In order to study the coupling problem between methane drainage and spontaneous combustion of residual coal in the collapsed zone after mining ignitable coal seams with high methane,we have analyzed the effects of dif...In order to study the coupling problem between methane drainage and spontaneous combustion of residual coal in the collapsed zone after mining ignitable coal seams with high methane,we have analyzed the effects of differ-ent methane drainage modes on spontaneous combustion of residual coal through numerical simulation. The results show that deep and large flux methane drainage modes increases the air leakage from work faces to the goaf and formed new spontaneous combustion zones induced by drainage near vents,which increases the risk of self-ignition of coal—reducing the self-ignition period and enlarging the scale of self-ignition. The spontaneous upstream combustion oxidation of the main fire zone can be suppressed when both drainage and nitrogen injection were adopted. Our research results provide an effective technical measure and theoretical basis to determine the best methane drainage scheme and drainage parameters.展开更多
Abstract Pyrite has a significant effect on the spontaneous combustion of coal. The presence of pyrite can change the propensity of coal towards spontaneous combustion. The influences of various pyrite contents on the...Abstract Pyrite has a significant effect on the spontaneous combustion of coal. The presence of pyrite can change the propensity of coal towards spontaneous combustion. The influences of various pyrite contents on the parameters of spontaneous combustion, such as index gases, temperature and released heat etc., were investigated in this study, Coal samples with different pyrite contents （0 %, 3 %, 5 %, 7 % and 9 %） were made by mixing coal and pyrite. The oxidation experiments under temperature-programmed condition were carried out to test the release rate of gaseous oxidation products at different temperatures. Differential scanning calorimeter （DSC） was employed to measure the intensity of heat release during coal oxidation for various pyrite contents. The results indicate that pyrite can nonlinearly accelerate the process of spontaneous combustion. The coal sample with a pyrite content of 5 % has the largest CO release rate and oxygen adsorption as well. However, the coal sample with a pyrite content of ？ % has the largest rate of heat flow according to the results from the DSC tests. Pyrite contents of 5 %-7 % in coal has the most significant effects on spontaneous combustion within the range of this study. The conclusions are conducive to the evaluation and control for the spontaneous combustion of coal.展开更多
Bio-leaching of pyrite by native strains of acidophilic bacteria was examined by laboratory scale tests. Three groups of batch trials in agitated flasks and three continuous column leaching tests were performed. The l...Bio-leaching of pyrite by native strains of acidophilic bacteria was examined by laboratory scale tests. Three groups of batch trials in agitated flasks and three continuous column leaching tests were performed. The leaching ability and efficiency of native bacteria was greatly improved by adaptation of the bacteria to the test conditions. These cultivated bacteria were then used for the leaching process. The changes in solution pH, Eh, Fe2~ concentration, and sulfate ion concentration were monitored throughout the tests. A portion of the pyritic sulfur is transformed into soluble sulfate ion. The desulfur- ization ratio of＇42.6g was obtained in a flask shaking test and a ratio of 39.4g was obtained during column leaching. A weight gain test was performed on leached and unleached samples by exposing the samples to humid air for several days. A smaller weight gain of the bio-leached samples indicates that removing sulfur from the sulphide ore helps reduce its oxidation rate and the potential for spontaneous combustion.展开更多
基金Project 50574038 supported by the National Natural Science Foundation of China
文摘In order to study the coupling problem between methane drainage and spontaneous combustion of residual coal in the collapsed zone after mining ignitable coal seams with high methane,we have analyzed the effects of differ-ent methane drainage modes on spontaneous combustion of residual coal through numerical simulation. The results show that deep and large flux methane drainage modes increases the air leakage from work faces to the goaf and formed new spontaneous combustion zones induced by drainage near vents,which increases the risk of self-ignition of coal—reducing the self-ignition period and enlarging the scale of self-ignition. The spontaneous upstream combustion oxidation of the main fire zone can be suppressed when both drainage and nitrogen injection were adopted. Our research results provide an effective technical measure and theoretical basis to determine the best methane drainage scheme and drainage parameters.
文摘Abstract Pyrite has a significant effect on the spontaneous combustion of coal. The presence of pyrite can change the propensity of coal towards spontaneous combustion. The influences of various pyrite contents on the parameters of spontaneous combustion, such as index gases, temperature and released heat etc., were investigated in this study, Coal samples with different pyrite contents （0 %, 3 %, 5 %, 7 % and 9 %） were made by mixing coal and pyrite. The oxidation experiments under temperature-programmed condition were carried out to test the release rate of gaseous oxidation products at different temperatures. Differential scanning calorimeter （DSC） was employed to measure the intensity of heat release during coal oxidation for various pyrite contents. The results indicate that pyrite can nonlinearly accelerate the process of spontaneous combustion. The coal sample with a pyrite content of 5 % has the largest CO release rate and oxygen adsorption as well. However, the coal sample with a pyrite content of ？ % has the largest rate of heat flow according to the results from the DSC tests. Pyrite contents of 5 %-7 % in coal has the most significant effects on spontaneous combustion within the range of this study. The conclusions are conducive to the evaluation and control for the spontaneous combustion of coal.
基金provided by the National Natural Science Foundation of China (Nos. 50934002 and 51074103)the Program for Changjiang Scholars and Innovative Research Team in University (No.IRT0950)
文摘Bio-leaching of pyrite by native strains of acidophilic bacteria was examined by laboratory scale tests. Three groups of batch trials in agitated flasks and three continuous column leaching tests were performed. The leaching ability and efficiency of native bacteria was greatly improved by adaptation of the bacteria to the test conditions. These cultivated bacteria were then used for the leaching process. The changes in solution pH, Eh, Fe2~ concentration, and sulfate ion concentration were monitored throughout the tests. A portion of the pyritic sulfur is transformed into soluble sulfate ion. The desulfur- ization ratio of＇42.6g was obtained in a flask shaking test and a ratio of 39.4g was obtained during column leaching. A weight gain test was performed on leached and unleached samples by exposing the samples to humid air for several days. A smaller weight gain of the bio-leached samples indicates that removing sulfur from the sulphide ore helps reduce its oxidation rate and the potential for spontaneous combustion.
