When coal is exposed to air it begins to react with the oxygen present. The predominant gas evolved from the oxidation process is carbon monoxide. If the heat from the oxidation process is not dissipated to the surroundings the coal temperature increases to create a self-heating incubation process. As the coal temperature increases the amount of carbon monoxide produced from the oxidation process increases. Consequently, monitoring carbon monoxide in an underground coal mine atmosphere is a good indicator of the development of a heating. Due to the nature of the underground mine ventilation, consideration needs to be given to how best to use the carbon monoxide data obtained from gas monitoring results when setting spontaneous combustion Trigger Action Response Plan (TARP) triggers. This paper will demonstrate the application of three carbon monoxide gas indicator measures, namely raw CO, CO Make and Graham’s Ratio with respect to the atmosphere being sampled in the mine. The sensitivity of the raw CO and CO Make indicators can be reviewed in a practical manner for TARP trigger level setting to ensure valid separation of background mine conditions from heating development at various temperature stages. The Graham’s Ratio has been used as an absolute indicator of coal temperature. However, recent detailed gas monitoring has shown that a more effective application of this gas ratio indicator is obtained by plotting the Graham’s Ratio value against the Oxygen deficiency of the mine atmosphere being sampled. A practical example of this approach will be presented.

In the last five and a half years, the coal industry has recorded 12 fatalities and, at Grosvenor mine alone, five very seriously injured miners. Six of these fatalities were recorded between December 2018 and January 2020 the highest number of fatalities recorded in just over a 12-month period since the Moura #2 disaster 30 years ago, where 11 men lost their lives.
Since 2018, 17 miners have suffered fatal injuries: 12 in the coal mining industry and five in the metalliferous industry. These fatalities are preventable and therefore unacceptable. Human error plays a significant role in practically all incidents and fatalities. If these are to be reduced, the industry must adopt a mature no blame safety culture which requires legislative reform. Enhanced security of employment in the industry would also enhance a positive safety culture.
The author has been advocating for reform of accident investigation to the relevant authorities for some time now; it was the main reason that he completed his PhD into mine safety in 2016.
A successful inquiry relies on the objective collection of evidence, free from the complexity of criminal investigation and separate from the conflicting interests of involved parties.
All parties in the industry need to work together in support of a safety culture, based on trust and openness, and not an adversarial legal approach based on a blame culture bound by the complexities of legal privilege.
The industry needs to implement programmes that achieve the objectives of changing attitudes and behaviour on mine sites with greater transparency regarding accident and near miss information.
The mining industry has been unable to share safety information due to legal privilege following the outcome of the Gretley Inquiry in 1998, over 20 years ago. The subsequent legislation continues to stifle transparency, meaning businesses are not willing to share their learnings from incidents, be it from the regulator or their own organisations.
The lessons and strategies indicated in this paper would benefit all participants in the QMI Health and Safety Conference regarding accident investigation and safety.