|
| Methane ignition in the laboratory |
Background
The mining industry’s use of advanced mining technologies has resulted in an increase in methane emissions and the associated risk of explosions or fire. The inability to forecast the potential for hazardous emissions and accumulations of methane or frictional ignitions has led to injuries and deaths among coal miners in underground coal mine explosions. Recent major explosions have occurred in Utah (2 fatalities) in 2000, in Alabama (13 fatalities) in 2001, and in West Virginia (3 fatalities) in 2003.
Rates of methane emission are unpredictable as a result of changing geologic conditions, in situ gas content, and constantly evolving mining practices, methods, and equipment. In addition, the interaction among these variables is not well known. Methane reservoir simulation software will be used to design and evaluate methane control technologies and strategies for longwall gobs. This software will be combined with commercially available mine ventilation modeling software to help predict methane emissions.
Frictional ignitions of methane and other gases are still relatively common in U.S. coal mines. Numbers have averaged about 60 per year from 1995 to 2004. Coal-measure rocks from both ignition-prone and non-ignition-prone basins will be used to create an index of incendivity that will be forwarded to industry.
Potential Outcome
In 2007, a systematic set of best practices for methane control, as well as premining and active mining evaluation techniques, will be made available to mine operators. Mine engineers will be able to use these techniques in combination with the methane reservoir model to optimize mine design and methane control technology. This will enable a mine operator to better predict methane emissions throughout a mine and design appropriate methane control measures to reduce the risk of methane explosions.
By 2007, the NIOSH-developed modified direct-method apparatus will become commercially available, which will allow mine operators to obtain reliable data on gas content. This will improve the accuracy of the methane reservoir model and further reduce the potential for methane gas explosions.
A qualitative index of incendivity will also become available in 2007. It will provide the industry and regulatory personnel with guidance on the character and likelihood of frictional ignition events and is expected to reduce the number of events leading to mine fires and explosions.