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Coal is the primary source of China's carbon emissions due to the energy structure and its resource endowment. This reality creates enormous pressure and impetus for low-carbon pathways of coal production and consumption. Based on a literature review on carbon emissions accounting methods, this paper builds a source-driven CO2 emissions accounting model for the coal development sector using the emissions factor method. Scenario analysis is employed to predict future carbon emission equivalents and to indicate possible implications for climate change mitigation in this sector. Carbon emissions from coal development are mainly derived from coal mine gas emissions, which yield 62% of the sector's total carbon emissions, followed by energy consumption. The recent decline in coal mining-driven CO2 emissions is mainly due to the strict deployment of coal mine gas and the changing structure of coal mines. The results from the scenarios suggest that the carbon emissions reduction potential will largely be determined by technology innovation in the coal mine gas industry. Policy implications for further addressing carbon emissions from the supply side of the coal industry include improvements in energy efficiency and coal mine gas extraction and utilization. [ABSTRACT FROM AUTHOR]

Based on the longwall panel layout at Renjiazhuang Coal Mine in Ningdong mining area,using the method for determining the mechanical and physical properties of rock mass based on the Hoek-Brown criterion, the characteristics of ground pressure distribution in multi-seam coal mining at different panels in No. 3 and No. 5 coal seams were simulated by FLAC software. In addition, the pressure and displacement of surrounding rock were monitored and the monitoring data were compared with the numerical simulation results. The results show that the properties of rock mass calculated by Hoek-Brown criterion are obviously different with the properties of rock sample obtained by standard experiments. They are not just a simple addition and reduction relationship. The method used to determine the rock mass parameters in this study took account for the factors of structure characteristics of rock mass, rock strength, excavation disturbance, etc. The comparison of the in-situ monitoring data and the numerical simulation results demonstrates the validity and rationality of the property determination method based on the Hoek-Brown criterion. [ABSTRACT FROM AUTHOR]

The mechanism of floor heave in the gob adjacent to the working face was analyzed. The aim was to understand the floor heave phenomena happened at No. 15423N working face in Jiulong Coal Mine, Fengfeng mining group. Core logging of floor strata and in-situ stress measurement near the investigated region were carried out. Moreover, the numerical simulation was used to obtain the in-situ stress of No. 15423N working face. Based on these data, a bi-directional loading similar simulation experiment was carried out to analyze the process and mechanism of floor heave of gob near working face above aquifer. A series of spring group were used to simulate the aquifer. The time-space evolution characteristics of stress and displacement field in floor strata were analyzed. The. results could be used to explain the mechanism of water inrush accidents in Jiulong Mine. [ABSTRACT FROM AUTHOR]

The characteristics of rock burst were analyzed based on the microseismic data from No. 8935 working face in Xinzhouyao Coal Mine, Datong Mining Group. The geology of this working face was characterized by the thick sandstone roof and coal seam, both with relative higher stiffness and strength. In order to investigate the mechanism and precursors of rock burst occurred in No. 8935 working face,the locations of microseismic, the relationship of microseismic energy and frequency and the spectrum of microseismic signals were analyzed. The results show that the rock burst in No. 8935 working face are mainly induced by the seismic caused by roof failure. The coal pillar near the goal is more easily to bump. The statistics results indicate that the rock burst are mainly occurred in the gate road near the pillar, less than 50 m ahead of working face and located in the hard roof adjacent with coal seam. Moreover,the frequency, energy, 6-value and frequency spectrogram of microseismic events are found to decrease before rock burst. It was found that the frequencies of the microseismic events before rock burst mainly concentrates upon 5-60 Hz. The sudden decreasing of frequency and increasing of amplitude of microseismic events can be regarded as a precursor of rock burst. [ABSTRACT FROM AUTHOR]

Abstract: Coupled gas flow and solid deformation processes in porous media have received considerable attention because of its importance in CBM exploitation and gas outbursts during coal mining. Coalbed methane is mainly adsorbed on coal. The dependence of gas adsorption on gas pressure has significant effect on the mechanical properties of coal, however, the effect was ignored in most of the previous modeling studies. Based on Truesdell’s postulate of the theory of mixtures, a new set of constitutive equations for the saturated mixtures of gas-filled coal which is composed of coal matrix, adsorbed gas and free gas is developed. Adsorbed gas pressure and the volume fraction of each component of the saturated mixtures are also presented. The proposed constitutive equations show that mechanical response of coal is determined by stress condition, mechanical properties of solid phase, gas pressure, gas adsorption, pore structure and its evolution. Without considering the adsorption effects and pore evolution, the effect of gas pressure in coal seam would be underestimated. [Copyright &y& Elsevier]

To get early warning for coal bumps effectively, the methods commonly used for the monitoring of coal bumps and their advantages and disadvantages were discussed, and monitoring problems of coal bumps currently were showed. Based on the mechanism of coal bumps, the application model of the hierarchical monitoring was established. It is widely considered that hierarchical monitoring mode of highly complementary can merger their respective characteristics and make up for their respective shortcomings. Taking the Xinzhouyao Cola Mine as an example, it shows that the dangerous areas of coal bumps can be real-time monitored and the dynamic development can be mastered by the microseismic technology in the whole mine. By the electromagnetic radiation cooperation the stress variation of surrounding rock of mining space can be mastered continuously and dynamically, and the further dangerous areas can be found. In addition, the detection of drilling cutting can confirm to dangerous degree effectively. The analysis methods of early warning for microseism, electromagnetic radiation and drilling cutting were comprehensively and detailedly researched in this paper. The engineering practice shows "global scope-zone-locality" in the space can be formed, and "real time-continuity-development" in the time can be achieved, and the disasters of coal bumps can be effectively early warned by the hierarchical monitoring technology of the stronger complementarity. [ABSTRACT FROM AUTHOR]

Abandoned coal mine reutilization plays a critical role in the sustainable development of the mining industry. Scientific decisions on reuse modes are a prerequisite and crucial issue to efficiently explore the idle resources of abandoned mines. This paper classified the reuse modes into 6 types with 19 sub-patterns and generalized the influence conditions into 3 categories with 17 sub-indexes, including mine conditions, natural and geological conditions, and supplementary conditions based on literature review and data sources. A logical deduction method named "condition-mode" was proposed from the constraint conditions and their degree of constraint to select the preliminary reutilization patterns of abandoned mines. Finally, a practical example of the Beijing west mining area was introduced to demonstrate the applicability and feasibility of the proposed method. The results indicate that this method can be employed to select some potential reuse patterns for abandoned underground coal mines. The most important implications are that the significance of more detailed analyses and techno-economic appraisals on multiple schemes from these decision results, which suggests a stepwise integration approach to generate a more promising subset of inference results. The research can provide a reference for the reuse of underground coal mines that have been closed or will be closed. • The reuse ways of abandoned coal mine are grouped into 6 modes with 19 sub-patterns. • The constraints of each pattern are analyzed and summarized into 3 categories. • Abandoned coal mines reutilization is an integration of solid, space, and wasteland. • A logical inference method from constraints to reuse modes is proposed. • The preliminarily screened reuse modes narrow the scope for further discussion. [ABSTRACT FROM AUTHOR]