Research Of Desorption Dynamic Characteristic And Outburst Predictors Index In Middle Coalseam Of The Renlou Coalmine

In this paper the7、8coal seam of Renlou middle coal seam was taken as objectof research, the coalseams construction environment and gas occurrence regularitywas illustrated. The physical parameters of coal samples were studied in the labthrough field sampling and laboratory measurement. Coal gas desorption kinetics wasstudied through conventional desorption experiments and adsorption experimentsunder conditions of moisture; At last prominent predictors was determined withindicators cuttings desorption experiments and index correction under naturalmoisture conditions. The main conclusions can be listed as follows:1）Combined mine geological data collection and analysis of experimental datagains the gas occurrence regularity of Renlou middle coal seam high gas pressure,low gas contention.The regional predictor index of7coal seam was determined to begas content and critical gas content was6m3/t, the gas pressure as auxiliary indicatorsand critical value was1MPa. The regional predictor index of8coal seam wasdetermined to be gas content and critical gas content was6m3/t, the gas pressure asauxiliary indicators and critical value was1.35MPa.2) Multiple physical parameters analysis was carried out on the experimentalcoal sample, the results showed that the vitrinite reflectance of Renlou coalmine is0.9247~1.01%, volatile content is35.91%~37.61%, the coal was moderate degree ofmetamorphism. The pore structure found that total surface area of Renlou middlecoalseam was mainly contributed by micropore and small pore and the proportionaccounted for was above99%, and the micropore proportion was about50%, andprovide space for gas adsorption.3）Experimental results of desorption show that the coal sample gas desorption isin relation to balance pressure, and is characterized by great desorption quantity anddesorption rate attenuation fast at initial time.The logarithm formula Qt Aln (t B)can reflects gas desorption characteristics of middle coal seam very well. The gasdiffusion coefficient has a linear correlation with the equilibrium pressure.Researchon gas diffusion coefficient of coal samples show that the gas diffusion properties of8#coal seam is stronger than the7#coal seam, This phenomenon shows that diffusioncoefficient increases with the pore diameter increasing, the better the small poredevelop the more conducive to the spread of methane in coalseam.4) Injected waters have impact on methane desorption quantity, gas desorptionindex of drill cuttings after the pressure relief, and the methane desorption quantity, gas desorption index of drill cuttings, are gradually decreased with the increase ofinjected water. The methane diffusion coefficient follow the same trend,but whenmoisture content was similar, methane diffusion coefficient grow bigger along withpressure.5) The fact that sensitive of drilling cuttings adsorption index h2is higherthanK1was proved through desorption cuttings indicators experiments.To thecharacteristic of natural moisture content features in the Renlou middle coal seam, thecuttings indicators h2was corrected. The corrected local sensitivity index criticalvalue of7,8coal seam was130Pa. The accurateness of cuttings indicators wasimproved.