Production method for cobalt sulfate
Provided is a method for separating impurities and cobalt without using an electrolysis process from a cobalt chloride solution containing impurities and producing a high purity cobalt sulfate. The production method for cobalt sulfate includes: a copper removal step (S 1 ) of adding a sulfurizing agent to a cobalt chloride solution containing one or more impurities of copper, zinc, manganese, calcium, and magnesium and generating a precipitate of sulfide of copper to separate to remove copper; a neutralization step (S 2 ) of adding a neutralizer or a carbonation agent to a cobalt chloride solution having undergone through the copper removal step (S 1 ) and generating cobalt hydroxide or basic cobalt carbonate to separate magnesium; a leaching step (S 3 ) of adding sulfuric acid to the cobalt hydroxide or the basic cobalt carbonate to obtain cobalt sulfate solution; and a solvent extraction step (S 4 ) of bringing an organic solvent containing an alkyl phosphoric acid-based extractant to the cobalt sulfate solution and extracting zinc, manganese, and calcium into the organic solvent to separate to remove zinc, manganese, and calcium. These steps are sequentially executed.
1 . A method for production of cobalt sulfate, comprising:
a copper removal step of adding H 2 S, Na 2 S, or NaHS to a cobalt chloride solution containing one or more impurities of copper, zinc, manganese, calcium, and magnesium and generating a precipitate of sulfide of copper to separate to remove copper;
a neutralization step of adjusting a pH of a cobalt chloride solution having undergone the copper removal step to 6.5 to 7.0 so as to form a precipitate in the liquid of the solution having undergone the neutralization step and separating the precipitate from the liquid;
a leaching step of adding sulfuric acid to the separated precipitate to obtain cobalt sulfate solution; and
a solvent extraction step of bringing an organic solvent containing an alkyl phosphoric acid-based extractant to the cobalt sulfate solution and extracting zinc, manganese, and calcium into the organic solvent to separate to remove zinc, manganese, and calcium, wherein
these steps are sequentially executed.
2 . The method for production of cobalt sulfate according to claim 1 , wherein
separation of the liquid and the precipitate in the neutralization step is performed by a countercurrent multistage method.
3 . The method for production of cobalt sulfate according to claim 1 , wherein
a cobalt sulfate solution obtained through the solvent extraction step is subjected to a crystallization step to obtain crystals of the cobalt sulfate.
4 . The method for production of cobalt sulfate according to claim 1 , wherein
in the copper removal step, a redox potential of the cobalt chloride solution is adjusted to −100 mV to 200 mV (based on an Ag/AgCl electrodes) and the pH to 1.3 to 3.0.
5 . The method for production of cobalt sulfate according to claim 1 , wherein
in the leaching step, the pH is adjusted to 2.0 to 5.0 to obtain the cobalt sulfate solution.
6 . The method for production of cobalt sulfate according to claim 1 , wherein
in the solvent extraction step, the alkyl phosphoric acid-based extractant is bis (2-ethylhexyl) hydrogen phosphate, and the pH of the cobalt sulfate solution where copper and magnesium are removed is adjusted to 1.5 to 3.0 to be subjected to a solvent extraction using the extractant, and impurity elements are extracted into the organic solvent.