Outburst Threshold Limits - Current Research Outcomes

Since outburst threshold limits were imposed on Bulli seam mines in 1994 the occurrence of coal and gas outburst incidents have virtually been eliminated from the Australian coal industry. With the reduction in incidents and therefore hazard to the industry there has been a corresponding drop in research effort in this area. Some mines have in recent years reviewed and raised threshold limit values and non-Bulli seam mines accept the method of threshold limit value determination introduced by GeoGAS, based upon the DRI900 concept. Detailed analysis of gas desorption data from a variety of Australian coal mines, representing different coal seams with variable gas content, gas composition, rank, type, structure, etc., has been undertaken and the results indicate significant relationships which impact the accepted method of outburst threshold determination. The relationships are discussed and a new method of determining outburst threshold limits, applicable to non-Bulli seam mines is presented.