Fractal oxidation kinetics and risk evaluation of spontaneous combustion in coal mines.

摘要

The spontaneous combustion of coal occurs when air supply is sufficient for the oxidation of coal and air velocity is insufficient for the dissipation of generated heat. Spontaneous combustion, if not eradicated immediately, may lead to coal ignition and even a full-blown fire. The fire may engulf a large area and spread further if they are not immediately attended to. This will not only endanger miners and mining operations, but also result in possible mine closures and even fatalities.;Porous structure has a significant effect on coal adsorption and spontaneous combustion. In this research, fractal theory was utilized to quantitatively describe the porous structure and predict the porosity and permeability. Fractal oxidation kinetics was proposed to study the oxygen absorption of coal, with results properly validated. This research also studied the relationship among coal oxidation products, the temperature, and coal properties to help mining engineers estimate the status and severity of spontaneous combustion. Additionally, catastrophe theory was utilized to evaluate the propensity of coal towards spontaneous combustion.;The Analytic Hierarchy Process was used to sequence the factors impacting spontaneous combustion. A comprehensive risk evaluation system of spontaneous combustion was then built. Field studies indicate that the evaluation system works well.;This study furthers fundamental research for the spontaneous combustion of coal. The basis for developing potential technologies to improve workplace safety in underground coal mines can now be established. The description of the spontaneous combustion process and the risk evaluation system can provide guidelines for preventing and controlling the spontaneous combustion of coal.