Évaluation de la capacité de matériaux industriels alcalins à neutraliser des résidus et stériles miniers acides
|Abstract:||Acid mine drainage (AMD) is the most serious environmental problem facing the mining industry. AMD is formed when sulfide minerals in waste rock or tailings are oxidized in the presence of water and oxygen to form highly acidic, sulfate and metals-rich drainage. Some methods exist to reduce the formation of AMD in a waste rock pile: layered co-mingling, cover, liner and co-disposal of waste rock with fine materials to limit oxygen fluxes. These methods are based on the use of mine tailings. The aims are to limit the transfer of oxygen and water in a waste rock pile during its construction and reduce thermal gas convection. However, mine tailings can themselves generate AMD and need to be neutralized by the addition of alkaline material. The purpose of this study is to evaluate the capacity of alkaline industrial wastes to neutralize tailings. Alkaline industrial wastes which were selected are cement kiln dust (CKD) and red mud bauxite (RMB). These alkaline materials are used to keep neutral conditions even if water saturation is disrupted. A series of batch leaching tests and column leaching tests were conducted in order to investigate the long-term neutralization potential of alkaline materials and the quality of the drainage water. The batch leaching tests have indicated the minimum percentage (10%) of alkaline material required to keep neutral pH conditions, and to discern whether mineral solubility controls exist for particular elements. Column leaching tests have shown the hydrogeochemical behaviour of different dispositions of materials. When the fine-grained layer overlays reactive waste rock, a delay was observed before obtaining near neutral pH. In the cases where the fine-grained layer is below or mixed with the waste rock, the near neutral pH values are directly reached. The co-disposition offers short-term neutralisation only. Finally, a sequential extraction method was used to determine the degree of fixation of metals.|
|Document Type:||Thèse de doctorat|
|Open Access Date:||11 April 2018|
|Collection:||Thèses et mémoires|
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