In order to gain a knowledge of the heat emitted from a variety of sources at the blind heading of an underground gold mine, the present study conducts an in situ measurement study in a blind heading within the load haul dumps (LHDs) that are operating. The measurements can provide a reliable data basis for the setting of numerical simulations. The results demonstrate that the distances between the forcing outlet and the mining face (denoted as Zm), as well as the heat generation from LHDs (denoted as QL), has brought significant impacts on the airflow velocity, relative humidity, and temperature distributions in the blind heading. Setting Zm to 5 m could achieve a relative optimal cooling performance, also indicating that when the LHD is fully operating in the mining face, employing the pure forcing system has a limited effect on the temperature decrease of the blind heading. According to the numerical simulations, a better cooling performance can be achieved based on the near-forcing-far-exhausting (NFFE) ventilation system.

At present, there are few studies on the development, evolution, and quantitative analysis of internal pores and cracks after heat treatment of coal. On the basis of this, low-temperature nitrogen adsorption, scanning electron microscopy, and X-ray diffraction (XRD) experiments were carried out on five kinds of temperature-treated bituminous coal and anthracite. The pore cracks of coal samples were studied qualitatively and quantitatively using linear fitting and the fractal theory. Through the analysis of the original diffractograms in the XRD experiment, the quantitative analysis of mineral composition in coal was realized. The results show that, with the increase of the temperature, the thermal damage of coal changes obviously and the micromorphology of the coal surface changes from the initial compact structure to the appearance of pores and small cracks and then to the mutual connection and evolution into large cracks. The development of pores and cracks of bituminous coal is more obvious than that of anthracite. Because anthracite has better heat resistance, there is no expansion and crack in its internal structure during the experiment. Through the fractal calculation of the coal nitrogen adsorption capacity, it is obtained that the overall pore volume and specific surface area of bituminous coal and anthracite are positively correlated with the fractal dimension (D 1) of the pore structure and V daf is negatively correlated with the fractal dimension (D 2) of the pore surface. In the temperature range from a normal temperature to 100 °C, the mineral crystal structure inside the coal body changes significantly, a large number of pores appear on the coal surface, and the total pore volume increases accordingly to reach the measured maximum value. The research of this paper is of great significance to reveal the effect of the temperature on coal damage and deformation and crack evolution.