111111111111111111111111111111111111111111111111111111111111111111111111111
US006680034B2
(12) United States Patent
Marsden et al.
(10) Patent No.:
(45) Date of Patent:
US 6,680,034 B2
Jan. 20,2004
(73) Assignee: Phelps Dodge Corporation, Phoenix,
AZ (US)
(56) References Cited
U.S. PATENT DOCUMENTS
(54) METHOD FOR RECOVERING METAL
VALUES FROM METAL-CONTAINING
MATERIALS USING HIGH TEMPERATURE
PRESSURE LEACHING
(21) Appi. No.: 09/912,922
(22) Filed: Jul. 25, 2001
(65) Prior Publication Data
us 2002/0034465 A1 Mar. 21,2002
4,266,972 A 5/1981 Redondo-Abad et al.
4,272,341 A 6/1981 Lamb
4,338,168 A 7/1982 Stanley et al.
4,405,569 A 9/1983 Dienstbach
4,415,540 A 11/1983 Wilkomirsky et al.
4,442,072 A 4/1984 Baglin et al.
4,507,268 A 3/1985 Kordosky et al.
4,571,264 A 2/1986 Weir et al.
4,619,814 A 10/1986 Salter et al.
4,775,413 A 10/1988 Horton et al.
4,814,007 A 3/1989 Lin et al.
4,875,935 A 10/1989 Gross et al.
4,880,607 A 11/1989 Horton et al.
4,892,715 A 1/1990 Horton
4,895,597 A 1/1990 Lin et al.
4,971,662 A 11/1990 Sawyer et al.
4,992,200 A 2/1991 Lin et al.
5,028,259 A 7/1991 Lin et al.
5,059,403 A 10/1991 Chen
5,073,354 A 12/1991 Fuller et al.
5,176,802 A 1/1993 Duyvesteyn et al.
5,223,024 A 6/1993 Jones
5,316,567 A 5/1994 Jones
5,356,457 A 10/1994 Alvarez et al.
5,670,035 A 9/1997 Virnig et al.
5,698,170 A 12/1997 King
5,730,776 A 3/1998 Collins et al.
5,770,170 A 6/1998 Collins et al.
5,849,172 A 12/1998 Allen et al.
5,869,012 A 2/1999 Jones
5,895,633 A 4/1999 King
5,902,474 A 5/1999 Jones
5,917,116 A 6/1999 Johnson et al.
5,989,311 A 11/1999 Han et al.
5,993,635 A 11/1999 Hourn et al.
FOREIGN PATENT DOCUMENTS
AU 0219785 12/1958
AU 219785 12/1958
WO WO 01/00889 A1 1/2001
OTHER PUBLICATIONS
Subject to any disclaimer, the term of this
patent is extended or adjusted under 35
U.S.c. 154(b) by 148 days.
(75) Inventors: John O. Marsden, Phoenix, AZ (US);
Robert E. Brewer, Safford, AZ (US);
Joanna M. Robertson, Thatcher, AZ
(US); Wayne W. Hazen, Lakewood,
CO (US); Philip Thompson, West
Valley City, UT (US); David R.
Baughman, Golden, CO (US)
Related U.S. Application Data
(60) Provisional application No. 60/220,622, filed on Jul. 25,
2000.
(51) Int. CI? C22B 15/00
(52) U.S. Cl. 423/24; 423/26; 205/580;
205/581
(58) Field of Search 423/24, 27, 26;
205/580, 581
( *) Notice:
20 Claims, 3 Drawing Sheets-
Primary Examiner~teven Bos
(74) Attorney, Agent, or Firm~nell & Wilmer, LLP
The present invention relates generally to a process for
recovering copper and other metal values from metalcontaining
materials through pressure leaching operations.
In accordance with the various aspects of the present
invention, metal-containing pregnant leach solutions from
pressure leaching operations need not be significantly
diluted to facilitate effective metal recovery using solvent
extraction and electrowinning.
G. M. Ritcey, et aI., "Solvent Extraction, Principles and
Applications to Process Metallurgy," Part II, 1979, pp.
218-221, no month.
Jan Szymanowski, Ph. D., "Hydroxyoximes and Copper
Hydrometallurgy," CRC Press, 6 pages, no date.
Dalton, et aI., "The CUPREX Process-a new chloridebased
hydrometallurgical process for the recovery of copper
from sulphidic ores," 11 pages, 1987, no month.
(List continued on next page.)
(57) ABSTRACT
7/1966 Zimmerley et al.
9/1970 Green
1/1972 Mackiw et al.
4/1972 Barry et al.
6/1972 Spedden et al.
2/1975 Lindblad et al.
7/1975 Dubeck et al.
4/1976 Pawlek et al.
5/1976 Anderson
6/1976 Parker et al.
6/1976 Touro
10/1976 Kunda et al.
11/1976 Queneau et al.
4/1977 Johnson
4/1977 Ackerley et al.
6/1977 Domic et al.
6/1977 Faugeras
8/1977 Wong
8/1977 Stanley et al.
9/1977 Subramanian et al.
1/1978 Wong
5/1978 Riggs et al.
10/1978 Fountain et al.
4/1979 Dain
6/1979 Weir et al.
8/1979 Reynolds
3/1981 Baczek et al.
3,260,593 A
3,528,784 A
3,637,371 A
3,656,888 A
3,669,651 A
3,868,440 A
3,896,208 A
3,949,051 A
3,958,985 A
3,961,028 A
3,962,402 A
3,985,553 A
3,991,159 A
4,017,309 A
4,020,106 A
4,028,462 A
4,029,733 A
4,039,405 A
4,039,406 A
4,046,851 A
4,069,119 A
4,091,070 A
4,120,935 A
4,150,976 A
4,157,912 A
4,165,362 A
4,256,553 A
US 6,680,034 B2
Page 2
OlliER PUBLICATIONS
Evans, et aI., "International Symposium of Hydrometallurgy,"
Mar. 1, 1973, 2 pages.
Duyesteyn, et aI., "The Escondida Process for Copper Concentrates,"
1998, no month.
King, et aI., "The Total Pressure Oxidation of Copper
Concentrates," 1993, no month.
King, J. A., "Autoclaving of Copper Concentrates," paper
from COPPER 95, vol. III: Electrorefining and Hydrometallurgy
of Copper, International Conference held in Santiago,
Chile, Nov. 1995.
Mackiw, V. N., "Direct Acid Pressure Leaching of Chalcocite
Concentrate," vol. 19, No.2, Feb. 1967.
Hirsch, H. E., "Leaching of Metal Sulphides," Patents, UK,
No. 1,598,454, 1981, 7 pages, no month.
Chimielewski, T., "Pressure Leaching of a Sulphide Copper
Concentrate with Simultaneous Regeneration of the Leaching
Agent," Hydrometallurgy, vol. 13, No.1, 1984, pp.
63-72, no month.
Dannenberg, R. 0., "Recovery of Cobalt and Copper From
Complex Sulfide Concentrates," Government Report, 20
pages, Report No. BM RI 9138, U.S. Dept. of the Interior,
1987, no month.
Berezowsky, R.M.G.S., "The Commercial Status of Pressure
Leaching Technology," JOM, vol. 43, No.2, 1991, pp.
9-15 no month.
Hacki, R. P., "Effect of Sulfur-Dispersing Surfactants on the
Oxygen Pressure Leaching of Chalcopyrite," paper from
COPPER 95, vol. III, pp. 559-577, Met Soc of CIM, Nov.
1995.
Hackl, R.P., "Passivation of Chalcopyrite During Oxidative
Leaching in Sulfate Media," Hydrometallurgy, vol. 39, pp.
25-48, 1995, no month.
L.W. Beckstead, et aI, "Acid Ferric Sulfate Leaching of
Attritor-Ground Chalcopyrite Concentrate," vol. II, Extractive
Metallurgy of Copper, Chapter 31, pp. 611-632, no date.
Jim A. King, et aI., paper entitled: "The Total Pressure
Oxidation of Copper Concentrates," vol. I, Fundamental
Aspects, 1993, no month.
Dreisinger, D. B., "Total Pressure Oxidation of EI Indio Ore
and Concentrate," COPPER 1999, Fourth International Conference,
Phoenix, Arizona, USA, Oct. 1999.
Richmond, G. D., "The Commissioning and Operation of a
Copper Sulphide Pressure Oxidation Leach Process at Mt.
Gordon," ALTA COPPER 1999: Copper Sulphides Symposium
& Copper Hydrometallurgy Forum, Gold Coast,
Queensland, Australia Conference, 1999, no month.
International Preliminary Examination Report, dated Dec.
17,2002, for PCT/USOl/23468.
Written Opinion from European Patent Office-for PCT/
USOl/23468. No date.
D. J. Butcher et aI., "The Development of a Pressure
Oxidation Flowsheet for the Guelb Moghrein Project, Mauritania"
pp 1-38, 1998, Copper Sulphides Symposium,
Brisbane, Australia.
Opposition to CL 1766-2001 by Anglo American, PLC
(with accompanying English translation of substantive
assertions), no date.
u.s. Patent Jan. 20, 2004 Sheet 1 of 3 US 6,680,034 B2
100
j
102
104
~ METAL-BEARING MATERIAL
~ REACTIVE PROCESSING
106~L~ METAL RECOVERY _
FIG. 1
u.s. Patent Jan. 20,2004 Sheet 2 of 3 US 6,680,034 B2
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FROM FIG 2A
RAFFINATE SOLUTION
CHEMICAL pH ADJUST
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FINAL METAL
CONTAINING SOLUTION
LIQUID/SOLID SEPARATION
COPPER-CONTAINING SOLUTION
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US 6,680,034 B2
2
In solvent extraction (or solution extraction or liquid ion
exchange, as it is sometimes called), the pregnant leach
solution typically is mixed with an organic solvent (i.e., an
extractant), which selectively removes the copper from the
5 pregnant leach solution. The copper-loaded extractant is
then mixed with an aqueous acid solution, which strips the
copper from the extractant, producing a solution stream
suitable for electrowinning. This resultant solution stream is
highly concentrated in copper and relatively pure, and
10 typically is processed into high quality cathode copper in an
electrowinning circuit.
In general, electrowinning of copper consists of the electrolytic
deposition (sometimes called "plating") of copper
onto a cathode and the evolution of oxygen at an anode. In
15 a simple design of an exemplary electrowinning unit, a set
of cathodes and anodes are set in a reaction chamber
containing the copper-containing electrolyte. When the unit
is energized, copper ions are reduced onto the cathode (i.e.,
plated). Plating of copper typically occurs on copper starter
20 sheets or stainless steel blanks. Anodes are quasi-inert in the
electrolyte and provide a surface for oxygen evolution. The
copper plates produced by the electrowinning unit can be in
excess of 99.99 percent pure.
Purification of copper from the pregnant leach solution by
25 solvent extraction has proven to be a successful means of
providing a concentrated copper solution suitable for electrowinning
of highly pure copper metal. However, prior art
teachings suggest the importance of ensuring that the acid
concentration of the pregnant leach solution is appropriately
30 controlled, often through neutralization, such as through the
use of lime or acid-consuming ore.
Still others have recognized that the use of lime to
neutralize the acid in the solution not only increases operating
costs due to lime consumption but also may result in
35 the formation of a low pulp density slurry, thus tending to
make it more difficult to recover the copper from that slurry.
In response, Placer Dome, Inc., of Vancouver, British
Columbia, Canada, has proposed in, for example, U.S. Pat.
Nos. 5,698,170 and 5,895,633 methods to recover copper
40 from copper-containing materials, especially copper from
copper sulfides such as chalcopyrite, wherein a coppercontaining
solution containing an acid is contacted, that is,
diluted, with an aqueous diluent containing no more than
about 5 grams/liter acid to yield a diluted copper-containing
45 solution having an acid concentration ranging from about 2
to about 8 gramslliter prior to the step of solvent extracting
the copper from the diluted copper-containing solution. In
their patents, Placer Dome requires the significant use of a
diluting solution to lower acid levels in the copper-
50 containing solution sufficiently for favorable equilibrium
conditions during solvent extraction, which technique Placer
Dome suggests significantly reduces copper losses relative
to many existing processes in which neutralization of the
acid in the solution before solvent extraction is employed.
To achieve these results, Placer Dome teaches that the
desired acid concentration ranges can be obtained when a
sufficient amount of diluting solution is contacted with the
copper-containing solution to yield the diluted coppercontaining
solution. Specifically, Placer Dome teaches that
60 the ratio of the volume of copper-containing solution to the
volume of diluting solution must range from about 1:10 to
about 1:500. In this manner, the acid generated in pressure
leaching is neutralized after, and preferably not before,
solvent extraction and electrowinning.
While Placer Dome's patented process is usable in many
situations, in cases where it is desirable to reduce operating
costs and/or the metal-bearing ore at a particular site does
(1) 55
FIELD OF THE INVENTION
CROSS-REFERENCE TO RELATED
APPLICATIONS
BACKGROUND OF THE INVENTION
1
METHOD FOR RECOVERING METAL
VALUES FROM METAL-CONTAINING
MATERIALS USING HIGH TEMPERATURE
PRESSURE LEACHING
The present invention relates generally to a process for
recovering copper and other metal values from metalcontaining
materials, and more specifically, to a process for
recovering copper and other metal values from metalcontaining
materials using high temperature pressure leaching
processes.
Smelting is one approach for recovering a metal, such as
copper, from a metal-bearing sulfide material. However, due
to the high cost of smelting, the copper sulfide minerals in
an ore body typically are first concentrated by flotation
techniques to provide a smaller volume for smelting. The
concentrate is then shipped to a smelter, which processes the
concentrate pyrometallurgically at high temperatures to
form a crude copper product that is subsequently refined to
a highly pure metal.
The recovery of copper from copper sulfide concentrates
using pressure leaching has proven to be a potentially
economically attractive alternative to smelting. Pressure
leaching operations generally produce less fugitive emissions
than smelting operations, and thus, environmental
benefits may be realized. Further, pressure leaching circuits
may be more cost effectively constructed on-site at a
concentrator, eliminating the expense associated with concentrate
transportation that smelting operations may require.
Further, any by-product acid produced in the pressure leaching
circuit may be able to be used in adjacent heap leaching
operations, thus offsetting some of the costs associated with
purchased acid.
The mechanism by which pressure leaching processes
effectuate the release of copper from sulfide mineral
matrices, such as chalcopyrite, is generally dependent on
temperature, oxygen availability, and process chemistry. In
high temperature pressure leaching processes, that is, pressure
leaching processes operating above about 2150 c., the
dominant oxidation reaction is believed to be as follows:
This application claims priority to u.s. Provisional Patent
Application, Serial No. 60/220,622 entitled "Methods for
Recovering Copper and Other Metal Values from Copper
Sulfide Concentrate Using High Temperature Pressure Oxidation"
filed on Jul. 25, 2000, which is incorporated by
reference herein.
If insufficient oxygen is present in the process vessel, the
conversion of iron to hematite (Fe2 0 3) generally will be
incomplete, resulting in the formation of ferrous sulfate, an
undesirable reaction by-product.
In high temperature pressure leaching, the sulfur contained
in the metal-bearing material (e.g., concentrate) typically
is converted to sulfate. In connection with such pressure
leaching processing operations, the copper typically is
recovered from the resulting solution by solvent extraction 65
and electrowinning techniques to provide a cathode copper
product of high purity.
3
US 6,680,034 B2
4
not warrant such conditions, it would be desirable to obtain
high metal recovery in processes where such dilution is not
required.
SUMMARY OF THE INVENTION
While the way in which the present invention provides
these advantages over the prior art is described in greater
detail hereinbelow, in general, the process for recovering
copper and other metal values from a metal-bearing material
is improved, according to various aspects of the present
invention, in that the pressure leach solution need not be
significantly diluted before the copper and/or other metal
values are recovered, for example, through solvent
extraction, electrowinning, or other processes. In this
manner, capital and operating costs can be reduced without
sacrificing the extraction of copper or other metals.
Thus, in accordance with an exemplary embodiment of
the present invention, a process for recovering copper from
a copper-containing material generally includes the steps of:
(i) providing a feed stream containing copper-containing
material; (ii) pressure leaching the copper-containing feed
stream to yield a copper-containing solution; and (iii) recovering
cathode copper from the copper-containing solution
using solvent extraction and electrowinning without significantly
diluting the copper-containing solution. In general,
recovery processes in accordance with the present invention
yield high copper recovery, for example in excess of 98%,
while at the same time yielding various other important
benefits.
BRIEF DESCRIPTION OF THE DRAWING
The subject matter of the present invention is particularly
pointed out and distinctly claimed in the concluding portion
of the specification. A more complete understanding of the
present invention, however, may best be obtained by referring
to the detailed description and claims when considered
in connection with the drawing figures, wherein like numerals
denote like elements and wherein:
FIG. 1 illustrates a general flow diagram of a metal
recovery process in accordance with one general embodiment
of the present invention;
FIG. 2A illustrates a more detailed flow diagram of a
metal recovery process in accordance with one exemplary
embodiment of the present invention; and,
FIG. 2B illustrates further aspects of the metal recovery
process of FIG. 2A.
DETAILED DESCRIPTION OF EXEMPLARY
EMBODIMENTS OF THE INVENTION
The present invention exhibits significant advancements
over prior art processes, particularly with regard to metal
recovery ratios and process cost advantages. Moreover,
existing metal recovery processes that utilize a conventional
atmospheric or pressure leaching/solvent extraction/
electrowinning process sequence may, in many instances, be
easily retrofitted to exploit the many commercial benefits the
present invention provides.
Referring to FIG. 1, in accordance with various aspects of
the present invention, a metal-bearing material 102 is provided
for processing in accordance with metal recovery
process 100. Metal-bearing material 102 may be an ore, a
concentrate, or any other material from which 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. Various aspects and embodiments of the present
invention, however, prove especially advantageous in con-
S nection with the recovery of copper from copper sulfide
concentrates and/or ores, such as, for example, chalcopyrite
(CuFeS2 ), chalcocite (Cu2S), bornite (CusFeS4 ), and covellite
(CuS). Thus, metal-bearing material 102 preferably is a
copper ore or concentrate, and most preferably, is a copper
10 sulfide ore or concentrate.
Metal-bearing material 102 may be prepared for metal
recovery processing in any manner that enables the conditions
of metal-bearing material 102-such as, for example,
composition and component concentration-to be suitable for
15 the chosen processing method, as such conditions may affect
the overall effectiveness and efficiency of processing 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
20 depend upon the operating parameters of the chosen processing
scheme, equipment cost and material specifications.
For example, as discussed in some detail hereinbelow,
metal-bearing material 102 may undergo comminution,
flotation, blending, and/or slurry formation, as well as
25 chemical and/or physical conditioning.
With continued reference to FIG. 1, after metal-bearing
material 102 has been suitably prepared, metal-bearing
material is subjected to reactive processing (step 104) to put
a metal value or values in metal-bearing material 102 in a
30 condition such that they may be subjected to later metal
recovery steps, namely metal recovery step 106. For
example, exemplary suitable processes include reactive processes
that tend to liberate the desired metal value or values
in the metal bearing material 102 from the metal-bearing
35 material 102. In accordance with a preferred embodiment of
the present invention, processing step 104 comprises pressure
leaching, preferably, high temperature pressure leaching.
As used herein, the term "pressure leaching" refers to a
metal recovery process in which material is contacted with
40 an acidic solution and oxygen under conditions of elevated
temperature and pressure. In accordance with various
aspects of the present invention, processing step 104 may
comprise any type of pressure leaching process.
As previously briefly noted, pressure leaching processes
45 are generally dependent upon, among other things,
temperature, oxygen availability, and process chemistry.
While various parameters for each may be utilized, in
accordance with preferred aspects of the present invention,
the temperature during pressure leaching preferably is main-
50 tained in the range of about 170° C. to about 235° c., most
preferably in the range from about 200° C. to about 230° c.,
and optimally on the order of about 225° C.
To maintain the temperature in this desired range, a
cooling liquid may be employed. As will be appreciated,
55 pressure leaching of many metal sulfides tends is an exothermic
reaction, and the heat generated is generally more
than that required to heat the feed slurry to the desired
operating temperature. Excess heat may be removed and the
desired operating temperature maintained by contacting
60 cooling liquid with the feed slurry in the reactor vessel. The
cooling liquid can be recycled liquid phase from the product
slurry, neutralized raffinate solution, fresh make-up water, or
mixtures thereof, or may be provided by any other suitable
source. The amount of cooling liquid added during pressure
65 leaching will vary according to the amount of sulfide minerals
reacted (and thus the heat generated by the pressure
leaching reaction).
US 6,680,034 B2
5
The duration of pressure leaching in any particular application
depends upon a number of factors, including, for
example, the characteristics of the metal-containing material
and the pressure leaching process pressure and temperature.
Preferably, the duration of pressure leaching in accordance 5
with various aspects of the present invention ranges from
about less than 1 hour to about 3 hours, and optimally is on
the order of about forty-five (45) to ninety (90) minutes.
While any reactor vessel for pressure leaching may be used,
preferably an agitated, multiple-compartment pressure 10
leaching vessel is employed.
In accordance with various aspects of the present
invention, processing step 104 via pressure leaching of
metal-bearing material 104 produces a product slurry having
a relatively high acid and metals content, and is character- 15
ized by high metal (e.g., copper) recoveries through metal
recovery step 106. For example, no less than about 98% of
the metal (e.g., copper) in the preferred chalcopyrite and
other copper sulfides can generally be recovered through
pressure oxidation utilizing the above-described conditions. 20
Contrary to prior art processes, such as for example the
aforementioned Placer Dome processes, where significant
amounts of diluting solution are combined with the pressure
leaching liquor to reduce the acid concentration, in accordance
with various aspects of the present invention, dilution 25
is not used, or if used, relatively low dilution ratios are used.
In cases where low dilution of the pressure leaching product
slurry is employed, dilution ratios of less than about 1:10
metal containing solution to make-up solution are employed.
Preferably, dilution is conducted such that the dilution ratio 30
is on the order of between about 1:4 and about 1:8 of
metal-containing solution to make-up solution.
With continued reference to FIG. 1, in accordance with
various aspects of the present invention, metal recovery step 35
106 preferably comprises conventional solvent extraction
and electrowinning (SXIEW). It should be appreciated,
however, that other metal recovery processes may be used.
Where metal recovery step 106 comprises SXIEW, such
processing preferably is conducted in a conventional man- 40
ner. As such, suitable extraction reagents should be
employed. Preferably, such extraction reagents include
aldoxime, aldoxime/ketoxime mixtures and/or modified
aldoximes. For example, particularly preferred solvent
extraction reagents include LIX reagents, such as, for 45
example, LIX 622N, which comprises of mixture of
5-dodecylsalicylaldoxime and tridecanol in a high flash
point hydrocarbon diluent, available from Cognis Corporation;
LIX 984, also available from Cognis Corporation,
which is a mixture of 5-dodecylsalicylaldoxime and 50
2-hydroxy-5-nonylacetophenoneoxime in a high flash point
hydrocarbon diluent; or M-5774, available from Avecia, an
Acorga™ solvent extraction reagent, which comprises a
modified aldoxime (5-nonyl salicylaldoxime). Other suitable
solvent extraction reagents, however, may be 55
employed.
As will be appreciated by the disclosure set forth herein,
metal recovery process 100 enables various advantages over
recovery processes wherein more significant dilution is
required. For example, by using relatively low dilution 60
ratios, lower operation costs potentially can be obtained,
primarily due to the lower volume of fluids which need to be
handled within metal recovery process 100.
Referring now to FIGS. 2A and 2B, a further exemplary
embodiment of the present invention is illustrated. In accor- 65
dance with this embodiment, a metal-bearing material 200,
preferably a copper-bearing material, is comminuted in step
6
202 to form a comminuted material 204. Preferably, metalbearing
material 200 comprises a copper sulfide-bearing
material.
Preferably, comminuted material 204 is subjected to froth
flotation (step 208) to separate copper sulfide-bearing materials
from gangue minerals. The flotation concentrate,
namely the concentrated copper sulfide-bearing material
210, is obtained and preferably contains copper and other
metals.
Further comminution of concentrated copper sulfidebearing
material 210 may be necessary to yield a desired size
distribution for pressure leaching. As will be appreciated,
increasing the fineness of material 210 tends to increase the
reaction rate during pressure leaching, and thus may permit
the use of smaller, more economical pressure leaching
apparatus. Accordingly, material 210 has a particle size of
about 80% passing less than about 150 microns, more
preferably less than about 100 microns, and optimally
between about 30 to about 75 microns. In some instances, in
order to achieve the optimal particle size, or to expose fresh
surfaces or to break up lumps, a regrinding step 212 may be
employed. During regrinding step 212, solution (e.g., feed
slurry 206 or otherwise) may be added to the flotation
concentrate 210 to facilitate the grinding process. A product
slurry 214 is then formed, preferably with the addition of, for
example, sulfuric acid, dispersants, and the like prior to high
temperature pressure leaching (step 220). Preferably, product
slurry 214 has less than about 50% solids by weight.
Product slurry 214 is next subjected to high temperature
pressure leaching (step 220), preferably at a temperature in
the range of about 210° C. to about 235° C. in a sealed,
agitated, multi-compartment pressure leaching vessel with
oxygen overpressure of at least about 70 psig. for about 1-3
hours. During pressure leaching step 220, oxygen preferably
is added continuously to the pressure leaching vessel to
maintain the oxygen overpressure optimal for the desired
chemical reactions to proceed. That is, sufficient oxygen is
suitably injected to preferably maintain an oxygen partial
pressure in the pressure leaching vessel ranging from about
50 to about 300 psig, and more preferably in the range of
about 60 to about 150 psig. The total pressure in the sealed
pressure leaching vessel is superatmospheric, and can range
from about 300 to about 750 psig, and is preferably in the
range of about 400 to about 600 psig. A product slurry 222
is obtained in a conventional manner therefrom.
Product slurry 222 may be flashed (step 224) to release
pressure and evaporatively cool product slurry 222 through
release of steam to form a flashed product slurry 226.
Flashed product slurry 226 preferably thereafter has a temperature
ranging from about 85° C. to about 100° C.
Solution recovered from steam generated from flashing step
224 may be cooled and used as process make-up solution
(not shown).
In accordance with further aspects of this preferred
embodiment, after product slurry 222 has been subjected to
atmospheric flashing (step 224) using, for example, a flash
tank, to achieve approximately ambient conditions of pressure
and temperature, flashed product slurry 226 may be
further conditioned in preparation for later metal-value
recovery steps. In some cases, use of a heat exchanger may
be advantageous to cool the slurry such that solid-liquid
phase separation may take place. Preferably, one or more
solid-liquid phase separation stages (step 228) 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 decantaUS
6,680,034 B2
7 8
tion reagents collect the copper in copper-containing
solution 230. The copperbearing reagents are then subjected
to more acidic conditions to shift the equilibrium conditions
to cause the copper to be exchanged for the acid in a highly
5 acidic acid stripping solution (not shown). Various process
stages may be used, as necessary, to provide a suitable
stream to feed the electrowinning process and to yield a
substantially barren solvent for re-use in the extraction
process. During solvent extraction 252, copper from coppercontaining
solution 230 may be loaded selectively onto an
10 organic chelating agent, such as the aforementioned
aldoximes or aldoxime/ketoxime blends. Preferably, an
extraction reagent, such as LIX 984 or Acorga™ M-5774, is
dissolved in an organic diluent to result in the extraction of
copper from metal-containing solution which can be recov-
15 ered through conventional electrowinning (step 254) to yield
the desired metal product 256. As previously mentioned,
LIX 984 is a mixture of 5-dodecylsalicylaldoxime and
2-hydroxy-5-nonylacetophenone oxime in a high flash point
hydrocarbon diluent, which forms complexes with various
20 metal cations, such as Cu2
+. Other solvent extraction
reagents may be used in accordance with various aspects of
the present invention. Such extraction reagents should,
however, be selected to facilitate suitable extraction and
subsequent stripping operations. 25
Solvent extraction step 252 and electrowinning step 254
may also involve various solvent stripping and recycle
operations (both of which are not shown) which can be
operated in a conventional manner. Preferably, no less than
30 about 98% of the copper in copper-containing solution 230
is recovered as cathode copper product 256 by solvent
extraction 252 and electrowinning 254.
With continued reference to FIG. 2B, electrowinning step
254 also preferably proceeds in a conventional manner to
35 yield a pure, cathode copper product 256. In accordance
with the various aspects of this embodiment of the present
invention, a high-quality, uniformly plated cathode copper
product 256 may be realized without subjecting coppercontaining
solution 230 to significant dilution prior to sol-
40 vent extraction. As those skilled in the art will appreciate, a
variety of methods and apparatus are available for the
electrowinning of copper and other metal values, any of
which may be suitably used in accordance with this embodiment
of the present invention.
Raffinate solution 260 from solvent-extraction step 252
may be used in a number of ways. For example, all or a
portion of raffinate 260 may be used in heap leaching
operations 262. In some cases, in accordance with various
aspects of this embodiment of the present invention, use of
50 raffinate 260 in heap leaching operations 262 may be desirable
inasmuch as raffinate 260 may have higher acid levels
and in some cases thereby more advantageously affecting
heap leaching operations 262. Alternatively, the pH of
raffinate solution 260 may be chemically adjusted, such as is
55 shown in step 264 and the resulting product sent to impoundment
(step 266). In accordance with yet another aspect of
this embodiment of the present invention, raffinate solution
260 may be agitated in a tank leach operation (step 268).
With reference again to FIG. 2A, if the metal content of
60 the washed solids, that is residue 280, from solid-liquid
separation step 228 is sufficiently high to warrant further
processing, the metals contained therein may be recovered
through conventional means such as, for example, through
smelting (step 282) or established precious metals recovery
65 processing (step 284). If, however, the metals content of
residue 280 is too low to justify further treatment, the
residue may be sent to an impoundment area (step 286).
tion (CCD) circuits, thickeners, 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, or any other suitable device
in a solid-liquid separation apparatus. However, it should be
appreciated that any technique of conditioning flashed product
slurry 226 for later metal value recovery is within the
scope of the present invention. Preferably, flashed product
slurry 226 is subjected to solid-liquid phase separation (step
228) to yield a resultant liquid phase copper-containing
solution 230 and a solid phase residue 280.
Flashed product slurry 226 is suitably subjected to solidliquid
phase separation (step 228), by multiple stages of
counter current decantation (CCD) washing in thickeners.
Wash solution and a suitable flocculant may be added as
desired during step 228. In accordance with one alternative
aspect of this embodiment of the present invention, flashed
product slurry 226 may be thickened in a primary thickener
to recover approximately 95% or more of the soluble copper
in a high grade pregnant leach solution. In this case, primary
thickener underflow then proceeds to a multiple-stage CCD
washing circuit, and wash solution and a suitable flocculent
may be added as required (not illustrated).
Referring now to FIG. 2B, in order to optimize solution
extraction of the copper, the pH of copper-containing solution
230 from solid-liquid phase separation step 228, in
accordance with various aspects of this embodiment of the
present invention, preferably is adjusted to a pH of about 1
to about 2.2, more preferably to a pH of about 1.2 to about
2.0, and still more preferably to a pH of about 1.4 to about
1.8. This adjustment may be accomplished in a variety of
manners. In accordance with one aspect of the present
invention, copper-containing solution 230 is subjected to a
chemical pH adjustment step 232, which optionally can be
followed by further solid-liquid separation (step 234) to
yield a final metal-containing solution 236 for solvent
extraction. In such case, the residue 238 from step 234 can
be impounded (step 240) or otherwise disposed of.
Alternatively, or in combination with the method
described above, the pH of copper-containing solution 230
may be adjusted through dilution (step 250). In contradistinction
to the prior art methods that rely on significant
dilution, in accordance with the present invention, when 45
dilution is employed, low dilution ratios of make-up solution
to copper-containing solution 230 are used. Dilution step
250 may be accomplished by dilution with process solution,
fresh water or any other suitable liquid vehicle at dilution
ratios of copper-bearing solution to make-up solution of less
than about 1:10, and more preferably on the order of
between about 1:4 to about 1:8. Once the pH of the coppercontaining
solution 230 has been appropriately adjusted,
metal recovery preferably is achieved by solvent extraction
(step 252), if necessary, using relatively high concentrations
of extractants in the organic diluent, followed by electrowinning
(step 254).
In accordance with the present invention, in some
instances copper-containing solution may be directly electrowon.
If the properties of solution 230 permit, electrowinning
step 254 may be performed directly (that is, without
first subjecting solution 230 to solvent extraction).
When appropriate, solvent extraction, in accordance with
preferred aspects of this embodiment of the present
invention, is conducted prior to electrowinning and is conducted
in a generally conventional fashion. Typically, equilibrium
conditions are selected such that the solvent extracUS
6,680,034 B2
9 10
* * * * *
13. A copper recovery process comprising the steps of:
a) providing a copper sulfide-bearing material;
b) comminuting said copper sulfide-bearing material to
provide a comminuted copper sulfide-bearing material
in a slurry form;
c) subjecting said slurry to flotation to separate copper
sulfide-bearing materials and to form a concentrated
copper sulfide-bearing material;
d) pressure leaching said concentrated copper sulfidebearing
material at a temperature in the range of about
210° C. to about 235° C. in an oxygen-containing
atmosphere in a sealed, agitated multiple-compartment
pressure leaching vessel to form a product slurry;
e) separating said product slurry into a copper-containing
solution and a solids-containing residue;
f) adjusting the pH of said copper-containing solution to
a pH of less than about 2.2 by combining said coppercontaining
solution with a make-up diluting solution to
yield a pH-adjusted copper-containing solution,
wherein the ratio of said copper-containing solution to
said make-up diluting solution is in the range of from
about 1:4 to about 1:8;
g) solvent extracting and electrowinning said pH adjusted
copper-containing solution to yield a raffinate solution
and copper cathode;
h) applying said acid-containing raffinate solution in a
heap leaching operation.
30 14. The process of claim 13, further comprising the step
of subjecting said residue of step (e) to a further processing.
15. The process of claim 14, wherein said step of further
processing comprises precious metal recovery.
16. The process of claim 14 wherein said step of further
35 processing comprises impounding.
17. The process of claim 13, wherein in said solvent
extracting step, said pH-adjusted copper-containing solution
is contacted with an extraction reagent comprising an
aldoxime/ketoxime mixture.
40 18. The process of claim 13, wherein said step of adjusting
the pH of said copper-containing solution comprises
combining said copper-containing solution with a make-up
diluting solution to yield a pH-adjusted copper-containing
wherein the ratio of said copper-containing solution to said
45 make-up diluting solution is in the range of from about 1:4
to about 1:8 and the pH of said pH-adjusted coppercontaining
solution is from about 1.4 to about 1.8.
19. In a process for recovering copper from a coppercontaining
material comprising the steps of pressure leach-
50 ing a copper-containing material with a liquid to yield a
residue and a copper-containing solution, wherein the copper
in said copper-containing solution is recovered through
solvent extraction of the copper from the copper-containing
solution, the process being improved wherein the copper-
55 containing solution is diluted prior to solvent extraction in a
diluting step, and the ratio by volume of the coppercontaining
solution to the diluting solution is less than about
1:8.
20. The process of claim 19 wherein in said diluting step
60 the ratio by volume of the copper-containing solution to the
diluting solution ranges from about 1:4 to about 1:8.
10
a) pressure leaching a copper-containing material with a 15
liquid to yield a residue and a copper-containing solution;
b) diluting said copper-containing solution with a diluting
solution to form a diluted copper-containing solution,
wherein a ratio of said copper-containing solution to 20
said diluting solution is less than about 1:8 and the pH
of said diluted copper containing solution is less than
about 2.2; and
c) solvent extracting said copper from said diluted copper- 25
containing solution.
2. The process of claim 1, wherein in said diluting step,
the ratio by volume of said copper-containing solution to
said diluting solution ranges from about 1:4 to about 1:8.
3. The process of claim 2, further comprising providing an
extraction reagent for use in said step of solvent extracting
said copper from said diluted copper-containing solution.
4. The process of claim 3, wherein said step of providing
an extraction reagent comprises providing an aldoxime/
ketoxime mixture.
5. The process of claim 3, wherein said step of providing
an extraction reagent comprises providing an extraction
reagent comprising aldoximes, modified aldoximes, or
aldoxime/ketoxime mixtures.
6. The process of claim 2, wherein said pressure leaching
step comprises high temperature pressure leaching at a
temperature from about 210° C. to about 235° C.
7. The process of claim 6, wherein said pressure leaching
step is at superatmospheric pressure at a temperature of
about 225° C. in an oxygen-containing atmosphere.
8. The process of claim 2, further comprising the step of
comminuting said copper-containing material prior to the
step of pressure leaching.
9. The process of claim 8, wherein said comminuting step
comprises comminuting said copper-containing material to a
P8G of less than about 75 microns.
10. The process of claim 2, further comprising the step of
recovering any precious metals contained in said pressure
leaching residue.
11. The process of claim 2, further comprising the step of
electrowinning said copper from said solvent extraction step
to form cathode copper.
12. The process of claim 1, wherein in said solvent
extracting step, said diluted copper-containing solution is
contacted with an extraction reagent comprising an
aldoxime/ketoxime mixture.
The present invention has been described above with
reference to various exemplary embodiments. It should be
appreciated that the particular embodiments shown and
described herein are illustrative of the invention and not
intended to limit in any way the scope of the invention as set 5
forth in the appended claims. For example, although reference
has been made throughout this disclosure primarily to
copper recovery, it is intended that the invention also be
applicable to the recovery of other metal values.
What is claimed:
1. A process for recovering copper from a coppercontaining
material, comprising the steps of:
t;lina��ih �T��l;mso-pagination:none;mso-layout-grid-align:none;text-autospace:none'>material and a solution stream comprising copper
and acid.
4. The method of claim 3, wherein said separating step
comprises reacting at least a portion of the copper in a
copper-containing electrolyte stream in the presence of
sulfur dioxide, whereby at least a portion of said copper in
said copper-containing electrolyte stream precipitates as
copper sulfide onto at least a portion of the coppercontaining
material in said feed stream.
5. The method of claim 1, wherein said leaching step
comprises leaching at least a portion of said pressure leaching
feed stream in a pressure leaching vessel at a temperature
of from about 100 to about 2500 C. and at a total operating
pressure of from about 50 to about 750 psi.
6. The method of claim 1, wherein said leaching step
35 comprises leaching at least a portion of said pressure leaching
feed stream in a pressure leaching vessel and wherein
said leaching step further comprises injecting oxygen into
the pressure leaching vessel to maintain an oxygen partial
pressure in the pressure leaching vessel of from about 50 to
about 200 psi.
7. The method of claim 5, wherein said leaching step
further comprises injecting oxygen into the pressure leaching
vessel to maintain an oxygen partial pressure in the
pressure leaching vessel of from about 50 to about 200 psi.
8. The method of claim 1, wherein said conditioning step
comprises subjecting at least a portion of said product slurry
to solid-liquid separation, wherein at least a portion of said
copper-containing solution is separated from said residue.
9. The method of claim 8, wherein said conditioning step
further comprises blending at least a portion of said coppercontaining
solution with at least a portion of one or more
copper-containing streams to achieve a desired copper concentration
in said copper-containing solution.
10. The method of claim 8, wherein said conditioning step
further comprises blending at least a portion of said coppercontaining
solution with at least a portion of one or more
copper-containing streams to achieve a copper concentration
of from about 20 to about 75 gramslliter in said coppercontaining
solution.
11. The method of claim 1, further comprising the step of
using at least a portion of said acid stream yielded from said
separating step in at least one of heap leaching, vat leaching,
dump leaching, stockpile leaching, pad leaching, agitated
tank leaching, or bacterial leaching operations.
containing suspended parallel flat cathodes of copper alternating
with flat anodes of lead alloy, arranged perpendicular
to the long axis of the tank. A copper-bearing leach solution
may be provided to the tank, for example at one end, to flow
perpendicular to the plane of the parallel anodes and 5
cathodes, and copper can be deposited at the cathode and
water electrolyzed to form oxygen and protons at the anode
with the application of current. As with conventional electrowinning
cells, the rate at which direct current can be
passed through the cell is effectively limited by the rate at
which copper ions can pass from the solution to the cathode 10
surface. This rate, called the limiting current density, is a
function of factors such as copper concentration, diffusion
coefficient of copper, cell configuration, and level of agitation
of the aqueous solution.
The general chemical process for electrowinning of cop- 15
per from acid solution is believed to be as follows:
2CUS04+2H2°---;>2Cuo+2H2S04+02
Cathode half-reaction: Cu2++2e----;>Cuo
Anode half-reaction: 2H20---;>4H++02+4e- 20
Turning again to FIG. 1, in a preferred embodiment the
invention, product stream 107 is directed from electrolyte
recyc~e tank 1060 to an electrowinning circuit 1070, which
contams one or more conventional electrowinning cells.
In accordance with a preferred aspect of the invention,
electrowinning circuit 1070 yields a cathode copper product 25
116, optionally, an offgas stream 117, and a relatively large
volume of copper-containing acid, herein designated as lean
electrolyte streams 108 and 115. As discussed above in the
illustrated embodiment of the invention, lean ele~trolyte
streams 108 and 115 are directed to copper precipitation 30
stage 1010 and electrolyte recycle tank 1060, respectively.
Lean electrolyte streams 108 and 115 generally have a lower
copper concentration than product stream 107, but typically
have a copper concentration of less than about 40 grams/
liter.
The present invention has been described above with
reference to a number of exemplary embodiments. It should
be appreciated that the particular embodiments shown and
described herein are illustrative of the invention and its best
mode and are not intended to limit in any way the scope of 40
the invention as set forth in the claims. Those skilled in the
art having read this disclosure will recognize that changes
and modifications may be made to the exemplary embodi~
ents .without departing from the scope of the present
mventlon. For example, although reference has been made
throughout to copper, it is intended that the invention also be 45
applicable to the recovery of other metals from metalcontaining
materials. Further, although certain preferred
aspects of the invention, such as techniques and apparatus
for conditioning process streams and for precipitation of
copper, for example, are described herein in terms of exem- 50
plary embodiments, such aspects of the invention may be
achieved through any number of suitable means now known
or hereafter devised. Accordingly, these and other changes
or modifications are intended to be included within the scope
of the present invention, as expressed in the following 55
claims.
What is claimed is:
1. A method for recovering copper from a coppercontaining
material, comprising the steps of:
providing a feed stream comprising a copper-containing 60
material and acid;
separating at least a portion of said copper-containing
material from said acid in said feed stream to yield an
acid stream comprising at least a portion of contami