Leaching of zinc from a lead-zinc flotation tailing sample using ferric sulphate and sulfuric acid media

Zinc is one of the most important metal required in metallurgical and chemical industries. As the high-grade resources diminished, the treatment of processing plants tailings can be considered as a metal significant source. Leaching is regarded as the first step of the hydrometallurgical methods and ferric sulphate/sulphuric acid leaching has been found to be as a highly effective technique for treating low-grade ores and tailings. Thus, this research was performed to describe the behavior of important factors affecting the leaching of zinc from a tailing sample obtained from lead-zinc flotation circuit in ferric sulphate and sulfuric acid media. It was found that 0.5 mol L-1 ferric sulphate is enough to dissolve both oxidized and sulphidic minerals. Response surface modeling was employed for parametric optimization (viz. stirring speed, sulphuric acid concentration, acid-toferric sulphate ratio and temperature). The findings showed the parametric degree of influence on zinc leaching was in order as: temperature > quadratic effect of stirring > quadratic effect of liquid/solid ratio > acid/ferric sulphate ratio > quadratic effect of sulphuric concentration. The optimum conditions established from model were found to be a stirring speed of about 320 rpm, 1.14 mol L-1 sulphuric acid concentration, 2.49 acid/ferric sulphate ratio, 10.10 ml/g liquid/solid ratio and 80 degrees C temperature. Under these conditions, the highest recovery of zinc was achieved of approximately 94.3%.