To test the effectiveness of N_(2) and CO_(2) in preventing coal from spontaneously combusting,researchers used an adiabatic oxidation apparatus to conduct an experiment with different temperature starting points.Non-...To test the effectiveness of N_(2) and CO_(2) in preventing coal from spontaneously combusting,researchers used an adiabatic oxidation apparatus to conduct an experiment with different temperature starting points.Non-adsorbed helium(He)was used as a reference gas,and coal and oxygen concentration temperature variations were analyzed after inerting.The results showed that He had the best cooling effect,N_(2) was second,and CO_(2) was the worst.At 70℃and 110℃,the impact of different gases on reducing oxygen concentration and the cooling effect was the same.However,at the starting temperature of 150℃,CO_(2) was less effective in lowering oxygen concentration at the later stage than He and N_(2).N_(2) and CO_(2) can prolong the flame retardation time of inert gas and reduce oxygen displacement with an initial temperature increase.When the starting temperature is the same,N_(2) injection cools coal samples and replaces oxygen more effectively than CO_(2) injection.The flame retardancy of inert gas is the combined result of the cooling effect of inert gas and the replacement of oxygen.These findings are essential for using inert flame retardant technology in the goaf.展开更多
The goal of this study was to investigate coal quality features and their relationship to coal spontaneous combustion characteristics in multi-seam coal mines to better predict when coal spontaneous combustion is like...The goal of this study was to investigate coal quality features and their relationship to coal spontaneous combustion characteristics in multi-seam coal mines to better predict when coal spontaneous combustion is likely to occur.To that end,coal samples of various particle sizes were obtained from five coal seams(Nos.6,8,9,12 and 20)in the Shuangyashan City Xin’an Coal Mine.The samples were then respectively heated using a temperature programming system to observe and compare similarities and differences in the sponta-neous combustion process of different particle sizes in response to rising temperature.The experimental results show,that in all five coal seams,the concentration of CO,C_(2)H_(4),and C_(2)H_(6) increased with a certain degree of regularity as a function of rising temperature.However,of these three gasses,only CO and C_(2)H_(4) can be used as indicators to predict coal mine spontaneous combustion.The critical temperature for samples from all five coal seams ranged from 50–85℃,while the dry cracking temperature of coal seams 8 and 12(80–100℃)were lower than those of 6,9,and 20(100–120℃).Furthermore,the production rate of CO,C_(2)H_(4),and C_(2)H_(6) is related to both coal particle size and temperature.The smaller the particle size,the faster the production rate;and the higher the temperature,the more gas that gets produced.All five coal seems are mainly com-posed of long flame coal.However,they differ in that the No.12 coal seam contains weak cohesive coal;the No.8 coal seam contains lean and gas coal;and the Nos.6,9,and 20 coal seams contain a certain amount of anthracite.During the programmed coal heating,the CO,C_(2)H_(4),and C_(2)H_(6) release trend for the coal seams was No.12>No.8>Nos.6,9,and 20.These results demonstrate that the presence of weak cohesive coal and anthracite highly influence the concentration of CO,C_(2)H_(4),and C_(2)H_(6) released during coal spontaneous combustion.展开更多
The fully-mechanized caving coal technique (FMCCT) is a great technique progress of mining method in thick coal seams in China, and it has succeeded in some suitable condition mines. This paper introduces some technic...The fully-mechanized caving coal technique (FMCCT) is a great technique progress of mining method in thick coal seams in China, and it has succeeded in some suitable condition mines. This paper introduces some technical measures and achieved outcomes in gas and fire precaution and support selection for the use of the fully-mechanized caving coal technique in the complex-condition coal seams based on the practice of Weijiadi Coal Mine, in which the technique is used in the gently inclined extremelythick soft coal seam with the dangers of coal and gas outburst and spontaneous combustion.展开更多
基金support was received from the National Natural Science Foundation of China(52074156).
文摘To test the effectiveness of N_(2) and CO_(2) in preventing coal from spontaneously combusting,researchers used an adiabatic oxidation apparatus to conduct an experiment with different temperature starting points.Non-adsorbed helium(He)was used as a reference gas,and coal and oxygen concentration temperature variations were analyzed after inerting.The results showed that He had the best cooling effect,N_(2) was second,and CO_(2) was the worst.At 70℃and 110℃,the impact of different gases on reducing oxygen concentration and the cooling effect was the same.However,at the starting temperature of 150℃,CO_(2) was less effective in lowering oxygen concentration at the later stage than He and N_(2).N_(2) and CO_(2) can prolong the flame retardation time of inert gas and reduce oxygen displacement with an initial temperature increase.When the starting temperature is the same,N_(2) injection cools coal samples and replaces oxygen more effectively than CO_(2) injection.The flame retardancy of inert gas is the combined result of the cooling effect of inert gas and the replacement of oxygen.These findings are essential for using inert flame retardant technology in the goaf.
基金support from the Major Project of Engineering Science and Technology in Heilongjiang Province in 2020(Grant No.2020ZX04A01)support from the Scientific Research Projects of Undergraduate Universities in Heilongjiang Province(Grant No.2020-KYYWF-0534).
文摘The goal of this study was to investigate coal quality features and their relationship to coal spontaneous combustion characteristics in multi-seam coal mines to better predict when coal spontaneous combustion is likely to occur.To that end,coal samples of various particle sizes were obtained from five coal seams(Nos.6,8,9,12 and 20)in the Shuangyashan City Xin’an Coal Mine.The samples were then respectively heated using a temperature programming system to observe and compare similarities and differences in the sponta-neous combustion process of different particle sizes in response to rising temperature.The experimental results show,that in all five coal seams,the concentration of CO,C_(2)H_(4),and C_(2)H_(6) increased with a certain degree of regularity as a function of rising temperature.However,of these three gasses,only CO and C_(2)H_(4) can be used as indicators to predict coal mine spontaneous combustion.The critical temperature for samples from all five coal seams ranged from 50–85℃,while the dry cracking temperature of coal seams 8 and 12(80–100℃)were lower than those of 6,9,and 20(100–120℃).Furthermore,the production rate of CO,C_(2)H_(4),and C_(2)H_(6) is related to both coal particle size and temperature.The smaller the particle size,the faster the production rate;and the higher the temperature,the more gas that gets produced.All five coal seems are mainly com-posed of long flame coal.However,they differ in that the No.12 coal seam contains weak cohesive coal;the No.8 coal seam contains lean and gas coal;and the Nos.6,9,and 20 coal seams contain a certain amount of anthracite.During the programmed coal heating,the CO,C_(2)H_(4),and C_(2)H_(6) release trend for the coal seams was No.12>No.8>Nos.6,9,and 20.These results demonstrate that the presence of weak cohesive coal and anthracite highly influence the concentration of CO,C_(2)H_(4),and C_(2)H_(6) released during coal spontaneous combustion.
文摘The fully-mechanized caving coal technique (FMCCT) is a great technique progress of mining method in thick coal seams in China, and it has succeeded in some suitable condition mines. This paper introduces some technical measures and achieved outcomes in gas and fire precaution and support selection for the use of the fully-mechanized caving coal technique in the complex-condition coal seams based on the practice of Weijiadi Coal Mine, in which the technique is used in the gently inclined extremelythick soft coal seam with the dangers of coal and gas outburst and spontaneous combustion.
