Study on the influence of coal fire on the temporal and spatial distribution of CO2 and CH4 gas emissions.

In order to study the impact of gas released from coal fire combustion on the spatial-temporal distribution of CO2 and CH4 and other greenhouse gas emissions, the impact of regional coal fire on CO2 and CH4 emission flux was comprehensively evaluated using Landsat 8 and GOSAT satellite data in Xinjiang. In addition, typical fire areas are selected, a single-channel algorithm is used to invert the surface temperature of the coal field, the spatial distribution of the coal fire area is extracted by setting the threshold, and the influence law of CO2 and CH4 emissions in the typical fire area is accurately analyzed. The results show that during 2017-2018, CO2 and CH4 emissions in Xinjiang were generally dispersed and locally concentrated, while CO2-O and CH4-O were at low levels in most regions, fluctuating in the ranges of 0.01 ~ 0.14 g·m-2·day-1 and 0.001 ~ 0.003 g·m-2·day-1, respectively. However, the emission intensity of CO2-O and CH4-O in coal fire concentrated areas is higher, which are 1.6 ~ 3.8 g·m-2 day-1 and 0.013 ~ 0.026 g·m-2·day-1, respectively. CO2-F and CH4-ag have similar laws. The fire area of Daquan Lake is scattered, and there are four areas with the surface temperature over 35 °C: A, B, C, and D, respectively. The Sandaoba fire area is more concentrated, and only two areas are E and F when the surface temperature exceeds 35 °C. CO2 and CH4 released by burning in Daquan Lake and Sandaoba fire areas increased CO2-F and CH4-ag by 2.08 and 0.89 times, respectively. The results provide a reference for coal fire control and carbon emission reduction.

A visual knowledge map analysis of mine fire research based on CiteSpace.

Mine fire has always been a serious disaster in coal industry; many academic achievements have poured out in the past two decades for solving this problem. In this study, visual analysis was conducted to grasp the hotspots and development trend of mine fire research. Papers that published in 1999-2020 were retrieved as the data basis from Web of Science, and CiteSpace was used to carry out knowledge map analysis. The results shown that number of papers has increased steadily since 2005 and achieved explosive growth since 2014. Deng J is the first published author among many scholars. China, the USA, and Australia are active areas in mine fire research and China University of Mining and Technology ranks first in this field. The highest co-occurrence frequency keyword is "spontaneous combustion." International Journal of Coal Geology and Fuel provide guidance for mine fire research. Fire prevention technology, low carbon, ecology, and sustainable development are the hot research in recent years. The prevention and control of mine fire from combustion mechanism should be further strengthened.

Macromolecule simulation studies on mechanical properties and CH4/CO2 adsorption characteristics in bituminous coal matrix based on uniaxial tension-compression effect.

With the increasing complication of production and geology conditions, and the increase of mining intensity and depth in coal mine, the coal structure presents varying degrees of deformation. In order to study the influence of uniaxial tension-compression effect on mechanical properties of coal matrix and CH4/CO2 adsorption characteristics, a macromolecular model reflecting the realistic bituminous coal structure was established. Results demonstrate that the influence of tension strain on the microporous structural parameters is greater than that of compression strain, and the tension strain weakens the mechanical properties but enhances the adsorbates adsorption amount. For the pure gases adsorption, there is a negative linear correlation between the total energy and adsorption amount. Additionally, the strain ranging from -0.20 to 0.20, the distribution of punctated adsorbates density develops to that of banded adsorbates density, and the mean adsorption density and saturated adsorption amount increase linearly. For the binary components adsorption (1:1), the CH4 adsorption strength increases while the CO2 adsorption strength slightly decreases. The minimum of total energy decreases in a quadratic polynomial relationship with the strain, and the proportion of van der Waals energy is 75.8-85.5%. Nevertheless, the competitive adsorption and strain have little effect on the potential energy range of the adsorbates. Furthermore, the diffusibility of CO2 molecular layers is relatively good, and the strain enhances the stability of CH4 molecular layers for the saturated binary adsorption. The findings provide essential guidance for the improvement of carbon capture and storage and CO2-enhanced coalbed methane technologies in the deformation area of coal seam.

Status of research on hydrogen sulphide gas in Chinese mines.

In the process of coal mining, the abnormal gushing of hydrogen sulphide in mines poses a major threat to the health of coal miners and the safe production of mines, as these types of accidents have occurred in many coal-producing countries. China is the largest coal producer and consumer in the world and is one of the countries that are substantially affected by hydrogen sulphide in mines. Based on the existing studies, many investigators in China have conducted research on the actual situation in China and obtained some results. This paper summarizes the previous findings and the current status of hydrogen sulphide in Chinese mines, and predicts the direction of future development. In this paper, we discuss the cause, abnormal distribution, abnormal gushing and prevention and control measures for hydrogen sulphide in mines. In addition, this paper also evaluates the impact of the hydrogen sulphide in mines on the environment and health. This paper outlines a systematic research framework regarding hydrogen sulphide in mines and assesses the interrelationship between subtopics within this system framework. Currently, the scientific research on hydrogen sulphide in mines is not sufficient to meet the needs of the affected individuals Therefore, researchers must increase their efforts in this area to jointly address the challenge of analysing hydrogen sulphide in mines. In addition, we hope that this paper will provide some guidance for the study of hydrogen sulphide in mines.

Firefighting of subsurface coal fires with comprehensive techniques for detection and control: a case study of the Fukang coal fire in the Xinjiang region of China.

Coal fires are global disasters, and China suffers the most serious coal fire disasters in the world. This paper introduces detailed detection and extinguishing methods for the wide range and complex coal fires at the No. 1 well in the Fukang mining area. First, the characteristics of the large and complex coal fire areas in the No. 1 well in the Fukang mining area are introduced, and 5 large fire areas are detected using the comprehensive detection range method, which detects fire areas before fire engineering practices are implemented. From the characteristics of this large-scale, complex coal fire, the zonal fire extinguishing scheme is formulated, designed, and applied, and the "shallow open fire stripping-construction of the boundary isolation zone-drilling and grouting in the deep fire area" series of events is utilized in the zonal fire extinguishing scheme. A new type of sodium silicate gel in compressive moisturizing plastic packing materials is used, an automatic grouting system is developed, and effective grouting processes are proposed, which can be adjusted according to the grouting effect analysis of the grouting parameters to determine the natural sedimentation and diffusion radius. After the construction was completed, the fire extinguishing effect was tested, revealing that the temperature in the fire zone cooled in a short time, and no subsequent heating phenomenon occurs. The method proposed in this paper provides guidance and a reference for other coal fires in the world.