CA2463268C - Process for purification of aqueous solution of nickel sulfate containing cobalt and calcium - Google Patents
Process for purification of aqueous solution of nickel sulfate containing cobalt and calcium Download PDFInfo
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- CA2463268C CA2463268C CA2463268A CA2463268A CA2463268C CA 2463268 C CA2463268 C CA 2463268C CA 2463268 A CA2463268 A CA 2463268A CA 2463268 A CA2463268 A CA 2463268A CA 2463268 C CA2463268 C CA 2463268C
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- nickel
- cobalt
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- calcium
- aqueous solution
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- 229910017052 cobalt Inorganic materials 0.000 title claims abstract description 131
- 239000010941 cobalt Substances 0.000 title claims abstract description 131
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 title claims abstract description 131
- LGQLOGILCSXPEA-UHFFFAOYSA-L nickel sulfate Chemical compound [Ni+2].[O-]S([O-])(=O)=O LGQLOGILCSXPEA-UHFFFAOYSA-L 0.000 title claims abstract description 80
- 229910000363 nickel(II) sulfate Inorganic materials 0.000 title claims abstract description 80
- 239000011575 calcium Substances 0.000 title claims abstract description 72
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 title claims abstract description 70
- 239000007864 aqueous solution Substances 0.000 title claims abstract description 70
- 229910052791 calcium Inorganic materials 0.000 title claims abstract description 70
- 238000000034 method Methods 0.000 title claims abstract description 36
- 238000000746 purification Methods 0.000 title claims abstract description 18
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 202
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 100
- 239000012074 organic phase Substances 0.000 claims abstract description 93
- 238000006243 chemical reaction Methods 0.000 claims abstract description 58
- 239000008346 aqueous phase Substances 0.000 claims abstract description 27
- 239000003960 organic solvent Substances 0.000 claims abstract description 22
- ZDFBXXSHBTVQMB-UHFFFAOYSA-N 2-ethylhexoxy(2-ethylhexyl)phosphinic acid Chemical compound CCCCC(CC)COP(O)(=O)CC(CC)CCCC ZDFBXXSHBTVQMB-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000004215 Carbon black (E152) Substances 0.000 claims abstract description 8
- 229930195733 hydrocarbon Natural products 0.000 claims abstract description 8
- 150000002430 hydrocarbons Chemical class 0.000 claims abstract description 8
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims description 12
- 238000000638 solvent extraction Methods 0.000 claims description 8
- 229910000361 cobalt sulfate Inorganic materials 0.000 claims description 6
- 229940044175 cobalt sulfate Drugs 0.000 claims description 6
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 claims description 6
- 150000004996 alkyl benzenes Chemical class 0.000 claims description 4
- 150000004945 aromatic hydrocarbons Chemical class 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims 2
- 238000000605 extraction Methods 0.000 abstract description 41
- 239000012535 impurity Substances 0.000 description 29
- 239000002253 acid Substances 0.000 description 17
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 14
- -1 nickel sulfate Chemical class 0.000 description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 239000000243 solution Substances 0.000 description 8
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 6
- 239000012071 phase Substances 0.000 description 6
- 238000000926 separation method Methods 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 4
- 125000000524 functional group Chemical group 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 229910052749 magnesium Inorganic materials 0.000 description 4
- 239000011777 magnesium Substances 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 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 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 3
- 229910021529 ammonia Inorganic materials 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 239000012045 crude solution Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 150000002815 nickel Chemical class 0.000 description 3
- 229910052708 sodium Inorganic materials 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 239000007858 starting material Substances 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 229910052725 zinc Inorganic materials 0.000 description 3
- 239000011701 zinc Substances 0.000 description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910017709 Ni Co Inorganic materials 0.000 description 2
- ABLZXFCXXLZCGV-UHFFFAOYSA-N Phosphorous acid Chemical compound OP(O)=O ABLZXFCXXLZCGV-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-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000007865 diluting Methods 0.000 description 2
- 239000003085 diluting agent Substances 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000012046 mixed solvent Substances 0.000 description 2
- 150000002816 nickel compounds Chemical class 0.000 description 2
- 229910000480 nickel oxide Inorganic materials 0.000 description 2
- 229910000008 nickel(II) carbonate Inorganic materials 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- GVPFVAHMJGGAJG-UHFFFAOYSA-L cobalt dichloride Chemical compound [Cl-].[Cl-].[Co+2] GVPFVAHMJGGAJG-UHFFFAOYSA-L 0.000 description 1
- 229910001429 cobalt ion Inorganic materials 0.000 description 1
- XLJKHNWPARRRJB-UHFFFAOYSA-N cobalt(2+) Chemical compound [Co+2] XLJKHNWPARRRJB-UHFFFAOYSA-N 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000007772 electroless plating Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229910001453 nickel ion Inorganic materials 0.000 description 1
- ZULUUIKRFGGGTL-UHFFFAOYSA-L nickel(ii) carbonate Chemical compound [Ni+2].[O-]C([O-])=O ZULUUIKRFGGGTL-UHFFFAOYSA-L 0.000 description 1
- 125000005461 organic phosphorous group Chemical group 0.000 description 1
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 description 1
- 238000005191 phase separation Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000000611 regression analysis Methods 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000000126 substance Substances 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
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D11/00—Solvent extraction
- B01D11/04—Solvent extraction of solutions which are liquid
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D11/00—Solvent extraction
- B01D11/04—Solvent extraction of solutions which are liquid
- B01D11/0446—Juxtaposition of mixers-settlers
-
- 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
-
- 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
- C22B3/26—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds
- C22B3/38—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds containing phosphorus
- C22B3/384—Pentavalent phosphorus oxyacids, esters thereof
- C22B3/3844—Phosphonic acid, e.g. H2P(O)(OH)2
-
- 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
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The present invention provides a high-efficiency process for purification of a crude aqueous solution of nickel sulfate, which can increase cobalt treatment capacity and produce a purified aqueous solution of nickel sulfate with reduced cobalt and calcium concentrations by improving cobalt extraction efficiency in the exchange reaction. The process uses a multi-stage, countercurrent reaction tank system, wherein the aqueous solution of nickel sulfate is supplied as an aqueous phase to a last stage of the reaction tank system and a mixed organic solvent containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant, loaded with nickel and diluted with a hydrocarbon to an extractant concentration of 20 to 30% by volume, is supplied as a organic phase to a first stage of the reaction tank system, while keeping the aqueous phase at a pH level of 4.5 to 5:5 in the last stage, and a calcium concentration and a nickel, cobalt and calcium total concentration in the organic phase at 0.4g/L or less and 25g/L or less, respectively, in the last stage.
Description
a SPECIFICATION
PROCESS FOR PURIFICATION OF AQUEOUS SOLUTION OF NICKEL
SULFATE CONTAINING COBALT AND CALCIUM
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention relates td a process for purification of an aqueous solution of nickel sulfate containing cobalt and calcium, more particularly an industrially high efficiency process for :purification of the aqueous solution of nickel sulfate containing cobalt and calcium, the former being present at a high concentration, which can increase cobalt treatment capacity and produce a purified aqueous solution of nickel sulfate having reduced cobalt and calcium concentrations by improving cobalt extraction efficiency in the exchange reaction.
DESCRIPTION OF THE PRIOR ART
A process for purification of a crude aqueous solution of nickel sulfate containing a variety of impurities produces a high-purity nickel sulfate solution at industrially high efficiency. The thus-produced high purity aqueous solution of nickel sulfate can be treated by various processes, adopted as required, to obtain high-purity nickel compounds, e.g., nickel sulfate by concentration (e. g., crystallization), nickel oxide by roasting, and nickel carbonate by neutralization with sodium carbonate.
Those nickel compounds; e.g., nickel sulfate, oxide and carbonate, have various industrial applications.
These include materials for general electrolytic plating, for electroless plating for computer hard disks, and for catalysts and batteries. Nickel sulfate, in particular, has been extensively used as a material for plating and as a material for secondary batteries. One of the raw materials for nickel salts, e.g., nickel sulfate, is crude nickel sulfate containing cobalt at a relatively low concentration.
A crude aqueous solution of nickel sulfate, produced by treating a raw material containing cobalt at several percent, is also used fairly extensively. These raw materials include nickel matte, and compound hydroxide or sulfate of nickel and cobalt. Therefore, the process for producing a purified aqueous solution of nickel sulfate from the crude solution or the like generally includes a step for separating nickel and cobalt from each other. Cobalt is rarer and more expensive than nickel, and is separated and purified into various products, e.g., electrolytically purified cobalt, and cobalt chloride and carbonate, to improve economic efficiency of the above process. The industrial applications of nickel salts often require impurities present in the aqueous solution of nickel sulfate to be minimized. These impurities include ammonia, sodium, iron, zinc, copper, calcium and magnesium, in addition to cobalt.
Solvent extraction is a normal choice for purifying a crude aqueous solution of nickel sulfate containing impurities. The solvent extraction processes fall into two general concepts for purifying the solution;
(1) extraction of impurities in an organic phosphorous-containing extractant, e.g:, acidic phosphonic or phosphinic acid ester, and (2) extraction of nickel in an organic extractant, followed by stripping of the nickel-loaded organic phase with sulfuric acid.
However, each concept involves problems resulting from release of a hydrogen ion while impurities or nickel present in a crude aqueous solution is being extracted with an acid extractant, which invariably needs use of sodium hydroxide or ammonia as a neutralizer.
When impurities are to be extracted from a crude aqueous solution of nickel sulfate with an acid extractant, for example, impurities (e. g., cobalt, calcium, iron, zinc, copper or the like), which are generally extracted at a lower pH level than nickel; can be separated in the extractant by adjusting pH of the system to purify the solution. However, this involves problems resulting from contamination of the purified aqueous solution with the sodium or ammonium ion, incorporated as a neutralizer necessary for the extraction process.
On the other hand, when nickel is to be extracted with an acid extractant from a crude aqueous solution of nickel sulfate in the extractant, it is loaded together with impurities, which are extracted at a lower pH level than nickel. Stripping with sulfuric acid to recover nickel from the above loaded extractant is difficult to remove all of these impurity elements.
Some processes have been proposed to solve these problems, where a crude aqueous solution of nickel sulfate containing cobalt and other impurities is brought into contact with an acid extractant treated beforehand to extract nickel therein (such an extractant is hereinafter sometimes referred to ws nickel-loaded, acid extractant) to exchange (substitute) nickel in the nickel-loaded, acid extractant with impurities, beginning with cobalt, which are extracted in an acid extractant in preference to nickel, in order to produce a purified aqueous solution of nickel sulfate and, at the same time, the organic extractant with concentrated cobalt. These processes may be represented by the ones described below:
(1) A solvent extraction process for separating impurities, e.g., cobalt; calcium, magnesium and iron, from a crude aqueous solution of nickel sulfate with a nickel-containing alkyl phosphonic acid ester or alkyl phosphinic acid as an extractant (disclosed in, e.g., Japanese Patent Laid-open Publication No. 10-30135 (pages l and 2)).
(2) A nickel sulfate purification process comprising a series of steps: an extraction step with an acid extractant for separating nickel from a crude aqueous solution of nickel sulfate containing sodium or ammonia at a high concentration to prepare a nickel-loaded organic phase; a step for washing the nickel-loaded organic phase prepared in the preceding extraction step with a nickel-containing washing solution; and an exchanging step fox exchanging (substituting) nickel in the nickel-loaded organic phase washed in the preceding step with impurities, e.g., cobalt, present in the crude aqueous solution of nickel sulfate, by reacting the organic phase with the crude solution containing cobalt at a high concentration, to produce a purified aqueous solution of nickel sulfate and, at the same time, an organic phase in which cobalt is concentrated.
This process further comprises steps; a stripping step with diluted sulfuric acid for selectively stripping nickel from the impurity-loaded organic extractant prepared in the preceding exchanging step; a stripping step with hydrochloric acid for recovering cobalt from the organic phase prepared in the preceding stripping step for selective stripping of nickel; a step for washing the organic phase prepared in the preceding cobalt recovery step; and a r stripping step with sulfuric acid for separating other impurities from the organic phase washed in the preceding step; where part of the impurity-free organic phase prepared in the preceding impurity stripping step is recycled back to the extraction step as an acid extractant, and the remainder is used for diluting the nickel-loaded organic phase (disclosed in, e.g., Japanese Patent Laid-open Publication No. 10-310437 (pages 1 to 5)).
These proposals have been contributing to producing a high-purity, refined aqueous solution of nickel sulfate from a crude aqueous solution of nickel sulfate containing impurities and recovering cobalt. More recently, however, demands have been increasing for processes which can treat a crude aqueous solution of nickel sulfate containing cobalt and other impurities at a higher concentration to produce a highly pure aqueous solution of nickel sulfate and, at the same time, improve efficiency of recovering expensive cobalt.
To satisfy these demands, an application of the above processes (disclosed in, e.g., Japanese Patent Laid-open Publication No. 10-310437 (pages 1 to 5)) is expected, because of their potential for producing a highly pure aqueous solution of nickel sulfate from a crude aqueous solution of nickel sulfate and, at the same time, an organic solvent in which cobalt is concentrated. These processes can be of industrially high efficiency, when they can have increased capacity for treating a starting material of higher cobalt concentration, because an existing production system for purifying an aqueous solution of nickel sulfate can be positively utilized for nickel/cobalt separation to increase recovered cobalt production.
PROCESS FOR PURIFICATION OF AQUEOUS SOLUTION OF NICKEL
SULFATE CONTAINING COBALT AND CALCIUM
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention relates td a process for purification of an aqueous solution of nickel sulfate containing cobalt and calcium, more particularly an industrially high efficiency process for :purification of the aqueous solution of nickel sulfate containing cobalt and calcium, the former being present at a high concentration, which can increase cobalt treatment capacity and produce a purified aqueous solution of nickel sulfate having reduced cobalt and calcium concentrations by improving cobalt extraction efficiency in the exchange reaction.
DESCRIPTION OF THE PRIOR ART
A process for purification of a crude aqueous solution of nickel sulfate containing a variety of impurities produces a high-purity nickel sulfate solution at industrially high efficiency. The thus-produced high purity aqueous solution of nickel sulfate can be treated by various processes, adopted as required, to obtain high-purity nickel compounds, e.g., nickel sulfate by concentration (e. g., crystallization), nickel oxide by roasting, and nickel carbonate by neutralization with sodium carbonate.
Those nickel compounds; e.g., nickel sulfate, oxide and carbonate, have various industrial applications.
These include materials for general electrolytic plating, for electroless plating for computer hard disks, and for catalysts and batteries. Nickel sulfate, in particular, has been extensively used as a material for plating and as a material for secondary batteries. One of the raw materials for nickel salts, e.g., nickel sulfate, is crude nickel sulfate containing cobalt at a relatively low concentration.
A crude aqueous solution of nickel sulfate, produced by treating a raw material containing cobalt at several percent, is also used fairly extensively. These raw materials include nickel matte, and compound hydroxide or sulfate of nickel and cobalt. Therefore, the process for producing a purified aqueous solution of nickel sulfate from the crude solution or the like generally includes a step for separating nickel and cobalt from each other. Cobalt is rarer and more expensive than nickel, and is separated and purified into various products, e.g., electrolytically purified cobalt, and cobalt chloride and carbonate, to improve economic efficiency of the above process. The industrial applications of nickel salts often require impurities present in the aqueous solution of nickel sulfate to be minimized. These impurities include ammonia, sodium, iron, zinc, copper, calcium and magnesium, in addition to cobalt.
Solvent extraction is a normal choice for purifying a crude aqueous solution of nickel sulfate containing impurities. The solvent extraction processes fall into two general concepts for purifying the solution;
(1) extraction of impurities in an organic phosphorous-containing extractant, e.g:, acidic phosphonic or phosphinic acid ester, and (2) extraction of nickel in an organic extractant, followed by stripping of the nickel-loaded organic phase with sulfuric acid.
However, each concept involves problems resulting from release of a hydrogen ion while impurities or nickel present in a crude aqueous solution is being extracted with an acid extractant, which invariably needs use of sodium hydroxide or ammonia as a neutralizer.
When impurities are to be extracted from a crude aqueous solution of nickel sulfate with an acid extractant, for example, impurities (e. g., cobalt, calcium, iron, zinc, copper or the like), which are generally extracted at a lower pH level than nickel; can be separated in the extractant by adjusting pH of the system to purify the solution. However, this involves problems resulting from contamination of the purified aqueous solution with the sodium or ammonium ion, incorporated as a neutralizer necessary for the extraction process.
On the other hand, when nickel is to be extracted with an acid extractant from a crude aqueous solution of nickel sulfate in the extractant, it is loaded together with impurities, which are extracted at a lower pH level than nickel. Stripping with sulfuric acid to recover nickel from the above loaded extractant is difficult to remove all of these impurity elements.
Some processes have been proposed to solve these problems, where a crude aqueous solution of nickel sulfate containing cobalt and other impurities is brought into contact with an acid extractant treated beforehand to extract nickel therein (such an extractant is hereinafter sometimes referred to ws nickel-loaded, acid extractant) to exchange (substitute) nickel in the nickel-loaded, acid extractant with impurities, beginning with cobalt, which are extracted in an acid extractant in preference to nickel, in order to produce a purified aqueous solution of nickel sulfate and, at the same time, the organic extractant with concentrated cobalt. These processes may be represented by the ones described below:
(1) A solvent extraction process for separating impurities, e.g., cobalt; calcium, magnesium and iron, from a crude aqueous solution of nickel sulfate with a nickel-containing alkyl phosphonic acid ester or alkyl phosphinic acid as an extractant (disclosed in, e.g., Japanese Patent Laid-open Publication No. 10-30135 (pages l and 2)).
(2) A nickel sulfate purification process comprising a series of steps: an extraction step with an acid extractant for separating nickel from a crude aqueous solution of nickel sulfate containing sodium or ammonia at a high concentration to prepare a nickel-loaded organic phase; a step for washing the nickel-loaded organic phase prepared in the preceding extraction step with a nickel-containing washing solution; and an exchanging step fox exchanging (substituting) nickel in the nickel-loaded organic phase washed in the preceding step with impurities, e.g., cobalt, present in the crude aqueous solution of nickel sulfate, by reacting the organic phase with the crude solution containing cobalt at a high concentration, to produce a purified aqueous solution of nickel sulfate and, at the same time, an organic phase in which cobalt is concentrated.
This process further comprises steps; a stripping step with diluted sulfuric acid for selectively stripping nickel from the impurity-loaded organic extractant prepared in the preceding exchanging step; a stripping step with hydrochloric acid for recovering cobalt from the organic phase prepared in the preceding stripping step for selective stripping of nickel; a step for washing the organic phase prepared in the preceding cobalt recovery step; and a r stripping step with sulfuric acid for separating other impurities from the organic phase washed in the preceding step; where part of the impurity-free organic phase prepared in the preceding impurity stripping step is recycled back to the extraction step as an acid extractant, and the remainder is used for diluting the nickel-loaded organic phase (disclosed in, e.g., Japanese Patent Laid-open Publication No. 10-310437 (pages 1 to 5)).
These proposals have been contributing to producing a high-purity, refined aqueous solution of nickel sulfate from a crude aqueous solution of nickel sulfate containing impurities and recovering cobalt. More recently, however, demands have been increasing for processes which can treat a crude aqueous solution of nickel sulfate containing cobalt and other impurities at a higher concentration to produce a highly pure aqueous solution of nickel sulfate and, at the same time, improve efficiency of recovering expensive cobalt.
To satisfy these demands, an application of the above processes (disclosed in, e.g., Japanese Patent Laid-open Publication No. 10-310437 (pages 1 to 5)) is expected, because of their potential for producing a highly pure aqueous solution of nickel sulfate from a crude aqueous solution of nickel sulfate and, at the same time, an organic solvent in which cobalt is concentrated. These processes can be of industrially high efficiency, when they can have increased capacity for treating a starting material of higher cobalt concentration, because an existing production system for purifying an aqueous solution of nickel sulfate can be positively utilized for nickel/cobalt separation to increase recovered cobalt production.
Treatment of a starting material of higher cobalt concentration will give a crude aqueous solution of nickel sulfate of higher cobalt concentration. There are two concepts to increase cobalt treatment capacity for the step of exchanging nickel in the nickel-loaded organic phase with cobalt and other impurities present in a crude aqueous solution of nickel sulfate in these processes;
(1) increasing the flow rate of the nickel-loaded organic phase to increase the amount of cobalt to be extracted per unit time, and (2) increasing the cobalt concentration in the organic phase from the exchanging reaction step. The former concept of increasing the treatment flow rate is a simple approach, but needs large investments to increase capacity of the solvent extraction reaction facilities, e.g., mixer settler, in proportion to the increased flow rate to keep a residence time required for separation of the nickel-loaded organic phase from a crude aqueous solution of nickel sulfate, which may harm economic efficiency.
For the latter concept, on the other hand, it is affective to increase the concentration of cobalt in the exchanged organic phase by increasing the concentration of an acid extractant in the nickel-loaded organic phase and cobalt extraction efficiency. When phosphoric or phosphonic acid is used as an acid extractant for the exchanging reaction, 1 mol of cobalt or calcium can be extracted per 2 moll of the extractant. It is the maximum attainable extraction rate of cobalt or calcium (hereinafter referred to as the stoichiometric extraction rate). With 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant, the stoichiometric extraction rate of cobalt is I8.3g/L in the organic solvent containing the extractant at 20~ by volume and a diluent. On a commercial scale, however, cobalt extraction efficiency is generally low at 40 to 60~ of the stoichiometric extraction rate.
The low extraction rate results from intentional control of the cobalt concentration to stabilize its extraction, because (1) driving force for the extraction reaction is decreased with an extractant having a larger number of functional groups bound to the nickel or cobalt ions than an extractant having a larger number of functional groups bound to the hydrogen ions, (2) utilization of nickel in the exchanging reaction is decreased, when pH level of the reaction system is increased to increase extraction capacity, which is accompanied by accelerated extraction of nickel to increase its concentration in the exchanged organic phase, and (3) an increased cobalt concentration in the organic phase generally increases its viscosity, which decreases efficiency for separating the organic phase from the aqueous solution phase. Therefore, there are problems to be solved also for increasing the cobalt concentration in the exchanged organic phase to increase cobalt extraction capacity.
Therefore, there are demands for methods which can increase the cobalt concentration in the exchanged organic phase, i.e., increase the cobalt extraction efficiency, while controlling a viscosity increase of the phase, without increasing plant capacity, in order to increase cobalt treatment capacity.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an industrially highly efficient process for purification of an aqueous solution of nickel sulfate containing cobalt and calcium, the former being present at a high concentration, which can increase cobalt treatment capacity and produce a purified aqueous solution of nickel sulfate with reduced cobalt and calcium concentrations by improving cobalt extraction efficiency in the exchange reaction, in consideration of the above-described problems involved in the conventional techniques.
The inventors of the present invention extensively studied an aqueous nickel sulfate solution purification process based on solvent extraction involving an exchanging reaction in a multi-stage, countercurrent reaction tank system, attempting to attain the above object. As a result, the inventors found that cobalt extraction efficiency can be improved by bringing an aqueous solution phase of nickel sulfate containing cobalt and calcium into contact with a mixed organic solvent phase containing an extractant at a specific concentration, and keeping the aqueous phase at a specific pH level, and a calcium concentration and a nickel, cobalt and calcium total concentration in the organic phase at a specific level. Hence, the present invention was achieved.
The present invention provides a process for purification of an aqueous solution of nickel sulfate, comprising:
a solvent extraction involving an exchanging reaction in a multi-stage, countercurrent reaction tank system, wherein:
an aqueous solution of nickel sulfate containing cobalt and calcium as impurities is supplied as an aqueous phase to a last stage of the reaction tank system and a mixed organic solvent containing as an extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester loaded with nickel and diluted with a hydrocarbon to an extractant concentration of 20 to 30% by volume, is supplied as an organic phase to a first stage of the reaction tank system, to bring these phases into contact with each other for the exchanging reaction, and the aqueous phase is kept at a pH level of 4.5 to 5.5 in the last stage, and a calcium concentration and a nickel, cobalt and calcium total concentration in the organic phase are kept at 0.4g/L or less and 25g/L or less, respectively, in the last stage.
According to a first major embodiment of the present invention, the mixed organic solvent contains the extractant at a concentration of 25 to 30~ by volume.
According to a second major embodiment of the present invention, the nickel, cobalt and calcium total concentration in the organic phase is 20g/L or less in the last stage.
According to a third major embodiment of the present invention, the aqueous phase is kept at a pH level of 4.8 to 5.2 in the last stage.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a graph showing viscosities of the organic phase plotted against nickel, cobalt and calcium total concentrations in the organic phase.
Figure 2 is a graph showing nickel, cobalt and calcium total concentrations in the organic phase plotted against pH levels for the exchanging reaction.
Figure 3 is a graph showing cobalt extraction efficiencies (ratios of cobalt amounts in the organic phase to the stoichiometric cobalt extraction rate) plotted against calcium concentrations in the organic phase.
DETAILED DESCRIPTION OF THE INVENTION
The process of the present invention for purification of an aqueous solution of nickel sulfate containing cobalt and calcium is described in detail.
The process of the present invention for purification of an aqueous solution of nickel sulfate containing cobalt and calcium, the former being present at a high concentration, is of industrially high efficiency, because it can increase cobalt treatment capacity without increasing plant capacity by improving cabalt extraction efficiency in the exchange reaction between the aqueous solution and nickel-loadedacid extractant: As such, it is suitable for an exchanging reaction step in a nickel sulfate purification process comprising several steps; e.g., extraction step for producing the nickel-loaded organic phase, step for exchanging with cobalt present in a crude aqueous solution of nickel sulfate, step for stripping of nickel from the exchanged organic phase in which cobalt is concentrated, cobalt recovering step, and impurity stripping step.
The process of the present invention for purification of an aqueous solution of nickel sulfate containing cobalt and calcium uses a multi-stage, countercurrent reaction tank system, wherein the aqueous solution of nickel sulfate is supplied as the aqueous phase to the last stage and a mixed organic solvent containing an extractant of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester loaded with nickel and diluted with a hydrocarbon, is supplied as the organic phase to the first stage, to bring these phases into contact with each other for an exchanging reaction, the aqueous phase being kept at a given pH level in the last stage, and the calcium concentration and the nickel, cobalt and calcium total concentration in the organic phase being kept at a given concentration in the last stage.
(1) Aqueous solution of nickel sulfate The aqueous solution of nickel sulfate to be treated by the present invention contains Cobalt and calcium. The particularly preferable solution is a crude aqueous solution of nickel sulfate containing cobalt at a high concentration, produced by treating a raw material containing cobalt at several percent. The crude aqueous solution, for example, contains nickel sulfate at 40-70 g/L, cobalt sulfate at 20-50 g/L and calcium sulfate at 0.1-1 g/L, but always nickel sulfate is contained at a higher concentration than cobalt sulfate. It may be adjusted beforehand at a given pH level, to help adjust pH
level for the exchanging reaction.
(2) Mixed organic solvent containing a nickel-loaded acid extractant In the present invention, a nickel-loaded acid extractant is prepared beforehand for the exchanging reaction. In the present invention, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester is used as the acid extractant, which is diluted with a hydrocarbon to a given extractant concentration to prepare the mixed organic solvent. The extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester can efficiently extract cobalt, calcium and magnesium.
It has a separation coefficient in a sulfuric acid solution of cobalt/nickel: 650, calcium/nickel: 110 and magnesium/nickel: 50. It has a still higher separation coefficient for zinc, iron and copper, by which is meant that these elements are preferentially extracted.
Acid extractants are generally viscous, and are mixed with a diluent before use. In the present invention, it is diluted with a hydrocarbon. The hydrocarbon is not limited for the present invention, and may be aliphatic or aromatic, of which an alkylbenzene as an aromatic hydrocarbon is particularly preferable. The mixed organic solvent for the present invention contains the extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester at 20 to 30o by volume, preferably 25 to 30~. At below 20% by volume, cobalt extraction rate per unit amount of the mixed organic solvent is insufficient. At above 30o by volume, on the other hand, the mixed organic solvent may be excessively viscous to deteriorate organic solvent/aqueous phase separation efficiency and cause unstable operation and decreased productivity. The mixed organic solvent of the above composition for the present invention is suitable for exchanging of impurities present in the aqueous solution of nickel sulfate, e.g., cobalt and calcium which are extracted in preference to nickel, with nickel loaded beforehand by the extractant.
It is an economically recommended practice to recycle the exchanged organic phase containing impurities back to a series of nickel stripping, cobalt recovery and impurity stripping step in the nickel sulfate purification process (disclosed in, e.g., Japanese Patent Laid-open Publication No. 10-310437 (pages 1 to 5)), in order to recover nickel remaining in the organic phase, recover cobalt and remove impurities other than cobalt in the respective step, and to clean and recover the organic phase for reuse.
The mixed organic solvent can load nickel by common solvent extraction. For example, nickel can be extracted from an aqueous solution of nickel sulfate as the starting material with the acid extractant described above in a multi-stage, countercurrent reaction tank system, wherein the extractant is supplied to the first stage while the aqueous solution to the last stage for the extraction reaction at a pH of 5.0 to 7Ø It is preferable to keep a concentration of nickel loaded in the mixed organic solvent in excess of the stoichiometric level, so that the impurity elements may be efficiently extracted by the exchanging reaction. An insufficient amount of nickel may keep these impurity elements in the purified aqueous solution of nickel sulfate, even when the exchanging reaction proceeds completely. At the stoichiometric level, on the other hand, the exchanging reaction cannot proceed completely, because nickel in the organic phase is depleted as the reaction proceeds.
(3) Purification system and method In the present invention, the reactor system for the exchanging reaction may be selected from various multi-stage, countercurrent reaction tank systems capable of efficiently separating the organic and aqueous phase from each other after contacting them. The particularly preferable one is a continuous, multi-stage, countercurrent mixer settler system, where the nickel-loaded mixed solvent and the crude aqueous solution of nickel sulfate come into contact with each other, the former supplied to the first stage and the latter to the last stage. Therefore, the purified aqueous solution of nickel sulfate is discharged from the first stage mixer settler, and the exchanged organic phase containing cobalt from the last stage mixer settler.
The exchanged organic phase preferably contains nickel at 1 to 4.5g/L. Nickel in the organic phase is depleted as the exchanging reaction proceeds. When it is depleted to a concentration below lg/L, the nickel/cobalt exchanging reaction proceeds insufficiently, to increase concentration of cobalt in the purified aqueous solution of nickel sulfate. At above 4.5g/L, on the other hand, recovery of nickel in the purified aqueous solution of nickel sulfate may be retarded. The nickel/cobalt exchanging reaction will proceed smoothly at a nickel concentration of 1 to 4.5g/L in the organic phase.
In the present invention, the aqueous phase in the last stage of the mufti-stage, countercurrent reaction tank system is adjusted at a pH level of 4.5 to 5.5, preferably 4.8 to 5.2. Increasing the pH level accelerates extraction of nickel and cobalt in the organic phase. At a pH level below 4.5, cobalt concentration in the exchanged organic phase decreases to deteriorate cobalt extraction efficiency.
At a pH level above 5.5, on the other hand; nickel concentration in the organic phase increases to deteriorate the nickel recovery rate in the purified aqueous solution of nickel sulfate, but also cobalt extraction efficiency resulting from increased number of nickel atoms bound to functional groups in the extractant to substantially reduces number of functional groups to be bound to cobalt. A
conventional exchanging step with an acid extractant loaded with nickel at an adequate concentration, releasing no hydrogen ion, needs no neutralizer to have an adequate pH
level, because the exchanging stage can be kept at a pH
level of 4 to 6, when the aqueous solution of nickel sulfate to be supplied to the stage is adjusted beforehand at a pH
level in the above range. However, the present invention is characterized by finer adjustment of pH level, which may be realized with sulfuric acid.
Table 1 gives the relationship between the pH
level of the aqueous phase and the nickel concentration in the organic phase in the last stage settler in the multi-stage countercurrent reaction tank system, where a crude aqueous solution of nickel sulfate is treated with a mixed solvent containing nickel-loaded 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant, diluted with an alkyl benzene to a given extractant concentration.
Table 1 pH level of the Nickel concentration No aqueous phase in the in the organic phase settler (g/L) 1 4.3 0.99 2 4.8 1.20 3 5.0 2.19 4 5.3 3.90 5 5.4 4.50 As shown in Table 1, the nickel concentration in the organic phase decreases as the pH level decreases, and the nickel/cobalt exchanging reaction proceeds smoothly at a nickel concentration in the organic phase in the above-described range from 1 to 4.5g/L, which is achieved at a pH
level of 4.5 to 5.5:
It is essential according to the present invention to keep the calcium concentration and the nickel, cobalt and calcium total concentration in the organic phase each at a given level in the last stage of the multi-stage countercurrent reaction tank system. This prevents viscosity increase of the organic phase and makes cobalt extraction efficiency more stable than the conventional operation without harming the nickel/cobalt exchanging reaction.
The nickel, cobalt and calcium total concentration in the organic phase is adjusted at 25g/L or less, preferably 20g/L or less, often at least lOg/L, preferably at least 15g/L, in the last stage of the multi-stage, countercurrent reaction tank system for the present invention. At a nickel; cobalt and calcium total concentration in the organic phase above 25g/L, the mixed organic solvent may be excessively viscous and this may decrease efficiency for separating the organic phase from the aqueous phase and cause an unstable operation and notably deteriorated productivity.
Fig.l indicates viscosities of the organic phase plotted against nickel, cobalt and calcium concentrations in the organic phase, the relationship being similar to that given in Table 1. As shown, the viscosity of the organic phase starts to notably increase as the nickel, cobalt and calcium total concentration in the organic phase increases beyond 25g/L. The nickel, cobalt and calcium total concentration also depends on the pH level for the exchanging reaction.
b Fig.2 indicates nickel, cobalt and calcium total concentrations in the organic phase plotted against pH
levels for the exchanging reaction in a range of high extractant concentration in the organic phase, the relationship being similar to that given :in Table 1. As shown, the nickel, cobalt and calcium total concentration in the organic phase increases as the pH level increases to accelerate extraction. It is also noted that the total concentration of nickel, cobalt and calcium extracted in the organic phase increases as the extractant concentration increases at the same pH level.
The calcium concentration in the organic phase is adjusted at 0.4g/L or less in the last stage of the multi-stage countercurrent reaction tank system for the present invention. At a calcium concentration above 0.4g/L, cobalt extraction efficiency may not be improved, but decreased to 40 to 600 of the stoichiometric extraction rate, which is on a level with that associated with the conventional operation.
Fig.3 indicates cobalt extraction efficiencies (ratios of cobalt amounts in the organic phase to the stoichiometric cobalt extraction rate) platted against calcium concentrations in the organic phase, the relationship being similar to that given in Table 1. The solid line in Fig.3, obtained by the regression analysis, indicates that a cobalt extraction efficiency of 60% or more can be secured at a calcium concentration of 0.4g/L or less.
The calcium concentration is usually at least about 0.05g/L.
The relationship between the calcium concentration and the viscosity of the organic phase in the last stage is not clear, conceivably resulting from a locally increased calcium concentration in the aqueous phase as the calcium concentration in the organic phase increases during the exchanging reaction, to cause separation of insoluble calcium sulfate and increased viscosity of the organic phase when contaminated with calcium sulfate.
The nickel, cobalt and calcium total concentration in the organic phase depends on the pH level of the exchanging reaction at a given extractant concentration.
The concentration of calcium, which is distributed almost completely in the organic phase, can be adjusted by controlling the flow rate of the crude aqueous solution of nickel sulfate or the amount of the organic phase for dilution.
EXAMPLES
The present invention is described in more detail by EXAMPLES, which by no means should be construed to limit the present invention. The following analytical procedures were used in EXAMPLES.
(1) Analysis of metals: Determined by atomic absorption spec rometry (2) Viscosity of the organic phase: Determined by a B-type rotational viscometer The exchanging step Was carried out by a 4-stage, countercurrent, mixer settler system (effective mixer volume: 300mL, effective settler volume: 3,OOOmL), where the organic phase was supplied to the first stage of the system and the aqueous phase to the fourth (last) stage.
A mixed organic solvent was prepared as the organic phase by diluting 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC-88A~, Daihachi Chemical Industry) with an alkylbenzene (Clean Sol G~, Nippon Qil Corporation) to 25~ by volume and then treated to load nickel at 25g/L.
The organic phase was incorporated, as required, with the organic phase for dilution, prepared by stripping step for cobalt/calcium separation. A crude aqueous solution of nickel sulfate containing nickel, cobalt and calcium at 50 to 60, 30 to 40 and 0.6g/L, respectively, was used as the aqueous phase, which was adjusted at a pH level of 4.5 to 5Ø
These organic phase and aqueous phase were supplied at 90 and 30 to 40mL/minute to adjust calcium load.
The aqueous phase was finely adjusted at a pH level of 4.8 to 5.2 with sulfuric acid in the settler in the fourth stage of the mixer settler system. The mixer settler system was continuously operated at 40 to 45°C for 8 hours or more while keeping the calcium concentration and the nickel, cobalt and calcium total concentration in the organic phase at 0.40g/L or less and 20g/L or less, respectively, in the fourth mixer settler. Samples were collected from the exchanged aqueous phase and organic phase, as required, to analyze the nickel, cobalt and calcium concentrations.
Table 2 gives nickel, cobalt anal calcium concentrateons in the aqueous phase, i.e., purified aqueous solution of nickel sulfate; discharged from the first mixer settler and exchanged organic phase from the fourth mixer settler; totaled nickel, cobalt and calcium concentration in that organic phase; and efficiency of cobalt extracted in that organic phase.
Table 2 Composition of the Composition Co of the purified aqueous exchanged extraction organic phase solution of nickel No (g/L) efficiency .
sulfate (g/L) (%) Ni Co Ca Total Ni Co Ca 1 3.43 14.40 0.40 18.23 63 100 0.006 0.018 2 4.00 14.50 0.37 18.87 63 100 0.007 0.006 3 2.06 16.20 0.39 18.65 71 98.7 0.007 0.006 4 1.12 16.10 0.25 17.47 70 99.4 0.007 <0.005 4.12 15.36 0.37 19.87 67 102 0.006 <0.005 As shown in Table 2, efficiency of cobalt extracted in the organic phase can be secured at 60% or 5 more, cobalt is mostly extracted in the aqueous phase, and the purified crude solution of nickel sulfate containing impurities at a very low concentration (cobalt: lOmg/L or less, and calcium: 20mg/L or less) can be stably produced, when the aqueous phase in the settler of the fourth mixer settler is kept at a pH of 4.8 to 5.2, and the calcium concentration and the nickel, cobalt and calcium total concentration in the organic phase discharged from the fourth stage of the mixer settler are kept at 0.40g/L or less and 20g/L or less, respectively.
As described above, the process of the present invention for purification of an aqueous solution of nickel sulfate containing cobalt and calcium, the former being present at a high concentration, is of industrially high efficiency, because it can increase cobalt treatment capacity and produce a purified aqueous solution of nickel sulfate with reduced cobalt and calcium concentrations by improving cobalt extraction efficiency in the exchange reaction. As such, it is of very high industrial value.
(1) increasing the flow rate of the nickel-loaded organic phase to increase the amount of cobalt to be extracted per unit time, and (2) increasing the cobalt concentration in the organic phase from the exchanging reaction step. The former concept of increasing the treatment flow rate is a simple approach, but needs large investments to increase capacity of the solvent extraction reaction facilities, e.g., mixer settler, in proportion to the increased flow rate to keep a residence time required for separation of the nickel-loaded organic phase from a crude aqueous solution of nickel sulfate, which may harm economic efficiency.
For the latter concept, on the other hand, it is affective to increase the concentration of cobalt in the exchanged organic phase by increasing the concentration of an acid extractant in the nickel-loaded organic phase and cobalt extraction efficiency. When phosphoric or phosphonic acid is used as an acid extractant for the exchanging reaction, 1 mol of cobalt or calcium can be extracted per 2 moll of the extractant. It is the maximum attainable extraction rate of cobalt or calcium (hereinafter referred to as the stoichiometric extraction rate). With 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant, the stoichiometric extraction rate of cobalt is I8.3g/L in the organic solvent containing the extractant at 20~ by volume and a diluent. On a commercial scale, however, cobalt extraction efficiency is generally low at 40 to 60~ of the stoichiometric extraction rate.
The low extraction rate results from intentional control of the cobalt concentration to stabilize its extraction, because (1) driving force for the extraction reaction is decreased with an extractant having a larger number of functional groups bound to the nickel or cobalt ions than an extractant having a larger number of functional groups bound to the hydrogen ions, (2) utilization of nickel in the exchanging reaction is decreased, when pH level of the reaction system is increased to increase extraction capacity, which is accompanied by accelerated extraction of nickel to increase its concentration in the exchanged organic phase, and (3) an increased cobalt concentration in the organic phase generally increases its viscosity, which decreases efficiency for separating the organic phase from the aqueous solution phase. Therefore, there are problems to be solved also for increasing the cobalt concentration in the exchanged organic phase to increase cobalt extraction capacity.
Therefore, there are demands for methods which can increase the cobalt concentration in the exchanged organic phase, i.e., increase the cobalt extraction efficiency, while controlling a viscosity increase of the phase, without increasing plant capacity, in order to increase cobalt treatment capacity.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an industrially highly efficient process for purification of an aqueous solution of nickel sulfate containing cobalt and calcium, the former being present at a high concentration, which can increase cobalt treatment capacity and produce a purified aqueous solution of nickel sulfate with reduced cobalt and calcium concentrations by improving cobalt extraction efficiency in the exchange reaction, in consideration of the above-described problems involved in the conventional techniques.
The inventors of the present invention extensively studied an aqueous nickel sulfate solution purification process based on solvent extraction involving an exchanging reaction in a multi-stage, countercurrent reaction tank system, attempting to attain the above object. As a result, the inventors found that cobalt extraction efficiency can be improved by bringing an aqueous solution phase of nickel sulfate containing cobalt and calcium into contact with a mixed organic solvent phase containing an extractant at a specific concentration, and keeping the aqueous phase at a specific pH level, and a calcium concentration and a nickel, cobalt and calcium total concentration in the organic phase at a specific level. Hence, the present invention was achieved.
The present invention provides a process for purification of an aqueous solution of nickel sulfate, comprising:
a solvent extraction involving an exchanging reaction in a multi-stage, countercurrent reaction tank system, wherein:
an aqueous solution of nickel sulfate containing cobalt and calcium as impurities is supplied as an aqueous phase to a last stage of the reaction tank system and a mixed organic solvent containing as an extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester loaded with nickel and diluted with a hydrocarbon to an extractant concentration of 20 to 30% by volume, is supplied as an organic phase to a first stage of the reaction tank system, to bring these phases into contact with each other for the exchanging reaction, and the aqueous phase is kept at a pH level of 4.5 to 5.5 in the last stage, and a calcium concentration and a nickel, cobalt and calcium total concentration in the organic phase are kept at 0.4g/L or less and 25g/L or less, respectively, in the last stage.
According to a first major embodiment of the present invention, the mixed organic solvent contains the extractant at a concentration of 25 to 30~ by volume.
According to a second major embodiment of the present invention, the nickel, cobalt and calcium total concentration in the organic phase is 20g/L or less in the last stage.
According to a third major embodiment of the present invention, the aqueous phase is kept at a pH level of 4.8 to 5.2 in the last stage.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a graph showing viscosities of the organic phase plotted against nickel, cobalt and calcium total concentrations in the organic phase.
Figure 2 is a graph showing nickel, cobalt and calcium total concentrations in the organic phase plotted against pH levels for the exchanging reaction.
Figure 3 is a graph showing cobalt extraction efficiencies (ratios of cobalt amounts in the organic phase to the stoichiometric cobalt extraction rate) plotted against calcium concentrations in the organic phase.
DETAILED DESCRIPTION OF THE INVENTION
The process of the present invention for purification of an aqueous solution of nickel sulfate containing cobalt and calcium is described in detail.
The process of the present invention for purification of an aqueous solution of nickel sulfate containing cobalt and calcium, the former being present at a high concentration, is of industrially high efficiency, because it can increase cobalt treatment capacity without increasing plant capacity by improving cabalt extraction efficiency in the exchange reaction between the aqueous solution and nickel-loadedacid extractant: As such, it is suitable for an exchanging reaction step in a nickel sulfate purification process comprising several steps; e.g., extraction step for producing the nickel-loaded organic phase, step for exchanging with cobalt present in a crude aqueous solution of nickel sulfate, step for stripping of nickel from the exchanged organic phase in which cobalt is concentrated, cobalt recovering step, and impurity stripping step.
The process of the present invention for purification of an aqueous solution of nickel sulfate containing cobalt and calcium uses a multi-stage, countercurrent reaction tank system, wherein the aqueous solution of nickel sulfate is supplied as the aqueous phase to the last stage and a mixed organic solvent containing an extractant of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester loaded with nickel and diluted with a hydrocarbon, is supplied as the organic phase to the first stage, to bring these phases into contact with each other for an exchanging reaction, the aqueous phase being kept at a given pH level in the last stage, and the calcium concentration and the nickel, cobalt and calcium total concentration in the organic phase being kept at a given concentration in the last stage.
(1) Aqueous solution of nickel sulfate The aqueous solution of nickel sulfate to be treated by the present invention contains Cobalt and calcium. The particularly preferable solution is a crude aqueous solution of nickel sulfate containing cobalt at a high concentration, produced by treating a raw material containing cobalt at several percent. The crude aqueous solution, for example, contains nickel sulfate at 40-70 g/L, cobalt sulfate at 20-50 g/L and calcium sulfate at 0.1-1 g/L, but always nickel sulfate is contained at a higher concentration than cobalt sulfate. It may be adjusted beforehand at a given pH level, to help adjust pH
level for the exchanging reaction.
(2) Mixed organic solvent containing a nickel-loaded acid extractant In the present invention, a nickel-loaded acid extractant is prepared beforehand for the exchanging reaction. In the present invention, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester is used as the acid extractant, which is diluted with a hydrocarbon to a given extractant concentration to prepare the mixed organic solvent. The extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester can efficiently extract cobalt, calcium and magnesium.
It has a separation coefficient in a sulfuric acid solution of cobalt/nickel: 650, calcium/nickel: 110 and magnesium/nickel: 50. It has a still higher separation coefficient for zinc, iron and copper, by which is meant that these elements are preferentially extracted.
Acid extractants are generally viscous, and are mixed with a diluent before use. In the present invention, it is diluted with a hydrocarbon. The hydrocarbon is not limited for the present invention, and may be aliphatic or aromatic, of which an alkylbenzene as an aromatic hydrocarbon is particularly preferable. The mixed organic solvent for the present invention contains the extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester at 20 to 30o by volume, preferably 25 to 30~. At below 20% by volume, cobalt extraction rate per unit amount of the mixed organic solvent is insufficient. At above 30o by volume, on the other hand, the mixed organic solvent may be excessively viscous to deteriorate organic solvent/aqueous phase separation efficiency and cause unstable operation and decreased productivity. The mixed organic solvent of the above composition for the present invention is suitable for exchanging of impurities present in the aqueous solution of nickel sulfate, e.g., cobalt and calcium which are extracted in preference to nickel, with nickel loaded beforehand by the extractant.
It is an economically recommended practice to recycle the exchanged organic phase containing impurities back to a series of nickel stripping, cobalt recovery and impurity stripping step in the nickel sulfate purification process (disclosed in, e.g., Japanese Patent Laid-open Publication No. 10-310437 (pages 1 to 5)), in order to recover nickel remaining in the organic phase, recover cobalt and remove impurities other than cobalt in the respective step, and to clean and recover the organic phase for reuse.
The mixed organic solvent can load nickel by common solvent extraction. For example, nickel can be extracted from an aqueous solution of nickel sulfate as the starting material with the acid extractant described above in a multi-stage, countercurrent reaction tank system, wherein the extractant is supplied to the first stage while the aqueous solution to the last stage for the extraction reaction at a pH of 5.0 to 7Ø It is preferable to keep a concentration of nickel loaded in the mixed organic solvent in excess of the stoichiometric level, so that the impurity elements may be efficiently extracted by the exchanging reaction. An insufficient amount of nickel may keep these impurity elements in the purified aqueous solution of nickel sulfate, even when the exchanging reaction proceeds completely. At the stoichiometric level, on the other hand, the exchanging reaction cannot proceed completely, because nickel in the organic phase is depleted as the reaction proceeds.
(3) Purification system and method In the present invention, the reactor system for the exchanging reaction may be selected from various multi-stage, countercurrent reaction tank systems capable of efficiently separating the organic and aqueous phase from each other after contacting them. The particularly preferable one is a continuous, multi-stage, countercurrent mixer settler system, where the nickel-loaded mixed solvent and the crude aqueous solution of nickel sulfate come into contact with each other, the former supplied to the first stage and the latter to the last stage. Therefore, the purified aqueous solution of nickel sulfate is discharged from the first stage mixer settler, and the exchanged organic phase containing cobalt from the last stage mixer settler.
The exchanged organic phase preferably contains nickel at 1 to 4.5g/L. Nickel in the organic phase is depleted as the exchanging reaction proceeds. When it is depleted to a concentration below lg/L, the nickel/cobalt exchanging reaction proceeds insufficiently, to increase concentration of cobalt in the purified aqueous solution of nickel sulfate. At above 4.5g/L, on the other hand, recovery of nickel in the purified aqueous solution of nickel sulfate may be retarded. The nickel/cobalt exchanging reaction will proceed smoothly at a nickel concentration of 1 to 4.5g/L in the organic phase.
In the present invention, the aqueous phase in the last stage of the mufti-stage, countercurrent reaction tank system is adjusted at a pH level of 4.5 to 5.5, preferably 4.8 to 5.2. Increasing the pH level accelerates extraction of nickel and cobalt in the organic phase. At a pH level below 4.5, cobalt concentration in the exchanged organic phase decreases to deteriorate cobalt extraction efficiency.
At a pH level above 5.5, on the other hand; nickel concentration in the organic phase increases to deteriorate the nickel recovery rate in the purified aqueous solution of nickel sulfate, but also cobalt extraction efficiency resulting from increased number of nickel atoms bound to functional groups in the extractant to substantially reduces number of functional groups to be bound to cobalt. A
conventional exchanging step with an acid extractant loaded with nickel at an adequate concentration, releasing no hydrogen ion, needs no neutralizer to have an adequate pH
level, because the exchanging stage can be kept at a pH
level of 4 to 6, when the aqueous solution of nickel sulfate to be supplied to the stage is adjusted beforehand at a pH
level in the above range. However, the present invention is characterized by finer adjustment of pH level, which may be realized with sulfuric acid.
Table 1 gives the relationship between the pH
level of the aqueous phase and the nickel concentration in the organic phase in the last stage settler in the multi-stage countercurrent reaction tank system, where a crude aqueous solution of nickel sulfate is treated with a mixed solvent containing nickel-loaded 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant, diluted with an alkyl benzene to a given extractant concentration.
Table 1 pH level of the Nickel concentration No aqueous phase in the in the organic phase settler (g/L) 1 4.3 0.99 2 4.8 1.20 3 5.0 2.19 4 5.3 3.90 5 5.4 4.50 As shown in Table 1, the nickel concentration in the organic phase decreases as the pH level decreases, and the nickel/cobalt exchanging reaction proceeds smoothly at a nickel concentration in the organic phase in the above-described range from 1 to 4.5g/L, which is achieved at a pH
level of 4.5 to 5.5:
It is essential according to the present invention to keep the calcium concentration and the nickel, cobalt and calcium total concentration in the organic phase each at a given level in the last stage of the multi-stage countercurrent reaction tank system. This prevents viscosity increase of the organic phase and makes cobalt extraction efficiency more stable than the conventional operation without harming the nickel/cobalt exchanging reaction.
The nickel, cobalt and calcium total concentration in the organic phase is adjusted at 25g/L or less, preferably 20g/L or less, often at least lOg/L, preferably at least 15g/L, in the last stage of the multi-stage, countercurrent reaction tank system for the present invention. At a nickel; cobalt and calcium total concentration in the organic phase above 25g/L, the mixed organic solvent may be excessively viscous and this may decrease efficiency for separating the organic phase from the aqueous phase and cause an unstable operation and notably deteriorated productivity.
Fig.l indicates viscosities of the organic phase plotted against nickel, cobalt and calcium concentrations in the organic phase, the relationship being similar to that given in Table 1. As shown, the viscosity of the organic phase starts to notably increase as the nickel, cobalt and calcium total concentration in the organic phase increases beyond 25g/L. The nickel, cobalt and calcium total concentration also depends on the pH level for the exchanging reaction.
b Fig.2 indicates nickel, cobalt and calcium total concentrations in the organic phase plotted against pH
levels for the exchanging reaction in a range of high extractant concentration in the organic phase, the relationship being similar to that given :in Table 1. As shown, the nickel, cobalt and calcium total concentration in the organic phase increases as the pH level increases to accelerate extraction. It is also noted that the total concentration of nickel, cobalt and calcium extracted in the organic phase increases as the extractant concentration increases at the same pH level.
The calcium concentration in the organic phase is adjusted at 0.4g/L or less in the last stage of the multi-stage countercurrent reaction tank system for the present invention. At a calcium concentration above 0.4g/L, cobalt extraction efficiency may not be improved, but decreased to 40 to 600 of the stoichiometric extraction rate, which is on a level with that associated with the conventional operation.
Fig.3 indicates cobalt extraction efficiencies (ratios of cobalt amounts in the organic phase to the stoichiometric cobalt extraction rate) platted against calcium concentrations in the organic phase, the relationship being similar to that given in Table 1. The solid line in Fig.3, obtained by the regression analysis, indicates that a cobalt extraction efficiency of 60% or more can be secured at a calcium concentration of 0.4g/L or less.
The calcium concentration is usually at least about 0.05g/L.
The relationship between the calcium concentration and the viscosity of the organic phase in the last stage is not clear, conceivably resulting from a locally increased calcium concentration in the aqueous phase as the calcium concentration in the organic phase increases during the exchanging reaction, to cause separation of insoluble calcium sulfate and increased viscosity of the organic phase when contaminated with calcium sulfate.
The nickel, cobalt and calcium total concentration in the organic phase depends on the pH level of the exchanging reaction at a given extractant concentration.
The concentration of calcium, which is distributed almost completely in the organic phase, can be adjusted by controlling the flow rate of the crude aqueous solution of nickel sulfate or the amount of the organic phase for dilution.
EXAMPLES
The present invention is described in more detail by EXAMPLES, which by no means should be construed to limit the present invention. The following analytical procedures were used in EXAMPLES.
(1) Analysis of metals: Determined by atomic absorption spec rometry (2) Viscosity of the organic phase: Determined by a B-type rotational viscometer The exchanging step Was carried out by a 4-stage, countercurrent, mixer settler system (effective mixer volume: 300mL, effective settler volume: 3,OOOmL), where the organic phase was supplied to the first stage of the system and the aqueous phase to the fourth (last) stage.
A mixed organic solvent was prepared as the organic phase by diluting 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC-88A~, Daihachi Chemical Industry) with an alkylbenzene (Clean Sol G~, Nippon Qil Corporation) to 25~ by volume and then treated to load nickel at 25g/L.
The organic phase was incorporated, as required, with the organic phase for dilution, prepared by stripping step for cobalt/calcium separation. A crude aqueous solution of nickel sulfate containing nickel, cobalt and calcium at 50 to 60, 30 to 40 and 0.6g/L, respectively, was used as the aqueous phase, which was adjusted at a pH level of 4.5 to 5Ø
These organic phase and aqueous phase were supplied at 90 and 30 to 40mL/minute to adjust calcium load.
The aqueous phase was finely adjusted at a pH level of 4.8 to 5.2 with sulfuric acid in the settler in the fourth stage of the mixer settler system. The mixer settler system was continuously operated at 40 to 45°C for 8 hours or more while keeping the calcium concentration and the nickel, cobalt and calcium total concentration in the organic phase at 0.40g/L or less and 20g/L or less, respectively, in the fourth mixer settler. Samples were collected from the exchanged aqueous phase and organic phase, as required, to analyze the nickel, cobalt and calcium concentrations.
Table 2 gives nickel, cobalt anal calcium concentrateons in the aqueous phase, i.e., purified aqueous solution of nickel sulfate; discharged from the first mixer settler and exchanged organic phase from the fourth mixer settler; totaled nickel, cobalt and calcium concentration in that organic phase; and efficiency of cobalt extracted in that organic phase.
Table 2 Composition of the Composition Co of the purified aqueous exchanged extraction organic phase solution of nickel No (g/L) efficiency .
sulfate (g/L) (%) Ni Co Ca Total Ni Co Ca 1 3.43 14.40 0.40 18.23 63 100 0.006 0.018 2 4.00 14.50 0.37 18.87 63 100 0.007 0.006 3 2.06 16.20 0.39 18.65 71 98.7 0.007 0.006 4 1.12 16.10 0.25 17.47 70 99.4 0.007 <0.005 4.12 15.36 0.37 19.87 67 102 0.006 <0.005 As shown in Table 2, efficiency of cobalt extracted in the organic phase can be secured at 60% or 5 more, cobalt is mostly extracted in the aqueous phase, and the purified crude solution of nickel sulfate containing impurities at a very low concentration (cobalt: lOmg/L or less, and calcium: 20mg/L or less) can be stably produced, when the aqueous phase in the settler of the fourth mixer settler is kept at a pH of 4.8 to 5.2, and the calcium concentration and the nickel, cobalt and calcium total concentration in the organic phase discharged from the fourth stage of the mixer settler are kept at 0.40g/L or less and 20g/L or less, respectively.
As described above, the process of the present invention for purification of an aqueous solution of nickel sulfate containing cobalt and calcium, the former being present at a high concentration, is of industrially high efficiency, because it can increase cobalt treatment capacity and produce a purified aqueous solution of nickel sulfate with reduced cobalt and calcium concentrations by improving cobalt extraction efficiency in the exchange reaction. As such, it is of very high industrial value.
Claims (9)
1. A process for purification of an aqueous solution of nickel sulfate, also containing cobalt sulfate and calcium sulfate and having a concentration of nickel sulfate higher than cobalt sulfate and calcium sulfate, by a solvent extraction involving an exchanging reaction in a multi-stage countercurrent reaction tank system, which comprises:
supplying the aqueous solution of nickel sulfate as an aqueous phase to a last stage of the reaction tank system and supplying a mixed organic solvent containing as an extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester loaded with nickel and diluted with a hydrocarbon to an extractant concentration of 20 to 30% by volume, as an organic phase to a first stage of the reaction tank system, to bring the aqueous and organic phases into contact with each other for the exchanging reaction, wherein the aqueous phase is kept at a pH level of 4.5 to 5.5 in the last stage, and a calcium concentration and a nickel, cobalt and calcium total concentration in the organic phase are kept at 0.4g/L
or less and 25g/L or less, respectively, in the last stage, and discharging the aqueous solution of nickel sulfate so purified from the first stage of the reaction tank system and discharging the mixed organic solvent from the last stage of the reaction tank system.
supplying the aqueous solution of nickel sulfate as an aqueous phase to a last stage of the reaction tank system and supplying a mixed organic solvent containing as an extractant 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester loaded with nickel and diluted with a hydrocarbon to an extractant concentration of 20 to 30% by volume, as an organic phase to a first stage of the reaction tank system, to bring the aqueous and organic phases into contact with each other for the exchanging reaction, wherein the aqueous phase is kept at a pH level of 4.5 to 5.5 in the last stage, and a calcium concentration and a nickel, cobalt and calcium total concentration in the organic phase are kept at 0.4g/L
or less and 25g/L or less, respectively, in the last stage, and discharging the aqueous solution of nickel sulfate so purified from the first stage of the reaction tank system and discharging the mixed organic solvent from the last stage of the reaction tank system.
2. The process according to claim 1, wherein the extractant concentration of the mixed organic solvent is 25 to 30% by volume.
3. The process according to claim 1 or 2, wherein the nickel, cobalt and calcium total concentration in the organic phase is 20g/L or less in the last stage.
4. The process according to claim 1, 2 or 3, wherein the aqueous phase is kept at a pH level of 4.8 to 5.2 in the last stage.
5. The process according to any one of claims 1 to 4, wherein the multi-stage countercurrent reaction tank system is a 4-stage countercurrent mixer settler system.
6. The process according to any one of claims 1 to 5;
wherein the hydrocarbon is an aromatic hydrocarbon.
wherein the hydrocarbon is an aromatic hydrocarbon.
7. The process according to claim 6, wherein the aromatic hydrocarbon is an alkylbenzene.
8. The process according to any one of claims 1 to 7, wherein the mixed organic solvent is loaded with nickel in excess of a stoichiometric level.
9. The process according to any one of claims 1 to 8, wherein the aqueous solution of nickel sulfate supplied to the last stage of the reaction tank system has a nickel sulfate concentration of 40 to 70g/L, a cobalt sulfate concentration of 20 to 50g/L and a calcium sulfate concentration of 0.1 to 1g/L, provided that the nickel sulfate concentration is higher than the cobalt sulfate concentration.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003103593A JP4259165B2 (en) | 2003-04-08 | 2003-04-08 | Purification method of aqueous nickel sulfate solution containing cobalt and calcium |
| JP2003-103593 | 2003-04-08 |
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| CA2463268A1 CA2463268A1 (en) | 2004-10-08 |
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| JP (1) | JP4259165B2 (en) |
| AU (1) | AU2004201049B2 (en) |
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| GB (1) | GB2400368B (en) |
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| JP5881952B2 (en) * | 2011-01-24 | 2016-03-09 | 住友金属鉱山株式会社 | Method for producing cobalt sulfate |
| EP2784166B1 (en) * | 2011-11-22 | 2019-05-22 | Sumitomo Metal Mining Co., Ltd. | Method for producing high-purity nickel sulfate |
| JP5598778B2 (en) | 2013-01-25 | 2014-10-01 | 住友金属鉱山株式会社 | Method for producing high-purity nickel sulfate and method for removing impurity element from solution containing nickel |
| JP6094822B2 (en) * | 2014-02-03 | 2017-03-15 | 住友金属鉱山株式会社 | Method for quantifying fat-soluble phosphorus compounds |
| CN104591304B (en) * | 2015-01-13 | 2016-04-27 | 江西赣锋锂业股份有限公司 | A kind for the treatment of process of sulfur acid nickel waste material |
| JP7516910B2 (en) | 2020-06-25 | 2024-07-17 | 住友金属鉱山株式会社 | Method for producing nickel sulfate aqueous solution |
| CN113816439A (en) * | 2021-08-20 | 2021-12-21 | 广东邦普循环科技有限公司 | Method and system for purifying nickel sulfate |
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| JPS5924168B2 (en) * | 1977-05-14 | 1984-06-07 | 株式会社大八化学工業所 | Separation method of cobalt and nickel by solvent extraction method |
| US4246240A (en) * | 1978-07-24 | 1981-01-20 | Nippon Mining Co., Ltd. | Process for separating cobalt and nickel from a solution containing cobalt and nickel |
| GB2034290A (en) * | 1978-11-10 | 1980-06-04 | Nippon Mining Co | Separation of Cobalt from Nickel by Solvent Extraction |
| DE3411885C2 (en) * | 1984-03-30 | 1987-03-05 | Hermann C. Starck Berlin, 1000 Berlin | Use of an extractant mixture for Co/Ni separation |
| JPS61170528A (en) * | 1985-01-22 | 1986-08-01 | Sutaaroi Sangyo Kk | Method for recovering cobalt |
| JP3867871B2 (en) * | 1997-04-30 | 2007-01-17 | 住友金属鉱山株式会社 | Nickel sulfate solvent extraction method |
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| JP4259165B2 (en) | 2009-04-30 |
| GB2400368B (en) | 2007-09-26 |
| AU2004201049B2 (en) | 2009-11-05 |
| AU2004201049A1 (en) | 2004-10-28 |
| GB0406885D0 (en) | 2004-04-28 |
| JP2004307270A (en) | 2004-11-04 |
| CA2463268A1 (en) | 2004-10-08 |
| GB2400368A (en) | 2004-10-13 |
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