Separation and Recovery of Trace Silver from Sintering Filtrated Dust of Ferrous Metallurgy via Complexation Leaching

In this work, by using the sintering filtrated dust (SFD) from ferrous metallurgy as a raw material, the process of separating and recovering trace silver, including the steps of complexation leaching by Na2S2O3-CuCl, purification by hydrogen peroxide, and precipitation transformation, was researched and developed. The process is characterized by a high leaching selectivity and a high recovery. The recommended conditions for leaching trace silver from SFD were as follows: a leaching time of 120 min, a leaching temperature of 60 °C, a solid–liquid ratio of 6 L/kg, a Na2S2O3 concentration of 45 g/L, and a CuCl dosage of 5.0 g/L. Through a two-step hydrogen peroxide process, removal of the impurity ions Cu and Pb and high-efficiency recovery of trace silver were realized. The purity of the silver sulfide product obtained from the recovery was 97.0%, and the total silver recovery was 80.1%. In addition, the reaction mechanism of the recovery process was investigated in this work, and effective removal of impurity ions was realized by regulating the reaction time.