Review of applicability of using indicator gas coefficients for determining the temperature of the place of spontaneous combustion of coal

Spontaneous combustion of coal beds is considered to be one of the most hazardous effects of coal mining. The most dangerous factor of this process is its abruptness due to several types of coal possible emergence of reaction at low-temperature conditions and subtle reaction behavior at initial stage of the process, which may turn into environmental disaster. Therefore, on many mines and strip mines, in terms of occupation health and safety program and fire- preventing measures realization, fire monitoring system are introduced, as well as spontaneous combustion source monitoring system to apply fire-preventing measures. The most effective type of monitoring systems is gas monitoring, at which cause in many countries, including Russia, spontaneous combustion source indication methods based on fire gases concentration measurement are developed. Those methods are based on sharp increase of some specific gases, such as carbon monoxide and methane, at some point of spontaneous combustion source temperature, which differs depending on coal type and coal deposit. However, the application of those methods does not always allow the advance detection of coal spontaneous combustion areas, due to its low accuracy and dependence of fire-indication gases from external exposure. For that reason, many authors are advising ratios of fire gases or indicator gases ratios as a means of higher-precise spontaneous combustion sources indication method. In this paper, the analysis of those ratios applicability is conducted as well as existing underground fires indication methods.