Recovery of zinc and silver from zinc acid-leaching residue by sulphation roasting-water leaching of zinc and iron-silver chlorination leaching method

Recovering zinc and silver from zinc acid-leaching residue was investigated in this study. The process of sulphation roasting, water leaching, silver chlorination leaching, PbCl₂ crystallization and lead replacement was used. The leaching rate of zinc and iron is 92.66% and 94.67% when sulphation roasting temperature is 300°C, sulphate consumption is 70~84 g Hectogram material, time is 120 min. Leach liquor retain to main process to recover zinc. Under the conditions that the concentrations of Fe³⁺, CI^- and H⁺ is 18g·L^-1, 250 g·L^-1 and 2.3mol ·L^-1 separately, leaching temperature is 95°C±1, mechanical agitation for 1.5 h. Leaching rate of silver and lead is 94.17% and 97.89%. Coarse silver powder was prepared by lead-cementation and cementation rate is higher than 99%.