China Nonferrous Metallurgy

Lead-silver slag is a kind of hazardous waste produced in the hot acid leaching process of zinc hydrometallurgy. The clean and efficient enrichment and recovery of valuable metals is of great significance to promote the green recycling development of zinc hydrometallurgy industry. Valuable metals were recovered from lead-silver slag after desulfurization by fuming method. The fuming volatilization method is used to recover valuable metals from lead silver slag after desulfurization. The feasibility of fuming volatilization of Zn, Pb, In and Cd was studied with FactSage 8.1 thermodynamic software. The main factors affecting the metal volatilization rate in the fuming volatilization process were experimentally studied. The results showed that in the process of fuming and volatilizing, Zn, In and Cd were firstly reduced and then oxidized, and finally enriched in smoke and dust as oxides; under the optimum conditions of fuming and volatilization temperature 1250℃, fuming and volatilization time 60 min and carbon ratio 25%, the volatilization rates of Zn, Pb, In and Cd were 99.69%, 82.26%, 99.09% and 99.90% respectively, which realized the efficient enrichment and recovery of metals. SEM images showed that the fuming slag contained metal Fe, calcium aluminosilicate, etc., iron resources could be recovered through magnetic separation with re-utilization value. The study provides theoretical and data support for industrial application of pyrometallurgical treatment of lead-silver slag.