The Impact of Physical Properties on the Leaching of Potentially Toxic Elements from Antimony Ore Processing Wastes

This study reports on the assessment of the impact of antimony mine wastes from Xikuangshan (XKS) Antimony Mine in Lengshuijiang City, Hunan Province. We focus on the leaching of a number of potentially toxic elements (PTEs) from residues from the processing of antimony ore. The PTE content of ore processing waste and solutions generated by leaching experiments were determined for a suite of PTEs associated with the ore mineralization. These were Sb, As, Hg, Pb, Cd and Zn. As anticipated, high concentrations of the PTEs were identified in the waste materials, far exceeding the standard background values for soil in Hunan Province. For Sb and As, values reached >1800 mg·kg^-1 and >1200 mg·kg^-1, respectively (>600 and >90 times higher than the soil background). The leaching of Sb, As, Hg, Pb, Cd and Zn decreased with an increase in grain size and leachable portions of metal ranged between 0.01% to 1.56% of total PTE content. Leaching tests identified the release of PTEs through three stages: a. alkaline mineral dissolution and H⁺ exchanging with base cation; b. oxidation and acid production from pyrite and other reducing minerals; and c. the adsorption and precipitation of PTEs.