Waste Substitution Extraction of Coal Strip Mining Pillars

In order to solve problems of environmental pollution caused by waste rock emission, low recovery rate of strip mining, a green mining approach for pillars extraction with waste backfill is presented. The physical composition, density, and the compaction deformation characteristics of the waste rock were evaluated by laboratory tests. The stress-strain curve and the stress-compaction degree curve were obtained and that the grain size of 0 similar to 50mm was elected to be the optimum gradation. Then, the strata movement and ground subsidence situation of different mining designs were predicted by a numerical study and a physical simulation, and then, the optimum design was obtained. Field test showed that the deformation of ground buildings could be controlled to meet the grade I standard; about 125000 tons of waste rock could be disposed and about 125000 tons of coal be recovered every year using this technology; the waste rock produced in the heading face could be disposed as backfill material without being transported to the ground, which can reduce environmental damage to a certain extent and achieve good economic benefits.