Université du Québec en Abitibi-Témiscamingue, 445 Boul. de l'université, Rouyn-Noranda, QC, Canada.
J Hazard Mater. 2011 Jan 30;185(2-3):1467-76. doi: 10.1016/j.jhazmat.2010.10.070. Epub 2010 Oct 25.
Arsenic (As) is a toxicant in tailings from sulphur deposits. It represents an environmental risk because of its high solubility. Tailings can be mixed with water (typically 25%) and a low proportion of hydraulic binder (3-7%) to produce a cemented paste backfill (CPB), stored in underground mine openings. CPB is a tailings storage technique, but it could also provide environmental advantages by stabilization of polluting elements such as As. Tailings from Casa Berardi mine (QC, Canada) contain As (3800 ppm), mainly in arsenopyrite form. For this study, three different CPBs were synthesized in laboratory using Casa Berardi tailings and three different binders. These pastes were submitted to various leaching tests after 28 days of curing. The results indicate that As is released at higher concentration for a fly ash-based CPB than for slag- and Portland cement-based CPB. However, at lower pH, As is better stabilized in fly ash-based samples. These differences can be explained by a variation of solubility of As-compounds in each CPB. Several mechanisms of As release occur, as diffusion and/or dissolution/precipitation. The accelerated weathering test results show that sulphide reactivity is buffered by the neutralizing minerals contained in CPB, and influence the As release behaviour by decreasing the oxidation of As-bearing sulphides.
砷（As）是来自硫磺矿床的尾矿中的一种有毒物质。由于其高溶解性，它代表了一种环境风险。尾矿可以与水（通常为 25％）和少量的液压胶凝材料（3-7％）混合，制成胶结膏体充填料（CPB），储存在地下采矿硐室中。CPB 是一种尾矿储存技术，但通过稳定砷等污染元素，也可以提供环境优势。来自 Casa Berardi 矿（QC，加拿大）的尾矿含有砷（3800ppm），主要以毒砂形式存在。在这项研究中，使用 Casa Berardi 尾矿和三种不同的胶凝材料在实验室中合成了三种不同的 CPB。这些膏体在固化 28 天后进行了各种浸出试验。结果表明，与基于矿渣和波特兰水泥的 CPB 相比，基于粉煤灰的 CPB 中砷的释放浓度更高。然而，在较低的 pH 值下，基于粉煤灰的样品中砷的稳定性更好。这些差异可以通过每种 CPB 中砷化合物的溶解度变化来解释。砷的释放发生了几种机制，如扩散和/或溶解/沉淀。加速风化试验结果表明，CPB 中所含的中和矿物缓冲了硫化物的反应性，通过减少含砷硫化物的氧化来影响砷的释放行为。
