Method for producing extra fine cobalt metal powder

摘要

Extra fine cobalt metal powder (up to about 0.8 microns) having less than 100 parts per million cation impurities is produced by a process in which cobalt pentammine chloride is digested in a dilute ammonium hydroxide solution to form a black precipitate, which is separated and heated in a hydrogen atmosphere to reduce the precipitate directly to cobalt metal powder. The cobalt pentammine chloride may be obtained by digesting a cobalt source in hydrochloric acid, adding ammonium hydroxide, oxidizing the cobaltous ion to cobaltic ion, and reducing the pH with hydrochloric acid to less than 1.0 in order to precipitate cobalt pentammine chloride. The final cobalt metal powder is useful, for example, as a starting material in the manufacture of cemented carbides.