Coal provides a powerful energy guaranty for power generation, metallurgy, chemical industry and other industries (Benjamin and Lin 2020; Bhandary and Gallagher 2022; Zhang et al. 2019). Coal is also a basic source of energy in China, which accounts for around 40% of the world's coal production. According to the statistics from the National Bureau of Statistics of China (NBSPRC 2021), China's coal consumption accounted for 56.0% of total energy consumption in 2021, with raw coal production reaching a record high of 4.07 billion tonnes, up 4.7% year-on-year. In recent years, with the proposal of the goal of “carbon peak, carbon neutrality”, the efficient and cleaner production of coal has become a critical link to promote sustainable development in China (Wang et al. 2021b).
The continuous increase in coal production, which cannot be replaced by other energy sources in a short period of time, poses a great threat to human health and the ecological environment. Based on the data released by the International Energy Agency (IEA 2022), the carbon dioxide emissions from energy in 2021 reached an all-time height, of which the carbon dioxide emissions from coal reached 15.3 billion tons, accounting for 40%. Large emissions of carbon dioxide will bring about climate change and increase global warming. In addition, the discharge of wastewater and waste residue in the coal production process will also bring damage to water resources and land resources (De Valck et al. 2021; Forrest and Loate 2018; Wang et al. 2022). In recent years, some scholars have performed relevant research on the construction of green mines (Jiskani et al. 2021; Qi et al. 2020), and others have studied the relevant directions of mine ecological restoration and comprehensive utilization of resources (Chen et al. 2022; Li and Wang 2019; Lyu et al. 2022; Mazumder et al. 2021), so as to better solve the environmental problems of mines. Coal mining environmental governance is a hot issue in the world, but also a great challenge faced by China.
Efficiently intelligent mining and ecologically environment friendliness are the main ways of sustainable development of the coal industry (Wang et al. 2019a). To achieve the goal of cleaner and efficient coal production, the environmental problems caused by coal mining should first be assessed in order to propose targeted measures. Life cycle assessment (LCA) is an effective tool to quantify environmental pollution and identify environmental problems at different stages of a product, thus providing decision support for different industries and government agencies (ISO 14040 2006; ISO 14044 2006). As one of the most promising environmental impact declaration methods, it has been widely used in the construction, agriculture, industry and other fields (Anand and Amor 2017; Cetinkaya et al. 2012; Sun et al. 2022; van der Werf et al. 2020; Visentin et al. 2021).
LCA quantitative research on coal mainly focuses on coal-fired power generation and coal-to-chemicals. Wang et al. (2019b) conducted energy efficiency analysis on the whole life cycle of coal mining, and the results revealed that mine design had the greatest potential to improve energy efficiency in the whole life cycle, followed by coal processing, conversion and utilization, and resource reuse. Jung et al. (2022) conducted LCA of a coal-fired power plant with CO2 capture module and found that global warming potential decreased from 1.04 kg CO2/kWh to 0.23 kg CO2/kWh, a reduction of 78%. Thus, it is confirmed that CO2 capture technology substantially affects greenhouse gas emission reduction. Peng et al. (2021) used the LCA method to quantitatively study the direct and indirect emissions of volatile organic compounds (VOCs) in the process of coal-fired power generation, which provided ideas and basis for the emission reduction in VOCs. Śliwińska et al. (2017) conducted LCA on the coal gasification technology of methanol and electricity co-generation, and obtained the greenhouse gas emissions from the process. Peng et al. (2020) calculated the emissions of heavy metals arsenic and lead during the combustion of coal and coal gangue in pulverised coal boilers and circulating fluidised bed boilers and their environmental impacts based on the ReCiPe 2016 method. Liu and Liu (2021) made a comparative analysis of the life cycle energy consumption and greenhouse gas emissions of underground coal gasification and surface coal gasification, and concluded that underground coal gasification has more advantages in hydrogen production. Zhang et al. (2021) compared four coal-to-liquid routes, direct coal liquefaction, indirect coal liquefaction, coal-based methanol to gasoline and coal tar hydrogenation, with conventional route from a life cycle perspective, taking into account environmental, technological and economic factors. Wang et al. (2021a) combined the life cycle and supply chain to study the carbon emissions of the coal industry, considered the impact of carbon emissions in terms of economics, and proposed emission reduction strategies.
It is worth noting that all the above studies have focused on the consumption scenario of coal, while few studies have been devoted to the environmental issues in the process of coal mining and production. Therefore, studies on the environmental impact of the life cycle of coal production are still lacking internationally, including in China. It should be pointed out that as the upstream process of the coal industry chain, the environmental impact of coal mining cannot be ignored. It plays an important role in realising the green and sustainable development of the coal industry to accurately grasp the environmental impact brought by coal mining and carry out environmental governance at the source level. Based on this, this study conducted life cycle analysis of the coal mining process using the LCA, quantitatively study the environmental pollution of the coal mining process, accurately grasp the pollution links, so as to put forward suggestions and measures to effectively improve the environmental impact of coal mining to achieve cleaner coal production.