The MCLE (Matte Chlorine Leach Electrowinning) process, which is SMM's (Sumitomo Metal Mining's) original technology for obtaining electrolytic nickel with high purity, can leach metallic elements such as Ni, Cu and Co from raw nickel matte by using chlorine gas as an oxidant and remove efficiently some impurities such as Cu, Co and As from the resulting leach chloride solution. Copper is a very important element in the process because cuprous and cupric ions act as electron carriers in chlorine gas leaching. However, copper is one of the major impurities contained in the nickel matte, being accumulated in the leaching circuit. In the MCLE process, copper is removed by electrowinning from the chloride solution a metallic powder form. This is rarely practiced on a commercial scale, and details of this copper removal as well as of other minor impurities are presented.
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