Production of battery-grade manganese dioxide
AssigneeMetallurgie Hoboken-Overpelt
InventorsAndre van der Heyden, Marc Coussement, Antoine Van Peteghem
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Abstract
Battery-grade MnO.sub.2 is produced by (a) treating a MnCl.sub.2 solution with Cl.sub.2 and Mg(OH).sub.2 whereby obtaining a MgCl.sub.2 solution that contains a MnO.sub.2 precipitate; and said MgCl.sub.2 solution contains at least 85 g/l of magnesium (b) allowing to digest the precipitate in the MgCl.sub.2 solution in presence of Cl.sub.2 under pressure; (c) separating the digested precipitate from the solution; and (d) washing and drying the precipitate. Owing to step (b), operating conditions in step (a) may be such that a concentrated MgCl.sub.2 solution is obtained, which is important for the further processing of that solution by pyrohydrolysis.
Claims15
A process for the production of battery-grade manganese dioxide which comprises:
- (a) contacting a manganese chloride solution with chlorine, while maintaining the pH of the solution between 0.5 and 3 by adding MgO and/or Mg(OH).sub.2 so as to thereby produce a MgCl.sub.2 solution poor in manganese and which contains a MnO.sub.2 precipitate that is contaminated by magnesium, the operating conditions being such that the produced MgCl.sub.2 solution contains at least 85 g./l. of magnesium,
- (b) allowing the MnO.sub.2 precipitate to digest in said MgCl.sub.2 solution in the presence of chlorine under pressure in an autoclave so as to reduce substantially the magnesium content of said MnO.sub.2 precipitate,
- (c) separating the digested MnO.sub.2 precipitate from the MgCl.sub.2 solution,
- (d) washing and drying the MnO.sub.2 precipitate.
A process according to claim wherein step (b) lasts at least 1 hour.
Dependencies are inferred from the claim text.