Patent ID: 7951282

Claim:
A process for the hydrometallurgical processing of manganese containing materials, the process characterised by: combining a manganese dioxide containing feedstock having less than 40% Mn with an acidic solution to form a leach solution; and leaching the leach solution by passing a volume of sulphur dioxide gas as the leaching agent through said leach solution to produce a manganese compound, while maintaining the level of dithionate ion generated in the leach solution at less than about 5 g/l by maintaining an excess of manganese dioxide in the leach solution and maintaining the oxidation reduction potential of the leach solution at a level of at least about 550 mV (vs Ag/AgCl reference electrode), wherein the leach solution further contains levels of soluble iron and the ferrous concentration is maintained at a level below about 0.5 g/l by the excess of manganese dioxide.