Ions release stages of Cu-Pb-Zn mine tailings waste: A column leaching simulation

Abstract

Characterizing the leaching behavior and temporal variability of tailings is conducive to managing and preventing ionic toxicity to indigenous communities and environment. For this purpose, this work selected Cu-Pb-Zn tailings waste from Huili County, Sichuan province in China, as a research case, conducting a 60-day column leaching experiment to simulate the leaching behavior of the tailings. The results reveal that the weathering features of tailings, both salt-based ions and potential toxic elements (PTEs), could be subdivided into the rapid dissolution stage and carbonate dissolution stage. Additionally, acid rain can accelerate the weathering of calcite and dolomite, as well as the leaching of PTEs. The weathering of calcite precedes that of dolomite. A bulk release of PTEs occurs in the early stages, ranging approximately between 10.9 % and 33.6 % in the initial seven days, with As and Zn showing notable significance. Therefore, ecological effects of this abnormality necessitate thorough examination, given that the release of PTEs occurs over an extended and prolonged duration. Acid rain can promote ion desorption and weathering of major minerals, thereby facilitating the leaching of salt-based ions and PTEs. This study emphasizes the early rapid release stage of ions pollution from tailings, providing a preliminary understanding of the environmental impacts that may arise from tailings deposition and acidic rain leaching.