A method for extracting valuable metals from low nickel matte by non-oxidative leaching with H2SO4

Abstract

The Rapid development of new energy vehicle industry leads to the sharp demand for nickel, cobalt and precious metals in recent years. Because of the similar chemical properties, these metals often exist in Ni-Cu sulfide ores. Traditional treatment of Ni-Cu sulfide ores includes smelting and converting operation. In the smelting process, nickel, copper, cobalt and precious metals are enriched. And then, the low nickel matte obtained by smelting operation was treated by converting process. However, nearly half of cobalt is transferred into slag phase in converting process, leading to a large loss of cobalt. Aiming to increase the recovery of cobalt and precious metals from Ni-Cu sulfide ores, the low nickel matte is treated directly by hydrometallurgical process instead of converting. Because of the weaker affinity of Fe, Co and Ni for sulfur than Cu, the sulfides of Fe, Co and Ni may be decomposed in sulfuric acid solution, while Cu2S and inert precious metals cannot be leached and still remained in the residue. The hydrogen sulfide emitted in the leaching process of low nickel matte can be used to prepare sulfur by Claus method, which has been widely applied in chemical industry. Based on the above considerations, this work developed a promising method for treating low nickel matte. Atmospheric H2SO4 leaching, oversaturated sulfate solutions leaching and iron removal process were carried out, respectively. The leaching efficiencies of more than 99% of nickel, cobalt and iron were obtained, while copper ion cannot be detected in the solution. This process provides a new pathway for the comprehensive utilization of copper-nickel sulfide ore.