Unveiling the heterogeneity of environmental impacts of China's coal washing plants by a configuration-specific life cycle assessment

Coal washing is considered a promising method of mitigating coal-induced air pollution in China because of the limited end-of-pipe treatment potential for coal pollution. However, the estimated benefits of coal washing have been overly optimistic due to the lack of comprehensive research on the environmental burden of coal washing and its related indirect impacts. Moreover, the specific coal quantity and quality requirements for various downstream sectors cannot be effectively addressed because the environmental effects of the differentiated scales and technologies used in coal washing plants have not been determined. The objective of this study is to quantify both the direct and indirect environmental impacts of Chinese coal washing plants and innovatively reveal the internal disparities and their formation mechanisms. A total of 2367 coal washing plants were investigated, and 20 configurations that combined both the washing scale and technology were categorized. Plant-level input and output data were modeled by the ReCiPe 2016 methodology to perform a configuration-specific life cycle assessment. The results showed that enlarging the plant scale increased the environmental benefits by 11.0–38.4 % in most cases. Washing coal via flotation and heavy medium methods generally resulted in higher environmental impacts of 2.0–16.0 % and 0.6–7.3 % compared to that of jigging due to the use of chemical reagents and medium powders, respectively. Different configuration structures across provinces induced spatially heterogeneous environmental impacts, which were high in southern and eastern China and low in northern and western China. The results highlighted the considerable environmental impacts of coal washing hidden in the coal production and consumption chain. Moreover, the findings reveal a spatially explicit configuration strategy for downstream-specific demands and show that enhancing solid waste utilization can reduce toxic environmental impacts.