The serious environmental pollution caused by the spontaneous combustion of coal gangue has become a problem which cannot be ignored in the world mining industry. It is urgently necessary to clarify the law of the temperature distribution of spontaneous combustion in gangue dumps and to grasp its future dynamic evolution of spontaneous combustion. In this study, the internal temperature of the second platform of the Yinying coal mine gangue dump was monitored on the basis of the self-developed wireless temperature monitoring system. Its temperature distribution was analysed, and areas of low (280 °C) were delimited. The finite element method was also used to simulate its internal temperature development of 1–5 years. The results show that: (1) The high temperature area is mainly distributed on the side close to the slope. In the area 3 m deep, the high temperature started to propagate quickly. At a depth of 4 m, medium and high temperature represented 90% of the platform’s total surface area. At 6 m deep, temperature peaked at 667 °C. (2) The conduction of the internal temperature of the spontaneous combustion of gangue discharge is a non-linear conduction, and the conduction of heat in the horizontal direction is lower than the vertical direction. (3) During the spontaneous combustion of gangue discharge over the next five years, the overall temperature increase is faster at first, then it decreases and eventually stabilises. The high-temperature zones extend 10 m from the slope to the interior in five years, and the high-temperature zones are oval-shaped. This study provides a theoretical reference for the prevention and control of spontaneous combustion of coal gangue dumps.
Coal gangue spontaneous combustion is a serious catastrophe associated with mining activities. Generally, the areas of coal gangue spontaneous combustion are regions of tremendous heat accumulation. Mastering the regularity of deep temperature distribution and eliminating internal heat is an effective method to control spontaneous combustion. In this study, using self-developed heat pipe (HP) and intelligent cloud monitoring software, three sets of single pipe experiments were conducted in different temperature areas of the coal gangue dump in Yinying Coal Mine. A fitted model between shallow and deep temperatures was established using the least squares method to perform goodness-of-fit tests and significance analysis, and to analyze the internal temperature variation under the action of an HP. The results show that the quadratic model fits better and the regression is significant, and can be used as an empirical regression formula for the shallow temperature estimation of the deep temperature. The temperature was clearly suppressed by the HP, and the average cooling range reaches 21.44% within 700 h. However, the temperature of the control group without an HP continued to rise by 8%. In the three experimental groups, the effective control radius of the single HP was 3 m. The best cooling was achieved when the gangue depth was 1 to 4 m and the temperature was between 90 °C and 450 °C. The study shows that the HP has a great effect on thermal removal and inhibits spontaneous combustion of the gangue. In addition, this paper also provides a theoretical basis for the technology of HP treatment of spontaneous combustion gangue dumps.