Abstract: A process is provided for leaching nickeliferous sulfide material, such as NiS precipitate and thermally activated nickel sulfide material, e.g., nickel matte, the process comprising subjecting nickeliferous sulfide material in the finely divided state to leaching in hydrochloric acid of concentration ranging from about 3 N to 8 N at a temperature of over 50.degree. C., the temperature and acid concentration being selected to dissolve at least about 50% by weight of the total contained nickel.

Abstract: A method is provided for leaching comminuted nickeliferous sulfide matte containing by weight about 20 to 75% nickel, about 5 to 50% copper, non-stoichiometric sulfur in the range of over 4 to about 24%, over 0.5 to about 20% iron, the sum of the nickel, copper and sulfur contents being at least about 80% of the matte composition, with the balance gangue or slag and incidental impurities.Nickel is selectively leached from the comminuted matte using sulfuric acid or spent copper electrolyte solution at substantially atmospheric pressure while vigorously aerating the solution, wherein the pH is raised sufficiently to produce a nickel solution with an iron content of less than about 10 ppm and a copper content of over 5 ppm, the copper being thereafter selectively removed from the nickel solution by passing the solution through an ion-exchange resin selective to the absorption of copper.

Abstract: Cobalt, copper and nickel values are separated from ammoniacal aqueous solutions by contacting the solutions with a chelate exchange resin of polymerized ar-vinylbenzylamino dicarboxylic acids whereby the cobalt, copper and nickel values are loaded on the chelate exchange resin, stripping the cobalt, copper and nickel values from the loaded chelate exchange resin by contacting the loaded resin with a mineral acid and restoring the capacity of the chelate exchange resin when it falls below a predetermined value by reacting the degraded chelate exchange resin with an aqueous solution of a halo salt of a carboxylic acid, the aqueous solution being maintained at a pH value greater than about 8.