Mitigating environmental impacts of coal mining through BAS-based metal recovery: a life cycle perspective

Valorizing coal mine waste is an essential approach to reducing the environmental impact of mining while decreasing dependence on conventional disposal methods. To assess its environmental implications, this study examines the life cycle assessment (LCA) of biomass acid sludge (BAS) in coal mine waste valorization. The LCA evaluates the extraction of key components, transportation, processing, and final disposal throughout the life cycle. Acid mine drainage from coal mining generates large volumes of metal-rich sludge, posing a significant environmental challenge worldwide. The current research focuses on assessing the environmental impacts associated with the metal recovery process from coal mine waste via the BAS-based treatment process and chemical extraction technique. According to the literature review, there are very few studies that examine the life-cycle environmental impact of such an integrated system. Thus, the current research aims to identify the hot spots for environmental impacts and the environmental burdens at various stages of the suggested recovery process. This process entailed the utilization of toluene and tributyl phosphate (TBP) and played a significant role in causing environmental impacts. The LCIA results indicate that the BAS-associated treatment system has notable contributions across several environmental impact categories. For the functional unit of 1 tonne of treated coal-mine waste, the calculated impacts included −3933.67 kg CO2-eq for global warming, 181.22 kg SO2-eq for aquatic acidification, and 38,998.14 MJ primary for nonrenewable energy use. The results further indicate that chemical inputs, particularly toluene and tributyl phosphate, are important contributors to several impact categories. It is clear from the results obtained that utilizing BAS for coal mine waste valorization can lead to a substantial reduction in environmental impacts compared to conventional methods of handling waste. This shows that BAS is applicable in the valorization of coal mine wastes.