Super Large-Scale Filtered Tailing Disposal on Coal-Mining Subsidence Land
Polish Journal of Environmental Studies
The Sijiaying Iron Mine (Hebei Iron and Steel Group, China) is Asia's biggest iron mine, and produces more than 70 million tons of tailing slurry annually, with a mass concentration of 20%  . As villages and farmland surround the mine, building a conventional tailings impoundment (CTI) near the iron mine will require an area of 4.2 km 2 , the demolition of three villages, the relocation of 1,000 people, and a total investment of more than 500 million CNY. Furthermore, wastewater, gas, and
... ewater, gas, and residue will cause serious pollution issues, making it a significant danger source if the dam were to seep or break  . Under the context of farmland protection in China and the downturn in the iron ore market   , such a large land expropriation and investment is impossible. In the past 20 years, paste tailings have been proved to be an environmentally friendly, cost-effective backfill and tailings disposal method  . Fourie  analyzed the advantages of paste and thickened tailings technology Pol. Abstract This paper evaluates the feasibility and stability of the construction of a super-large-scale filtered tailings storage facility on coal-mining subsidence land. Properties of the coal gangue were analyzed by laboratory tests and change laws of the land subsidence were observed in the field. Comparisons of slope stability between the super large-scale filtered tailings storage facility and conventional tailings impoundment in normal, flooded, sustained rainfall, and strong earthquake conditions were conducted using Slide software. The results show that the filtered tailings storage facility has less chance of failure, lower seepage probability, and smaller impact scope than conventional tailings impoundment. With little free water in filtered tailings, the average slope safety factors of filtered tailings storage are as high as 1.78 in normal, 1.73 in flood, 1.18 in sustained rainfall, and 1.11 in a magnitude-8.0 earthquake. As an environmentally friendly, costeffective chain-cutting disaster mitigation measure, filtered tailings disposal shows great advantages in reducing tailing emissions, dam construction scale, and operational costs, improving water conservation, dam stability, and service life.