METHOD FOR PRODUCING HIGH-PURITY COBALT SULFATE SOLUTION AND METHOD FOR PRODUCING COBALT SULFATE

To provide a method for producing a high-purity cobalt sulfate solution capable of effectively increasing the purity of cobalt of a cobalt sulfate solution containing relatively small amount of nickel ions and to provide a method for producing cobalt sulfate.SOLUTION: There is provided a method for producing, from a cobalt sulfate solution containing nickel ions, a high-purity cobalt sulfate solution having a higher purity of cobalt compared to the cobalt sulfate solution, wherein the cobalt/nickel concentration ratio of the cobalt sulfate solution is 100 or more and the method comprises a nickel separation step in which the cobalt sulfate solution is brought into contact with a solvent containing a bis(2,4,4-trimethylpentyl)phosphinic acid to adjust pH, cobalt ions are extracted into the solvent while the nickel ions in the cobalt sulfate solution are left in the liquid and subsequently, the cobalt ions extracted into the solvent are back-extracted with sulfuric acid.SELECTED DRAWING: Figure 1 【課題】比較的少量のニッケルイオンを含む硫酸コバルト溶液のコバルトの純度を有効に高めることのできる高純度硫酸コバルト溶液の製造方法及び、硫酸コバルトの製造方法を提供する。【解決手段】ニッケルイオンを含む硫酸コバルト溶液から、当該硫酸コバルト溶液に比してコバルトの純度が高い高純度硫酸コバルト溶液を製造する方法であって、前記硫酸コバルト溶液のコバルト／ニッケル濃度比が１００以上であり、前記硫酸コバルト溶液を、ビス（２，４，４−トリメチルペンチル）ホスフィン酸を含む溶媒と接触させてｐＨを調整し、前記硫酸コバルト溶液中のニッケルイオンを液中に残しつつコバルトイオンを前記溶媒に抽出した後、該溶媒に抽出されたコバルトイオンを硫酸で逆抽出するニッケル分離工程を含む。【選択図】図１