A study of fire propagation in coal seam with numerical simulation of heat transfer and chemical reaction rate in mining field

Abstract

Spontaneous combustion of coal is a problem that affects the mining operation and generates environmental, economic, social and geotechnical impacts. This phenomenon has been divided into two processes: ignition and propagation. Fire propagation develops in coal seams because of a set of factors such as direction and wind speed, fracturing and temperature. In this work, heat transfer and chemical kinetics are studied from conservation equations of energy and species, respectively, using the software COMSOL Multiphysics to simulate the propagation of fires in coal seams. Two possible scenarios were analyzed that usually occur in the walls of the coal seams, such as fire focus and fire complete screens. It was found that the propagation kinetics of the fire changes depending on the temperature, the fracturing of rock mass and the area of fire influence. For temperature values lower than 300 °C, there is consumption around 250 cm3/h, values around 700 °C, the consumption is 1500 cm3/h, and for fires of 1200 °C have values of 3000 cm3/h. Depending on the speed of propagation can vary from 4 to 17 cm/day, considering on the level and fracturing of the final wall of the open pit. Keywords: Spontaneous combustion of coal, Open pit mines, Simulation, Heat transfer, Chemical reaction, COMSOL