Increasing reports of hydrogen emissions in underground coal mines with no apparent cause have created some confusion among mining professionals. The traditional view of hydrogen being an indicator of an advanced heating has come into question as a result, and some are advocating the hydrogen is present as seam gas.

Mining graduate Luke Hogarth was rewarded for his efforts on repeated tests of sub-bituminous coal by finding a significant hydrogen emission associated with the early stages of hot spot development. One of the tests created a sealed ‘coal stew’ effect, which resulted in hydrogen levels as high as 0.9% at temperatures less than 100°C. The coal has no seam gas present. Hence, the logical conclusion is that in areas of low airflow over/through bulk coal there is a predisposition to generate hydrogen at low temperatures. Israeli researchers have recorded this effect in stockpiles of bituminous coal and in laboratory experiments under static conditions.

"The reason why this low temperature evolution of hydrogen has been missed in the small-scale experiments of UK and Australian researchers is due to the fact that these tests on gas evolution have used high airflow rates with small coal masses. Hence, the ‘coal stew’ effect was eliminated," Basil Beamish who manages the UQ facility said.

This is unfortunate as there are possible incidences recorded in the past that may not have been advanced heatings at all, Beamish said. The new findings with bulk coal and low airflow rates have major implications for gas evolution interpretations leading to a heating.

“Our testing allows us to differentiate between coals from mines anywhere in Australia and provides a true gas evolution pattern resulting from hot spot development. Differences between gassy and gas-drained coal are also readily recognised. As such the most appropriate gas indicators can be determined for any area of a mine,” he said.

Hogarth was awarded the “Simtars - Dr Peter Golledge Thesis Prize for Mine Safety Research Excellence” for his work. Anyone interested in the bulk coal self-heating testwork being conducted at UQ should contact Dr Basil Beamish, b.beamish@minmet.uq.edu.au.