Abstract: A process for the recovery of magnesium oxide from a source containing magnesium salts, said process including the steps of: (a) adding an alkali and sulfur dioxide to the source containing magnesium salts, in a leach step to form a magnesium bi-sulfite containing leachate;(b) separating the insoluble materials from the leachate; (c) stripping excess sulfur dioxide from the leachate and precipitating the magnesium as solid magnesium sulfite hydrate; (d) separating the solid magnesium sulfite hydrate from the magnesium depleted leachate; and (e) calcining the solid magnesium sulfite hydrate and recovering the magnesium as magnesium oxide.

Abstract: An atmospheric leach process in the recovery of nickel and cobalt from lateritic ores, said processing including the steps of: a) separating the lateritic ore into a low magnesium containing ore fraction, and a high magnesium containing ore fraction by selective mining or post mining classification; b) separately slurrying the separated ore fractions; c) leaching the low magnesium containing ore fraction with concentrated sulphuric acid as a primary leach step; and d) introducing the high magnesium content ore slurry following substantial completion of the primary leach step and precipitating iron as goethite or another low sulphate containing form of iron oxide or iron hydroxide, wherein sulphuric acid released during iron precipitation is used to leach the high magnesium ore fraction as a secondary leach step.