Release Law of Sb, As, and Hg in Antimony Smelting Slag Under Simulated Acid Rain

Abstract

The exploitation and smelting of heavy metals causes serious environmental pollution, which has received extensive attention from researchers all over the world [1][2][3]. The smelting slag produced by the smelting mines is not only land-occupying, but also causes lasting environmental pollution, for large amounts of harmful elements in the smelting slag are released after rain [4][5][6][7]. As the world's largest antimony (Sb) producer, China produces on average 80% of global Sb annually [8].Xikuangshan (XKS) in Hunan, the world's largest Sb mine, is reported to produce 25% of the world's total. The XKS mine has been mining and smelting for almost 120 years. Its longtime and large-scale mining and smelting has produced large amounts of smelting slag. With surface runoff and precipitation infiltration, harmful elements like Sb and the associated elements As and Hg have been released, threatening the environment and human beings [10][11][12][13][14]. When an excessive amount of Sb, As, or Hg enters the human body, it will cause diseases to the liver, skin, tumors, respiratory and cardiovascular systems, and even cancer [15][16][17][18][19]. Sb, As, Hg, and their compounds are listed as pollutants of priority interest by the United States Pol. J. Environ. Stud. Vol. 26, No. 2 (2017), 925-933 Original Research AbstractThis study takes the Southern antimony smelting slag depot in Xikuangshan (XKS) Sb mine in the city of Lengshuijiang, Hunan, China, as the research object and explores the release law of Sb, As, and Hg in smelting slag under different pH-value simulated acid rain by a semi-dynamic leaching experiment of simulating the local rain. The results show that the leachate pH value is positively correlated with the pH value of simulated acid rain, while the leachate conductivity is negatively correlated with it. The leaching rates of As and Hg are negatively correlated with the pH value of the simulated acid rain, while the leaching rate of Sb is positively correlated with it; in the leaching process, the leachate pH value goes downward slowly after shooting up, but the leachate conductivity is continuously reduced; the releasing process of Sb, As, and Hg consists of two stages, and their leaching rate forms such an order as Sb > Hg > As. The diffraction peak intensity of the main mineral composition of quartz and calcite decreases significantly after leaching; the smelting slag's surface becomes less rough than before leaching, with fewer pores and edges, and the contents of S, Si, Al, Fe, Ca, and Sb on the slag surface decrease while the content of O, As, and Hg increases.Keywords: antimony smelting slag, simulated rain, metal(loid)s, release law *e-mail: zsjaw0745@sina.com DOI: 10.15244/pjoes/65470 926 Zhou S., et al. Environmental Protection Agency [20] and the European Union [21].Until the present, studies at home and abroad are mainly on minerals' adsorption of Sb (III and V) and its desorption, as well as Sb smelting slag's impact on the surrounding environment [22][23][24][25][26][27], but f...

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“…The slight alkalinity highlights the strong acid neutralization capacity with the PTEs forming hydroxides or complexes after dissolution. During the storage of the waste, the PTEs dissolved and released will be reduced in their ability to migrate immediately, and in the long term the hazard potential is localized within the site, but sensitive to future change in environmental conditions [38].…”

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