THE CENIM LNETI PROCESS - A NEW PROCESS FOR THE HYDROMETALLURGICAL TREATMENT OF COMPLEX SULFIDES IN AMMONIUM-CHLORIDE SOLUTIONS

A new process for the hydrometallurgical treatment of complex sulphides is presented. This process is based on an oxidizing leach of the sulphides in an ammonium chloride medium, which produces ammonia which forms metal ammine complexes with the solubilized metals (Cu and Zn). The leaching occurs at a practically constant and neutral pH, and produces a solution which is totally free of iron. Impurity elements, such as As, Sb, Bi and Sn, are detected in the solution only at trace levels. The presence of ammonia in the fertile leaching solutions facilitates its treatment by solvent extraction with acid cationic extractants, a stage in which the leaching solution is regenerated. The paper presents a basic, general description of the process, illustrated with the results obtained using one of the bulk concentrates analyzed.