Study on Multi-field Evolution and Influencing Factors of Coal Spontaneous Combustion in Goaf

TLDR

The coupled disaster of coal spontaneous combustion and gas explosion in the goaf poses a serious threat to mine safety. The study aims to investigate the multi‑field evolutions and key influencing factors of coal spontaneous combustion under methane gas conditions in a coal mine goaf to provide a theoretical basis for disaster prevention and control. This investigation was conducted using a specially designed hot experimental platform and numerical simulations. Ventilation air leakages increase coal spontaneous combustion intensity but reduce methane accumulation ranges; at temperatures above 200 °C, distinct oxygen‑poor, methane‑rich, and high‑temperature zones appear, and rising combustion temperatures further alter gas density and accumulation beyond the effect of ventilation leakage.

Abstract

The coupled disaster of coal spontaneous combustion and gas explosion in the goaf threatens coal mine safety production. In order to further study the mechanism of coupled disasters and provide theoretical basis for disaster prevention and control, the multi-field evolutions and the key influencing factors of coal spontaneous combustion within methane gas condition of coal mine goaf had been investigated based on the special designed hot experimental platform and numerical simulations. Results show that the leakages of ventilation air into the goaf is positively related to the intensity of coal spontaneous combustion, but that is negatively related to the ranges of methane accumulations in the goaf. During the early stage of coal spontaneous combustion, the distributions of oxygen and methane in the goaf is less affected by the temperatures. When the temperature of coal spontaneous combustion exceeds 200°C, the oxygen-poor area, methane accumulation areas and a banded high-temperature distributions area in the non-spontaneous combustion areas would be clearly formed in the goaf. The changes of gas density in the goaf indicates that coal spontaneous combustion temperature in the goaf is another important factor influencing the change of gas density and gas accumulations, in addition to the ventilation air leakages.