Research Progress and Challenges in Coal Gangue Resource Utilization Technologies

Coal gangue is the largest mining solid waste with an annual output of more than 720 million tons and a cumulative stockpiling of more than 7 billion tons in China, and the environmental pressure is huge. Under the impetus of the "double carbon" strategy, its resource utilization has become a national priority. At present, in terms of power generation, circulating fluidized bed (CFB) boiler technology has achieved an annual consumption of 3.5 million tons of coal gangue; in the field of building materials, the amount of spontaneous combustion coal gangue replacing cement in the preparation of ultra-high performance concrete (UHPC) by coal gangue can reach 40%. In terms of underground filling, the overburden bed separation grouting and intelligent filling system achieve large-scale application; in road engineering, multi-source solid waste collaborative utilization technology significantly improves roadbed performance. Nevertheless, it still faces challenges such as complex composition, high cost and secondary pollution. In the future, it is necessary to further rely on the two-wheel drive of policy and technology to promote the transformation of coal gangue from 'waste treatment' to' resources', so as to achieve high-quality development of environmental protection and resource recycling.