| 摘要 |
PROBLEM TO BE SOLVED: To provide a production method capable of producing an aqueous solution of cobalt chloride of a low Ni concentration, in a method for solvent-extracting Co from an aqueous solution of nickel chloride containing Co by an organic solvent composed of an amine-based extraction agent and a diluent.SOLUTION: A solvent extraction method is provided, in which Co is solvent-extracted from an aqueous solution of nickel chloride containing Co by an organic solvent composed of an amine-based extraction agent and a diluent using a countercurrent multistage extractor to produce an aqueous solution of cobalt chloride. The solvent extraction method includes three stages of an extraction stage for extracting Co from the aqueous solution of nickel chloride containing Co to the organic phase to obtain the aqueous solution of nickel chloride free of Co, a washing stage for bringing part of a water phase after back extraction into contact with the organic phase to which Co is extracted, to remove Ni in the organic phase, and a back extraction stage for removing Co from the organic phase after washing by a weak acidic aqueous solution to obtain an aqueous solution of cobalt chloride. In the washing stage, the organic phase is continuous in a mixer tank, where a volume ratio of the organic phase to the water phase is 3.0 or less. |
