Outburst of coal and gas represents a significant risk to the health and safety of mine personnel working in development and longwall production face areas.There have been over 878 outburst events recorded in twenty-t...Outburst of coal and gas represents a significant risk to the health and safety of mine personnel working in development and longwall production face areas.There have been over 878 outburst events recorded in twenty-two Australian underground coal mines.Most outburst incidents have been associated with abnormal geological conditions.Details of Australian outburst incidents and mining experience in conditions where gas content was above current threshold levels are presented and discussed.Mining experience suggests that for gas con-tent below 9.0 m^3/t,mining in carbon dioxide(CO2)rich seam gas conditions does not pose a greater risk of outburst than mining in CH4 rich seam gas conditions.Mining experience also suggests that where no abnormal geological structures are present that mining in areas with gas content greater than the current accepted threshold levels can be undertaken with no discernible increase in outburst risk.The current approach to determining gas content threshold limits in Australian mines has been effective in prevent-ing injury from outburst,however operational experience suggests the current method is overly conser-vative and in some cases the threshold limits are low to the point that they provide no significant reduction in outburst risk.Other factors that affect outburst risk,such as gas pressure,coal toughness and stress and geological structures are presently not incorporated into outburst threshold limits adopted in Australian mines.These factors and the development of an outburst risk index applicable to Australian underground coal mining conditions are the subject of ongoing research.展开更多
Desorption rate index(DRI)was presented to the Australian underground coal industry in 1995 as a means for determining outburst threshold limits for Australian coal seams.DRI is a measure of the gas volume released fr...Desorption rate index(DRI)was presented to the Australian underground coal industry in 1995 as a means for determining outburst threshold limits for Australian coal seams.DRI is a measure of the gas volume released from a coal sample in the first 30 s of crushing during the Q3 stage of gas content testing,multiplied by the ratio between measured Q3 and QM.Relationships were identified between QM and DRI for both CO2 and CH4 rich coal samples collected from the Bulli Seam at West Cliff Colliery and that identified relationship was referred to as the Bulli Seam Benchmark.The outburst mining gas content threshold limit values specified for the Bulli Seam at that time,when applied to the QM-DRI Bulli Seam benchmark,was shown to closely align with a DRI value of 900(DRI900),for both CO2 and CH4 rich seam gas conditions.The Australian coal industry adopted the DRI900 as the basis for determining outburst gas content TLV for Australian coal seams.Outburst mining experience in Australia has shown that gas content is not the only significant factor that impacts outburst risk,as all significant outburst events have been associated with abnormal geological conditions,such as faults and dykes.Therefore,assessing the potential application of additional outburst risk factors,to accurately define outburst risk zones,set safe mining threshold levels,and determine appropriate mining controls,warrants further investigation.Several Australian coal mines have implemented mining procedures enabling mining to continue in areas with gas content greater than the TLV determined using the DRI900 approach,without inducing an outburst.There is a broad lack of understanding among Australian coal mine operators as to the procedure and calculations used to determine DRI.Also,there has been growing concern regarding the accuracy and validity of the DRI900 method for determining outburst TLV.A comprehensive set of gas data has been collected from Australian coal seams,including the Bulli Seam,and this data has been used to investigate the DRI,Bulli Seam Benchmark,and the applicability of using DRI900 as the basis for assessing outburst risk and determining gas content TLV.The results are presented and discussed.展开更多
基金ACARP for financial support of project C26055the Australian underground coal mine operators that have supported this research project
文摘Outburst of coal and gas represents a significant risk to the health and safety of mine personnel working in development and longwall production face areas.There have been over 878 outburst events recorded in twenty-two Australian underground coal mines.Most outburst incidents have been associated with abnormal geological conditions.Details of Australian outburst incidents and mining experience in conditions where gas content was above current threshold levels are presented and discussed.Mining experience suggests that for gas con-tent below 9.0 m^3/t,mining in carbon dioxide(CO2)rich seam gas conditions does not pose a greater risk of outburst than mining in CH4 rich seam gas conditions.Mining experience also suggests that where no abnormal geological structures are present that mining in areas with gas content greater than the current accepted threshold levels can be undertaken with no discernible increase in outburst risk.The current approach to determining gas content threshold limits in Australian mines has been effective in prevent-ing injury from outburst,however operational experience suggests the current method is overly conser-vative and in some cases the threshold limits are low to the point that they provide no significant reduction in outburst risk.Other factors that affect outburst risk,such as gas pressure,coal toughness and stress and geological structures are presently not incorporated into outburst threshold limits adopted in Australian mines.These factors and the development of an outburst risk index applicable to Australian underground coal mining conditions are the subject of ongoing research.
基金ACARPthe Australian underground coal mine operators who have supported this research project
文摘Desorption rate index(DRI)was presented to the Australian underground coal industry in 1995 as a means for determining outburst threshold limits for Australian coal seams.DRI is a measure of the gas volume released from a coal sample in the first 30 s of crushing during the Q3 stage of gas content testing,multiplied by the ratio between measured Q3 and QM.Relationships were identified between QM and DRI for both CO2 and CH4 rich coal samples collected from the Bulli Seam at West Cliff Colliery and that identified relationship was referred to as the Bulli Seam Benchmark.The outburst mining gas content threshold limit values specified for the Bulli Seam at that time,when applied to the QM-DRI Bulli Seam benchmark,was shown to closely align with a DRI value of 900(DRI900),for both CO2 and CH4 rich seam gas conditions.The Australian coal industry adopted the DRI900 as the basis for determining outburst gas content TLV for Australian coal seams.Outburst mining experience in Australia has shown that gas content is not the only significant factor that impacts outburst risk,as all significant outburst events have been associated with abnormal geological conditions,such as faults and dykes.Therefore,assessing the potential application of additional outburst risk factors,to accurately define outburst risk zones,set safe mining threshold levels,and determine appropriate mining controls,warrants further investigation.Several Australian coal mines have implemented mining procedures enabling mining to continue in areas with gas content greater than the TLV determined using the DRI900 approach,without inducing an outburst.There is a broad lack of understanding among Australian coal mine operators as to the procedure and calculations used to determine DRI.Also,there has been growing concern regarding the accuracy and validity of the DRI900 method for determining outburst TLV.A comprehensive set of gas data has been collected from Australian coal seams,including the Bulli Seam,and this data has been used to investigate the DRI,Bulli Seam Benchmark,and the applicability of using DRI900 as the basis for assessing outburst risk and determining gas content TLV.The results are presented and discussed.
