Study On Relationship Between Depositing Characteristic Of Falling Waste And Top Coal Recovery In Full-mechanized Caving

By using the synthetic study method of theoretical analysis, similar material simulation and numerical simulation with PFC, the paper further researches the quantitative relationship between the top-coal recovery and the depositing characteristics of direct roof on the floor in full-mechanized caving. This paper analyzed the losses in caving process; the main influence factors are as follow: seam thickness, thickness of direct roof, repose angle of gangue, the gap between the gangue and outer edge of rear conveyer and the depositing characteristics of direct roof on the floor. It's emphasis on the quantitative relationship between the top-coal recovery and former five factors. The results show general trend that the decrease of top-coal loss follows the increase of its thickness but the loss increase when its thickness is over 9m and that it first decrease then increase when the top-coal loss associated with the increased thickness of direct roof. The recovery is the maximum when the thickness of direct roof is about 1/2 of top-coal's thickness. The top-coal loss is influenced by the real depositing angle of gangue and the loss reduces when the depositing angle of gangue rise. The general trend of the gap to the loss is gradually increases. when the ratio of thickness of immediate roof and top-coal thickness greater than or equal to 1.6 , the top-coal after falling show triangle depositing state ,conversely, show quadrilateral depositing state .Also, the paper analyzed the quantitative relationship between the loss rate and depositing angle of gangue by the simulation test. These research results provide theoretical basis to illustrate the largest recovery of top-coal under specific seam condition and technical way to enhance the top-coal recovery.