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In the mine fire period, the smoke plume temperature, critical air velocity, back-flow layer and other fire parameters in the lanes are subjected to environmental factors such as lane dip angle and...

Judging development trends in coal spontaneous combustion (CSC) accurately has long been a global problem. Once a CSC phenomenon is found, the coal temperature tends to reach or exceed the critical temperature. To address this problem, the CSC characteristic parameter testing device is used to simulate the air reduction environment after the coal low temperature oxidation reaches the critical temperature, and long-flame coal was tested. The results show that the gas index can be used to judge the development trend and the characteristic temperature point for the initial stage of CSC. The development of oxidation at low temperature can be effectively predicted by using the composite indexes-Graham (G), CO/CO2 and 100× (C2H4/CO). Based on this information, a multi-index early warning method for comprehensive classification was proposed. The results have guiding significance for determining the development trend of CSC fires and fire prevention and extinguishing work. [Received: August 10, 2019; Accepted: May 26, 2020]

The environment of an underground roadway following a mine disaster affects multimedia communication during mine rescue. The propagation characteristics of electromagnetic waves in a wireless mesh network were studied by means of theoretical analysis, experiments, and simulations. The roadway shape factor, dust in the roadway, and its surface roughness are the main factors affecting signal attenuation. When the roadway shape factor tended to 2, signal attenuation was minimal; as the dust concentration in the roadway increased, signal attenuation increased. When operating frequencies of 600, 900, 1800, and 2400 MHz were evaluated in a curved roadway, it was found that attenuation of the 900 MHz signal was smallest and that of 2400 MHz was largest. Signal attenuation increased with increase in the incident angle of the electromagnetic waves and the undulation height of the roadway; variation of the incident angle exerted the greater influence.

Compared with optical life detection, audio detection and infrared detection, radar detection can penetrate obstacles without any influence from external noise, light and other environmental factors and has much broader applications and brighter prospects. In this paper, through elaborating the principle of radar detection technology and application situation of radar detection system in detail, the advantages and disadvantages of the present radar detection system are analyzed, and the future development trend of radar detection technology is also discussed. This paper summarized the mine emergency rescue technologies and equipment. Hopefully, this can guide the future system development for mine disaster rescue.

Oxygen concentration of the oxidation combustion zone in coalfield fire zone and coal spontaneous combustion dangerous area in coal mine such as goaf and sealed fire zone are all lower than that of normal atmospheric. Also, these two areas have the characteristics of high temperature. Therefore, in this paper, XKGW-1 type high temperature coal spontaneous combustion experiment device had been designed and manufactured independently. It was employed to investigate the entire process of coal spontaneous combustion by using the test method of temperature programmed. Five oxygen concentrations, 21, 17, 9, 5, and 3 vol%, were tested, observed, and elucidated. The changing tendency of coal spontaneous combustion index from room temperature to 450.0°C high temperature was explored under those oxygen concentrations. Experimental results showed that the effect of the oxygen concentration on the characteristic index of coal spontaneous combustion was very intricate and complex. The impacting result and degree varied with the range of the temperature. Consequently, during the practical application combined the effecting characteristics of the variable oxygen concentrations on coal spontaneous combustion into the on-site condition will significantly benefit the plan of the fire prevention. [Received: January 18, 2016; Accepted: April 19, 2016]