Université du Québec en Abitibi-Témiscamingue, 445 Boul. de l'université, Rouyn-Noranda, QC, Canada.
J Environ Manage. 2012 Jan;93(1):10-21. doi: 10.1016/j.jenvman.2011.08.015. Epub 2011 Sep 18.
Mine tailings coming from the exploitation of sulphide and/or gold deposits can contain significant amounts of arsenic (As), highly soluble in conditions of weathering. Open mine voids backfilling techniques are now widely practiced by modern mining companies to manage the tailings. The most common one is called cemented paste backfill (CPB), and consists of tailings mixed with low amounts of hydraulic binders (3-5%) and a high proportion of water (typically 25%). The CPB is transported through a pipe network, to be placed in the mine openings. CPB provides storage benefits and underground support during mining operations. Moreover, this technique could also enhance contaminant stabilization, by fixing the contaminants in the binder matrix. CPB composites artificially spiked with As were synthesized in laboratory, using two types of hydraulic binders: a Portland cement, and a mix of fly ash and Portland cement. After curing duration of 66 days, the CPB samples were subjected to several leaching tests in various experimental conditions in order to better understand and then predict the As geochemical behaviour within CPBs. The assessment of the As release indicates that this element is better stabilized in Portland cement-based matrices rather than fly ash-based matrices. The As mobility differs in these two matrices, mainly because of the different As-bearing minerals formed during hydration processes. However, the total As depletion does not exceed 5% at the end of the most aggressive leaching test, indicating that As is well immobilized in the two types of CPB.
矿渣是在开采硫化物和/或金矿时产生的，其中可能含有大量的砷（As），在风化条件下高度可溶。现在，现代矿业公司广泛采用露天矿空洞回填技术来处理尾矿。最常见的一种是胶结膏体回填（CPB），它由尾矿与少量水硬性粘结剂（3-5%）和高比例的水（通常为 25%）混合而成。CPB 通过管网输送，放置在矿山开口处。CPB 在采矿作业期间提供储存效益和地下支撑。此外，这种技术还可以通过将污染物固定在粘结基质中来增强污染物的稳定性。CPB 复合材料在实验室中人工添加了砷，使用了两种水硬性粘结剂：一种是波特兰水泥，另一种是粉煤灰和波特兰水泥的混合物。在 66 天的养护期后，CPB 样品在不同的实验条件下进行了多次浸出试验，以更好地了解和预测 CPB 内的 As 地球化学行为。对 As 释放的评估表明，该元素在基于波特兰水泥的基质中比基于粉煤灰的基质中更稳定。这两种基质中的 As 迁移性不同，主要是由于水合过程中形成的不同含 As 矿物。然而，在最具侵蚀性的浸出试验结束时，总 As 损耗不超过 5%，表明 As 在两种类型的 CPB 中被很好地固定。
