A Mixed-Chloride Atmospheric Leaching Process for the Recovery of Base Metals from Sulphide Materials

Base metal sulphide ores exist in many areas of the World and are a potential source of copper, nickel and cobalt. A large portion of copper and nickel is produced from sulphide concentrates by the conventional smelting and hydrometallurgical processes. Pyrometallurgical processes have several detriments including high capital costs, losses of valuable metal by-products in slags and residues, and environmental constraints pertaining to gaseous emissions and solid residues. Hydrometallurgical processes using autoclaves are capital intensive and offer materials handling and maintenance challenges. Process Research ORTECH has developed a unique atmospheric mixed chloride leaching process for the recovery of copper and nickel from sulphide concentrates. This process also produces value added by-products of high purity cobalt, iron oxide and recycles chloride lixiviant to the leaching stage. In this paper, leaching of sulphide concentrates with lixiviant containing hydrochloric acid and magnesium chloride, separation reaction mechanisms, production of elemental sulphur and a potential process flowsheet is described.