Risk assessment of potentially toxic elements pollution from mineral processing steps at Xikuangshan antimony plant, Hunan, China

We evaluate the direct release to the environment of a number of Potentially Toxic Elements (PTEs) from various processing nodes at Xikuangshan Antimony Mine in Hunan Province, China. Sampling wastewater, processing dust and solid waste and characterizing PTE content (major elements Sb, As, Zn and associated Hg, Pb and Cd) from processing activities, we extrapolate findings to assess wider environmental significance using Pollution Index and Potential Ecological Risk Index. The Sb, As, Zn in wastewater from antimony benefication industry and wider group of PTEs in the fine ore bin are significantly higher than their reference values. The content of Sb, As and Zn in tailings are relatively high, with the average value being 2674, 1040 and 590 mg·kg⁻¹, respectively. The content of PTEs in the surface soils surrounding the tailings is similar to that in tailings, and much higher than the background values. The results of pollution index evaluation of the degree of pollution by PTEs show that whilst dominated by Sb, some variation in order of significance is seen namely for: 1. the ore processing wastewater Sb > Pb > As > Zn > Hg > Cd; 2. in dust Sb > As > Cd > Pb > Hg >Zn; 3. surface soil (near tailings) Sb > Hg > Cd > As > Zn > Pb. From the assessment of potential ecological risk index, the levels are most significant at the three dust generation nodes and in the soil surrounding the tailings reservoir.