CA2443877C - Process for producing cobalt solution of low manganese concentration - Google Patents
Process for producing cobalt solution of low manganese concentration Download PDFInfo
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- CA2443877C CA2443877C CA2443877A CA2443877A CA2443877C CA 2443877 C CA2443877 C CA 2443877C CA 2443877 A CA2443877 A CA 2443877A CA 2443877 A CA2443877 A CA 2443877A CA 2443877 C CA2443877 C CA 2443877C
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- 239000011572 manganese Substances 0.000 title claims abstract description 139
- 229910017052 cobalt Inorganic materials 0.000 title claims abstract description 110
- 239000010941 cobalt Substances 0.000 title claims abstract description 110
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 title claims abstract description 110
- 229910052748 manganese Inorganic materials 0.000 title claims abstract description 96
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 title claims abstract description 89
- 238000000034 method Methods 0.000 title claims abstract description 47
- 239000002244 precipitate Substances 0.000 claims abstract description 60
- 230000001590 oxidative effect Effects 0.000 claims abstract description 31
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 28
- 239000012535 impurity Substances 0.000 claims abstract description 24
- 230000033116 oxidation-reduction process Effects 0.000 claims abstract description 21
- 229910021607 Silver chloride Inorganic materials 0.000 claims abstract description 6
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 claims abstract description 6
- GVPFVAHMJGGAJG-UHFFFAOYSA-L cobalt dichloride Chemical compound [Cl-].[Cl-].[Co+2] GVPFVAHMJGGAJG-UHFFFAOYSA-L 0.000 claims description 21
- 229910021446 cobalt carbonate Inorganic materials 0.000 claims description 16
- ZOTKGJBKKKVBJZ-UHFFFAOYSA-L cobalt(2+);carbonate Chemical compound [Co+2].[O-]C([O-])=O ZOTKGJBKKKVBJZ-UHFFFAOYSA-L 0.000 claims description 16
- 239000002002 slurry Substances 0.000 claims description 13
- 229910021503 Cobalt(II) hydroxide Inorganic materials 0.000 claims description 12
- ASKVAEGIVYSGNY-UHFFFAOYSA-L cobalt(ii) hydroxide Chemical compound [OH-].[OH-].[Co+2] ASKVAEGIVYSGNY-UHFFFAOYSA-L 0.000 claims description 12
- AMWRITDGCCNYAT-UHFFFAOYSA-L hydroxy(oxo)manganese;manganese Chemical compound [Mn].O[Mn]=O.O[Mn]=O AMWRITDGCCNYAT-UHFFFAOYSA-L 0.000 claims description 12
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 11
- 239000000460 chlorine Substances 0.000 claims description 11
- 229910052801 chlorine Inorganic materials 0.000 claims description 11
- 239000007800 oxidant agent Substances 0.000 claims description 11
- 238000004064 recycling Methods 0.000 claims description 7
- 238000004090 dissolution Methods 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 5
- 239000002253 acid Substances 0.000 claims description 4
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 4
- 239000011707 mineral Substances 0.000 claims description 4
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 3
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 3
- 239000003513 alkali Substances 0.000 claims description 3
- 229910052783 alkali metal Inorganic materials 0.000 claims description 3
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 3
- QWPPOHNGKGFGJK-UHFFFAOYSA-N hypochlorous acid Chemical compound ClO QWPPOHNGKGFGJK-UHFFFAOYSA-N 0.000 claims description 3
- 239000007791 liquid phase Substances 0.000 claims description 2
- 238000011084 recovery Methods 0.000 abstract description 6
- 239000000243 solution Substances 0.000 description 105
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 16
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 12
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 12
- 229910052802 copper Inorganic materials 0.000 description 12
- 239000010949 copper Substances 0.000 description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- 230000003647 oxidation Effects 0.000 description 10
- 238000007254 oxidation reaction Methods 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- 229910052759 nickel Inorganic materials 0.000 description 8
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 5
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 4
- 239000012045 crude solution Substances 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 4
- -1 e.g. Substances 0.000 description 4
- 238000005868 electrolysis reaction Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000000638 solvent extraction Methods 0.000 description 4
- 239000007858 starting material Substances 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000006227 byproduct Substances 0.000 description 3
- 238000000975 co-precipitation Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- 238000002386 leaching Methods 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 2
- 239000012074 organic phase Substances 0.000 description 2
- 230000020477 pH reduction Effects 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- WAEMQWOKJMHJLA-UHFFFAOYSA-N Manganese(2+) Chemical compound [Mn+2] WAEMQWOKJMHJLA-UHFFFAOYSA-N 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 125000001309 chloro group Chemical group Cl* 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 229910001437 manganese ion Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
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- 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
- C22B23/00—Obtaining nickel or cobalt
- C22B23/04—Obtaining nickel or cobalt by wet processes
- C22B23/0453—Treatment or purification of solutions, e.g. obtained by leaching
- C22B23/0461—Treatment or purification of solutions, e.g. obtained by leaching by chemical methods
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G45/00—Compounds of manganese
- C01G45/02—Oxides; Hydroxides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G51/00—Compounds of cobalt
-
- 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
- C22B23/00—Obtaining nickel or cobalt
- C22B23/06—Refining
-
- 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
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
- C22B3/44—Treatment or purification of solutions, e.g. obtained by leaching by chemical processes
-
- 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
- C22B47/00—Obtaining manganese
- C22B47/0018—Treating ocean floor nodules
- C22B47/009—Treating ocean floor nodules refining, e.g. separation of metals obtained by the above methods
-
- 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
- C22B23/00—Obtaining nickel or cobalt
- C22B23/04—Obtaining nickel or cobalt by wet processes
- C22B23/0407—Leaching processes
- C22B23/0415—Leaching processes with acids or salt solutions except ammonium salts solutions
- C22B23/0423—Halogenated acids or salts thereof
-
- 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
- C22B47/00—Obtaining manganese
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Metallurgy (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Ocean & Marine Engineering (AREA)
- Oceanography (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The present invention provides a process for producing a cobalt solution of low manganese concentration which can increase direct recovery rate of cobalt by industrially advantageously removing manganese from a cobalt solution containing manganese as an impurity by the oxidative neutralization process. The process containing 2 stages for producing a cobalt solution of low manganese concentration, the first stage being for oxidative neutralization of the cobalt solution controlled at an oxidation-reduction potential of 900mV or more (based on an Ag/AgCl electrode) and pH of 3 or less to remove most of the manganese in the form of oxide precipitate having a Co/Mn ratio of 0.3 to 1.0 by weight, and the second stage being for the continued oxidative neutralization of the cobalt solution produced in the first stage to remove a small quantity of the residual manganese in the form of oxide precipitate and thereby to produce the high-purity cobalt solution containing manganese at 0.05g/L or less, while keeping the same oxidation-reduction potential and pH conditions for the cobalt solution.
Description
SPECIFICATION
PROCESS FOR PRODUCING COBALT SOLUTION OF LOW
MANGANESE CONCENTRATION
BACK GROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention relates to a process for producing a cobalt solution of low manganese concentration, more specifically a process for producing a cobalt solution of low manganese concentration which can increase direct recovery rate of cobalt by industrially advantageously removing manganese from a cobalt solution containing manganese as an impurity by the oxidative neutralization process.
DESCRIPTION OF THE PRIOR ART
Cobalt is a metal which has been widely used for industrial purposes as a material for special alloys and magnetic materials. It is normally occurring in the form of oxide or sulfide, and produced mostly as a by-product of nickel and copper smelting. It is essential, therefore, to separate impurities, e.g., nickel and copper, from a cobalt product.
In general, the first stage for producing cobalt is dissolution of a cobalt-containing starting material in a mineral acid, e.g., hydrochloric or sulfuric acid, to form the cobalt solution. A starting material for cobalt contains a variety of impurities, and the cobalt solution will contain a variety of impurities, accordingly. Cobalt is commonly recovered from the solution as the metal by electrolysis, after the solution is treated to remove impurities. Purity of the electrolysis-produced cobalt metal depends on composition of the electrolyte, and it is necessary for production of high-purity cobalt metal to remove impurities from the cobalt solution.
At present, solvent extraction is used as a process for efficiently separate nickel from cobalt. In the solvent extraction carried out in a chloride bath, cobalt, which forms a stable chloro complex, is extracted in the organic phase to be separated from nickel, and then back-extracted from the organic phase with an aqueous solution of low chlorine ion concentration, e.g., water.
However, manganese and copper are very similar to cobalt in behavior in extraction and back extraction, with the result that the cobalt chloride solution as the back extract produced in the solvent extraction process contains manganese and copper.
Oxidative neutralization process is used to remove manganese and copper from the cobalt chloride solution containing manganese and copper.
For example, the applicant of the present invention has proposed to remove these impurities from a cobalt solution containing iron, manganese, zinc, calcium and copper by the treatment process involving an oxidative neutralization stage and extraction stage with phosphoric acid as the solvent (Patent Document 1).
In the above treatment process, the cobalt chloride solution is oxidized/neutralized while being controlled at an oxidation-reduction potential of 600mV or more (based on an Ag/AgCl electrode), to remove iron, manganese and copper. However, the oxidative neutralization process involves a problem of coprecipitation with cobalt as the major component of the solution partly oxidized/neutralized into the hydroxide as the impurities, e.g., iron, manganese and copper, precipitate.
PROCESS FOR PRODUCING COBALT SOLUTION OF LOW
MANGANESE CONCENTRATION
BACK GROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention relates to a process for producing a cobalt solution of low manganese concentration, more specifically a process for producing a cobalt solution of low manganese concentration which can increase direct recovery rate of cobalt by industrially advantageously removing manganese from a cobalt solution containing manganese as an impurity by the oxidative neutralization process.
DESCRIPTION OF THE PRIOR ART
Cobalt is a metal which has been widely used for industrial purposes as a material for special alloys and magnetic materials. It is normally occurring in the form of oxide or sulfide, and produced mostly as a by-product of nickel and copper smelting. It is essential, therefore, to separate impurities, e.g., nickel and copper, from a cobalt product.
In general, the first stage for producing cobalt is dissolution of a cobalt-containing starting material in a mineral acid, e.g., hydrochloric or sulfuric acid, to form the cobalt solution. A starting material for cobalt contains a variety of impurities, and the cobalt solution will contain a variety of impurities, accordingly. Cobalt is commonly recovered from the solution as the metal by electrolysis, after the solution is treated to remove impurities. Purity of the electrolysis-produced cobalt metal depends on composition of the electrolyte, and it is necessary for production of high-purity cobalt metal to remove impurities from the cobalt solution.
At present, solvent extraction is used as a process for efficiently separate nickel from cobalt. In the solvent extraction carried out in a chloride bath, cobalt, which forms a stable chloro complex, is extracted in the organic phase to be separated from nickel, and then back-extracted from the organic phase with an aqueous solution of low chlorine ion concentration, e.g., water.
However, manganese and copper are very similar to cobalt in behavior in extraction and back extraction, with the result that the cobalt chloride solution as the back extract produced in the solvent extraction process contains manganese and copper.
Oxidative neutralization process is used to remove manganese and copper from the cobalt chloride solution containing manganese and copper.
For example, the applicant of the present invention has proposed to remove these impurities from a cobalt solution containing iron, manganese, zinc, calcium and copper by the treatment process involving an oxidative neutralization stage and extraction stage with phosphoric acid as the solvent (Patent Document 1).
In the above treatment process, the cobalt chloride solution is oxidized/neutralized while being controlled at an oxidation-reduction potential of 600mV or more (based on an Ag/AgCl electrode), to remove iron, manganese and copper. However, the oxidative neutralization process involves a problem of coprecipitation with cobalt as the major component of the solution partly oxidized/neutralized into the hydroxide as the impurities, e.g., iron, manganese and copper, precipitate.
Production of a cobalt solution of low impurity concentration, in particular low manganese concentration, is accompanied by increased quantity of cobalt in the precipitate. The impurity-containing precipitate is separately treated after being discharged from the system, causing another problem that the coprecipitated cobalt cannot be directly recovered.
Under these situations, there are demands for the processes which can control coprecipitation with cobalt as impurities (e.g., iron, manganese and copper) precipitate, in order to effectively remove manganese.
[Patent document 11 Japanese Patent Laid-open Publication No.2000-17347 (refer to the claims) SUMMARY OF THE INVENTION
The present invention provides a process for producing a cobalt solution of low manganese concentration which can increase direct recovery rate of cobalt by industrially advantageously removing manganese from a cobalt solution containing manganese as an impurity by the oxidative neutralization process.
The inventors of the present invention have found, after having extensively studied. precipitation behavior of manganese and cobalt in the oxidation/neutralization reactions in the process for oxidative neutralization of a cobalt chloride solution to achieve the object, that (1) the reaction to form tetravalent manganese oxide proceeds in preference to the reaction to form trivalent cobalt hydroxide in the solution in a low pH range of 3.0 or less and high oxidative atmosphere, i.e., in a high oxidation-reduction potential range, and (2) cobalt hydroxide can be dissolved in preference to manganese oxide, when a precipitate containing these compounds is dissolved in hydrochloric acid, and that these phenomena can be utilized to realize a high, direct recovery rate of cobalt and to produce a high-purity cobalt solution, achieving the present invention.
The first aspect of the present invention is a process for producing a cobalt solution of low manganese concentration, comprising 2 stages for producing a cobalt solution of low manganese concentration by incorporating an oxidant and neutralizer in a cobalt solution containing manganese as an impurity, the first stage being for oxidative neutralization of the cobalt solution controlled at an oxidation-reduction potential of 900mV or more (based on an Ag/AgCI electrode) and pH of 3 or less to remove most of the manganese in the form of oxide precipitate having a Co/Mn ratio of 0.3 to 1.0 by weight, and the second stage being for the continued oxidative neutralization of the cobalt solution produced in the first stage to remove a small quantity of the residual manganese in the form of oxide precipitate and thereby to produce the high-purity cobalt solution containing manganese at 0.05g/L or less, while keeping the same oxidation-reduction potential and pH conditions for the cobalt solution.
The second aspect of the present invention is a process for producing a cobalt solution of low manganese concentration, comprising 3 stages for producing a cobalt solution of low manganese concentration by incorporating an oxidant and neutralizer in a cobalt solution containing manganese as an impurity, the first stage being for oxidative neutralization of the cobalt solution controlled at an oxidation-reduction potential of 900mV or more (based on an Ag/AgC1 electrode) and pH of 3 or less to remove most of the manganese in the form of oxide precipitate having a Co/Mn ratio of 0.3 to 1.0 by weight, the second stage being for the continued oxidative neutralization of the cobalt solution produced in the first stage to remove a small quantity of the residual manganese in the form of oxide precipitate and thereby to produce the high-purity cobalt solution containing manganese at 0.05g/L or less, while keeping the same oxidation-reduction potential and pH conditions for the cobalt solution, and the third stage being for dissolution of the precipitate containing the separated manganese oxide and cobalt hydroxide in a mineral acid to keep the solution at a pH of 0.05 to 2.0, and also for recycling the resulting slurry back to the first stage.
The third aspect of the present invention is the process of the first or second aspect for producing a cobalt solution of low manganese concentration, wherein the cobalt solution is oxidized/neutralized while being controlled at an oxidation-reduction potential of 950 to 1050mV
(based on an Ag/AgCl electrode) and pH of 2.4 to 2.8.
The fourth aspect of the present invention is the process of the first or second aspect for producing a cobalt solution of low manganese concentration, wherein the cobalt solution containing manganese as an impurity is a cobalt chloride solution.
The fifth aspect of the present invention is the process of the first or second aspect for producing a cobalt solution of low manganese concentration, wherein the oxidant is at least one type selected from the group consisting of chlorine, hypochlorous acid and ozone.
The sixth aspect of the present invention is the process of the first or second aspect for producing a cobalt solution of low manganese concentration, wherein the neutralizer is at least one type selected from the group consisting of hydroxide and carbonate of an alkali and alkali-earth metal, and cobalt carbonate.
The seventh aspect of the present invention is the process of the second aspect for producing a cobalt solution of low manganese concentration, wherein said the solution is controlled at a pH of 0.1 to 1.5 in said third stage.
In one embodiment, the invention relates to a process for producing a cobalt solution of low manganese concentration by incorporating an oxidant and a neutralizer in a cobalt solution containing manganese as an impurity, the process comprising three stages: the first stage being for oxidative neutralization of the cobalt solution controlled at an oxidation-reduction potential of 900mV
or more, based on an Ag/AgCI, electrode and a pH of 3 or less, to remove most of the manganese in the form of an oxide precipitate having a Co/Mn ratio of 0.3 to 1.0 by weight; the second stage being for the continued oxidative neutralization of the cobalt solution produced in the first stage to remove residual manganese in the form of an oxide precipitate containing the separated manganese oxide and cobalt hydroxide and thereby to produce the high purity cobalt solution containing manganese at 0.05g/L or less, while keeping the same oxidation-reduction potential and pH conditions for the cobalt solution; and the third stage being for preferential dissolution of cobalt hydroxide from the precipitate using a mineral acid to form a slurry, while keeping the liquid phase of the resulting slurry at a pH
of 0.05 to 2.0 and also for recycling the resulting slurry back to the first stage.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a graph showing the relationship between Mn concentration of the final solution and pH level for the oxidation/neutralization reaction of the cobalt chloride solution.
Figure 2 is a graph showing the relationship between Mn concentration of the final solution and oxidation-reduction potential (ORP) level for the oxidation/neutralization reaction of the cobalt chloride solution.
Figure 3 is a graph showing the relationship between Mn concentration of the final solution and Co/Mn weight ratio of the precipitate produced by the oxidation/neutralization reaction of the cobalt chloride solution.
Figure 4 is a graph showing the effects of pH level on Co and Mn leaching rates, when the precipitate is treated with hydrochloric acid.
DETAILED DESCRIPTION OF THE PRIOR ART
The process of the present invention for producing a cobalt solution of low manganese concentration is described in detail.
The present invention relates to a process for producing a cobalt solution of low manganese concentration, comprising 2 stages for producing 6a a cobalt solution of low manganese concentration by incorporating an oxidant and neutralizer in a cobalt solution containing manganese as an impurity, the first stage being for oxidative neutralization to remove most of the manganese in the form of oxide precipitate and the second stage being for the continued oxidative neutralization to remove a small quantity of the residual manganese in the form of oxide precipitate. The process may include, as required, the third stage for separating part of cobalt hydroxide from the separated (removed) precipitate by preferential dissolution and recycling it back to the first stage.
(1) First stage for removing most of manganese in the form of oxide precipitate This stage first sets a cobalt solution under specific conditions with respect to oxidation-reduction potential and pH level, to remove most of manganese in the form of oxide precipitate having a Co/Mn weight ratio in a specific range.
Cobalt solutions containing manganese as an impurity include a solution as a by-product of nickel or copper refining; solution resulting from a mixed sulfide of nickel and cobalt as a starting material which is leached and extracted with a solvent; cake containing iron which is removed as a by-product of purifying the spent electrolyte discharged from electrolyte refining stage of crude nickel; and solution produced from sulfide cake as a starting material, which is recovered by treating the residual solution from preferential reduction stage of nickel in the presence of hydrogen of elevated pressure with hydrogen sulfide.
The oxidants useful for the present invention include chlorine, hypochlorous acid and ozone, which have a sufficient oxidative power to oxidize the manganese ion to a valence number of +4. Chlorine is particularly preferable, when the cobalt solution is a chloride-based one.
The neutralizer for the present invention is at least one type selected from the group consisting of hydroxide and carbonate of an alkali and alkali-earth metal, e.g., sodium hydroxide, potassium hydroxide and sodium carbonate, and cobalt carbonate. Cobalt carbonate is more preferable, when impurity accumulation in the cobalt solution causes a problem.
When chlorine and cobalt carbonate are used as the oxidant and neutralizer, the divalent manganese in the solution is oxidized by chlorine, and the reaction to precipitate the tetravalent manganese proceeds. This reaction, however, is accompanied by oxidation of cobalt as the major component of the solution into the trivalent state to form the hydroxide, which coprecipitates with manganese oxide.
The present invention involves oxidation/neutralization of a cobalt solution containing manganese as an impurity in the presence of an oxidant and neutralizer, where manganese can be mostly removed in the form of oxide precipitate, when the solution is controlled at an oxidation-reduction potential of 900mV or more (based on an Ag/AgCl electrode) and pH of 3 or less.
The reasons for the oxidation-reduction potential and pH ranges for the cobalt solution are described by referring to Figs. 1 and 2.
A cobalt chloride solution containing Co at 80g/L and Mn at 0.45 or 0.38g/L as the starting solution was controlled at a given pH and oxidation-reduction potential (ORP) level for the oxidation/neutralization in the presence of chlorine and cobalt carbonate as the oxidant and neutralizer, to follow Mn concentration changes for 2 hours as reaction time.
The results are given in Figs. 1 and 2, where Fig.l shows the results with the cobalt chloride solution containing Co at 80g/L and Mn at 0.45g/L
as the starting solution, and Fig.2 the results with the cobalt chloride solution containing Co at 80g[L and Mn at 0.38g/L.
As shown, it is found that (1) decreasing pH or oxidation-reduction potential level tends to hinder removal of manganese, and (2) it is necessary to control the solution at a pH of 2.4 or more and ORP at 950mV or more, in order to keep the reaction effluent (final solution) at an Mn concentration of 0.05g/L or less, desired for production of high-purity cobalt metal by electrolysis.
Therefore, the present invention intending to remove manganese controls the first stage at a pH of 2.4 or more and ORP at 950mV or more, preferably at 2.4 to 2.8 and 950 to 1050mV, more preferably at 2.4 to 2.5 and 950 to 1000mV, while continuously charging chlorine and cobalt carbonate. The first stage operating at a pH above 2.8 or ORP beyond the above range is not economical, because of increased consumption of cobalt carbonate or chlorine.
Next, the reasons for the desired oxidation/neutralization reaction to remove most of manganese in the form of the oxide precipitate having a Co/Mn ratio of 0.3 to 1.0 by weight are described by referring to Fig.3.
A cobalt chloride solution containing Co at 80g/L and Mn at 1.8g/L and kept at a pH of 0.6 as the starting solution was subjected to the oxidation/neutralization in the presence of continuously charged chlorine and cobalt carbonate while controlling the solution at a pH of 2.45, ORP of 950 to 1050mV and 50 C for 2 hours, to follow Mn concentration of the reaction effluent (final solution) and Co/Mn weight ratio of the resulting precipitate.
As a result, it is found that the precipitate has a higher Co/Mn weight ratio as Mn concentration of the final solution decreases, and, for example, the ratio of the resulting precipitate is 1.5 or more when Mn concentration of the cobalt chloride solution is decreased to a level of 0.05g/L or less, desired for production of high-purity cobalt metal by electrolysis.
It is also found that Mn concentration of the reaction effluent is around 0.15g/L and manganese removal rate is around 90%, in order to produce the precipitate of limited coprecipitated cobalt quantity, or of Co/Mn ratio of 1.0 or less by weight.
Therefore, the optimum conditions for the first stage for the present invention are determined from the relationship between manganese precipitation rate (removal rate) and coprecipitated cobalt quantity, and it is preferable to keep Co/Mn ratio of the resulting precipitate of limited coprecipitated cobalt quantity at 1.0 or less by weight. Moreover, the Co/Mn ratio of 0.3 or more by weight, which corresponds to a manganese removal rate of 70% or more, is preferable in consideration of all of the stages involving manganese removal. Therefore, the Co/Mn ratio of the resulting precipitate is set at 0.3 to 1.0 by weight, preferably 0.3 to 0.8.
(2) Stage for producing a high-purity cobalt solution The second stage for the present invention continues the oxidation/neutralization reaction while controlling the cobalt solution, produced in the first stage, at a given oxidation-reduction potential and pH
level to remove a small quantity of the residual manganese in the form of oxide precipitate and thereby to produce the high-purity cobalt solution containing manganese at a specific level or less, as described above.
The second stage is controlled at a pH of 2.4 or more and ORP at 950mV or more, preferably at 2.4 to 2.8 and 950 to 1050mV, more preferably at 2.4 to 2.5 and 950 to 1000mV, as is the case with the first stage. The second stage operating at a pH above 2.8 or ORP above 1050mV is not economical, because of increased consumption of cobalt carbonate or chlorine.
The second stage conditions are set to decrease manganese concentration of the solution to 0.05g/L or less, preferably 0.03g/L or less, in order to give a high-purity cobalt product, as described above. In the second stage, quantity of manganese to be removed is small, because it has been mostly removed in the first stage, and quantity of coprecipitated cobalt decreases. In other words, coprecipitation of cobalt in the precipitate can be controlled, when manganese is removed in 2 stages.
(3) Stage for recycling cobalt in the form of slurry The third stage for the present invention is for separating part of cobalt hydroxide from the precipitate by preferential dissolution and recycling it back to the first stage directly in the form of slurry.
The cobalt hydroxide is preferentially dissolved out of the precipitate separated in the second stage at a specific pH level. How the pH level is determined is explained by referring to Fig.4.
The precipitate (Co concentration: 37.0%, Mn concentration: 17.0%), prepared in the second stage under the conditions of pH: 2.4 and ORP: 950 to 1050mV, was incorporated with hydrochloric acid to change its pH level, to follow Co and Mn leaching rates.
As a result, it is found that manganese is little leached out of the precipitate, while cobalt is preferentially leached out, until the pH level is decreased to 0.1 or so, and that at least 50% of cobalt can be leached out at a pH of around 1.5.
Therefore, cobalt is dissolved out of the precipitate preferably at a pH of 0.05 to 2.0 in the third stage, particularly preferably 0.1 to 1.5. Most of cobalt present in the precipitate is dissolved in the solution in the third stage, and the resulting slurry containing undissolved manganese is recycled back to the first stage. This allows cobalt to be effectively utilized, thereby directly contributing to improved yield of cobalt.
Cobalt hydroxide is leached out less at a higher pH level of the solution.
In this case, the recycled cobalt hydroxide precipitate works as a neutralizer for the first stage for the present invention, decreasing cobalt carbonate consumption. As a result, part of the precipitate formed in the second stage can be directly utilized as a neutralizer for the first stage.
Several methods, e.g., precipitation with a sulfide and cementation with cobalt metal, have been proposed to remove copper, when it is present in the cobalt chloride solution. It can be removed efficiently by these conventional techniques.
Moreover, electrolysis of the high-purity cobalt solution produced by the above methods gives cobalt metal of high quality.
EXAMPLES
The present invention is described by EXAMPLES, which by no means limit the present invention. Weight of the precipitate prepared in each of EXAMPLES is on a wet basis.
Cobalt chloride solution containing manganese:
The back-extract solution (Co concentration: 80.0g/L, Mn concentration:
1.85g/L, pH: 0.6) from the solvent extraction process was used as the cobalt chloride solution.
The first aspect of the present invention, removing manganese in 2 stages, was verified using a reactor tank holding about 100L of the reaction solution.
The solution was treated in the first stage for 2 hours, while it was controlled at a pH of 2.45 and ORP of 950mV in the presence of continuously charged chlorine gas and powdered cobalt carbonate. The resulting precipitate was filtered to obtain 1.2kg of a precipitate having a Co/Mn ratio of 0.40 by weight and 99L of a crude solution containing Mn at 0.45g/L. The first stage performed an Mn removal rate of 75.7% and Co yield of 99.3% (precipitate lost from the system: 0.7%).
The crude solution produced in the first stage was passed to the second stage, where it was treated under the same conditions as in the first stage in the presence of continuously charged chlorine gas and powdered cobalt carbonate. The precipitate produced in the second stage was filtered to obtain 98L of a high-purity cobalt chloride solution containing Mn at 0.01g/L and 0.7kg of a precipitate having a Co/Mn ratio of 1.7 by weight.
The Mn and Co distribution rates in the precipitate produced in the second stage were 23.8 and 0.9%, respectively, based on the Mn and Co amounts charged to the manganese removal process of the first stage.
Mn removal rate of 99.5% and direct Co yield of 98.4% were recorded by the process.
The second aspect of the present invention, comprising removal of manganese in 2 stages followed by a slurry recycling stage, was verified in a similar manner. In the first stage, 100L of the solution was treated in the first stage for 2 hours, while it was controlled at a pH of 2.45 and ORP of 950mV in the presence of continuously charged chlorine gas and powdered cobalt carbonate, after it was incorporated with 1.3L of the slurry produced in the second stage, and treated with and dissolved in hydrochloric acid to be adjusted at a pH of 0.1 The resulting precipitate was filtered to obtain 1.8kg of a precipitate having a Co/Mn ratio of 0.40 by weight and 100L of a crude solution containing Mn at 0.45g[L. The first stage performed an Mn removal rate of 75.7% and Co yield of 99.2% (precipitate lost from the system: 0.8%).
The crude solution produced in the first stage was passed to the second stage, where it was treated under the same conditions as in the first stage in the presence of continuously charged chlorine gas and powdered cobalt carbonate. The precipitate produced in the second stage was filtered to obtain 99L of a high-purity cobalt chloride solution containing Mn at 0.01g[L and 1.1kg of a precipitate having a Co/Mn ratio of 1.7 by weight.
The Mn and Co distribution rates in the precipitate produced in the second stage were 23.8 and 0.9%, respectively, based on the Mn and Co amounts charged to the manganese removal process of the first stage.
Then, the precipitate produced in the second stage was passed to a leaching tank, where it was treated with hydrochloric acid for 1 hour at a pH of 0.1, to prepare the slurry to be recycled back to the first stage.
Mn removal rate of 99.3% and direct Co yield of 99.2% were recorded by the process.
Manganese was removed by a conventional process, where 100L of the solution was treated for 4 hours, while it was controlled at a pH of 3.00 and ORP of 900mV in the presence of continuously charged chlorine gas and powdered cobalt carbonate. The resulting precipitate was filtered to obtain 98L of a high-purity cobalt chloride solution containing Mn at 0.01g/L and 6.1kg of a precipitate having a Co/Mn ratio of 2Ø
This process performed an Mn removal rate of 99.5% and direct Co yield of 95.4% (precipitate lost from the system: 4.6%).
It is apparent, when the results of EXAMPLES are compared with those of COMPARATIVE EXAMPLE, that the present invention can have a greatly higher direct recovery rate of cobalt than the conventional process.
The present invention can remove manganese almost completely from a cobalt chloride solution containing manganese as an impurity while increasing a direct recovery rate of cobalt, and hence is of very high industrial value.
Under these situations, there are demands for the processes which can control coprecipitation with cobalt as impurities (e.g., iron, manganese and copper) precipitate, in order to effectively remove manganese.
[Patent document 11 Japanese Patent Laid-open Publication No.2000-17347 (refer to the claims) SUMMARY OF THE INVENTION
The present invention provides a process for producing a cobalt solution of low manganese concentration which can increase direct recovery rate of cobalt by industrially advantageously removing manganese from a cobalt solution containing manganese as an impurity by the oxidative neutralization process.
The inventors of the present invention have found, after having extensively studied. precipitation behavior of manganese and cobalt in the oxidation/neutralization reactions in the process for oxidative neutralization of a cobalt chloride solution to achieve the object, that (1) the reaction to form tetravalent manganese oxide proceeds in preference to the reaction to form trivalent cobalt hydroxide in the solution in a low pH range of 3.0 or less and high oxidative atmosphere, i.e., in a high oxidation-reduction potential range, and (2) cobalt hydroxide can be dissolved in preference to manganese oxide, when a precipitate containing these compounds is dissolved in hydrochloric acid, and that these phenomena can be utilized to realize a high, direct recovery rate of cobalt and to produce a high-purity cobalt solution, achieving the present invention.
The first aspect of the present invention is a process for producing a cobalt solution of low manganese concentration, comprising 2 stages for producing a cobalt solution of low manganese concentration by incorporating an oxidant and neutralizer in a cobalt solution containing manganese as an impurity, the first stage being for oxidative neutralization of the cobalt solution controlled at an oxidation-reduction potential of 900mV or more (based on an Ag/AgCI electrode) and pH of 3 or less to remove most of the manganese in the form of oxide precipitate having a Co/Mn ratio of 0.3 to 1.0 by weight, and the second stage being for the continued oxidative neutralization of the cobalt solution produced in the first stage to remove a small quantity of the residual manganese in the form of oxide precipitate and thereby to produce the high-purity cobalt solution containing manganese at 0.05g/L or less, while keeping the same oxidation-reduction potential and pH conditions for the cobalt solution.
The second aspect of the present invention is a process for producing a cobalt solution of low manganese concentration, comprising 3 stages for producing a cobalt solution of low manganese concentration by incorporating an oxidant and neutralizer in a cobalt solution containing manganese as an impurity, the first stage being for oxidative neutralization of the cobalt solution controlled at an oxidation-reduction potential of 900mV or more (based on an Ag/AgC1 electrode) and pH of 3 or less to remove most of the manganese in the form of oxide precipitate having a Co/Mn ratio of 0.3 to 1.0 by weight, the second stage being for the continued oxidative neutralization of the cobalt solution produced in the first stage to remove a small quantity of the residual manganese in the form of oxide precipitate and thereby to produce the high-purity cobalt solution containing manganese at 0.05g/L or less, while keeping the same oxidation-reduction potential and pH conditions for the cobalt solution, and the third stage being for dissolution of the precipitate containing the separated manganese oxide and cobalt hydroxide in a mineral acid to keep the solution at a pH of 0.05 to 2.0, and also for recycling the resulting slurry back to the first stage.
The third aspect of the present invention is the process of the first or second aspect for producing a cobalt solution of low manganese concentration, wherein the cobalt solution is oxidized/neutralized while being controlled at an oxidation-reduction potential of 950 to 1050mV
(based on an Ag/AgCl electrode) and pH of 2.4 to 2.8.
The fourth aspect of the present invention is the process of the first or second aspect for producing a cobalt solution of low manganese concentration, wherein the cobalt solution containing manganese as an impurity is a cobalt chloride solution.
The fifth aspect of the present invention is the process of the first or second aspect for producing a cobalt solution of low manganese concentration, wherein the oxidant is at least one type selected from the group consisting of chlorine, hypochlorous acid and ozone.
The sixth aspect of the present invention is the process of the first or second aspect for producing a cobalt solution of low manganese concentration, wherein the neutralizer is at least one type selected from the group consisting of hydroxide and carbonate of an alkali and alkali-earth metal, and cobalt carbonate.
The seventh aspect of the present invention is the process of the second aspect for producing a cobalt solution of low manganese concentration, wherein said the solution is controlled at a pH of 0.1 to 1.5 in said third stage.
In one embodiment, the invention relates to a process for producing a cobalt solution of low manganese concentration by incorporating an oxidant and a neutralizer in a cobalt solution containing manganese as an impurity, the process comprising three stages: the first stage being for oxidative neutralization of the cobalt solution controlled at an oxidation-reduction potential of 900mV
or more, based on an Ag/AgCI, electrode and a pH of 3 or less, to remove most of the manganese in the form of an oxide precipitate having a Co/Mn ratio of 0.3 to 1.0 by weight; the second stage being for the continued oxidative neutralization of the cobalt solution produced in the first stage to remove residual manganese in the form of an oxide precipitate containing the separated manganese oxide and cobalt hydroxide and thereby to produce the high purity cobalt solution containing manganese at 0.05g/L or less, while keeping the same oxidation-reduction potential and pH conditions for the cobalt solution; and the third stage being for preferential dissolution of cobalt hydroxide from the precipitate using a mineral acid to form a slurry, while keeping the liquid phase of the resulting slurry at a pH
of 0.05 to 2.0 and also for recycling the resulting slurry back to the first stage.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a graph showing the relationship between Mn concentration of the final solution and pH level for the oxidation/neutralization reaction of the cobalt chloride solution.
Figure 2 is a graph showing the relationship between Mn concentration of the final solution and oxidation-reduction potential (ORP) level for the oxidation/neutralization reaction of the cobalt chloride solution.
Figure 3 is a graph showing the relationship between Mn concentration of the final solution and Co/Mn weight ratio of the precipitate produced by the oxidation/neutralization reaction of the cobalt chloride solution.
Figure 4 is a graph showing the effects of pH level on Co and Mn leaching rates, when the precipitate is treated with hydrochloric acid.
DETAILED DESCRIPTION OF THE PRIOR ART
The process of the present invention for producing a cobalt solution of low manganese concentration is described in detail.
The present invention relates to a process for producing a cobalt solution of low manganese concentration, comprising 2 stages for producing 6a a cobalt solution of low manganese concentration by incorporating an oxidant and neutralizer in a cobalt solution containing manganese as an impurity, the first stage being for oxidative neutralization to remove most of the manganese in the form of oxide precipitate and the second stage being for the continued oxidative neutralization to remove a small quantity of the residual manganese in the form of oxide precipitate. The process may include, as required, the third stage for separating part of cobalt hydroxide from the separated (removed) precipitate by preferential dissolution and recycling it back to the first stage.
(1) First stage for removing most of manganese in the form of oxide precipitate This stage first sets a cobalt solution under specific conditions with respect to oxidation-reduction potential and pH level, to remove most of manganese in the form of oxide precipitate having a Co/Mn weight ratio in a specific range.
Cobalt solutions containing manganese as an impurity include a solution as a by-product of nickel or copper refining; solution resulting from a mixed sulfide of nickel and cobalt as a starting material which is leached and extracted with a solvent; cake containing iron which is removed as a by-product of purifying the spent electrolyte discharged from electrolyte refining stage of crude nickel; and solution produced from sulfide cake as a starting material, which is recovered by treating the residual solution from preferential reduction stage of nickel in the presence of hydrogen of elevated pressure with hydrogen sulfide.
The oxidants useful for the present invention include chlorine, hypochlorous acid and ozone, which have a sufficient oxidative power to oxidize the manganese ion to a valence number of +4. Chlorine is particularly preferable, when the cobalt solution is a chloride-based one.
The neutralizer for the present invention is at least one type selected from the group consisting of hydroxide and carbonate of an alkali and alkali-earth metal, e.g., sodium hydroxide, potassium hydroxide and sodium carbonate, and cobalt carbonate. Cobalt carbonate is more preferable, when impurity accumulation in the cobalt solution causes a problem.
When chlorine and cobalt carbonate are used as the oxidant and neutralizer, the divalent manganese in the solution is oxidized by chlorine, and the reaction to precipitate the tetravalent manganese proceeds. This reaction, however, is accompanied by oxidation of cobalt as the major component of the solution into the trivalent state to form the hydroxide, which coprecipitates with manganese oxide.
The present invention involves oxidation/neutralization of a cobalt solution containing manganese as an impurity in the presence of an oxidant and neutralizer, where manganese can be mostly removed in the form of oxide precipitate, when the solution is controlled at an oxidation-reduction potential of 900mV or more (based on an Ag/AgCl electrode) and pH of 3 or less.
The reasons for the oxidation-reduction potential and pH ranges for the cobalt solution are described by referring to Figs. 1 and 2.
A cobalt chloride solution containing Co at 80g/L and Mn at 0.45 or 0.38g/L as the starting solution was controlled at a given pH and oxidation-reduction potential (ORP) level for the oxidation/neutralization in the presence of chlorine and cobalt carbonate as the oxidant and neutralizer, to follow Mn concentration changes for 2 hours as reaction time.
The results are given in Figs. 1 and 2, where Fig.l shows the results with the cobalt chloride solution containing Co at 80g/L and Mn at 0.45g/L
as the starting solution, and Fig.2 the results with the cobalt chloride solution containing Co at 80g[L and Mn at 0.38g/L.
As shown, it is found that (1) decreasing pH or oxidation-reduction potential level tends to hinder removal of manganese, and (2) it is necessary to control the solution at a pH of 2.4 or more and ORP at 950mV or more, in order to keep the reaction effluent (final solution) at an Mn concentration of 0.05g/L or less, desired for production of high-purity cobalt metal by electrolysis.
Therefore, the present invention intending to remove manganese controls the first stage at a pH of 2.4 or more and ORP at 950mV or more, preferably at 2.4 to 2.8 and 950 to 1050mV, more preferably at 2.4 to 2.5 and 950 to 1000mV, while continuously charging chlorine and cobalt carbonate. The first stage operating at a pH above 2.8 or ORP beyond the above range is not economical, because of increased consumption of cobalt carbonate or chlorine.
Next, the reasons for the desired oxidation/neutralization reaction to remove most of manganese in the form of the oxide precipitate having a Co/Mn ratio of 0.3 to 1.0 by weight are described by referring to Fig.3.
A cobalt chloride solution containing Co at 80g/L and Mn at 1.8g/L and kept at a pH of 0.6 as the starting solution was subjected to the oxidation/neutralization in the presence of continuously charged chlorine and cobalt carbonate while controlling the solution at a pH of 2.45, ORP of 950 to 1050mV and 50 C for 2 hours, to follow Mn concentration of the reaction effluent (final solution) and Co/Mn weight ratio of the resulting precipitate.
As a result, it is found that the precipitate has a higher Co/Mn weight ratio as Mn concentration of the final solution decreases, and, for example, the ratio of the resulting precipitate is 1.5 or more when Mn concentration of the cobalt chloride solution is decreased to a level of 0.05g/L or less, desired for production of high-purity cobalt metal by electrolysis.
It is also found that Mn concentration of the reaction effluent is around 0.15g/L and manganese removal rate is around 90%, in order to produce the precipitate of limited coprecipitated cobalt quantity, or of Co/Mn ratio of 1.0 or less by weight.
Therefore, the optimum conditions for the first stage for the present invention are determined from the relationship between manganese precipitation rate (removal rate) and coprecipitated cobalt quantity, and it is preferable to keep Co/Mn ratio of the resulting precipitate of limited coprecipitated cobalt quantity at 1.0 or less by weight. Moreover, the Co/Mn ratio of 0.3 or more by weight, which corresponds to a manganese removal rate of 70% or more, is preferable in consideration of all of the stages involving manganese removal. Therefore, the Co/Mn ratio of the resulting precipitate is set at 0.3 to 1.0 by weight, preferably 0.3 to 0.8.
(2) Stage for producing a high-purity cobalt solution The second stage for the present invention continues the oxidation/neutralization reaction while controlling the cobalt solution, produced in the first stage, at a given oxidation-reduction potential and pH
level to remove a small quantity of the residual manganese in the form of oxide precipitate and thereby to produce the high-purity cobalt solution containing manganese at a specific level or less, as described above.
The second stage is controlled at a pH of 2.4 or more and ORP at 950mV or more, preferably at 2.4 to 2.8 and 950 to 1050mV, more preferably at 2.4 to 2.5 and 950 to 1000mV, as is the case with the first stage. The second stage operating at a pH above 2.8 or ORP above 1050mV is not economical, because of increased consumption of cobalt carbonate or chlorine.
The second stage conditions are set to decrease manganese concentration of the solution to 0.05g/L or less, preferably 0.03g/L or less, in order to give a high-purity cobalt product, as described above. In the second stage, quantity of manganese to be removed is small, because it has been mostly removed in the first stage, and quantity of coprecipitated cobalt decreases. In other words, coprecipitation of cobalt in the precipitate can be controlled, when manganese is removed in 2 stages.
(3) Stage for recycling cobalt in the form of slurry The third stage for the present invention is for separating part of cobalt hydroxide from the precipitate by preferential dissolution and recycling it back to the first stage directly in the form of slurry.
The cobalt hydroxide is preferentially dissolved out of the precipitate separated in the second stage at a specific pH level. How the pH level is determined is explained by referring to Fig.4.
The precipitate (Co concentration: 37.0%, Mn concentration: 17.0%), prepared in the second stage under the conditions of pH: 2.4 and ORP: 950 to 1050mV, was incorporated with hydrochloric acid to change its pH level, to follow Co and Mn leaching rates.
As a result, it is found that manganese is little leached out of the precipitate, while cobalt is preferentially leached out, until the pH level is decreased to 0.1 or so, and that at least 50% of cobalt can be leached out at a pH of around 1.5.
Therefore, cobalt is dissolved out of the precipitate preferably at a pH of 0.05 to 2.0 in the third stage, particularly preferably 0.1 to 1.5. Most of cobalt present in the precipitate is dissolved in the solution in the third stage, and the resulting slurry containing undissolved manganese is recycled back to the first stage. This allows cobalt to be effectively utilized, thereby directly contributing to improved yield of cobalt.
Cobalt hydroxide is leached out less at a higher pH level of the solution.
In this case, the recycled cobalt hydroxide precipitate works as a neutralizer for the first stage for the present invention, decreasing cobalt carbonate consumption. As a result, part of the precipitate formed in the second stage can be directly utilized as a neutralizer for the first stage.
Several methods, e.g., precipitation with a sulfide and cementation with cobalt metal, have been proposed to remove copper, when it is present in the cobalt chloride solution. It can be removed efficiently by these conventional techniques.
Moreover, electrolysis of the high-purity cobalt solution produced by the above methods gives cobalt metal of high quality.
EXAMPLES
The present invention is described by EXAMPLES, which by no means limit the present invention. Weight of the precipitate prepared in each of EXAMPLES is on a wet basis.
Cobalt chloride solution containing manganese:
The back-extract solution (Co concentration: 80.0g/L, Mn concentration:
1.85g/L, pH: 0.6) from the solvent extraction process was used as the cobalt chloride solution.
The first aspect of the present invention, removing manganese in 2 stages, was verified using a reactor tank holding about 100L of the reaction solution.
The solution was treated in the first stage for 2 hours, while it was controlled at a pH of 2.45 and ORP of 950mV in the presence of continuously charged chlorine gas and powdered cobalt carbonate. The resulting precipitate was filtered to obtain 1.2kg of a precipitate having a Co/Mn ratio of 0.40 by weight and 99L of a crude solution containing Mn at 0.45g/L. The first stage performed an Mn removal rate of 75.7% and Co yield of 99.3% (precipitate lost from the system: 0.7%).
The crude solution produced in the first stage was passed to the second stage, where it was treated under the same conditions as in the first stage in the presence of continuously charged chlorine gas and powdered cobalt carbonate. The precipitate produced in the second stage was filtered to obtain 98L of a high-purity cobalt chloride solution containing Mn at 0.01g/L and 0.7kg of a precipitate having a Co/Mn ratio of 1.7 by weight.
The Mn and Co distribution rates in the precipitate produced in the second stage were 23.8 and 0.9%, respectively, based on the Mn and Co amounts charged to the manganese removal process of the first stage.
Mn removal rate of 99.5% and direct Co yield of 98.4% were recorded by the process.
The second aspect of the present invention, comprising removal of manganese in 2 stages followed by a slurry recycling stage, was verified in a similar manner. In the first stage, 100L of the solution was treated in the first stage for 2 hours, while it was controlled at a pH of 2.45 and ORP of 950mV in the presence of continuously charged chlorine gas and powdered cobalt carbonate, after it was incorporated with 1.3L of the slurry produced in the second stage, and treated with and dissolved in hydrochloric acid to be adjusted at a pH of 0.1 The resulting precipitate was filtered to obtain 1.8kg of a precipitate having a Co/Mn ratio of 0.40 by weight and 100L of a crude solution containing Mn at 0.45g[L. The first stage performed an Mn removal rate of 75.7% and Co yield of 99.2% (precipitate lost from the system: 0.8%).
The crude solution produced in the first stage was passed to the second stage, where it was treated under the same conditions as in the first stage in the presence of continuously charged chlorine gas and powdered cobalt carbonate. The precipitate produced in the second stage was filtered to obtain 99L of a high-purity cobalt chloride solution containing Mn at 0.01g[L and 1.1kg of a precipitate having a Co/Mn ratio of 1.7 by weight.
The Mn and Co distribution rates in the precipitate produced in the second stage were 23.8 and 0.9%, respectively, based on the Mn and Co amounts charged to the manganese removal process of the first stage.
Then, the precipitate produced in the second stage was passed to a leaching tank, where it was treated with hydrochloric acid for 1 hour at a pH of 0.1, to prepare the slurry to be recycled back to the first stage.
Mn removal rate of 99.3% and direct Co yield of 99.2% were recorded by the process.
Manganese was removed by a conventional process, where 100L of the solution was treated for 4 hours, while it was controlled at a pH of 3.00 and ORP of 900mV in the presence of continuously charged chlorine gas and powdered cobalt carbonate. The resulting precipitate was filtered to obtain 98L of a high-purity cobalt chloride solution containing Mn at 0.01g/L and 6.1kg of a precipitate having a Co/Mn ratio of 2Ø
This process performed an Mn removal rate of 99.5% and direct Co yield of 95.4% (precipitate lost from the system: 4.6%).
It is apparent, when the results of EXAMPLES are compared with those of COMPARATIVE EXAMPLE, that the present invention can have a greatly higher direct recovery rate of cobalt than the conventional process.
The present invention can remove manganese almost completely from a cobalt chloride solution containing manganese as an impurity while increasing a direct recovery rate of cobalt, and hence is of very high industrial value.
Claims (6)
1. A process for producing a cobalt solution of low manganese concentration by incorporating an oxidant and a neutralizer in a cobalt solution containing manganese as an impurity, the process comprising three stages:
the first stage being for oxidative neutralization of the cobalt solution controlled at an oxidation-reduction potential of 900mV or more, based on an Ag/AgCl electrode, and a pH of 3 or less, to remove most of the manganese in the form of an oxide precipitate having a Co/Mn ratio of 0.3 to 1.0 by weight;
the second stage being for the continued oxidative neutralization of the cobalt solution produced in the first stage to remove residual manganese in the form of an oxide precipitate containing the separated manganese oxide and cobalt hydroxide and thereby to produce the high purity cobalt solution containing manganese at 0.05g/L or less, while keeping the same oxidation-reduction potential and pH conditions for the cobalt solution; and the third stage being for preferential dissolution of cobalt hydroxide from the precipitate using a mineral acid to form a slurry, while keeping the liquid phase of the resulting slurry at a pH of 0.05 to 2.0 and also for recycling the resulting slurry back to the first stage.
the first stage being for oxidative neutralization of the cobalt solution controlled at an oxidation-reduction potential of 900mV or more, based on an Ag/AgCl electrode, and a pH of 3 or less, to remove most of the manganese in the form of an oxide precipitate having a Co/Mn ratio of 0.3 to 1.0 by weight;
the second stage being for the continued oxidative neutralization of the cobalt solution produced in the first stage to remove residual manganese in the form of an oxide precipitate containing the separated manganese oxide and cobalt hydroxide and thereby to produce the high purity cobalt solution containing manganese at 0.05g/L or less, while keeping the same oxidation-reduction potential and pH conditions for the cobalt solution; and the third stage being for preferential dissolution of cobalt hydroxide from the precipitate using a mineral acid to form a slurry, while keeping the liquid phase of the resulting slurry at a pH of 0.05 to 2.0 and also for recycling the resulting slurry back to the first stage.
2. A process according to claim 1, wherein said cobalt solution is oxidized/neutralized while being controlled at an oxidation-reduction potential of 950 to 1050mV, based on an Ag/AgCl electrode, and pH of 2.4 to 2.8.
3. The process according to claim 1 or 2, wherein said cobalt solution containing manganese as an impurity is a cobalt chloride solution.
4. The process according to any one of claims 1 to 3, wherein said oxidant is at least one member selected from the group consisting of chlorine, hypochlorous acid and ozone.
5. The process according to any one of claims 1 to 4, wherein said neutralizer is at least one member selected from the group consisting of hydroxide and carbonate of an alkali and alkali-earth metal, and cobalt carbonate.
6. The process according to any one of claims 1 to 5, wherein said solution is controlled at a pH of 0.1 to 1.5 in said third stage.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002291489A JP4240982B2 (en) | 2002-10-03 | 2002-10-03 | Method for producing cobalt solution with low manganese concentration |
| JP2002-291489 | 2002-10-03 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2443877A1 CA2443877A1 (en) | 2004-04-03 |
| CA2443877C true CA2443877C (en) | 2010-09-14 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2443877A Expired - Fee Related CA2443877C (en) | 2002-10-03 | 2003-10-02 | Process for producing cobalt solution of low manganese concentration |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JP4240982B2 (en) |
| AU (1) | AU2003246344B2 (en) |
| CA (1) | CA2443877C (en) |
| GB (1) | GB2394469B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4801372B2 (en) * | 2005-05-10 | 2011-10-26 | 正同化学工業株式会社 | Method for removing manganese from cobalt sulfate solution |
| JP6221968B2 (en) * | 2014-07-01 | 2017-11-01 | 住友金属鉱山株式会社 | Purification method of cobalt chloride solution |
| CN110475752B (en) * | 2017-03-08 | 2022-08-09 | 尤米科尔公司 | Precursor for cathode material for rechargeable lithium ion batteries |
| CN110983053A (en) * | 2019-12-26 | 2020-04-10 | 甘肃睿思科新材料有限公司 | Method for separating nickel, cobalt and manganese in nickel, cobalt and manganese raw material with high manganese-cobalt ratio |
| CN114196826A (en) * | 2020-09-17 | 2022-03-18 | 常宁市华兴冶化实业有限责任公司 | Method for recovering and producing cobalt sulfate heptahydrate from cobalt slag |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU3267600A (en) * | 1999-03-24 | 2000-10-09 | Lakefield Research Limited | Purification of cobalt solutions containing iron and manganese with oxidation mixture of s02 and oxygen |
-
2002
- 2002-10-03 JP JP2002291489A patent/JP4240982B2/en not_active Expired - Lifetime
-
2003
- 2003-09-17 AU AU2003246344A patent/AU2003246344B2/en not_active Expired
- 2003-10-01 GB GB0322971A patent/GB2394469B/en not_active Expired - Lifetime
- 2003-10-02 CA CA2443877A patent/CA2443877C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| GB2394469B (en) | 2007-02-28 |
| AU2003246344A1 (en) | 2004-04-22 |
| CA2443877A1 (en) | 2004-04-03 |
| JP2004123469A (en) | 2004-04-22 |
| GB0322971D0 (en) | 2003-11-05 |
| GB2394469A (en) | 2004-04-28 |
| AU2003246344B2 (en) | 2008-01-24 |
| JP4240982B2 (en) | 2009-03-18 |
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