Research On Parameter Optimization In Fully Mechanized Top-coal Caving Face Of LongQuan NO.4Coal Mine

The coal resources are non-renewable resources、 in the coal mining process, we should be possible to improve the rate of coal mining.In the process of caving mining process reasonable parameters can greatly increase the coal recovery rate. In recent years, the cutting hight of fully mechanized caving face a increase gradually,it can enhance top coal caving and improve the recovery rate of coal to a certain extent,but it can also increase the probability of coal wall spalling,too much high cutting hight lead roof accident occur frequently.Therefore, it requires that we must choose a reasonable cutting hight to achieve the safe and efficient high degree of uniformity to the high recovery.At the same time,Choose the most reasonable caving process parameters in the case of coal cutting height have been determined.lt can improve the top coal recovery rate,thereby the recovery rate of fully mechanized caving face coal have been improved.on the basis of the Longquan coal seam occurrence and results of detailed analysis of previous studies.First, we simulate and analyze the destruction yield law of fully mechanized top-coal caving face end and central surrounding rock and the law of preceding abutment pressures distribution on working face and the law of coal wall movement with different supporting strength, different mining hight by using the FLAC3D numerical simulation software in4th of Longquan coal seam. Second,using similar simulation, simulate and analyze the movement law of top-coal and gangue and the top coal recovery rate at different Coal drawing on Cutting Height of3.5Meters. Third,using PFC2D numerical simulation software, simulate and analyze the top coal recovery rate at different Caving way.of Longquan coal mine fully mechanized caving face.Finally, we analyze the composition the loss of top coal of fully mechanized top-coal caving face and Proposed measures to improve the top coal recovery rate about Longquan coal.By analyzing the following main conclusions are given:1、Appropriate increase the mining height, the peak point of preceding abutment pressures will forward and increase and top coal plastic failure region also will be widened.2、At the mining hight2.5m,although the seam strength is low, working face ends due to factors of Pillar, the working face advancing mining effect smaller than the face in the middle,top coal above the bracket not fully plastic failure. With the increasing of the mining hight, top-coal of working face upper are completely failure,at the same time, the ends of the working face obeserve the lay,From the numerical simulation to determine the feasibility of Longquan mine ends caving. 3、 Comprehensive consideration of the top coal caving, the stability of the coal wall, improving resource recovery rates and the ventilation and safety of the working face, the Longquan coal seam reasonable apheresis height is3.5m, caving thanis1:0.85.4、 determine the Longquan Coal Mine caving Working Face of Cutting Height is3.5m,"mining once and caving once" and "single round of interval" caving parameters,the reasonable support strength of the Longquan coal seam of fully mechanized caving face0.85MPa-0.95MPa.5、 determine Longquan coal specific measures to improve the recovery rate of top coal.