ACIDIC LEACHING OF CADMIUM FROM ZINC PLANT RESIDUE

In the present paper cadmium leaching from zinc plant residue using sulphuric acid was examined. The zinc plant residue is a hazardous waste which is produced in the hydrometallurgical zinc plant and it contains considerable amounts of metals such as zinc, cadmium and nickel. The effects of sulphuric acid and other important factors such as reaction time, solid-to-liquid ratio, particle size, stirring speed and temperature on cadmium recovery were investigated. The concentration of cadmium in solution was observed to increase with the increase of the reaction time, acid concentration, stirring speed and temperature. Decreasing of solid/liquid ratio and particle size were also beneficial for cadmium recovery. The largest cadmium leaching recovery (97%) was obtained after 30 minutes of treatment at 25 degrees C using H2SO4 (8% (v/v)) at solid-to-liquid ratio of 0.10. XRD and SEM analyses of the residues obtained after leaching showed that the cadmium containing phase had been decomposed in the leaching residues. The results indicated that it is possible to use this waste as a secondary resource for cadmium recovery.