Leaching behavior of zinc and copper from zinc refinery residue and filtration performance of pulp under the hydrothermal process

This study aims to investigate the leaching behavior and filtration performance of zinc refinery residue under hydrothermal conditions. The relationships between the structure and morphology of silicon in the leaching residue and the pulp filtration performance were explored by determining the pulp filtration speed, analyzing quantitatively the silicon content in the leachate, and characterizing the leaching residue structure. The results show that hydrothermal leaching induces the coagulation–hydrolysis of the silicon in solution, consequently altering the microstructure of the leaching residue, and that silicon oxygen tetrahedra ([SiO4]4？) form the main skeleton structure of the residue. The results obtained also show that the leaching rates of zinc and copper are 98.1% and 98.7%, respectively, and that the filtration speed is 526.32 L/(m2·h) under the conditions of sulfuric acid concentration of 140 g/L, leaching temperature of 160°C, leaching time of 3.0 h, oxygen partial pressure of 0.75 MPa, stirring speed of 600 r/min, and a liquid-to-solid ratio of 10 mL/g.