Improved Calculation Model for the Shortest Spontaneous Combustion Period

Disasters caused by the spontaneous combustion of coal have occurred in major coal-producing countries, resulting in the loss of resources and human life and severe environmental pollution. The development of an efficient model to calculate the shortest spontaneous combustion period (SSCP) has been a long-standing challenge. In this study, we propose a continuous model that calculates the SSCP by changing the traditional time summation form into a time integration form. The proposed model can reduce the calculation errors and determine the heating time to any temperature, which overcomes the limitations of the traditional model. The accuracy and convenience of the improved model were validated through a comparison with the results of the traditional model and a numerical model. The parameter sensitivities were analyzed in the improved model. The results showed that the SSCPs calculated using the improved continuous model are in good agreement with those of the traditional and numerical models. The results also indicated that the continuous model is more accurate and convenient than the traditional model. Parameters such as the heat release intensity, water content, specific heat capacity, and gas content influence the SSCP results in the sensitivity analysis. This model can potentially help prevent and control the risk of coal spontaneous combustion and should be further tested in practical mine management.