Release of Multiple Contaminants from Mine Waste Materials

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Large volumes of waste rocks are generated by mining and mineral beneficiation activities. When these materials are exposed to water and air, various toxic elements, such as selenium, arsenic, nickel, and cadmium, may be leached out and mobilized to receiving waters and soil, resulting in significant impacts on water quality and aquatic ecosystems. These elements tend to occur and are released together, more often with different release dynamics, therefore posing complex environmental and ecological risks.******The current common practice to deal with mine drainage is the installation of water treatment facilities. The expense and complexity of managing long-term water treatment poses a liability to government and society as a whole. A more preferable option is to prevent the release of toxic elements at the source, i.e. source control. To select and implement the most appropriate source control strategies, it is essential to obtain sound knowledge on the fundamental processes that determine the dynamics of contaminant release from waste rock piles, such as reaction kinetics, mass transport, heat transport, and microbial activities.******The long-term objective of this research is to develop and implement various source control strategies to preclude the release of multiple toxic elements from mine waste materials at the source, thus reducing long-term reliance on water treatment. Achieving this objective requires fundamental knowledge on the key processes that determine the release dynamics. Therefore, the short-term objectives of this research over the next five years are to identify and simulate the key geochemical and hydrodynamic processes that control contaminant release dynamics via laboratory test and numerical modelling, with a focus on selenium and associated elements (arsenic, cadmium, strontium) from coal mine waste.******The findings of this research will advance knowledge on the release dynamics of multiple toxic elements from mine waste materials. This knowledge will be of important use to other researchers who study the complex environmental and ecological risks posed by multiple toxic elements. Together, it will provide the scientific bases for the establishment of environmental guidelines. The findings on key parameters that control multiple contaminant release at the source will assist the mining industry and regulators in developing practical source control strategies by manipulating those key parameters. The fully-coupled model developed allows for the evaluation of the effectiveness of different mitigation strategies and selecting alternatives. This will reduce long-term reliance on water treatment, an expensive option that may extend into perpetuity. This research will also provide an exemplary framework for predicting and managing the release of multiple toxic elements from a diversity of waste rock. *** **