Sulphidation of valleriite in SO2 solutions

Direct flotation of valleriite-containing cupriferous ores is characterized by recovery of only around 60% of the copper and nickel. Valleriite leaching using aqueous SO2 at 90–95 °C resulted in the formation of sulphides of the non-ferrous metals. The leaching also resulted in a significant upgrading of the copper and nickel from 5.5% in the ore to 9.8% in the solid product due to dissolution of Fe, Mg and Al. Flotation of the sulphide from this residue gave > 90% recovery of the non-ferrous metals into the concentrate. Additionally, passing the ore through a disintegrator prior to leaching enhanced the leaching rates.