| abstract |
Provided is a method for producing solutions, by which two solutions, namely a high-purity nickel sulfate solution and a mixed solution of nickel sulfate and cobalt sulfate are able to be obtained at the same time from a sulfuric acid solution containing nickel, cobalt and calcium. A method for producing solutions according to the present invention uses a sulfuric acid solution containing nickel, cobalt and calcium and performs a first step S1 for producing a mixed solution of nickel sulfate and cobalt sulfate from the sulfuric acid solution and a second step S2 for producing a solution of nickel sulfate from the sulfuric acid solution in parallel. In the first step, the sulfuric acid solution is subjected to solvent extraction by means of an extractant, thereby obtaining a first organic solvent after extraction containing calcium and a first extraction residue containing nickel and cobalt. In the second step, the sulfuric acid solution is subjected to solvent extraction by means of an extractant, thereby obtaining a second organic solvent after extraction containing cobalt and calcium and a second extraction residue containing nickel. |