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To explore the feasibility of reusing solid waste to stabilize high-content arsenic (As) and antimony (Sb) tailings, red mud, fly ash, dried sludge, ferrous sulfate (FeSO4), and rice husk ash (RHA) were used as the stabilizer to stabilize the Sb tailings in Qing Long and Du Shan. The combined treatment with 5% red mud, 10% fly ash, 5% dried sludge, 1% FeSO4, and 1% rice husk ash had the best stabilization effects on As and Sb, the leaching concentrations of As and Sb decreased considerably under neutral conditions, this indicates that the leaching behavior of As and Sb is controlled by the alkaline and acid-retarding capacity of the materials. In addition, the leaching of heavy metals decreases with the formation of (C-S-H) and calcite (CaCO3), indicating that heavy metals exist in the form of metal hydration or hydroxide and precipitate on the surface of calcium silicate hydrate (C-S-H) and calcite particles. Leaching of heavy metals in stabilized materials can be considered as a pH-dependent and control process of stabilization products. [ABSTRACT FROM AUTHOR]

To investigate the heavy metal enrichment mechanisms and release characteristics of typical deposits in karst areas, the Sb tailing pond of Dachang, Qinglong, Guizhou Province, China, one of the three largest Sb mines in the word, was selected as the study area. In this study, samples were collected from tailings (0~120 cm) and analyzed for changes in Sb and As content at different pH values by simulated acid rain static release experiments, and solid waste materials (fly ash, quicklime, and zeolite powder) were selected to design an orthogonal test to explore the optimal stabilization effect of Sb and As. The results showed that the average contents of Sb and As exceeded background values of Guizhou soil to different degrees. The content of As leaching revealed slight differences in the leachate. Sb was sensitive to more acidic conditions, and its release content can pose an ecological risk. Further, the best stabilization effect of Sb and As was observed after adding different ratios of fly ash, quicklime, and zeolite powder for a period of maintenance, which can be used as promising stabilizing materials for mine tailings remediation. This study provides comprehensive theoretical support for enhancing source control and risk management of heavy metals. [ABSTRACT FROM AUTHOR]

Total concentrations and different forms of antimony (Sb) in soils of Laokuang District (LKQ-1, LKQ-2, LKQ-3), Beikuang District (BKQ-4, BKQ-5, BKQ-6) and Nankuang District (NKQ-7, NKQ-8, NKQ-9, NKQ-10) of Xikuangshan, Hunan province, China were analyzed. The soil Sb concentrations in the whole-ore heap of LKQ-1 and the mining land of NKQ-7 were up to 4258 and 3174 mg/kg respectively, which were both 2000 times above the background soil Sb level in China. In terms of vertical distribution, the Sb concentrations gradually declined with the rise of soil depth. Tessier's 5-step sequential extraction method showed Sb mainly existed in stable forms (organic-matter-bound form, residual form), and the available form accounted for 18%. The proportions of different forms ranked as residual form >iron/manganese oxides >organic-matter-bound form >carbonate-bound form > water-soluble form. Vegetation affected the form distribution of Sb in a complex way and may increase the bioavailability of Sb, so ecological restoration of Sb can be realized through the absorption by vegetation. Analysis of the geoaccumulation index and the potential ecological risk index showed that Xikuangshan was under extremely severe Sb pollution and very serious potential ecological risk. The Sb mining and smelting activities of humans aggravated local Sb pollution. [ABSTRACT FROM AUTHOR]