Abstract
The issues under consideration are spontaneous combustion of coal and the danger of endogenous fires for mining enterprises. The ways of detecting the hotbeds of spontaneous combustion which allow to increase the safety of mining works and to reduce economic damage from endogenous fires are analyzed. The temperature control is demonstrated to be ineffective due to thermal insulation properties of coal, and the gas analysis method - insufficient for detecting the initial stages of coal self-heating. It is proposed to detect the self-heating of coal by the condensation aerosol content formed at the cooling of the air heated in the source. The calculations of the condensation aerosol content in the air depending on the temperature of the coal self-heating spot are given. Dependences determining the temperature of coal self-heating spot, depending on the condensation aerosol content in the air passing through the coal have been obtained. Various sorbents for measuring condensation aerosol content in the air have been studied. The most effective sorbent of water vapor and condensation aerosol is macro-porous silica gel. A device detecting coal self-heating in mines, mine dumps, and coal storages has been developed. Tests in mine conditions proved the effectiveness of the method for detecting coal self-heating.
Highlights
Coal refers to substances capable of oxidizing by air oxygen at natural ambient temperatures
The amount of heat released exceeds the loss of heat to the environment, which can lead to an increase of the coal temperature and to spontaneous combustion
The pressure of saturated water vapor in the air depends on the temperature and can be defined by the formula
Summary
Coal refers to substances capable of oxidizing by air oxygen at natural ambient temperatures. The process of oxygen sorption and the chemical reactions of coal combustible components oxidation are accompanied by the release of heat. The amount of heat released exceeds the loss of heat to the environment, which can lead to an increase of the coal temperature and to spontaneous combustion. The increase of coal crushing leads to the increase of active centers in the mine mass, which speeds up the sorption of oxygen resulting in the higher probability of spontaneous combustion. Endogenous fires resulting from the development of spontaneous combustion cause enormous damages to coal enterprises. Endogenous fires are dangerous for coal mines. The toxic gases releasing from the oxidizing coal are able to spread over long distances of mine openings, creating danger for people's health and life. The situation can get even worse due to methane emissions in mines since the hotbeds of spontaneous combustion may result in explosions of combustible gases and coal dust
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