Process for the recovery of metals from used nickel/metal/rare earth hydride storage batteries

A process for recovering metals from used nickel hydride storage batteries, the batteries having nickel, rare earths and metals, cobalt, iron, manganese, zinc, cadmium, and aluminum, in which storage battery scrap has been mechanically comminuted and divided up into at least a coarse fraction and a fine fraction capable of being treated separately from one another, comprising the steps of:

• (a) digesting and dissolving the fine fraction in a strong acid mixture comprising sulphuric acid and hydrogen peroxide to generate a sulphuric acid digest having a pH less than 1,
• (b) performing a double sulphate precipitation of rare earths and metals by raising the pH of the sulphuric acid digest from about 1.5 to 2.0 by stepwise addition of an alkali to the sulphuric acid digest, thereby precipitating the rare earths as double sulphate salts,
• (c) separating a rare earth sulfate salt precipitate from the digest, thereby obtaining a filtrate,
• (d) precipitating iron and aluminums by raising the pH of the filtrate above 2.0,
• (e) raising the pH of the filtrate from step (d) to a range of 3.0 to 4.0 by addition of an alkali, adding a solvent extractant to said filtrate raised to pH 3.0 to 4.0 thereby separating the nickel and the cobalt which remain quantitatively in an aqueous phase in said filtrate raised to pH 3.0 to 4.0 from the metals Zn, Mn, Cd, Al, Fe and rare earths remaining following the precipitations of steps (b) and (d) which are extracted into the organic phase, the nickel and cobalt remaining in the aqueous phase in the same atomic ratio in which they were present in the storage battery scrap.