 may be impounded, disposed
of, or subjected to further processing, such as, for
example, precious metal recovery. For example, if residue
stream 114 contains economically significant amounts of
gold, silver, and/or other precious metals, it may be desirable
to recover this gold fraction through a cyanidation process or
other suitable recovery process now known or hereafter
devised. If gold or other precious metals are to be recovered
from residue stream 114 by cyanidation techniques, the content
ofimpurities in the stream, such as elemental sulfur, iron
precipitates, unreacted copper minerals, acid, and soluble
copper and soluble impurities, is preferably minimized. Such
materials may promote high reagent consumption in the cyanidation
process and thus increase the expense ofthe precious
metal recovery operation. As mentioned above, it is therefore
preferable to use a large amount ofwash water or other diluent
during the solid-liquid separation process to maintain low
copper and acid levels in the solids-containing residue stream
in an attempt to optimize the conditions for subsequent precious
metal recovery.
As previously noted, careful control ofthe conditions of a
copper-containing solution entering an electrowinning circuit-
especially maintenance ofa substantially constant copper
composition---can enhance the quality of the electrowon
copper by, among other things, enabling even plating of copper
on the cathode and avoidance of surface porosity in the
cathode copper, which degrades the copper product and thus
may diminish its economic value. In accordance with this
aspect of the invention, such process control can be accomplished
using any of a variety of techniques and equipment
configurations, so long as the chosen system and/or method
maintains a sufficiently constant feed stream to the electrowinning
circuit.
Referring again to FIG. 1, in an exemplary aspect of the 45
invention, copper-containing solution stream circuit 106
from solid-liquid separation stage 1050 is sent to an electrolyte
recycle tank 1060. Electrolyte recycle tank 1060 suitably
facilitates process control for first electrowinning circuit
1070, as will be discussed in greater detail below. Copper- 50
containing solution stream 106, which generally contains
from about 40 to about 120 grams/liter of copper and from
about 10 to about 60 grams/liter acid, is preferably blended
with a lean electrolyte stream 115 in electrolyte recycle tank
1060 at a ratio suitable to yield a product stream 107, the 55
conditions ofwhich may be controlled to optimize the resultant
product of first electrowinning circuit 1070.
Referring briefly to an alternative embodiment of the
invention illustrated in FIG. 2, an additional lean electrolyte
stream 205 may be blended with lean electrolyte stream 115 60
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 ofthis alternative embodiment, lean electrolyte stream 65
205 preferably has a composition similar to that oflean electrolyte
stream 115. Further, as discussed above, other streams
US 7,462,272 B2
15 16
(which may also comprise a portion of the lean electrolyte
produced in first electrowinning circuit 1070).
In accordance with various exemplary embodiments ofthe
invention as illustrated in FIG. 3, lean electrolyte stream 123
is directed optionally, wholly or in part to electrolyte recycle
tank 1080, electrolyte recycle tank 1060, and/or to copper
precipitation stage 1010. Those skilled in the art will appreciate
the ability to effectively manage stream flow control to
other streams and operations of the invention. Although not
10 illustrated as such in FIGS. 1 and 3, at least a portion of lean
electrolyte stream 123 may optionally be directed for further
processing in accordance with a process such as that illustrated
in FIG. 2.
The present invention has been described above with ref-
15 erence to a number of exemplary embodiments. It should be
appreciated that the particular embodiments shown and
described herein are illustrative of the invention and its best
mode and are not intended to limit in any way the scope ofthe
invention. Those skilled in the art having read this disclosure
20 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
25 metals from metal-containing materials. Further, although
certain preferred aspects of the invention, such as techniques
and apparatus for conditioning process streams and for precipitation
of copper, for example, are described herein in
tenns of exemplary embodiments, such aspects ofthe inven-
30 tion 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.
What is claimed is:
1. A method of recovering copper from a copper-bearing
material, comprising the steps of:
providing a feed stream containing copper-containing
material and acid;
subjecting the feed stream to pressure leaching at a temperature
of from about 100° C. about 250° C. to yield a
product slurry comprising a copper-bearing solution and
a residue;
conditioning said product slurry through one or more
chemical or physical conditioning steps to yield a copper-
containing solution suitable for electrowinning;
electrowinning copper from at least a portion of said copper-
containing solution in a first electrowinning stage to
produce copper cathode and a first stage lean electrolyte
stream, without subjecting the copper-containing solution
to solvent/solution extraction;
electrowinning copper from at least a portion of said first
stage lean electrolyte stream in a second electrowinning
stage to produce copper cathode and a second stage lean
electrolyte stream; and
recycling at least a portion of said first stage lean electrolyte
stream to said pressure leaching step.
2. The method ofclaim 1, wherein said step of providing a
feed stream comprising a copper-bearing material comprises
providing a feed stream comprising a copper-bearing sulfide
60 ore, concentrate, or precipitate.
3. The method ofclaim 1, wherein said step of providing a
feed stream comprising a copper-bearing material comprises
providing a feed stream comprising at least one of chalcopyrite,
chalcocite, bornite, covellite, digenite, and enargite, or
65 mixtures or combinations thereof.
4. The method ofclaim 1, wherein said step of providing a
feed stream comprising a copper-bearing material comprises
may be directed to copper precipitation stage 1010 via lean
electrolyte stream 125 (which, as discussed hereinbelow, may
comprise a portion oflean electrolyte stream 123 from second
electrowinning circuit 1090), and lean electrolyte stream 115
is directed to electrolyte recycle tank 1060.As those skilled in
the art are aware, it may be preferable to regulate the flow
amount, flow direction or other aspects ofthe lean electrolyte
streams directed from electrowinning circuit 1070 to further
maximize the efficiency of the described invention.
In accordance with an exemplary aspect of an alternative
preferred embodiment, a portion of lean electrolyte stream
108 is directed to pressure leaching feed stage 1031. Lean
electrolyte stream 108 may exhibit copper concentration sufficient
to combine with pressure leaching feed stream 103 to
further maximize the operational and economic efficiency of
the present invention. In addition, as briefly noted above,
stream 108 may provide suitable cooling liquid to pressure
leaching step 1031.
Again referring to FIG. 3, in an exemplary alternative to an
aspect of the invention, all of copper-containing stream 106
may not be directed to electrolyte recycle tank 1060. To
achieve optimum operational and economic efficiency in
accordance with various embodiments of the present invention,
it may be desirable to direct a portion ofcopper-containing
feed stream 106 to operations other than electrowinning.
As depicted in FIG. 3, a portion of copper-containing stream
106 may be directed to pressure leaching feed stream 103.
Moreover, a portion ofcopper-containing stream 106 may be
directed to precipitation stage 1010.
Referring back again to FIG. 1, electrolyte stream 120 from
first electrowinning circuit 1070-which comprises at least a
portion of the lean electrolyte produced in first electrowinning
circuit 1070 that is not recycled to other process operations-
is subjected to further processing in a second elec- 35
trowinning circuit 1090. In an exemplary aspect of the
embodiment, lean electrolyte stream 120 is sent to electrolyte
recycle tank 1080. Electrolyte recycle tank 1080 suitably
facilitates process control for electrowinning circuit 1090, as
will be discussed in greater detail below. Lean electrolyte 40
stream 120, which generally contains from about 20 to about
40 grams/liter of copper and from about 100 to about 180
grams/liter ofacid, is preferably blended with lean electrolyte
stream 123 from second electrowinning circuit in electrolyte
recycle tank 1080 at a ratio suitable to yield a product stream 45
121, the conditions of which may be chosen to optimize the
resultant product of electrowinning circuit 1090.
With reference to FIG. 1, copper from the product stream
121 is suitably electrowon to yield a pure, cathode copper
product. In accordance with various aspects ofthe invention, 50
a process is provided wherein, upon proper conditioning of a
copper-containing solution, a high quality, unifonnly-plated
cathode copper product 122 may be realized without subjecting
the copper-containing solution to a solvent/solution
extraction process prior to entering the electrowinning cir- 55
cuit.
In furtherance of an exemplary aspect of the embodiment,
second electrowinning circuit 1090 yields a cathode copper
product 122, offgas, and a remainder volume of copper-containing
acid, designated in FIG. 1 as lean electrolyte stream
123. In accordance with one exemplary embodiment, at least
a portion oflean electrolyte stream 123 is directed to electrolyte
recycle tank 1080 in an amount suitable to yield a product
stream 121, the conditions of which may be chosen to optimize
the resultant product of second electrowinning circuit
1090. Optionally, a portion oflean electrolyte stream 123 may
be recycled to copper separation stage 1010 via stream 125
US 7,462,272 B2
17 18
* * * * *
14. The method of claim 1, wherein said conditioning step
further comprises blending at least a portion of said copperbearing
solution with at least a portion ofone or more copperbearing
streams to achieve a desired copper concentration in
said copper-bearing solution.
15. The method of claim 1, wherein said step of electrowinning
copper from at least a portion of said first stage lean
electrolyte stream in a second electrowinning stage comprises
electrowinning copper from at least a portion of said
10 first stage lean electrolyte stream without subjecting said first
stage lean electrolyte stream to solvent/solution extraction.
16. The method of claim 5, wherein said step of electrowinning
copper from at least a portion of said first stage lean
electrolyte stream in a second electrowinning stage com15
prises electrowinning copper from at least a portion of said
first stage lean electrolyte stream without subjecting said first
stage lean electrolyte stream to solvent/solution extraction.
17. The method of claim 1, further comprising the step of
using a portion ofsaid second stage lean electrolyte stream in
20 a leaching operation.
18. The method of claim 5, further comprising the step of
recycling a portion of said second stage lean electrolyte
stream to said separating step.
19. A method of recovering copper from a copper-bearing
25 material, comprising the steps of:
providing a feed stream containing copper-containing
material and acid;
subjecting the copper-containing feed stream to pressure
leaching to yield a product slurry comprising a copperbearing
solution and a residue;
conditioning the product slurry through one or more
chemical or physical conditioning steps to yield a copper-
containing solution suitable for electrowinning;
electrowinning copper from the copper-containing solution
in a first electrowinning stage to produce copper
cathode and a first stage lean electrolyte stream, without
subjecting the copper-containing solution to solvent/solution
extraction;
recycling a portion ofsaid first stage lean electrolyte stream
to said pressure leaching step;
electrowinning copper from a portion of said first stage
lean electrolyte stream in a second electrowinning stage
to produce copper cathode and a second stage lean electrolyte
stream;
recycling a portion of said second stage lean electrolyte
stream to said pressure leaching step.
providing a feed stream comprising a copper-bearing material
and a solution stream comprising copper and acid.
5. The method of claim 1, further comprising the step of
separating at least a portion of said copper-containing material
from said acid in said feed stream to yield a coppercontaining
feed stream comprising a copper-bearing material.
6. The method of claim 5, wherein said separating step
comprises reacting at least a portion ofthe copper in a coppercontaining
electrolyte stream to precipitate at least a portion
ofsaid copper in said copper-containing electrolyte stream as
copper sulfide in said feed stream.
7. The method of claim 5, wherein said separating step
comprises reacting at least a portion ofthe copper in a coppercontaining
electrolyte stream in the presence of sulfur dioxide,
whereby at least a portion of said copper in said coppercontaining
electrolyte stream precipitates as copper sulfide in
said feed stream.
8. The method ofclaim 1, wherein said leaching step comprises
leaching at least a portion of said feed stream in a
pressure leaching vessel at a temperature of from about 1400
C. about 1800 C. and at a total operating pressure of from
about 100 psi to about 750 psi.
9. The method ofclaim 1, wherein said leaching step comprises
leaching at least a portion of said feed stream in a
pressure leaching vessel at a temperature of from about 2000
C. about 2350 C. and at a total operating pressure of from
about 100 psi to about 750 psi.
10. The method of claim 1, wherein said step of pressure
leaching said feed stream comprises pressure leaching said 30
feed stream in the presence of a surfactant selected from the
group consisting of lignin derivatives, orthophenylene
diamine, alkyl sulfonates, and mixtures thereof.
11. The method of claim 1, wherein said step of pressure
leaching said feed stream comprises pressure leaching said 35
feed stream in the presence of a surfactant in an amount of
from about 2 to about 20 kilograms per tonne of concentrate
in the copper-containing feed stream.
12. The method ofclaim 1, wherein said conditioning step
further comprises blending at least a portion of said copper- 40
containing solution with at least a portion of a copper-containing
electrolyte stream to achieve a copper concentration
of from about 15 to about 80 grams/liter in said coppercontaining
solution.
13. The method ofclaim 1, wherein said conditioning step 45
comprises subjecting at least a portion of said product slurry
to solid-liquid separation, wherein at least a portion of said
copper-bearing solution is separated from said residue.