Evaluation of copper refining furnace dusts

Copper refining furnace dust subjected to this experimental study was kindly supplied by Sarkuysan Electrolytic Copper Production Company (Turkey) and contain 6.73 % Cu, 6,86 % Zn, 2.92 % Pb, 1.71 % Sn, 0.02 % Ni, and 0.13 % As. After determining the physical and chemical properties of dust samples, (1) pyrite roasting of dust followed by acidic leaching of hot calcine and (2) direct acidic leaching experiments were carried out to bring the metallic values into solution. In the pyrite roasting experiments; the effects of roasting time, pyrite/dust ratio, roasting temperature and in the leaching tests; the effects of sulfuric acid concentration, leaching time, solid/liquid ratio, and stirring speed on the metal dissolution efficiencies were investigated and optimum conditions were determined. Approximately 83% of copper and 79% of zinc were extracted at the optimum experimental conditions of 450°C roasting temperature, 30 minutes roasting time, 1/4 pyrite/dust ratio, 120 min leaching at room temperature, 1/10 solid/liquid (S/L) ratio and 0.1 M H ₂SO₄ concentration. Dissolution efficiencies of 85% Zn and 90% Cu were obtained by the direct acidic leaching experiments under the optimum conditions of 0.5 M H₂SO₄ concentration, 70°C, 1/20 S/L ratio, stirring speed of 600 rpm, and 90 minutes of leaching period. As a result of this experimental study, direct acid leaching seems to give higher metal dissolutions than those of roasting followed by acid leaching.