A process flowsheet for the elimination of copper contained in sulphuric acid pickling baths of steel pieces has been developed. A preliminary study of solvent extraction options has lead to the choice of a suitable extracting system containing both Cyanex 302 and LIX 860. With this extractant mixture, copper is quantitatively and selectively extracted in a few minutes. The stripping step has been optimised with the use of thiourea as stripping agent. A regeneration step of the extractant is necessary because of the degradation of Cyanex 302. The feasibility of copper deposition from the strip solution has been demonstrated. A continuous micro-pilot scale test has been performed with good results (constant and low copper concentration in the pickling bath and electrowinning of copper) and a model has been developed for the design of the industrial process.
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