Suitable retention and recovery technology of floor coal at ends of fully mechanized face with great mining heights

Gateways at faces of great mining heights are mostly driven along the roof of coal seams. For gateway height restrictions, a 1–3 m floor coal is retained, leaving a triangular floor coal at the face ends, causing a loss of coal. In order to improve coal recovery rates and to ensure efficiency of equipment at coal mining faces, we investigated suitable retention methods and recovery technology of floor coal at face ends. The upper floor coal can directly be recovered by a shearer with floor dinting. The lower floor coal is recovered by shearer with floor dinting after advanced floor dinting and retaining a step for protecting coal sides in a haulage gateway. Field practice shows that this method can improve the coal recovery rates at fully mechanized working faces with great mining heights.