title: Use of EDTA in modified kinetic testing for contaminated drainage prediction from waste rocks: case of the Lac Tio mine.
abstract: 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.
authors.affiliation: 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, benoit.plante@uqat.ca.
authors.forename: Benoît
authors.initials: B
authors.lastname: Plante
authors.forename: Mostafa
authors.initials: M
authors.lastname: Benzaazoua
authors.forename: Bruno
authors.initials: B
authors.lastname: Bussière
authors.forename: El-Hadji-Babacar
authors.initials: el-HB
authors.lastname: Kandji
authors.forename: Aurélie
authors.initials: A
authors.lastname: Chopard
authors.forename: Hassan
authors.initials: H
authors.lastname: Bouzahzah
mesh_terms: D002614:Chelating Agents / Q000737:chemistry*; D004492:Edetic Acid / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D007700:Kinetics; D008670:Metals / Q000032:analysis*; D008903:Minerals / Q000032:analysis*; D008906:Mining; D011792:Quebec; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D014877:Water Pollution, Chemical / Q000517:prevention & control*
chemical_list: D002614:Chelating Agents; D008670:Metals; D008903:Minerals; D014874:Water Pollutants, Chemical; D004492:Edetic Acid