A contribution to improve the calculation of the acid generating potential of mining wastes. (May 2017)

• Record Type: Journal Article
• Authors: Chopard, Aurélie; Benzaazoua, Mostafa; Bouzahzah, Hassan; Plante, Benoît; Marion, Philippe
• Is Part Of: Chemosphere. Volume 175(2017)
• Page Start: 97
• Page End: 107
• Publication Date: 2017-05
• Subjects: Acid mine drainage (AMD) -- Drainage quality -- Sulfides -- Oxidation rates -- Static tests -- Acid-generating potential (AP); Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2017.02.036
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Mine wastes from sulfide-bearing ore extraction and processing are often stored at the surface of mine sites and could generate mine drainage. Prediction tests are completed to predict the water quality associated with the deposition of mining wastes. Static tests can quickly assess the acid-generating potential (AP) and the neutralization potential (NP). Whereas some studies recommend to take into account a mineral reactivity factor for the NP determination, the reactivity rates of acidifying minerals are not considered in the AP calculation. The aim of this study is to bring contribution to the improvement of the static test determination by adding kinetic factors in the AP determination. Eight sulfides (pyrite, Ni-pyrite, pyrrhotite, Ni-pyrrhotite, chalcopyrite, galena, sphalerite, arsenopyrite) and a sulfosalt (gersdorffite) were separately submitted to kinetic tests in modified weathering cells. This test was selected for its rapidity of results and for the low amount of material used, as it is somewhat difficult to obtain pure minerals samples. Five synthetic tailings were composed by mixing pure sulfides in various proportions and submitted to the same kinetic tests. The oxidation rates of synthetic tailings were compared with the weighted combined oxidation rates of individual pure sulfides. The oxidation rates of the synthetic tailings calculated from those of pure sulfides are within the same order of magnitude than those obtained through the kinetic experiments. The AP of synthetic tailings were calculated according to standard equations of the literature and compared with the new method. Highlights: Oxidation rates of sulfidic tailings can be estimated from their sulfides content. A kinetic factor is suggested in the calculation of the acid-generating potential. Arsenopyrite, pyrrhotite, and gersdorffite have a strong influence on the kinetics.