Water-preserved Mining Technology for Shallow Buried Coal Seam in Ecologically-vulnerable Coal field: A case study in the Shendong Coal field of China

In order to solve the contradiction between large scale mining of coal resources in shallow buried coal seam with thin overlying strata in the ecologically-vulnerable coal fields and ecological protection in Western China, the height of water-preserved pillar is determined and the Classification of Water-preserved Mining for shallow buried coal seams with different thickness of overlying strata is established. A series of water-preserved mining supporting technologies on longwall mining working face is proposed, namely (1) advancing at uniform velocity on large size longwall mining working face; (2) calculation and determination for reasonable supporting resistance of supports; and (3) reducing the mining height or filling regionally. The mining practice of Bulianta coal mine 32202 working face in Shendong Coal field shows that the water flowing fracture in the overlying strata under mining of longwall working face can close gradually after mining, and the structure of unconsolidated water-bearing strata is not damaged and the ecological environment in the coal field will not be deteriorated. The research results can realize water-preserved mining while improving the recovery of coal resources to the most extent and are applicable to the current status that large scale mechanical mining on longwall working face are generally used for shallow buried coal seams in Western China.