Nickel-metal hydride storage battery used method for recovering the metal

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In the recycling of used nickel/metal hydride storage batteries, the battery scrap is dissolved in sulphuric acid after mechanical separation of the coarse constituents by magnetic and air separation. A solvent extraction is performed with the digestion solution, from which the rare earths (from the hydrogen-storage alloys in the negative electrodes) and iron and aluminum have been selected by precipitation, under conditions pH, choice of solvent, volumetric ratio of the phases) which are such that the aqueous phase contains nickel and cobalt in the same atomic ratio as that in which they were present in the scrap. This makes possible a joint recovery by simultaneous electrolysis, in which process the deposition product forms a master alloy which can be used, together with the precipitated rare earths which have been electrometallurgically reprocessed as misch metal, for the production of fresh hydrogen-storage alloys.