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Xu T.,Shanghai Maritime University | Wang D.-M.,China University of Mining and Technology | Wang D.-M.,State Key Laboratory of Coal Resource and Mine Safety | Xin H.-H.,China University of Mining and Technology | And 3 more authors.
Energy Sources, Part A: Recovery, Utilization and Environmental Effects

A comparison of in-situ series diffuse reflection Fourier transform infrared and non-series Fourier transform infrared in studying the conversion of functional groups in the process of coal oxidation is studied. It is found that non-series Fourier transform infrared could not monitor the changes of functional groups precisely while in-situ Fourier transform infrared can. In-situ Fourier transform infrared was also used to monitor the oxidation processes of low ranks of coal at low temperatures (30-220°C) and a series data was obtained. The variation regularity of six main functional groups was discussed and found that in-situ Fourier transform infrared would make it possible to reveal the mechanism of coal oxidation. © Copyright Taylor & Francis. Source

Xu T.,Shanghai Maritime University | Wang D.-M.,China University of Mining and Technology | Wang D.-M.,State Key Laboratory of Coal Resource and Mine Safety | He Q.-L.,Key Laboratory of Safe and Effective Coal Mining of Education
International Journal of Coal Preparation and Utilization

Moisture has a complex influence on the spontaneous combustion tendency of coal. The exothermicity of four different ranks of coal (lignite, gas coal, fat coal, and anthracite) with different total moisture contents during the oxidation process was tested by TA-DSC (Thermogravimetric Analysis- Differential Scanning Calorimetry). It was found that, for different ranks of coal, the effect of the moisture content can be quite different and for the same rank of coal, different moisture contents will affect the coal's exothermicity in very different ways. In addition, the critical moisture content at which the coal is most highly prone for spontaneous combustion was also obtained. It was found that different ranks of coal have different critical moisture contents. For lignite and anthracite, the critical moisture content was 25% and 20%, respectively. For the gas coal and fat coal, the lower the moisture content is, the greater the chance for the coal to have spontaneous combustion. © Taylor & Francis Group, LLC. Source

Wang X.-F.,China University of Mining and Technology | Wang X.-F.,State Key Laboratory of Coal Resource and Mine Safety | Wang X.-F.,Key Laboratory of Deep Coal Resource Mining | Zhang D.-S.,China University of Mining and Technology | And 6 more authors.
Journal of Mountain Science

This paper provides an improved understanding of the movement mechanisms of both bed-rock gully and sandy soil gully when underground mining occurs underneath, followed by systematic analysis of the contributing factors such as mining advance direction, gully slope angle, gully erosion coefficient and mining height. This paper presents the results from monitoring, theoretical analyses and up to date modeling based on the geological features in the gully affected area, and the implications of these results to the success of roof support trial. It was observed that when mining occurred towards the gully, sliding of slope block along the fracture surface occurred, which resulted in unstable roof condition; when mining progressed away from the gully, polygon blocks developed in the gully slope and rotated in reversed direction forming hinged structure; within the bed-rock slope, the hinged structure was unstable due to shear failure of the polygon block; however, within the sandy soil slope, the structure was relatively stable due to the gradual rotating and subsiding of the polygon block. The increase of the value of slope angle and mining height lead to a faster and more intensive fracture development within the gully slope, which had a pronounced effect on gully slope stability and underground pressure. Various remediation approaches are hence proposed in this paper including introducing more powerful support and reasonable mining height, setting up working face along or away from gullies, using room and pillar, strip mining and backfill instead of longwall mining. © 2013 Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag Berlin Heidelberg. Source

Zhang D.,China University of Mining and Technology | Zhang D.,State Key Laboratory of Coal Resource and Mine Safety | Fan G.,China University of Mining and Technology | Fan G.,State Key Laboratory of Coal Resource and Mine Safety | And 3 more authors.
International Journal of Rock Mechanics and Mining Sciences

The large-scale mining of shallow coal seams has a significant impact on the overlying aquifers and surface ecological environment. To protect the aquifers and maximize the coal resource recovery, field trials were undertaken during the operation of the LW32201 in Bulianta coal mine, Shendong, China. With a severely weathered rock (SWR) layer and two key strata (KS) in the overlying strata, aquifer protection in longwall mining (APLM) relies mainly on the rapid advance. In some localized zones, special measures should be taken to achieve the APLM, including lowering mining height, backfill and slurry injection. To further understand the mechanism and applicable conditions of the APLM and validate the effectiveness of the APLM, variation of the water table in the aquifer was observed as the longwall face passed through the zone. This paper also discusses the mechanism and basic requirements of the APLM and the relationship between the fall of the water table and the surface subsidence. The results of the field trials indicated that APLM in shallow coal seams could be successful under suitable conditions. © 2010 Elsevier Ltd. Source

Nong Z.,State Key Laboratory of Coal Resource and Mine Safety | Nong Z.,China University of Mining and Technology | Jia-Guang K.,State Key Laboratory of Coal Resource and Mine Safety | Jia-Guang K.,China University of Mining and Technology | And 4 more authors.
aEngineering Plasticity and Its Applications - Proceedings of the 10th Asia-Pacific Conference, AEPA 2010

Development and wider application of gob-side entry retaining have been stagnated by inadequate understanding of the dynamic stress evolution of its surrounding rocks. Numerical simulation and field measurement are combined to reveal its stress evolution in roadway excavation, gob-side entry retaining and entry stabilization under three typical roof conditions respectively. Results show that in roadway excavation, with increase in thickness of the immediate roof, supporting pressure increases. In the mininginduced stress adjusting period, with decrease in thickness of the immediate roof, the abutment stress concentration coefficient increases and maximum abutment stress occurs farther from the work face. These findings are of great value to roadway bolting. Source

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