The release of what are called ‘fugitive’ methane emissions from ventilation air from underground coal mines is a significant source of greenhouse gas emissions. In fact, the impact of methane is 25 times greater than carbon emissions. Methane is also combustible in air making it a safety risk if concentrations get too high.
With the support of LETA, the mining industry is seeking ways to safely mitigate underground ventilation air methane (VAM) emissions.
The VAM Abatement Conceptual Design Project was jointly funded by the Federal Government as part of its ‘Coal Mining Abatement Support Package’ and LETA. It is exploring the science and engineering needed to provide the safe operation of mine ventilation connected to VAM abatement systems.
Existing research efforts explored systems that prevent methane igniting within a VAM reactor and stop ignition propagation back into the mine. No reliable system has yet been designed to meet Australian safety standards.
This body of research found Regenerative Thermal Oxidation (RTO) technology to be an effective and commercially viable way to mitigate low concentration methane emissions found in underground mine ventilation air.
However, current RTO technology sees methane containing air exhausted from the mine pass over the hot bed of the RTO reactor, which provided an ignition risk, suggesting a different approach is needed.
The VAM abatement project has found that the ignition risk could be managed by two independent systems that divert underground mine ventilation air containing elevated levels of methane from reaching the VAM abatement reactors, as well as isolating the reactors from the ventilation airstream.
For this split system to work, elevated levels of methane must be detected by sensors before the methane reaches the reactor with an appropriate margin of safety. The safety management system should also be able to divert ventilation air flows away from the abatement reactors.
The project aims to demonstrate VAM technology in Australian underground coal mines to manage and reduce fugitive emissions.
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