Innovative green approach for the selective extraction of high-purity selenium from hazardous selenium sludge

Abstract

Hazardous selenium sludge is a critical intermediate byproduct of the comprehensive recovery of selenium from copper anode slime, and the sustainable extraction of Se is an important basis for the development of high-tech Se-containing materials. Unfortunately, current processes are constrained by complex procedures, serious pollution, ineffectiveness and difficulty in separating Se-Te. This study has developed an innovative green approach utilizing the phase transformations of impurities combined with vacuum distillation to efficiently extract high-purity selenium from selenium sludge and to overcome these issues. The main impurities of Te, Cu, and Pb exist as elemental Te, PbTe, TeO, Cu2Se, and PbSe, and a green oxidizing reagent (H2O2) is employed to convert these impurities into low volatile TeO, CuSeO3, and PbSeO3. Then, high-purity selenium (Se 99.998%) is extracted by vacuum distillation. The appropriate dose of H2O2 is 15 ml per 100 g of sludge at 300 rpm, 0.5 h, and room temperature. Furthermore, the optimal vacuum distillation conditions are 733 K, 1 h, and 1–10 Pa. After completing the whole process, the total yield of high-purity selenium reaches 87.86%. This study provides an efficient and environmentally friendly process to dispose of hazardous selenium sludge and extract high-purity selenium for further use, which has important industrial applications.