Interpreting the Status of an Underground Coal Mine Heating for Valid Risk Management and Control

The status of an underground coal mine heating event is predominantly assessed based on gas sampling results from the affected area. The gas samples can be obtained in a number of different ways, but for accurate determination of the gases present analysis is normally performed using gas chromatography. Several gas indicators have been identified from past experiences that are used in combination to determine a Trigger Action Response Plan for individual mines. The upper levels of the Trigger Action Response Plan contain more urgent actions in response to the assessed level of advanced heating, with the ultimate level being withdrawal from the mine. Once this point is reached the only action that can be taken to control the event has to be done remotely and also, once activated it is difficult to re-enter the mine. Recent experience of a heating event provides new data that demonstrates the importance of understanding and interpreting the status of hot spot development to risk management and control applied by an Incident Management Team. This paper discusses the use of gas trending, including the development of: a new gas indicator ratio that is very sensitive to the heating status and control measures applied; and a hot spot tracking diagram that provides a good visual representation of the heating status and the response to actions taken.