WO2006040392A1 - Production of metallic copper by reducing copper (i) oxide using hydrogen - Google Patents
Production of metallic copper by reducing copper (i) oxide using hydrogen Download PDFInfo
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- WO2006040392A1 WO2006040392A1 PCT/FI2005/000400 FI2005000400W WO2006040392A1 WO 2006040392 A1 WO2006040392 A1 WO 2006040392A1 FI 2005000400 W FI2005000400 W FI 2005000400W WO 2006040392 A1 WO2006040392 A1 WO 2006040392A1
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- Prior art keywords
- copper
- oxide
- alkali
- chloride
- reduction
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- BERDEBHAJNAUOM-UHFFFAOYSA-N copper(i) oxide Chemical compound [Cu]O[Cu] BERDEBHAJNAUOM-UHFFFAOYSA-N 0.000 title claims abstract description 101
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims abstract description 45
- 229910052802 copper Inorganic materials 0.000 title claims abstract description 43
- 239000010949 copper Substances 0.000 title claims abstract description 43
- 239000001257 hydrogen Substances 0.000 title claims abstract description 22
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 22
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 21
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- 238000000034 method Methods 0.000 claims abstract description 40
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims abstract description 28
- 239000003513 alkali Substances 0.000 claims abstract description 27
- 229910001854 alkali hydroxide Inorganic materials 0.000 claims abstract description 24
- 150000008044 alkali metal hydroxides Chemical class 0.000 claims abstract description 24
- 238000005868 electrolysis reaction Methods 0.000 claims abstract description 12
- 239000002994 raw material Substances 0.000 claims abstract description 11
- 229910021591 Copper(I) chloride Inorganic materials 0.000 claims abstract description 8
- OXBLHERUFWYNTN-UHFFFAOYSA-M copper(I) chloride Chemical compound [Cu]Cl OXBLHERUFWYNTN-UHFFFAOYSA-M 0.000 claims abstract description 8
- 238000002386 leaching Methods 0.000 claims abstract description 7
- 238000011084 recovery Methods 0.000 claims abstract description 6
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000000460 chlorine Substances 0.000 claims abstract description 4
- 229910052801 chlorine Inorganic materials 0.000 claims abstract description 4
- 239000000243 solution Substances 0.000 claims description 37
- 239000002002 slurry Substances 0.000 claims description 22
- 238000001556 precipitation Methods 0.000 claims description 7
- 238000010923 batch production Methods 0.000 claims description 4
- 238000010924 continuous production Methods 0.000 claims description 4
- 239000007864 aqueous solution Substances 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 claims description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 2
- 239000011591 potassium Substances 0.000 claims description 2
- 229910052700 potassium Inorganic materials 0.000 claims description 2
- 150000003839 salts Chemical class 0.000 claims description 2
- 239000011734 sodium Substances 0.000 claims description 2
- 229910052708 sodium Inorganic materials 0.000 claims description 2
- ORTQZVOHEJQUHG-UHFFFAOYSA-L copper(II) chloride Chemical compound Cl[Cu]Cl ORTQZVOHEJQUHG-UHFFFAOYSA-L 0.000 claims 2
- 229910021592 Copper(II) chloride Inorganic materials 0.000 claims 1
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 abstract description 2
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 239000000654 additive Substances 0.000 description 6
- 230000006698 induction Effects 0.000 description 6
- 239000012141 concentrate Substances 0.000 description 4
- LBJNMUFDOHXDFG-UHFFFAOYSA-N copper;hydrate Chemical compound O.[Cu].[Cu] LBJNMUFDOHXDFG-UHFFFAOYSA-N 0.000 description 3
- KRFJLUBVMFXRPN-UHFFFAOYSA-N cuprous oxide Chemical compound [O-2].[Cu+].[Cu+] KRFJLUBVMFXRPN-UHFFFAOYSA-N 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- GJCXHYNLSNVSQZ-UHFFFAOYSA-L [Cu](Cl)Cl.Cl Chemical compound [Cu](Cl)Cl.Cl GJCXHYNLSNVSQZ-UHFFFAOYSA-L 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- PYKYMHQGRFAEBM-UHFFFAOYSA-N anthraquinone Natural products CCC(=O)c1c(O)c2C(=O)C3C(C=CC=C3O)C(=O)c2cc1CC(=O)OC PYKYMHQGRFAEBM-UHFFFAOYSA-N 0.000 description 2
- 150000004056 anthraquinones Chemical class 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical class [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 1
- 150000001447 alkali salts Chemical class 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- BWFPGXWASODCHM-UHFFFAOYSA-N copper monosulfide Chemical compound [Cu]=S BWFPGXWASODCHM-UHFFFAOYSA-N 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 231100000317 environmental toxin Toxicity 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 238000009854 hydrometallurgy Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000009853 pyrometallurgy Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B5/00—General methods of reducing to metals
- C22B5/02—Dry methods smelting of sulfides or formation of mattes
- C22B5/12—Dry methods smelting of sulfides or formation of mattes by gases
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B15/00—Obtaining copper
- C22B15/0063—Hydrometallurgy
- C22B15/0065—Leaching or slurrying
- C22B15/0067—Leaching or slurrying with acids or salts thereof
- C22B15/0069—Leaching or slurrying with acids or salts thereof containing halogen
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B15/00—Obtaining copper
- C22B15/0063—Hydrometallurgy
- C22B15/0084—Treating solutions
- C22B15/0089—Treating solutions by chemical methods
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Definitions
- the invention relates to a method for fabricating metallic copper in connection with the chloride-based hydrometallurgical production of copper.
- the copper raw material is leached using copper (II) chloride- alkali chloride solution to obtain a solution of copper (I) chloride.
- Copper is precipitated from the solution as copper (I) oxide and the alkali chloride solution that is formed is routed to chlorine-alkali electrolysis to produce the chlorine, alkali hydroxide and hydrogen required in raw material leaching and copper recovery.
- Metallic copper is prepared from copper (I) oxide by reducing it from a clearly alkaline solution using hydrogen at elevated pressure as either a batch or continuous process.
- US patent publication 6,007,600 describes a method for producing copper in a hydrometallurgical process from a copper-bearing raw material such as copper sulphide concentrate.
- the raw material is leached counter-currently with a strong alkali chloride - copper chloride solution in several stages to form a copper (I) chloride solution. Since both divalent copper and some impurities comprising of other metals are always left in the solution, the divalent copper is reduced and solution purification is performed on the solution.
- the pure cuprous (I) chloride solution is precipitated by means of alkali hydroxide into copper (I) oxide and the oxide is reduced further into elemental copper.
- the alkali chloride solution formed during copper (I) oxide precipitation is treated further in chlorine-alkali electrolysis, from where the chlorine gas and/or chloride solution obtained is used for raw material leaching, the alkali hydroxide generated in electrolysis is used for oxidule precipitation and the hydrogen generated is used for the reduction of the copper to elemental copper.
- US patent publication 6,007,600 relates to the copper recovery method as a whole, and it is mentioned that copper may be recovered from copper (I) oxide either in a pyrometallurgical process or in an autoclave. Autoclave reduction is not described further in the publication.
- cuprite i.e. naturally occurring copper (I) oxide
- I copper
- Hydrogen reduction takes place in an autoclave at a temperature of approximately 15O 0 C and at a hydrogen pressure of 1900 kPa (19 bar).
- dead time or an induction period related to the reduction before the reaction gets underway. The dead time lasts several hours.
- the use of certain additives such as hydrazine or anthraquinone may shorten the induction period.
- the purpose of the method according to the present invention is to reduce copper (I) oxide generated during the hydrometallurgical production of copper into pure metallic copper using hydrogen.
- the induction time related to the reduction of copper (I) oxide generated during hydrometallurgical production may be cut considerably without additives by applying reduction in strongly alkaline conditions.
- the purpose of this invention is to achieve a simple and inexpensive method of producing metallic copper from the copper (I) oxide generated during the hydrometallurgical production of copper.
- Sulphidic copper concentrate is the preferred feed material used in hydrometallurgical production. Copper concentrate is leached using an alkali chloride - copper (II) chloride solution and the copper (I) chloride solution generated is cleaned from impurities. Copper (I) oxide is precipitated from the copper (I) chloride solution by means of alkali hydroxide by known methods.
- the alkali chloride solution formed during copper (1) oxide precipitation is routed to chlorine-alkali electrolysis to produce the chlorine, alkali hydroxide and hydrogen required in raw material leaching and copper recovery.
- the pH of the copper (I) oxide slurry is adjusted to be strongly alkaline by means of alkali hydroxide generated in electrolysis, after which the reduction of copper (I) oxide into metallic copper is carried out in a pressurised space using the hydrogen obtained from electrolysis.
- the slurry to be fed to reduction is strongly alkaline.
- the pH value of the slurry is preferably in the range 9.5 - 13.5.
- the copper (I) oxide always also includes chlorides, which react with alkali hydroxide to form the corresponding alkali salt, which then remains in the solution.
- the amount of chloride is around 0.1 - 1.5%.
- the precipitated Cu 2 O slurry in a strong alkali chloride solution may be routed to a pressurised space as it is without thickening or the slurry may be thickened.
- the slurry may also be fed to reduction as thickened, filtered and washed and reslurried in water.
- the alkalinity of the slurry is achieved either during Cu 2 O precipitation, by adding alkali hydroxide to the Cu 2 O slurry to be fed into the pressurised space or by feeding the alkali hydroxide directly into the pressurised space.
- the reduction of copper (I) oxide can be performed either as a batch or continuous process.
- Copper (I) oxide is reduced into metallic copper in the method according to the invention using hydrogen at an elevated pressure.
- Current autoclave technology has advanced and utilisation of higher pressure and temperature does not produce any great problems.
- Copper (I) oxide reduction can therefore be performed at a partial hydrogen pressure of 40 - 50 bar and at a temperature between 140 - 220 0 C, preferably 170 - 220 0 C.
- the pH of the solution entering the autoclave is adjusted preferably to a value of 9.5 - 13.5 by means of the alkali hydroxide generated in the process.
- the pH adjustment of the slurry can be made in connection with the precipitation of copper (I) oxide that occurs using alkali hydroxide.
- Alkali hydroxide can also be added to the slurry before it is routed to the autoclave or the alkali hydroxide can be fed directly into the autoclave.
- Raising the pH of the solution to be fed to reduction by means of alkali hydroxide is advantageous to the process not only in shortening induction time but also in other regards.
- a small amount of chloride about 0.1 - 1.5%, always remains in the oxide powder.
- the chloride in the oxide powder leaches into the water and is made to react to its salt by means of the hydroxide.
- sodium hydroxide generated in chlorine-alkali electrolysis is beneficially used as the hydroxide, sodium chloride is generated, which does not precipitate with the copper but stays in solution.
- the copper powder is separated from the slurry after reduction and the solution is circulated back to copper concentrate leaching.
- alkalis such as potassium may be used in its place.
- copper (I) oxide reduction can also be performed either directly from the alkali chloride solution or from a thickened slurry without filtration, washing and reslurrying of the precipitate with water.
- the copper (I) oxide may be filtered, washed and reslurried in an aqueous solution before reduction within the framework of the method now developed.
- Copper (I) oxide reduction may be implemented either as a batch or continuous process.
- the table shows that the best result was achieved in tests 4-7, when the pH of the solution was high and no additives were fed into the solution.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Electrolytic Production Of Metals (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The invention relates to a method for fabricating metallic copper in connection with the chloride-based hydrometallurgical production of copper. In the method the copper raw material is leached using copper (II) chloride-alkali chloride solution to obtain a solution of copper (I) chloride. Copper is precipitated from the solution as copper (I) oxide and the alkali chloride solution that is formed is routed to chlorine-alkali electrolysis to produce the chlorine, alkali hydroxide and hydrogen required in raw material leaching and copper recovery. Metallic copper is prepared from copper (I) oxide by reducing it from using hydrogen at elevated pressure and temperature in strongly alkaline conditions.
Description
PRODUCTION OF METALLIC COPPER BY REDUCING COPPER (I) OXIDE USING HYDROGEN
FIELD OF THE INVENTION The invention relates to a method for fabricating metallic copper in connection with the chloride-based hydrometallurgical production of copper. In the method the copper raw material is leached using copper (II) chloride- alkali chloride solution to obtain a solution of copper (I) chloride. Copper is precipitated from the solution as copper (I) oxide and the alkali chloride solution that is formed is routed to chlorine-alkali electrolysis to produce the chlorine, alkali hydroxide and hydrogen required in raw material leaching and copper recovery. Metallic copper is prepared from copper (I) oxide by reducing it from a clearly alkaline solution using hydrogen at elevated pressure as either a batch or continuous process.
BACKGROUND OF THE INVENTION
US patent publication 6,007,600 describes a method for producing copper in a hydrometallurgical process from a copper-bearing raw material such as copper sulphide concentrate. According to the method, the raw material is leached counter-currently with a strong alkali chloride - copper chloride solution in several stages to form a copper (I) chloride solution. Since both divalent copper and some impurities comprising of other metals are always left in the solution, the divalent copper is reduced and solution purification is performed on the solution. The pure cuprous (I) chloride solution is precipitated by means of alkali hydroxide into copper (I) oxide and the oxide is reduced further into elemental copper. The alkali chloride solution formed during copper (I) oxide precipitation is treated further in chlorine-alkali electrolysis, from where the chlorine gas and/or chloride solution obtained is used for raw material leaching, the alkali hydroxide generated in electrolysis is used for oxidule precipitation and the hydrogen generated is used for the reduction of the copper to elemental copper. US patent publication 6,007,600 relates to the copper recovery method as a whole, and it is mentioned that
copper may be recovered from copper (I) oxide either in a pyrometallurgical process or in an autoclave. Autoclave reduction is not described further in the publication.
The fabrication of metallic copper from cuprite (CU2O), an aqueous slurry of it, is described in the congress presentation by Hevia, J. F. & Wadsworth, M. E.: "Hydrothermal Reduction of Copper Oxides", pp. 93-108 in EPD Congress 1994, The Minerals, Metals & Materials Society, Warrendale, 1994. According to the research they described in the presentation, cuprite i.e. naturally occurring copper (I) oxide, is reduced to metallic copper with hydrogen reduction. Hydrogen reduction takes place in an autoclave at a temperature of approximately 15O0C and at a hydrogen pressure of 1900 kPa (19 bar). There is what is known as dead time or an induction period related to the reduction before the reaction gets underway. The dead time lasts several hours. The use of certain additives such as hydrazine or anthraquinone may shorten the induction period.
A commercially available copper (I) oxide powder, intended mainly for pigment use, was used in the tests carried out by Hevia and Wadsworth, which is presumably fairly pure. In practice it has been found that the reduction of the copper (I) oxide generated during the hydrometallurgical fabrication is more difficult than that of commercial, pure CU2O. Therefore it has not been possible to estimate the effect of impurities etc. in the reduction tests described in the presentation. In reduction tests, the pH value of the slurry varied between 7 - 9 and in the article it is stated that the pH value was of no significance.
PURPOSE OF THE INVENTION
The purpose of the method according to the present invention is to reduce copper (I) oxide generated during the hydrometallurgical production of copper into pure metallic copper using hydrogen. The induction time related to the reduction of copper (I) oxide generated during hydrometallurgical
production may be cut considerably without additives by applying reduction in strongly alkaline conditions.
SUMMARY OF THE INVENTION The purpose of this invention is to achieve a simple and inexpensive method of producing metallic copper from the copper (I) oxide generated during the hydrometallurgical production of copper. Sulphidic copper concentrate is the preferred feed material used in hydrometallurgical production. Copper concentrate is leached using an alkali chloride - copper (II) chloride solution and the copper (I) chloride solution generated is cleaned from impurities. Copper (I) oxide is precipitated from the copper (I) chloride solution by means of alkali hydroxide by known methods. The alkali chloride solution formed during copper (1) oxide precipitation is routed to chlorine-alkali electrolysis to produce the chlorine, alkali hydroxide and hydrogen required in raw material leaching and copper recovery. The pH of the copper (I) oxide slurry is adjusted to be strongly alkaline by means of alkali hydroxide generated in electrolysis, after which the reduction of copper (I) oxide into metallic copper is carried out in a pressurised space using the hydrogen obtained from electrolysis.
One essential factor of the invention is that the slurry to be fed to reduction is strongly alkaline. The pH value of the slurry is preferably in the range 9.5 - 13.5.
Due to the method of production, the copper (I) oxide always also includes chlorides, which react with alkali hydroxide to form the corresponding alkali salt, which then remains in the solution. The amount of chloride is around 0.1 - 1.5%.
The precipitated Cu2O slurry in a strong alkali chloride solution may be routed to a pressurised space as it is without thickening or the slurry may be thickened. The slurry may also be fed to reduction as thickened, filtered and
washed and reslurried in water. The alkalinity of the slurry is achieved either during Cu2O precipitation, by adding alkali hydroxide to the Cu2O slurry to be fed into the pressurised space or by feeding the alkali hydroxide directly into the pressurised space.
The reduction of copper (I) oxide can be performed either as a batch or continuous process.
The essential features of the invention will become apparent in the attached claims.
DETAILED DESCRIPTION OF THE INVENTION
In the chloride-based hydrometallurgical production of copper, as described in the above-mentioned US patent 6,007,600, it is advantageous to get the copper in solution in monovalent form i.e. as copper (I) chloride. When chlorine-alkali electrolysis is connected to the process, the alkali chloride solution generated in the process stages is routed to chlorine-alkali electrolysis, which produces chlorine gas that is used in the leaching of the raw material, alkali hydroxide, which is used to precipitate copper (I) oxide and hydrogen, used to produce metallic copper.
Copper (I) oxide is reduced into metallic copper in the method according to the invention using hydrogen at an elevated pressure. Current autoclave technology has advanced and utilisation of higher pressure and temperature does not produce any great problems. Copper (I) oxide reduction can therefore be performed at a partial hydrogen pressure of 40 - 50 bar and at a temperature between 140 - 220 0C, preferably 170 - 220 0C.
The biggest problem in the hydrogen reduction of copper (I) oxide is what is known as dead time, i.e. the reactions get underway very slowly. It is mentioned in the prior art that this induction time has been shortened by using an additive, e.g. hydrazine or anthraquinone. Hydrazine is classified as
an environmental toxin, so its use is always to be avoided. Now it has been found that the induction time required for reduction can be considerably lessened even without additives, when the solution to be reduced is catalysed by making it strongly alkaline. In contrast to the impression given in the prior art, we have found that raising the pH has a powerful effect on the progression of reduction. According to the method now developed, the pH of the solution entering the autoclave is adjusted preferably to a value of 9.5 - 13.5 by means of the alkali hydroxide generated in the process. The pH adjustment of the slurry can be made in connection with the precipitation of copper (I) oxide that occurs using alkali hydroxide. Alkali hydroxide can also be added to the slurry before it is routed to the autoclave or the alkali hydroxide can be fed directly into the autoclave.
Raising the pH of the solution to be fed to reduction by means of alkali hydroxide is advantageous to the process not only in shortening induction time but also in other regards. In the chloride-based production of copper (I) chloride and further in that of copper (I) oxide, a small amount of chloride, about 0.1 - 1.5%, always remains in the oxide powder. When alkali hydroxide is fed into the oxide slurry entering reduction, the chloride in the oxide powder leaches into the water and is made to react to its salt by means of the hydroxide. When the sodium hydroxide generated in chlorine-alkali electrolysis is beneficially used as the hydroxide, sodium chloride is generated, which does not precipitate with the copper but stays in solution.
The copper powder is separated from the slurry after reduction and the solution is circulated back to copper concentrate leaching. Although we speak of sodium in the description, other alkalis such as potassium may be used in its place.
For process economy it is advantageous that copper (I) oxide reduction can also be performed either directly from the alkali chloride solution or from a thickened slurry without filtration, washing and reslurrying of the precipitate with water. Of course the copper (I) oxide may be filtered, washed and
reslurried in an aqueous solution before reduction within the framework of the method now developed. Copper (I) oxide reduction may be implemented either as a batch or continuous process.
Another benefit of this method that is worthy of mention is the fact that nothing is generated in any of the stages that has to be removed from the internal circulation of the process. Furthermore, the alkali hydroxide used as additive and the hydrogen required in reduction are obtained as products of chlorine-alkali electrolysis, as described in US patent publication 6,007,600.
EXAMPLES
Example 1
In order to clarify the method according to the invention, a series of tests was made, in which an aqueous slurry of copper (I) oxide was fed into an autoclave. The amount of copper (I) oxide in each test was 100 g/l. The partial pressure of hydrogen in every test was 45 bar and the temperature 2000C. The chloride content of the starting material was about 1 %. The pH of the solution fed into the autoclave in the tests varied between 8.3 - 13.2. The pH was raised by routing sodium hydroxide into the aqueous solution before it was fed into the autoclave. The other results are presented in Table 1 below. One indicator of the success of the test is the oxygen content of the copper powder produced, in other words, the lower the oxygen content, the more successful the reduction has been.
Table 1
The table shows that the best result was achieved in tests 4-7, when the pH of the solution was high and no additives were fed into the solution.
Claims
1. A method for the recovery of metallic copper from copper (I) oxide in connection with a chloride-based hydrometallurgical production of copper, whereby a copper raw material is leached with a solution of alkali chloride and copper (II) chloride to obtain copper (I) chloride solution, said solution is treated with alkali hydroxide to form copper (I) oxide, and the alkali chloride solution formed in copper (I) oxide precipitation is routed to chlorine-alkali electrolysis to produce the chlorine, alkali hydroxide and hydrogen required in raw material leaching and copper recovery, characterised in that the pH of the copper (I) oxide slurry is adjusted to be strongly alkaline by means of the alkali hydroxide generated in the method, after which the reduction of copper (I) oxide into metallic copper is performed in a pressurised space by means of hydrogen.
2. A method according to claim 1 , characterised in that the pH of the slurry to be reduced is adjusted to a value of 9.5 - 13.5.
3. A method according to claim 1 or 2, characterised in that reduction is carried out at a partial pressure of hydrogen of 40 - 50 bar.
4. A method according to any of claims 1 -3, characterised in that the reduction temperature is adjusted to be in the range of 140 - 22O0C.
5. A method according to claim 4, characterised in that the reduction temperature is adjusted to be in the range of 140 - 22O0C.
6. A method according to any of claims 1-5, characterised in that the copper (I) oxide routed to reduction contains chloride.
7. A method according to claim 6, characterised in that the amount of chloride is 0.1 - 1.5%.
8. A method according to claim 6 or 7, characterised in that the chloride in the copper (I) oxide dissolves and, in reaction with alkali hydroxide, forms the equivalent salt, which remains dissolved in solution.
9. A method according to any of claims 1-8, characterised in that the alkali used is sodium.
10. A method according to any of claims 1-8, characterised in that the alkali used is potassium.
11. A method according to any of claims 1 -10, characterised in that copper (I) oxide is reduced from a concentrated alkali chloride solution.
12. A method according to any of claims 1-10, characterised in that copper (I) oxide is precipitated from a concentrated alkali chloride solution before reduction.
13. A method according to any of claims 1 -10, characterised in that copper (I) oxide is precipitated from a concentrated alkali chloride solution, filtered, washed and slurried into an aqueous solution before reduction.
14. A method according to any of claims 1-13, characterised in that the reduction of copper (I) oxide is performed as a batch process.
15. A method according to any of claims 1-13, characterised in that the reduction of copper (I) oxide is performed as a continuous process.
16. A method according to any of claims 1 -15, characterised in that the pH of the copper (I) oxide slurry is adjusted to be strongly alkaline during copper (I) oxide precipitation.
17. A method according to any of claims 1 -15, characterised in that the pH of the copper (I) oxide slurry is adjusted to be strongly alkaline by feeding alkali hydroxide into the copper (I) oxide slurry that is to be routed into a pressurised space.
18. A method according to any of claims 1-15, characterised in that e the pH of the copper (I) oxide slurry is adjusted to be strongly alkaline by feeding alkali hydroxide into a pressurised space.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI20041332 | 2004-10-14 | ||
| FI20041332A FI117138B (en) | 2004-10-14 | 2004-10-14 | Production of metallic copper by reducing copper (I) oxide by hydrogen |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2006040392A1 true WO2006040392A1 (en) | 2006-04-20 |
Family
ID=33306029
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/FI2005/000400 WO2006040392A1 (en) | 2004-10-14 | 2005-09-22 | Production of metallic copper by reducing copper (i) oxide using hydrogen |
Country Status (2)
| Country | Link |
|---|---|
| FI (1) | FI117138B (en) |
| WO (1) | WO2006040392A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI119439B (en) * | 2007-04-13 | 2008-11-14 | Outotec Oyj | Method and apparatus for reducing copper (I) oxide |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4097271A (en) * | 1975-12-11 | 1978-06-27 | Cominco Ltd. | Hydrometallurgical process for recovering copper and other metal values from metal sulphides |
| US6007600A (en) * | 1997-08-29 | 1999-12-28 | Outokumpu Oyj | Method for producing copper in hydrometallurgical process |
| WO2003035916A1 (en) * | 2001-10-24 | 2003-05-01 | Outokumpu Oyj | A method for purifying the solution in the hydrometallurgical processing of copper |
| WO2003089675A1 (en) * | 2002-04-19 | 2003-10-30 | Outokumpu Oyj | Method for the purification of copper chloride solution |
-
2004
- 2004-10-14 FI FI20041332A patent/FI117138B/en not_active IP Right Cessation
-
2005
- 2005-09-22 WO PCT/FI2005/000400 patent/WO2006040392A1/en active Application Filing
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4097271A (en) * | 1975-12-11 | 1978-06-27 | Cominco Ltd. | Hydrometallurgical process for recovering copper and other metal values from metal sulphides |
| US6007600A (en) * | 1997-08-29 | 1999-12-28 | Outokumpu Oyj | Method for producing copper in hydrometallurgical process |
| WO2003035916A1 (en) * | 2001-10-24 | 2003-05-01 | Outokumpu Oyj | A method for purifying the solution in the hydrometallurgical processing of copper |
| WO2003089675A1 (en) * | 2002-04-19 | 2003-10-30 | Outokumpu Oyj | Method for the purification of copper chloride solution |
Also Published As
| Publication number | Publication date |
|---|---|
| FI20041332L (en) | 2006-04-15 |
| FI20041332A0 (en) | 2004-10-14 |
| FI117138B (en) | 2006-06-30 |
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