Life cycle assessment of opencast coal mine production: a case study in Yimin mining area in China.

China has the largest coal production in the world due to abundant resource requirements for economic development. In recent years, the proportion of opencast coal mine production has increased significantly in China. Opencast coal mining can lead to a large number of environmental problems, including air pollution, water pollution, and solid waste occupation. The previous studies on the environmental impacts of opencast coal mine production were focused on a single production process. Moreover, mined land reclamation was an important process in opencast coal mine production; however, it was rarely considered in previous research. Therefore, this study attempted to perform a whole environmental impact analysis including land reclamation stage using life cycle assessment (LCA) method. The Yimin opencast coal mine was selected to conduct a case study. The production of 100 tons of coal was used as the functional unit to evaluate the environmental risks in the stages of stripping, mining, transportation, processing, and reclamation. A total of six environmental impact categories, i.e., resource consumption, acidification, global warming, solid waste, eutrophication, and dust, were selected to conduct this assessment. The contribution rates of different categories of environmental impacts were significantly different, and different stages exhibited different consumption and emissions that gave rise to different environmental effects. Dust was the most serious environmental impact category, and its contribution rate was 36.81%, followed by global warming and acidification with contribution rates of 29.43% and 22.58%, respectively. Both dust and global warming were mainly affected in mining stage in Yimin opencast coal mine based on comprehensive analysis of environmental impact. Some economic and feasible measures should be used to mitigate the environmental impacts of opencast coal mine production, such as water spraying, clean transportation, increasing processing efficiency, and improving mining technologies. This study can be considered as a useful reference for a deeper understanding of key environmental impacts related to the whole coal production in opencast coal mine.