China Nonferrous Metallurgy

In view of the issues existing in the treatment of acidic heavy metal-bearing effluent produced in the process of lead-zinc smelting by lime neutralization, sulfidization process and their combined processes, the method combining sustained-release sulfidization process with staged neutralization is proposed in this paper, and a new sustained-release sulfidizing agent is used to carry out the purification and heavy metal removal test of acidic effluent from lead-zinc smelting, and the following conclusions are drawn: under the conditions that the dosage of sustained-release sulfidizing agent is twice the theoretical demand, the solution acidity is 60g/L, the sulfidization reaction time is 40min, and the stirring speed is 300r/min, as well as under normal temperature and pressure, the removal rate of heavy metal ions As, Tl, Cd in the acidic effluent can reach more than 99% and Hg removal rate is above 90%. The solution resulting from neutralization meets the discharge limit requirements in the Emission Standard of Pollutants for Lead, Zinc Industry (GB 25466—2010), and the produced gypsum residue reaches the level of recycling.