Abstract: Process and apparatus for recovering magnesium from foundry sludge and cell bleed electrolytes includes structure and/or steps for: (i) dissolving, in a water slurry, soluble chloride compounds in the magnesium-containing material; (ii) acidifying the water slurry to between substantially pH 4 and substantially pH 6; (iii) further acidifying the water slurry to between substantially pH 1 and substantially pH 0, and providing a magnesium chloride solution; (iv) precipitating calcium from the magnesium chloride solution; (v) separating solids from the magnesium chloride solution; (vi) stripping SO2 from the magnesium chloride solution; and (vii) precipitating NaCl from the magnesium chloride solution to provide a concentrated magnesium chloride solution.

Abstract: A process for recovery of platinum and palladium from an impure substantially gold-free precious and base metal-bearing acidic chloride or mixed chloride/sulphate solution comprises the steps of: contacting the acidic solution having a pH less than about 1.5 with an organic solution comprising an 8-hydroxy quinoline solvent extraction reagent, a phase modifier and an aromatic diluent to extract simultaneously platinum and palladium into the organic solution; scrubbing the loaded organic solution to remove co-extracted impurities and acid; stripping the loaded organic with a buffer solution operating in the pH range 2-5 at 20.degree.-50.degree. C. to selectively recover the platinum; stripping the platinum-free loaded organic with 3-8 M hydrochloric acid to recover the palladium; and regenerating the organic solution by washing with water.

Abstract: A process for recovery of gold from an impure precious and base metal-bearing acidic chloride or mixed chloride/sulphate solution comprises the steps of contacting the acidic solution with a polymeric acrylic ester adsorbent ion exchange resin to selectively adsorb gold, and stripping the gold from the loaded resin by elution with water.

Abstract: A process for producing a substantially pure, concentrated MgCl.sub.2 solution suitable for subsequent molten salt electrolysis to magnesium metal from an impure magnesite ore or concentrate is disclosed. The process comprises the steps of calcining a magnesite ore or concentrate at a temperature greater than 600.degree. C. to decompose most of the magnesite and form a reactive magnesia, dissolving such reactive magnesia with either concentrated hydrochloric acid or hydrogen chloride gas with the addition of a surface active wetting agent to produce an impure concentrated MgCl.sub.2 solution, and reacting such impure concentrated MgCl.sub.2 solution with a minimum of excess magnesia to increase the pH of the solution to at least 5.5 to precipitate undesirable impurities from solution and produce a substantially pure MgCl.sub.2 solution.

Abstract: A process for the recovery of gold from a precious metal bearing sludge concentrate is disclosed. The process comprises the steps of leaching the sludge with hydrochloric acid and hydrogen peroxide to solubilize at least gold, palladium and platinum, removing silver from the leach slurry as insoluble silver chloride and selectively precipitating gold from the leach solution remaining after removal of silver by reduction with SO.sub.2 in the presence of sodium ions.

Abstract: A hydrometallurgical process for the recovery of cobalt from cobaltite-pyrite concentrates containing substantial amounts of cobalt, arsenic, iron and sulphur is disclosed. The hydrometallurgical process comprises pressure leaching of the cobaltite-pyrite concentrates with a sodium chloride or sodium sulphate solution at a temperature in the range of 130.degree.-160.degree. C. and under oxygen partial pressures in the range of 75-200 psi to solubilize at least 90% of the cobalt content, while simultaneously precipitating most of the iron and arsenic as jarosite and ferric arsenate.

Abstract: A method is provided for recovering copper values from a copper-bearing hematite residue in a single stage. It comprises leaching the residue in an aqueous sulphuric acid solution in the presence of ammonium, sodium or potassium ions, at a temperature between about 80.degree. C. and the boiling point of the solution so that copper values are dissolved while iron is precipitated as jarosite. The method is particularly suitable for the treatment of residues resulting from an oxidizing pressure leach of copper concentrates.