EXTRACTION OF ZINC, LEAD, COPPER AND CADMIUM FROM SECONDARY ZINC ORES BY (HYDROMETALLURGICAL) LEACHING METHOD

Abstract

The annual increase in waste recycling by non-ferrous metal producers is steadily growing. These waste materials often contain various harmful heavy metal impurities, which pose significant environmental risks. This study examined the laboratory-scale extraction of zinc and copper, along with additional lead and cadmium, from the residue of zinc smelting using a hydrometallurgical method. The leaching technique was considered for extracting metals from the residue. Parameters such as the solution's concentration, temperature, and the solid/liquid ratio were examined to assess the efficiency of the leaching method. An aqueous solution of ammonium chloride (NH4Cl) was used as the leaching agent. Optimal conditions identified for this process were a temperature of 80°C, a 5M NH4Cl solution, a leaching duration of 2 hours, and a liquid/solid ratio of 1:25. These parameters confirmed the high selectivity of the leaching agent and demonstrated maximum efficiency. In practice, the obtained solution yielded maximum Zn and Cu recoveries of 93.2% and 67%, respectively. Additionally, the yields for Pb and Cd were 80% and 55%. These results underline the importance of optimizing the concentration of ammonium chloride and leaching parameters to improve the simultaneous extraction efficiency of different metals. The high selectivity and efficiency of ammonium chloride enhance its potential in metal recovery and reduce the environmental impact, opening new possibilities for developing waste recycling methods.