CA1045579A - Process for electrowinning of copper values from solid forms thereof - Google Patents
Process for electrowinning of copper values from solid forms thereofInfo
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- CA1045579A CA1045579A CA203,902A CA203902A CA1045579A CA 1045579 A CA1045579 A CA 1045579A CA 203902 A CA203902 A CA 203902A CA 1045579 A CA1045579 A CA 1045579A
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- Prior art keywords
- copper
- electrolyte
- cathode
- iron
- h2so4
- Prior art date
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
- C25C1/12—Electrolytic production, recovery or refining of metals by electrolysis of solutions of copper
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electrolytic Production Of Metals (AREA)
Abstract
PROCESS FOR ELECTROWINNING OF COPPER
VALUES FROM SOLID FORMS THEREOF
ABSTRACT
A process for electrowinning of copper values from cement copper and/or copper sulfide concentrates in which the copper bearing material is agitated in a cell in the presence of H2SO4 while temperatures are maintained above 60°C, current densities are above 60 amperes per square foot of cathode but below that current density at which electrolyte boils and deposited copper plate becomes brittle. The process is characterized by the fact that a concentration of soluble iron, in the range from 10 to 40 grams/liter, is kept in solution in the electrolyte at all times. The iron ranges from 20-40 gpl in the case of cement copper, and from 10-35 gpl in the case of copper sulfide concentrates. The soluble iron content is maintained high enough to provide a reservoir of ferric ions to aid in oxidizing and/ox leaching of the copper. Current densities must be high enough to effect electrolysis with the reduction of copper and liberation of hydrogen gas in quantity to prevent attack of the cathode by ferric iron.
VALUES FROM SOLID FORMS THEREOF
ABSTRACT
A process for electrowinning of copper values from cement copper and/or copper sulfide concentrates in which the copper bearing material is agitated in a cell in the presence of H2SO4 while temperatures are maintained above 60°C, current densities are above 60 amperes per square foot of cathode but below that current density at which electrolyte boils and deposited copper plate becomes brittle. The process is characterized by the fact that a concentration of soluble iron, in the range from 10 to 40 grams/liter, is kept in solution in the electrolyte at all times. The iron ranges from 20-40 gpl in the case of cement copper, and from 10-35 gpl in the case of copper sulfide concentrates. The soluble iron content is maintained high enough to provide a reservoir of ferric ions to aid in oxidizing and/ox leaching of the copper. Current densities must be high enough to effect electrolysis with the reduction of copper and liberation of hydrogen gas in quantity to prevent attack of the cathode by ferric iron.
Description
~Ls579 PROCE~S ~OR EIEC~ROWINNING OF
COPæER VA~UES FROM SO~ID ~OR~S ~ ~ ~EOF
~ his invention relate~ to improYed ways and means for the electrolgtic recover~ o~ copper directly from cement copper and~or copper sul~ide concen~rates in a system using an ~ SO4-base electrolyte into w~ich the solid copper-bearing ma~erial is introduced.
In elect~olysis, ions in solution will, under the in~luence of electric current, migrate to an electrode of oppos:ite polarityO ; 10 In the case of metal ions9 such aB copper, the metal deposits on the cathode whence it is recovered.
~ he usual electrolytic system for electrowi~ning o~ copper starts with a clear solution of CuSO4 which has been formed in ~ .
conventional manner such a~ by reaction between ~ SO4 and copper oxide. ~o~e workers have proposed direct electrow ~ g . by treating a sl~rry of crushed copper oxide ores in the cell itself thus avoiding the cost and e~pense of leach;ng, filtra- :
tion and purification as needed to produce a clear electrolgte.
~ ~ome recently proposed elect:rowinn~ng processes have, under ~ .
: 20 care~ully controlled conditions Or agi~ation, temperature and: .
.
current, proven succes~ul i~ the electrowi~ning of pure copper directly from slurries of crushed oxiae ores, ~u~ cement copper and copper ~ul~ideR are not amenable to treatmen~ in accordance with these propo~al~. .
In el~ctrolytic processes as hereto~ore prac~iced~ it ha~
been desireable to keep the dissolved iro~ conte~t o~ the ~ :
electrolyte below 2 gpl to a~oid sharp drop~ in current efficiency; and in any event3 the iron content was kept below . . -9 gpl i~ order to protect the cathode and an~ deposited copper
COPæER VA~UES FROM SO~ID ~OR~S ~ ~ ~EOF
~ his invention relate~ to improYed ways and means for the electrolgtic recover~ o~ copper directly from cement copper and~or copper sul~ide concen~rates in a system using an ~ SO4-base electrolyte into w~ich the solid copper-bearing ma~erial is introduced.
In elect~olysis, ions in solution will, under the in~luence of electric current, migrate to an electrode of oppos:ite polarityO ; 10 In the case of metal ions9 such aB copper, the metal deposits on the cathode whence it is recovered.
~ he usual electrolytic system for electrowi~ning o~ copper starts with a clear solution of CuSO4 which has been formed in ~ .
conventional manner such a~ by reaction between ~ SO4 and copper oxide. ~o~e workers have proposed direct electrow ~ g . by treating a sl~rry of crushed copper oxide ores in the cell itself thus avoiding the cost and e~pense of leach;ng, filtra- :
tion and purification as needed to produce a clear electrolgte.
~ ~ome recently proposed elect:rowinn~ng processes have, under ~ .
: 20 care~ully controlled conditions Or agi~ation, temperature and: .
.
current, proven succes~ul i~ the electrowi~ning of pure copper directly from slurries of crushed oxiae ores, ~u~ cement copper and copper ~ul~ideR are not amenable to treatmen~ in accordance with these propo~al~. .
In el~ctrolytic processes as hereto~ore prac~iced~ it ha~
been desireable to keep the dissolved iro~ conte~t o~ the ~ :
electrolyte below 2 gpl to a~oid sharp drop~ in current efficiency; and in any event3 the iron content was kept below . . -9 gpl i~ order to protect the cathode and an~ deposited copper
-2~
:
~5579 from attack by ferric iron which attaek defeats the recover~
of copper.
- It is the primary object of this invention to provide a - process for the direct electrowinning of copper from slurries of olid cement copper or copper sulfLde concentrates in an H2S04 electrolyte.
It is another object to pro~ide an electrowinning process for direct recovery of high purit~ copper from cement copper ; and copper sulfide concentrates at high current densities and e~ficiencies; and under conditions such that the cathode is protected ~rom ferric iron attack without generation of excess 04.
Another object is the provision of an electrowinning proce~s in which the capital cost and expense of operation is reduced by elimination of the equipment required for the u~ual steps of leaching, sedimentation, filtration and puri~ication.
~ he preæent invention is predicated on the discover~ that by maintaining a high dissolved iron content (above 10 gpl) in the electrolyte while at the same time high current densities, on the order of at least 60 amp/~t2, are emplo~ed~ two related eve~ts take placeO First, there will be sufficient ~ liberated at the ca~hode to continuously reduce ferric iron to ferrous -iron in the vicinity of the cathode to thu~ avoid attack on the depo~ited cathode copper which i~ turn enable~ the ~oluble iron, under care~ull~ selected ana controlled oper~ting condi-tions of temperature9 current and electrolyte co~position, to effect direct winning of pure co~per from a 81urr~ of cement or ~ulfide copper concentrates.
In brief, the process invention contempla~e~ the violent 57~
mixing of finely-divided cement copper or sulfide copper concentrates with a sulfuric acid-copper sul~ate ~olution i~ :
which is mainta~ned a sig~i~icant concentration o~ dis~ol~ed : iron while subjecting the mi2ture to a current field i~ an electrolgtic cellO
In the case o~ cement copper, the electrol~te is usually saturated at about 35-40 gpl iron and the iron concentratio~
is desirably mai~tained in a range of 20-40 gpl.
~lthough the exact ~unction of the dissolved iron is not known, it is theorized that the high current density employed in this invention oxidizes ferrous to ferric which then acts to oxidize or ionize elemental cement copper which, after going into solution, is in tur~ reduced hy electrolysis to elemental copper that is deposited at the ca~hodeO ~he iron must be pre~ent in a sufficient concentra~ion to oxidize the copper and al~o to provide a reservoir of ferrous iron to be 9imul-taneou~ly oxidized to ferric iron a~ the anode so that the proce~s may operate continuousl~ with ~erric iron in solution being consumed in o~idation of copper while ionized copper is reduced and plated at the cathode at the same rate that ferrous ~ .
iron i5 oxidized at the anode.
Assuming the reaction is as described, then the cement copper goes int.o solution in accordance with the equation:
Cu + 2Fe+++ --~ Cu++ + 2Fe+~
but this proceeds at a practical rate onl~ when the voltage ~ .
and current densities as well as ~ ~04 and ~US04 co~centra tion~ are su~ficientl~ high.
According to our studies, in the case o~ cement coppex the reactior prooeeds et a practic~l rato wh~n the di~so1ved ~ -,.
~)4SS79~ ~
iron concentration is 20-40 gpl, the H2S04 starting concen-tration is 200-240 gpl, the solution temperature is above 60C, the DC volta~e is from 2-5 ~olts (measured between the anode and cathode) the current density is above 60 amp/ft2 but below that which causes boiling o~ electrolyte and/or forma-tion of brittle plate, the latter being determined empirically.
(The top llmit we have so far observed is about 300 amp/ft2.) In order that the reaction proceed properly, it is also necessary that the slurry of cement copper in electrolyte be agitated violently. Also, the dissolved copper concentration of the electrolyte should be maintained in the range of 20-40 gpl.
Below 20 gpl Cu, a brittle and/or powdery plate will be formed.
; ~he upper limit is unimportant. ~his concentration is con-veniently obtained at the outset by the addition of copper sulfate, although it will build up by itself as pawer is supplied to the cell. ~
~he presence of at least 10 gpl of dissol~ed iron is -mandatory. In the case of cement copper -the minimum content is about 20 gpl. ~o start operations, it is usually necessary to add iron. ~his is conveniently done by adding ferric sulfate. The addition of a soluble copper salt (CuS04) at the outset is also desirable although, as noted, i~ iron is ; present, the copper concentration will be built up and then maintained at a selected levelO
In the case of sulfide concentrates, the specific opera-ting conditions may vary from those required from cement copper7 however, the basic re~uirements of dissolved iron and high current densities remain.
In the case of Cu2S a basic reaction is apparently:
_5 ~ 455~
Cu2S -~ 2Fe~+ --~ Cu~ ~ 2Fe++ ~ Cu~+
with the u++ thereafter being reduced~to plate at the cathode while ferrous iron is reoxidized at the anode.
CuS is only difficultly soluble in the acid electrolyte yet under the conditions of our process the ore is depleted ; relatively easily which means that some mechanism operates todissolve the copper. Our work shows that the rate of copper recovery varies directly with the iron content of the electro-l~te. ~hus, it is believed that the iron does enter into or perhaps catalyzes rapid dissolving of the copper.
In general, for sulfide concentrates during operation the electrolyte ~hould contain 10--25 gpl dissolved i:ron and at least 25 gpl dissolved copper. ~he electrolyte -temperature should be at least 25 gpl dissolved copper. ~he electrolyte temperature should be above 60C but below the boiling point of the solution. Volt~ge should be above about 2.5 volts.
Current densities should be above 60 amp/ft2 cathode area up to a maximum where brittle pla~e or boiling of electrolyte occurs. In general, high current densities result in higher recovery rates. ~;
It is important that the slurry be violently agitated in the cell during the process. This accomplishes several things.
It insures maximum contact between the solids and electrolyte~
avoids uncontrolled polarization at the electrodes, insures ~ -contact between liberated h~drogen gas and ferric iron adjacent ~ the cathode to protect the cathode and the depositea copper ; from attack by ferric iron. Also, if the agitation is carried ~`
~ out b~ movement of the cathode, the plate quality will be . .
~ ~urther enhanced by the moving cathode target.
''` '' '' ~ .....
~45S7~
Extensive tests were performed on cement copper and chalcocite concentrates from sev~ral sources.
r~he equipment used comprised an octagonal shaped tank with its wall serving as the anode. An oscillating cathode was mounted in the tank. r~he cathode was formed with several removable stainless steel plates which permitted variati~ in the cathode area to provide a wide variation of current densi-ties with a given power source. Paddles were mounted on the ~-~
cathode structure to agitate the slurry as the cathode recipro-cated. Power was supplied by a conventional full wave rectifier DC power supply. r~he cell tank was built to contain about 20 inches slurry and the cathodes were arranged to be immersed to a maximum depth of about 18 inches. Each cathode plate thus had an effective single side surface area o~ about .31 ft . In the test arrangements both sides were plated.
r~hus, each plate had a total effective area of .62 ft2.
The cell was filled and emptied manually. Additional copper-bearing materials were added and samples -taken as desired during operating. ~or final analysis of the tails, the tank was emptied entirely. All tests and assays were performed in accordance with accepted techniques.
In examples, -the acid content of the electrolyte is ; recited at the start of a test and is based on the known materials used in making up the solution. r~he acid requirements are simply tha~ only enough acid is required to keep the reaction going at an acceptable rate. r~oo much acid will slow ' down reaction rates. r~he current density affects the acid ; concentration. r~oo low a density will cause undesirable acid build-up in the system with reduction in recovery rates.
~, _7 ~0145~7g Increasing current will stop or even reverse acid build-up.
~hus, the current should be adjusted to maintain the acid at the proper level to maintain optimum recover~ rates without excess gas-release.
A series of tests was conducted on cement copper to demonstrate the ef~ect of dissolved iron on the plating process.
~he cement copper contained about 90Yo copper (dry basis). ~he electrolyte contained 200 gpl H2S0~ at the start. ~he iron content of the electrolyte was increased b~J the incremental addition of ferric sul~ate. ~'he dissolved copper content increased as a result of ~he process1 increasing as iron content increased.
~est DissolvedDits~olvedVoltageCurrent ~emp No. Iron Content Cu gpl Densit~2 e~ol Am~s/î t 1.6 10.6 2.8 ~.4 43 2 13.1 19.7 3.0 55.5 55
:
~5579 from attack by ferric iron which attaek defeats the recover~
of copper.
- It is the primary object of this invention to provide a - process for the direct electrowinning of copper from slurries of olid cement copper or copper sulfLde concentrates in an H2S04 electrolyte.
It is another object to pro~ide an electrowinning process for direct recovery of high purit~ copper from cement copper ; and copper sulfide concentrates at high current densities and e~ficiencies; and under conditions such that the cathode is protected ~rom ferric iron attack without generation of excess 04.
Another object is the provision of an electrowinning proce~s in which the capital cost and expense of operation is reduced by elimination of the equipment required for the u~ual steps of leaching, sedimentation, filtration and puri~ication.
~ he preæent invention is predicated on the discover~ that by maintaining a high dissolved iron content (above 10 gpl) in the electrolyte while at the same time high current densities, on the order of at least 60 amp/~t2, are emplo~ed~ two related eve~ts take placeO First, there will be sufficient ~ liberated at the ca~hode to continuously reduce ferric iron to ferrous -iron in the vicinity of the cathode to thu~ avoid attack on the depo~ited cathode copper which i~ turn enable~ the ~oluble iron, under care~ull~ selected ana controlled oper~ting condi-tions of temperature9 current and electrolyte co~position, to effect direct winning of pure co~per from a 81urr~ of cement or ~ulfide copper concentrates.
In brief, the process invention contempla~e~ the violent 57~
mixing of finely-divided cement copper or sulfide copper concentrates with a sulfuric acid-copper sul~ate ~olution i~ :
which is mainta~ned a sig~i~icant concentration o~ dis~ol~ed : iron while subjecting the mi2ture to a current field i~ an electrolgtic cellO
In the case o~ cement copper, the electrol~te is usually saturated at about 35-40 gpl iron and the iron concentratio~
is desirably mai~tained in a range of 20-40 gpl.
~lthough the exact ~unction of the dissolved iron is not known, it is theorized that the high current density employed in this invention oxidizes ferrous to ferric which then acts to oxidize or ionize elemental cement copper which, after going into solution, is in tur~ reduced hy electrolysis to elemental copper that is deposited at the ca~hodeO ~he iron must be pre~ent in a sufficient concentra~ion to oxidize the copper and al~o to provide a reservoir of ferrous iron to be 9imul-taneou~ly oxidized to ferric iron a~ the anode so that the proce~s may operate continuousl~ with ~erric iron in solution being consumed in o~idation of copper while ionized copper is reduced and plated at the cathode at the same rate that ferrous ~ .
iron i5 oxidized at the anode.
Assuming the reaction is as described, then the cement copper goes int.o solution in accordance with the equation:
Cu + 2Fe+++ --~ Cu++ + 2Fe+~
but this proceeds at a practical rate onl~ when the voltage ~ .
and current densities as well as ~ ~04 and ~US04 co~centra tion~ are su~ficientl~ high.
According to our studies, in the case o~ cement coppex the reactior prooeeds et a practic~l rato wh~n the di~so1ved ~ -,.
~)4SS79~ ~
iron concentration is 20-40 gpl, the H2S04 starting concen-tration is 200-240 gpl, the solution temperature is above 60C, the DC volta~e is from 2-5 ~olts (measured between the anode and cathode) the current density is above 60 amp/ft2 but below that which causes boiling o~ electrolyte and/or forma-tion of brittle plate, the latter being determined empirically.
(The top llmit we have so far observed is about 300 amp/ft2.) In order that the reaction proceed properly, it is also necessary that the slurry of cement copper in electrolyte be agitated violently. Also, the dissolved copper concentration of the electrolyte should be maintained in the range of 20-40 gpl.
Below 20 gpl Cu, a brittle and/or powdery plate will be formed.
; ~he upper limit is unimportant. ~his concentration is con-veniently obtained at the outset by the addition of copper sulfate, although it will build up by itself as pawer is supplied to the cell. ~
~he presence of at least 10 gpl of dissol~ed iron is -mandatory. In the case of cement copper -the minimum content is about 20 gpl. ~o start operations, it is usually necessary to add iron. ~his is conveniently done by adding ferric sulfate. The addition of a soluble copper salt (CuS04) at the outset is also desirable although, as noted, i~ iron is ; present, the copper concentration will be built up and then maintained at a selected levelO
In the case of sulfide concentrates, the specific opera-ting conditions may vary from those required from cement copper7 however, the basic re~uirements of dissolved iron and high current densities remain.
In the case of Cu2S a basic reaction is apparently:
_5 ~ 455~
Cu2S -~ 2Fe~+ --~ Cu~ ~ 2Fe++ ~ Cu~+
with the u++ thereafter being reduced~to plate at the cathode while ferrous iron is reoxidized at the anode.
CuS is only difficultly soluble in the acid electrolyte yet under the conditions of our process the ore is depleted ; relatively easily which means that some mechanism operates todissolve the copper. Our work shows that the rate of copper recovery varies directly with the iron content of the electro-l~te. ~hus, it is believed that the iron does enter into or perhaps catalyzes rapid dissolving of the copper.
In general, for sulfide concentrates during operation the electrolyte ~hould contain 10--25 gpl dissolved i:ron and at least 25 gpl dissolved copper. ~he electrolyte -temperature should be at least 25 gpl dissolved copper. ~he electrolyte temperature should be above 60C but below the boiling point of the solution. Volt~ge should be above about 2.5 volts.
Current densities should be above 60 amp/ft2 cathode area up to a maximum where brittle pla~e or boiling of electrolyte occurs. In general, high current densities result in higher recovery rates. ~;
It is important that the slurry be violently agitated in the cell during the process. This accomplishes several things.
It insures maximum contact between the solids and electrolyte~
avoids uncontrolled polarization at the electrodes, insures ~ -contact between liberated h~drogen gas and ferric iron adjacent ~ the cathode to protect the cathode and the depositea copper ; from attack by ferric iron. Also, if the agitation is carried ~`
~ out b~ movement of the cathode, the plate quality will be . .
~ ~urther enhanced by the moving cathode target.
''` '' '' ~ .....
~45S7~
Extensive tests were performed on cement copper and chalcocite concentrates from sev~ral sources.
r~he equipment used comprised an octagonal shaped tank with its wall serving as the anode. An oscillating cathode was mounted in the tank. r~he cathode was formed with several removable stainless steel plates which permitted variati~ in the cathode area to provide a wide variation of current densi-ties with a given power source. Paddles were mounted on the ~-~
cathode structure to agitate the slurry as the cathode recipro-cated. Power was supplied by a conventional full wave rectifier DC power supply. r~he cell tank was built to contain about 20 inches slurry and the cathodes were arranged to be immersed to a maximum depth of about 18 inches. Each cathode plate thus had an effective single side surface area o~ about .31 ft . In the test arrangements both sides were plated.
r~hus, each plate had a total effective area of .62 ft2.
The cell was filled and emptied manually. Additional copper-bearing materials were added and samples -taken as desired during operating. ~or final analysis of the tails, the tank was emptied entirely. All tests and assays were performed in accordance with accepted techniques.
In examples, -the acid content of the electrolyte is ; recited at the start of a test and is based on the known materials used in making up the solution. r~he acid requirements are simply tha~ only enough acid is required to keep the reaction going at an acceptable rate. r~oo much acid will slow ' down reaction rates. r~he current density affects the acid ; concentration. r~oo low a density will cause undesirable acid build-up in the system with reduction in recovery rates.
~, _7 ~0145~7g Increasing current will stop or even reverse acid build-up.
~hus, the current should be adjusted to maintain the acid at the proper level to maintain optimum recover~ rates without excess gas-release.
A series of tests was conducted on cement copper to demonstrate the ef~ect of dissolved iron on the plating process.
~he cement copper contained about 90Yo copper (dry basis). ~he electrolyte contained 200 gpl H2S0~ at the start. ~he iron content of the electrolyte was increased b~J the incremental addition of ferric sul~ate. ~'he dissolved copper content increased as a result of ~he process1 increasing as iron content increased.
~est DissolvedDits~olvedVoltageCurrent ~emp No. Iron Content Cu gpl Densit~2 e~ol Am~s/î t 1.6 10.6 2.8 ~.4 43 2 13.1 19.7 3.0 55.5 55
3 13.4 23.6 3.4 55.5 40
4 13.4 23.5 3.4 66.6 52 13.8 23.9 3.0 44.4 51 6 25.4 2~.4 3.7 66.6 54 In the foregoing tests copper deposited at the cathode, in the - time indicated, was:
~est 1: A~ter 45 minutes, only unacceptable powder deposited;
25 ~est 2: After 60 minutes brittle plates were formed -total copper recovered was 399 grams. Power consumption - . ., was .853 KWH/lb copper recovered;
~est 3: Af~r 60 minutes a plate o~ improved appearance~ ~ut still somewhat brittle was harvested--total weig~ o~
copper recovered was 358.4 gram~, power consumption was 1~09 KWE/lb copper recovered;
i57~
., ~est 4: After 60 minutes bright flexible plates were harvested. ~otal weight of copper recovered was 479 grams, power consumption was 967 K~JH/lb copper recovered; ~
~est 5: After 60 minutes dense bright flexible plates were -harvested. ~otal weight of copper recovered was 304 grams, power consumption was .925 KWH/lb copper recovered;
~est 6: After 60 minutes, dense bright flexible plates formed.
~otal weight of copper recovered 407 grams, power consumption was 1.2L~ KWH/lb copper recovered.
~he tests demonstrate that th6 ability of the sys-tem to dissolve and plate copper varies directly with the dissolved iron content and, further, that the quality of deposited plate - 15 increases as the dissolved iron content increases~ ~he plate quality is enhanced by the ability of the H2 to reduce corrosive ferric iron adjacent the cathode and by the constant avail-ability of ferric ions elsewhere in -the system to oxidize elemental copper into solution.
Other operating tests were performed in the same test equipment on various cement copper and chalcocite concentrate sa~ples. All tests were conducted with vigorous agitation.
All currents are Da.
~XAMPIE I
h wet chalcocite concentrate containing 37.2% copper by weight (as Cu2S) and ground to pass a 325 mesh screen (~yler) ;~` was mixed in the tank with 45 liters of an electrolyte initially containing in solution 100 gpl H2S04, 15 gpl ferric , ~
; iron and 30 gpl of copper. Voltage averaged 3 5 and a steady 3 current density of 75 amps/ft2 cathode area was applied. ~em-; _9_ ! . . ' , . ~ ~ . . ' . ' ' ~J9LS57~
perature was steady at 61C. ~t the end of 2 hours 447.5 grams of high grade copper plate was strippecl from the cathode.
Power consumption was 1.74 KWH/lb copper recovered. ~he initial charge was 2419 grams containing 900 grams copper of which 447
~est 1: A~ter 45 minutes, only unacceptable powder deposited;
25 ~est 2: After 60 minutes brittle plates were formed -total copper recovered was 399 grams. Power consumption - . ., was .853 KWH/lb copper recovered;
~est 3: Af~r 60 minutes a plate o~ improved appearance~ ~ut still somewhat brittle was harvested--total weig~ o~
copper recovered was 358.4 gram~, power consumption was 1~09 KWE/lb copper recovered;
i57~
., ~est 4: After 60 minutes bright flexible plates were harvested. ~otal weight of copper recovered was 479 grams, power consumption was 967 K~JH/lb copper recovered; ~
~est 5: After 60 minutes dense bright flexible plates were -harvested. ~otal weight of copper recovered was 304 grams, power consumption was .925 KWH/lb copper recovered;
~est 6: After 60 minutes, dense bright flexible plates formed.
~otal weight of copper recovered 407 grams, power consumption was 1.2L~ KWH/lb copper recovered.
~he tests demonstrate that th6 ability of the sys-tem to dissolve and plate copper varies directly with the dissolved iron content and, further, that the quality of deposited plate - 15 increases as the dissolved iron content increases~ ~he plate quality is enhanced by the ability of the H2 to reduce corrosive ferric iron adjacent the cathode and by the constant avail-ability of ferric ions elsewhere in -the system to oxidize elemental copper into solution.
Other operating tests were performed in the same test equipment on various cement copper and chalcocite concentrate sa~ples. All tests were conducted with vigorous agitation.
All currents are Da.
~XAMPIE I
h wet chalcocite concentrate containing 37.2% copper by weight (as Cu2S) and ground to pass a 325 mesh screen (~yler) ;~` was mixed in the tank with 45 liters of an electrolyte initially containing in solution 100 gpl H2S04, 15 gpl ferric , ~
; iron and 30 gpl of copper. Voltage averaged 3 5 and a steady 3 current density of 75 amps/ft2 cathode area was applied. ~em-; _9_ ! . . ' , . ~ ~ . . ' . ' ' ~J9LS57~
perature was steady at 61C. ~t the end of 2 hours 447.5 grams of high grade copper plate was strippecl from the cathode.
Power consumption was 1.74 KWH/lb copper recovered. ~he initial charge was 2419 grams containing 900 grams copper of which 447
5 grams or about 50% was recovered on the cathode.
- EXAr~E II
~ he same setup used in Example I was employed, but an additional 2419 grams of concentrate was added and the system operated at an average of 3.6 volts and a steady current density 10 of 74 amps/ft2~ for ~our hours. Temperature was steady at about 61a. After four hours the pl ates were again stripped.
I!hey were of high guality and weighed 919 grams. Also, a~ter :l~our hours time the electrolyte contained 33.0 grams OI copper and 13.8 grams oî ~errous iron in solution. A-t the beginning 15 of this test, the system contained about 1353 grams of copper as Cu2S and, of this, 919 grams or 68% was recovered at the cathode at a power consumption OI 1.72 KWH/lb copper.
E~IE III
An 1880 gram sample oî we-t chalcocite containing about 46.8% copper as Cu2S and ground to pass a 200 mesh screen (~yler) was mixed in 44 liters OI an electrolyte containing 200 gpl H2S04, 27.4 gpl dissolved iron and 39.3 gpl dissolved copper. I!he system was ~un for 4-1/2 hours during which the voltage varied Irom 3.9 volts during the îirst hour to 3.35 volts during the last hour. Current density was a constant 66.6 amps/ft2. ~emperature ranged from 47-64C.
At the end o~ the test, the electrolyte still contained 32.7 gpl copper as compared to the start oî 39O3 ~,pl. ~he weight o~ copper recovered at the cathode was 1179 grams. Of 30 thi~, 291 grams was taken ~rom the electrolgte while the ', ' ':
, ., , 7~ :
balance was recovered from the concentrate. Ignoring experi-mental error, the recovery was essentially 100%.
The following tests were carried out in a smaller cell - than the other tests. It was essentially of the same design, but shallower and with a smaller cathode area.
E~AMPIæ IV
.
A 1691 gram sample of wet cement copper, containing about ~7.~/0 copper was mixed with 27 liters of electrolyte con- -taining 200 gpl H2S04, 30 gpl dissolved f~rric iron and 30 gpl dissolved copper. ~he system was operated for a total of four hours. Additional amounts of cement copper, totalling 3182 grams, were added at about 1/2 hour intervals. ~hus, the cumu-lative total wet cement copper processed in the cell was 4873 grams containing 2335 grams of copper. Voltage ranged from a high of 4.9 to a low of 3.7. Current density at the cathode also varied from a high of 250 amps/ft2 to a low of 150 amps/ft2.
I ~hese values are shown in Table A.
~ABLE A
~ime Voltage Total Current ~emp _ _ Amp~rage Amps/ft _ -O(Start) 4.3 320 150 59 1-1/2 3.9 ~20 150 70 2 3.8 320 150 71 *2 4.9 430 200 71 2-1/2 4.2 430 200 76 *3 4.5 535 250 7 3-1/2 ~.2 535 250 82 (*changeover in current made at this time) ~S57~
Samples oî copper plate were taken from one cathode plate at 2 hours (47.6 grams) and from the same cathode plate at 3 hours (57.5 grams). At -the end of the test, all cathode plates were stripped, the product sheets weighed and compared with the ;~
product sheets taken during the test. A total of 2150 grams oî
copper was recovered at the cathode. All plates were of high guality, dense and fle}cible. At the finish, the electrol~te contained 40.4 gpl ferrous iron and 40.7 gpl copper All oî
the 2150 grams of plate copper plus the 288 grams increase i~ ;
dissolved copper content of the electrolyte during the test was extracted from the cement copper solids. On the basis of the weight of copper recovered from ths cathode the percent recovery is about 92% and if one considers the additional copper in solu-~; tion as being effectively recovered, and allowing for experimental error, the recovery is at 100%.
~ ~E V :.
A. 1480 gram sample of wet chalcocite conce~Ltrate co~taining 38.7% (573 grams) copper ground to pass a 325 ~yler nesh screen was mixed with 27 liters of electrolyte initially containing lO0 gpl H2S04, 30 gpl copper and 30 gpl iron as ferric sulfate.
q'he test was conducted for a total of six hours. Additional amounts of concentrate containing another 2074 grams copper were added in increments during the test. ~hus, a total OI
2647 grams copper as sulfide was processed. Voltage raIlged from a high of 5.2 to a low of 4.2 volts. Current density at the cathode was at 150 amp~ît2 during the first hour and 200 ,~
amp/ît~ during the balance of the test. ~emperature stæted ;
at 60C and climbed to 79C for the last three howrs. A total of 26~5 grams of copper was recovered a-t the cathode while the electrol;yte showed a loss of 10 grams copper. ~hus, 26~5 grams .:
. .
557~ :
of copper was recovered from the concentrate. ~his represents a recovery of 99.55~/o from the processed concentrate. ~otal power consumption was 11.249 KWH and 2470 a~llp hours. This is a power consumption of 1.93 KWH/lb cathode copper. Current efficience was 90.4Y~-calculated on the basis that a-t 100%
efficiency, one amp. hour will produce 1.185 grams copper.
The electrolyte was sampled at one hour intervals and the samples analyzed for copper and iron content. '~hese reults are listed in Table B.
;~ 10 ~ABIE B
Elapsed Copper Iron* Amp/ft2 ~oltage ime-h s gpl ~pl Cathode DC
O(start) 30. 30.* 150 4.9 1 39.8 25.1 150 1** 39.8 25.1 200 L~.
~, 2 39.8 28.1 200 5.2 3 37-4 29.9 200 5.o +~-~
~' ~ 35.7 30.5 200 4.3 ; 20 5 36-5 32.4 200 4.2
- EXAr~E II
~ he same setup used in Example I was employed, but an additional 2419 grams of concentrate was added and the system operated at an average of 3.6 volts and a steady current density 10 of 74 amps/ft2~ for ~our hours. Temperature was steady at about 61a. After four hours the pl ates were again stripped.
I!hey were of high guality and weighed 919 grams. Also, a~ter :l~our hours time the electrolyte contained 33.0 grams OI copper and 13.8 grams oî ~errous iron in solution. A-t the beginning 15 of this test, the system contained about 1353 grams of copper as Cu2S and, of this, 919 grams or 68% was recovered at the cathode at a power consumption OI 1.72 KWH/lb copper.
E~IE III
An 1880 gram sample oî we-t chalcocite containing about 46.8% copper as Cu2S and ground to pass a 200 mesh screen (~yler) was mixed in 44 liters OI an electrolyte containing 200 gpl H2S04, 27.4 gpl dissolved iron and 39.3 gpl dissolved copper. I!he system was ~un for 4-1/2 hours during which the voltage varied Irom 3.9 volts during the îirst hour to 3.35 volts during the last hour. Current density was a constant 66.6 amps/ft2. ~emperature ranged from 47-64C.
At the end o~ the test, the electrolyte still contained 32.7 gpl copper as compared to the start oî 39O3 ~,pl. ~he weight o~ copper recovered at the cathode was 1179 grams. Of 30 thi~, 291 grams was taken ~rom the electrolgte while the ', ' ':
, ., , 7~ :
balance was recovered from the concentrate. Ignoring experi-mental error, the recovery was essentially 100%.
The following tests were carried out in a smaller cell - than the other tests. It was essentially of the same design, but shallower and with a smaller cathode area.
E~AMPIæ IV
.
A 1691 gram sample of wet cement copper, containing about ~7.~/0 copper was mixed with 27 liters of electrolyte con- -taining 200 gpl H2S04, 30 gpl dissolved f~rric iron and 30 gpl dissolved copper. ~he system was operated for a total of four hours. Additional amounts of cement copper, totalling 3182 grams, were added at about 1/2 hour intervals. ~hus, the cumu-lative total wet cement copper processed in the cell was 4873 grams containing 2335 grams of copper. Voltage ranged from a high of 4.9 to a low of 3.7. Current density at the cathode also varied from a high of 250 amps/ft2 to a low of 150 amps/ft2.
I ~hese values are shown in Table A.
~ABLE A
~ime Voltage Total Current ~emp _ _ Amp~rage Amps/ft _ -O(Start) 4.3 320 150 59 1-1/2 3.9 ~20 150 70 2 3.8 320 150 71 *2 4.9 430 200 71 2-1/2 4.2 430 200 76 *3 4.5 535 250 7 3-1/2 ~.2 535 250 82 (*changeover in current made at this time) ~S57~
Samples oî copper plate were taken from one cathode plate at 2 hours (47.6 grams) and from the same cathode plate at 3 hours (57.5 grams). At -the end of the test, all cathode plates were stripped, the product sheets weighed and compared with the ;~
product sheets taken during the test. A total of 2150 grams oî
copper was recovered at the cathode. All plates were of high guality, dense and fle}cible. At the finish, the electrol~te contained 40.4 gpl ferrous iron and 40.7 gpl copper All oî
the 2150 grams of plate copper plus the 288 grams increase i~ ;
dissolved copper content of the electrolyte during the test was extracted from the cement copper solids. On the basis of the weight of copper recovered from ths cathode the percent recovery is about 92% and if one considers the additional copper in solu-~; tion as being effectively recovered, and allowing for experimental error, the recovery is at 100%.
~ ~E V :.
A. 1480 gram sample of wet chalcocite conce~Ltrate co~taining 38.7% (573 grams) copper ground to pass a 325 ~yler nesh screen was mixed with 27 liters of electrolyte initially containing lO0 gpl H2S04, 30 gpl copper and 30 gpl iron as ferric sulfate.
q'he test was conducted for a total of six hours. Additional amounts of concentrate containing another 2074 grams copper were added in increments during the test. ~hus, a total OI
2647 grams copper as sulfide was processed. Voltage raIlged from a high of 5.2 to a low of 4.2 volts. Current density at the cathode was at 150 amp~ît2 during the first hour and 200 ,~
amp/ît~ during the balance of the test. ~emperature stæted ;
at 60C and climbed to 79C for the last three howrs. A total of 26~5 grams of copper was recovered a-t the cathode while the electrol;yte showed a loss of 10 grams copper. ~hus, 26~5 grams .:
. .
557~ :
of copper was recovered from the concentrate. ~his represents a recovery of 99.55~/o from the processed concentrate. ~otal power consumption was 11.249 KWH and 2470 a~llp hours. This is a power consumption of 1.93 KWH/lb cathode copper. Current efficience was 90.4Y~-calculated on the basis that a-t 100%
efficiency, one amp. hour will produce 1.185 grams copper.
The electrolyte was sampled at one hour intervals and the samples analyzed for copper and iron content. '~hese reults are listed in Table B.
;~ 10 ~ABIE B
Elapsed Copper Iron* Amp/ft2 ~oltage ime-h s gpl ~pl Cathode DC
O(start) 30. 30.* 150 4.9 1 39.8 25.1 150 1** 39.8 25.1 200 L~.
~, 2 39.8 28.1 200 5.2 3 37-4 29.9 200 5.o +~-~
~' ~ 35.7 30.5 200 4.3 ; 20 5 36-5 32.4 200 4.2
6 30.2 30.1 200 4+.2 *At start iron was as ferric. At all other times values are for ferrous.
~*Amperage was increased at end of one hour +++500 ml H2S04 added at end of three hours. (In all work 60 Baume acid was used).
On visual inspection the cathode product was of high qualityO
Many other test$ were made in the same equipment on cement coppers and chalcocite concentrates from various sourcesO The .:
operating conditions were within t~e limits set forth i~ the foregoing examples and general tex*. In all cases~ it was possible to produce a good plate when 1;he dissolved iron content of the electrolyte and current densities were in the stated ranges.
Due to the cost, only pa~t of the copper product was subjected to laboratory assay ~or purit~. However, the copper produced in two additional runs made in accordance with this invention was assayed. One run was made on an Anaconda cement copper containing about 85% copper (dry basis), the resulting plate formally assayed at 99.9965% copper. Another run was made on a chalcocite concentrate containing only 26.L~% copper.
~he resulting plate ~ormally assayed at 99.9942/o copper. ~his is remarkable purit~ and clearly demonstrates the ability of the proce~s to produce high grade copper directly from hereto-fore difficultly treatable ma~erial~.
Although actual tests are reported only o~ cement copper and chalcocite sulfides, it is obvious that the process will apply to any copper-bearing sulfide concentrates.
As used herein, cement copper re~ers to that rinely ~`~ divided copper~ormed in well known manner by ~ of copper s~lutions on steel whereby the copper replaces the iron and is recovered.
Copper bearing sulfides amenable to processing in accord-ance with our process include the common naturally occurringore~, or concentrates thereo~, such as bornite (Cu2FeS2), chalcocite~Cu2S) chàlcopyrite (CuFeS2) and covellite (CuS~.
Also, act~al tests were conducted on Chrysocolla (CuSiO3-~H20), under the conditions outlined ~or sulfides; and it reacted ~',. '.
~ -14- ~
. .
~ sS79 similarly to the chalcocite concentrate, yielding a high ~uality copper.
An important feature o~ our process is the ~act that it operates without undesirable release ~rom the cell of gases, such as 2~ H2 or H2S and the like.
.
' . .
' .`
.
- ~:
,' .
, . . .:
,~:
.. ~:, ~ '',' : ~', ~ ',.;.'' ; :" ' ':
. :.
' ` ' ,~ ' . ~ ~ -. .
, , ' ~
, ~'` , '.
`,` ~ ,~ .
'; : ' '' -15~
~*Amperage was increased at end of one hour +++500 ml H2S04 added at end of three hours. (In all work 60 Baume acid was used).
On visual inspection the cathode product was of high qualityO
Many other test$ were made in the same equipment on cement coppers and chalcocite concentrates from various sourcesO The .:
operating conditions were within t~e limits set forth i~ the foregoing examples and general tex*. In all cases~ it was possible to produce a good plate when 1;he dissolved iron content of the electrolyte and current densities were in the stated ranges.
Due to the cost, only pa~t of the copper product was subjected to laboratory assay ~or purit~. However, the copper produced in two additional runs made in accordance with this invention was assayed. One run was made on an Anaconda cement copper containing about 85% copper (dry basis), the resulting plate formally assayed at 99.9965% copper. Another run was made on a chalcocite concentrate containing only 26.L~% copper.
~he resulting plate ~ormally assayed at 99.9942/o copper. ~his is remarkable purit~ and clearly demonstrates the ability of the proce~s to produce high grade copper directly from hereto-fore difficultly treatable ma~erial~.
Although actual tests are reported only o~ cement copper and chalcocite sulfides, it is obvious that the process will apply to any copper-bearing sulfide concentrates.
As used herein, cement copper re~ers to that rinely ~`~ divided copper~ormed in well known manner by ~ of copper s~lutions on steel whereby the copper replaces the iron and is recovered.
Copper bearing sulfides amenable to processing in accord-ance with our process include the common naturally occurringore~, or concentrates thereo~, such as bornite (Cu2FeS2), chalcocite~Cu2S) chàlcopyrite (CuFeS2) and covellite (CuS~.
Also, act~al tests were conducted on Chrysocolla (CuSiO3-~H20), under the conditions outlined ~or sulfides; and it reacted ~',. '.
~ -14- ~
. .
~ sS79 similarly to the chalcocite concentrate, yielding a high ~uality copper.
An important feature o~ our process is the ~act that it operates without undesirable release ~rom the cell of gases, such as 2~ H2 or H2S and the like.
.
' . .
' .`
.
- ~:
,' .
, . . .:
,~:
.. ~:, ~ '',' : ~', ~ ',.;.'' ; :" ' ':
. :.
' ` ' ,~ ' . ~ ~ -. .
, , ' ~
, ~'` , '.
`,` ~ ,~ .
'; : ' '' -15~
Claims (8)
PROPERTY OF PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for electrowinning of copper values from a finely-divided copper-bearing solid selected from the class consisting of cement copper and copper sulfides comprising the steps of establishing a source of copper for leaching by continuously agitating a quantity of said copper-bearing solids in an H2SO4 electrolyte contained in an electrolytic cell having a cathode and an anode, establishing and maintaining in said electrolyte a dissolved iron concentration of at least ten grams per liter and leaching copper from said source while depositing copper on said cathode by continuously passing a direct current of at least two volts through said electrolyte between said cathode and anode at a current density in excess of about 60 amperes per square foot of cathode area whereby to effect de-position of copper on said cathode concomitantly with liberation of hydrogen thereat.
2. The process according to claim 1 in which a dissolved copper concentration of at least 20 grams per liter is maintained in the electrolyte.
3. The process according to claim 1 in which said direct current has a voltage in the range from 2 volts to 5 volts.
4. The process according to claim 1 in which iron concentration of the electrolyte is established by the addition thereto of ferric sulfate.
5. The process according to claim 1 in which said copper-bearing solid comprises cement copper, and the iron content of said electrolyte is established in a range from 20-40 grams per liter by the addition thereto of ferric sulfate.
6. The process according to claim 5 in which the H2SO4 content of said electrolyte is adjusted by increasing current density to decrease H2SO4 content and by decreasing current density to increase H2SO4 content.
7. The process according to claim 1 in which said copper-bearing solid comprises a material in which the copper occurs as Cu2S, and the iron content of said electrolyte is established in the range of from 10 to 35 grams per liter.
8. The process according to claim 7 in which the H2SO4 content of said electrolyte is adjusted by increasing the density of said direct current to decrease H2SO4 and decreasing said density to increase said H2SO4.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US00382145A US3853724A (en) | 1973-07-24 | 1973-07-24 | Process for electrowinning of copper values from solid particles in a sulfuric acid electrolyte |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1045579A true CA1045579A (en) | 1979-01-02 |
Family
ID=23507704
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA203,902A Expired CA1045579A (en) | 1973-07-24 | 1974-07-03 | Process for electrowinning of copper values from solid forms thereof |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US3853724A (en) |
| JP (1) | JPS552478B2 (en) |
| CA (1) | CA1045579A (en) |
| DE (1) | DE2435206C3 (en) |
| GB (1) | GB1462917A (en) |
| IL (1) | IL45125A (en) |
| OA (1) | OA04748A (en) |
| PH (1) | PH10263A (en) |
| ZA (1) | ZA744155B (en) |
| ZM (1) | ZM11274A1 (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4026772A (en) * | 1975-07-16 | 1977-05-31 | Kennecott Copper Corporation | Direct electrochemical recovery of copper from dilute acidic solutions |
| US4164456A (en) * | 1978-06-15 | 1979-08-14 | Dart Industries Inc. | Electrolytic process |
| US5622615A (en) * | 1996-01-04 | 1997-04-22 | The University Of British Columbia | Process for electrowinning of copper matte |
| US6179988B1 (en) | 1997-08-29 | 2001-01-30 | Electrocopper Products Limited | Process for making copper wire |
| ES2169971B1 (en) * | 1999-10-01 | 2003-11-01 | Consejo Superior Investigacion | PROCEDURE FOR OBTAINING ELECTROLYTIC COPPER FROM COPPER BASED MATERIALS. |
| US7378011B2 (en) * | 2003-07-28 | 2008-05-27 | Phelps Dodge Corporation | Method and apparatus for electrowinning copper using the ferrous/ferric anode reaction |
| CN100421636C (en) * | 2003-11-14 | 2008-10-01 | 尤妮佳股份有限公司 | Disposable wearing article |
| US20060021880A1 (en) * | 2004-06-22 | 2006-02-02 | Sandoval Scot P | Method and apparatus for electrowinning copper using the ferrous/ferric anode reaction and a flow-through anode |
| US7393438B2 (en) * | 2004-07-22 | 2008-07-01 | Phelps Dodge Corporation | Apparatus for producing metal powder by electrowinning |
| US8097132B2 (en) * | 2006-07-04 | 2012-01-17 | Luis Antonio Canales Miranda | Process and device to obtain metal in powder, sheet or cathode from any metal containing material |
| US8273237B2 (en) * | 2008-01-17 | 2012-09-25 | Freeport-Mcmoran Corporation | Method and apparatus for electrowinning copper using an atmospheric leach with ferrous/ferric anode reaction electrowinning |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2792342A (en) * | 1956-01-26 | 1957-05-14 | Phelps Dodge Corp | Electrowinning of copper |
-
1973
- 1973-07-24 US US00382145A patent/US3853724A/en not_active Expired - Lifetime
-
1974
- 1974-01-09 ZM ZM112/74A patent/ZM11274A1/en unknown
- 1974-06-26 IL IL45125A patent/IL45125A/en unknown
- 1974-06-27 ZA ZA00744155A patent/ZA744155B/en unknown
- 1974-07-01 PH PH16004A patent/PH10263A/en unknown
- 1974-07-03 CA CA203,902A patent/CA1045579A/en not_active Expired
- 1974-07-20 OA OA55252A patent/OA04748A/en unknown
- 1974-07-22 DE DE2435206A patent/DE2435206C3/en not_active Expired
- 1974-07-23 GB GB3250974A patent/GB1462917A/en not_active Expired
- 1974-07-24 JP JP8502474A patent/JPS552478B2/ja not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5044115A (en) | 1975-04-21 |
| IL45125A (en) | 1977-05-31 |
| DE2435206A1 (en) | 1975-02-06 |
| AU7057674A (en) | 1976-01-08 |
| OA04748A (en) | 1980-08-31 |
| DE2435206C3 (en) | 1978-12-14 |
| ZA744155B (en) | 1975-07-30 |
| US3853724A (en) | 1974-12-10 |
| IL45125A0 (en) | 1974-09-10 |
| JPS552478B2 (en) | 1980-01-21 |
| PH10263A (en) | 1976-10-20 |
| GB1462917A (en) | 1977-01-26 |
| ZM11274A1 (en) | 1975-02-21 |
| DE2435206B2 (en) | 1978-04-20 |
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