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

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The present invention provides a method including the following three steps : (1) A leaching step of mixing a material containing positive and negative electrode active materials with a sulfuric acid solution and dissolving therein, and then separating a leachate from a residue; (2) A rare earth crystallization step of adding an alkali metal sulfate to the leachate to obtain a mixed precipitate of double sulfate of rare earth elements, and a rare-earth-element-free solution; and (3) A sulfide raw material recovery step of adding a sulfurizing agent to the rare-earth-element-free solution to separate a nickel and cobalt sulfide raw material and a residual solution, wherein a sulfide containing nickel and cobalt and a sulfate containing rare earth elements are obtained, whereby nickel, cobalt and rare earth elements are separated from a material containing positive and negative electrode active materials which constitutes a nickel-metal hydride battery.