METHOD FOR SEPARATING NICKEL AND COBALT FROM ACTIVE MATERIAL CONTAINED IN SPENT NICKEL-HYDROGEN BATT

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PROBLEM TO BE SOLVED : To provide a method for separating and recovering nickel, cobalt and rare earth elements (RE) from positive- and negative-electrode active materials that constitute a nickel-hydrogen battery. SOLUTION : The method is provided by which nickel, cobalt and RE are separated from a material containing positive- and negative-electrode active materials of a nickel-hydrogen battery, and a sulfide that contains both nickel and cobalt and an RE-containing sulfate are obtained, the method including the following three steps : (1) a leaching step of subjecting a material which contains positive- and negative-electrode active materials to mixing with a sulfuric acid solution and dissolving therein, and then separating the resultant into a leachate and a residue; (2) an RE crystallization step of adding an alkali metal sulfate to the leachate to obtain both a precipitate of an RE composite sulfate mixture and an RE-free fluid; and (3) a sulfide raw material recovery step of adding a sulfurizing agent to the RE-free fluid and thereby separating the RE-free fluid into a nickel/cobalt sulfide raw material and a residual fluid. COPYRIGHT : (C)2012, JPO&INPIT