PURPOSE:  To investigate existing and evolving methane control issues in coal mines and develop control strategies to reduce the risk of explosions in the underground workplace.

RESEARCH SUMMARY:  The inability to quantitatively forecast and control methane accumulations and emissions represents a significant risk for explosions in the underground workplace, and may have contributed to 106 U.S. coal miner deaths in 17 explosions since 1980. Recent explosions have occurred at mines in West Virginia (3 fatalities and 3 injuries, 2003), Alabama (13 fatalities, 3 injuries, 2001), and Utah (2 fatalities and 8 injuries, 2000). The inability to control methane emissions can be the product of: (1) inadequacies in the ventilation and/or methane control system configurations; (2) the inability to forecast the methane emission consequences of changes in mine design, or geologic conditions; or (3) uncertainty as to how to remediate methane emission problems. Frictional ignitions are an additional, poorly understood explosion hazard, and may be the source of a 1998 mine fire in Utah which eventually resulted in the abandonment of the mine.

This research effort is designed to investigate and quantify the geotechnical factors and mine design practices influencing methane emissions and the occurrence of frictional ignitions. It is expected that the primary initial outcome will be a set of methane control best practices. A comprehensive research methane emission and gas flow predictive model is also being developed. A version of the research model will be integrated with ventilation models commonly used in the mining industry so that methane control strategies can be evaluated and included in the ventilation planning process. Rock samples are being collected from historically friction ignition prone mines for geotechnical characterization to develop a qualitative incendivity index and will be used as input to ignition control technology techniques.

The adaptation of commercially available reservoir modeling software has successfully simulated gas flows in a longwall mining scenario. The simulations have shown that for the Pittsburgh Coalbed, the industry trend towards wider panels will probably result in increased methane emissions. Various gob gas venthole configurations have also been simulated to evaluate potential optimized methane drainage strategies for longwall panels of increased panel widths. Two unique empirical methods for predicting longwall face emissions for increased longwall face lengths have been presented to industry. An analysis of historical frictional ignition data has shown that the majority of these events occurred in the Mary Lee/Blue Creek and the Pocahontas No. 3 coalbeds. Most frictional events occurred on continuous miner sections associated with operating longwalls.