Feasibility and challenges of multi-source coal-based solid waste (CSW) for underground backfilling - A case study

The multi-source CSW produced in coal mining, power generation and coal chemical industry has become a bottleneck that restricts the green, low-carbon and high-quality development of coal power and coal chemical bases (CPCCBs) in China due to its large stock, many increments and low utilization rate. Underground backfilling has opened up a new way for CPCCBs to dispose of multi-source CSW, and it is also the most practical way, which is conducive to solve the surface accumulation of CSW and reducing the environmental pollution risk. Based on the physicochemical properties and pollution, the feasibility of underground backfilling with multisource CSW was systematically analyzed from four aspects: environment, technology, economy and policy. Most CSWs can be directly for underground backfilling; the high potential pollution risks of individual CSWs can reduce through technical measures such as heavy metal adsorption and complex passivation, then safely for underground backfilling. Although underground backfilling with multi-source CSWs is feasible, there are still some challenges before achieving large-scale engineering applications, such as potential risks of CGS, technical maturity, economic investment and administration. It requires the joint efforts and cooperation of research institutions, enterprises and governments to realize the harmless and large-scale underground backfilling with multi-source CSW.