Research Institute in Mining and the Environment (RIME), UQAT (Université du Québec en Abitibi-Témiscamingue), 445 boulevard de l'Université, Rouyn-Noranda, Québec, J9X 5E4, Canada,
Environ Sci Pollut Res Int. 2015 May;22(10):7882-96. doi: 10.1007/s11356-015-4106-6. Epub 2015 Jan 22.
The tools developed for acid mine drainage (AMD) prediction were proven unsuccessful to predict the geochemical behavior of mine waste rocks having a significant chemical sorption capacity, which delays the onset of contaminated neutral drainage (CND). The present work was performed in order to test a new approach of water quality prediction, by using a chelating agent solution (0.03 M EDTA, or ethylenediaminetetraacetic acid) in kinetic testing used for the prediction of the geochemical behavior of geologic material. The hypothesis underlying the proposed approach is that the EDTA solution should chelate the metals as soon as they are released by sulfide oxidation, inhibiting their sorption or secondary precipitation, and therefore reproduce a worst-case scenario where very low metal attenuation mechanisms are present in the drainage waters. Fresh and weathered waste rocks from the Lac Tio mine (Rio tinto, Iron and Titanium), which are known to generate Ni-CND at the field scale, were submitted to small-scale humidity cells in control tests (using deionized water) and using an EDTA solution. Results show that EDTA effectively prevents the metals to be sorbed or to precipitate as secondary minerals, therefore enabling to bypass the delay associated with metal sorption in the prediction of water quality from these materials. This work shows that the use of a chelating agent solution is a promising novel approach of water quality prediction and provides general guidelines to be used in further studies, which will help both practitioners and regulators to plan more efficient management and disposal strategies of mine wastes.
针对酸性矿山排水（AMD）预测而开发的工具在预测具有显著化学吸附能力的矿山废石的地球化学行为方面证明是不成功的，这会延迟受污染中性排水（CND）的出现。本工作旨在测试一种新的水质预测方法，即在用于预测地质材料地球化学行为的动力学测试中使用螯合剂溶液（0.03 M EDTA，或乙二胺四乙酸）。所提出方法的基本假设是，EDTA 溶液应在硫化物氧化释放金属时立即螯合这些金属，抑制其吸附或二次沉淀，从而再现非常低的金属衰减机制存在于排水中的最坏情况。来自拉蒂奥矿（里奥廷托，铁和钛）的新鲜和风化废石已知在现场尺度上产生 Ni-CND，在控制测试（使用去离子水）和使用 EDTA 溶液的小型湿度室中进行了测试。结果表明，EDTA 可有效地防止金属被吸附或作为次生矿物沉淀，因此能够在预测这些材料的水质时绕过与金属吸附相关的延迟。这项工作表明，使用螯合剂溶液是一种有前途的水质预测新方法，并为进一步研究提供了一般指南，这将有助于从业人员和监管机构规划更有效的矿山废物管理和处置策略。
