Optimization of Pure Copper Powders Production from Leach Solutions Containing Copper

Abstract

In this study, in first step, oxidized copper ore was dissolved under optimum conditions in an aqueous NH₃-(NH₄)₂SO₄ solution. In the second step, Chevreul's salt, Cu₂SO₃·CuSO₃·2H₂O, was precipitated under optimum conditions by passing SO₂ from the leach solutions obtained. In the third step, Chevreul's salt was dissolved in an acetonitrile-water (AN/H₂O) system in a nitrogen atmosphere. The optimum dissolution of Chevreul's salt at reaction temperature 87 °C, pH 2.75, stirring speed 700 rpm, solid-to-liquid ratio 0.225-g mL^-1 and AN/H₂O ratio 41 % (v/v =). Initial concentration of CuSO₄ solution was chosen as 0.25 M at a fixed value. In the fourth step, the copper powders were produced under optimum conditions by thermal disproportionation of copper(I) sulphate solutions in a nitrogen atmosphere. The best onditions on the dissolution and the precipitation were determinated by using 2ⁿ factorial experimental design and orthogonal central composite experimental design methods. The optimum conditions on the maximum copper precipitation at the reaction temperature 70 °C, the reaction time 35 min, the stirring speed 550 rpm, inner pressure (vacuum pressure) 201.3 mm Hg. The fixed parameter chosen at the precipitation reaction was the initial concentration of CuSO₄ solution, 0.25 M. Under these optimum conditions, the best precipitation yield was 99.33 %.