Enhanced alkaline extraction of zinc from low-grade lead-zinc oxide ore by grinding and leaching synergistic process

Using low-grade lead-zinc oxide ore from Lanping, Yunnan Province as raw material, and using basket grinder as mechanical activation equipment, the synergistic process of grinding and leaching to enhance alkaline leaching was investigated. Compared with the conventional stirring leaching process, the grinding and leaching synergistic process combines grinding and leaching processes. During the grinding and leaching process, not only the gangue coating of lead-zinc oxide minerals can be destroyed, exposing the zinc containing components, but also the physical and chemical properties, such as mineral structure, particle size, and specific surface area can be changed, enhancing the reaction activity of minerals, and achieving the goals of strengthening zinc leaching and shortening leaching time. The effects of NaOH concentration, leaching time, grinding leaching temperature, liquid-solid ratio, and grinding speed on zinc leaching rate were studied, and XRD and SEM-EDS were used to characterize and analyze the leaching residue under the optimal process conditions. The results show that the zinc leaching rate reaches 92.33% under the optimal process conditions, including NaOH concentration of 3 mol/L, leaching time of 60 min, grinding leaching temperature of 75 ℃, liquid-solid ratio of 10∶1 and grinding speed of 800 r/min. © 2023 Central South University of Technology. All rights reserved.