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Ju F.,China University of Mining and Technology | Sun Q.,China University of Mining and Technology | Huang P.,China University of Mining and Technology | He Q.,Huadian Coal Industry Group Co.
Caikuang yu Anquan Gongcheng Xuebao/Journal of Mining and Safety Engineering | Year: 2014

In response to the special mining condition of the weak roof and floor in the working face of the thin seam, the difficulties and key technology of gob-side entry retaining in thin seam have been proposed. By using the theory analysis and numerical simulation, the failure characteristics and deformation law of surrounding rocks of gob-side entry retaining in thin seam have been analyzed. The structure model of gob-side entry retaining has been set up in thin seam coal mining. At the same time, Through the numerical simulation analysis and expounding the basic principle gob-side entry retaining in thin seam, it has been put forward that the optimization scheme of gob-side entry retaining was to "built waste stone wall in the goaf first, then timely build cemented filling body and long steel beams and monomer pillar support in roadway at last". Accordingly, the gob-side entry retaining speed was improved obviously. The result of the actual measurement in Zhaoguan coal mine shows that the roof subsidence is only 197 mm; the floor heave is 83 mm; the convergence of two ribs is 327 mm, consequently, the mining efficiency reached up to 18 m/d. ©, 2014, China University of Mining and Technology. All right reserved. Source


Zhang J.-G.,Tsinghua University | Qian W.-Z.,Tsinghua University | Tang X.-P.,Tsinghua University | Tang X.-P.,Huadian Coal Industry Group Co. | And 5 more authors.
Wuli Huaxue Xuebao/ Acta Physico - Chimica Sinica | Year: 2013

Relationship between aromatics distribution, in the process of methanol to aromatics (MTA), and the conversion of methanol and the catalyst acidity was investigated over a series of Zn/P/ZSM-5 catalysts with different Si/Al molar ratios and zinc loading. To understand the contribution of aromatization, isomerization, dealkylation and alkylation reactivity of the catalyst to the aromatics distribution, coke deposition degree of Zn/P/ZSM-5 catalyst was tailored as using different feedstocks including methanol, xylene or the mixture of methanol and toluene. With the coke deposition, the amount of different types of acidic sites of catalyst varied significantly, characterized by NH3-temperature programmed desorption (NH3-TPD) and pyridine-infrared methods. Aromatization, dealkylation, alkylation, and isomerization showed sensitivity to a reduction in the density of strongly acidic sites. Dealkylation reaction was preferentially inhibited just by slightly decreasing the density of strong acid sites. However, aromatization and isomerization reaction were inhibited only when the density of strong acid sites was significantly decreased. In all cases, alkylation was found to be uninfluenced by acidic site density. A Zn/P/ZSM-5 catalyst with Si/Al molar ratio of 14 and 3% (w) Zn loading exhibited aromatics yields of 75% and xylene yields of about 35%, indicating potential for industrial application. © Editorial office of Acta Physico-Chimica Sinica. Source


Ding H.,China University of Mining and Technology | Ding H.,Huadian Coal Industry Group Co. | Miao X.,China University of Mining and Technology | Ju F.,China University of Mining and Technology | And 4 more authors.
International Journal of Mining Science and Technology | Year: 2014

This paper describes a specific case of mining in a water-rich coal seam in western China. Water inrushes, roof caving and other disasters induced by intensive mining operation could pose great threats to the safety of coal mines. The strata behavior during the high-intensity extraction in the water-rich coal seam is analyzed by employing the numerical simulation method and in situ monitoring. The results show that about 10 m ahead of the workface, the front abutment pressure peaks is at 34.13 MPa, while the peak of the side abutment pressure is located about 8 m away from the gateway with the value of 12.41 MPa; the height of the fracture zone, the first weighting step and the cycle weighting step are calculated to be 45, 50 and 20.8 m, respectively; pressure distribution in the workface is characterized by that the vertical pressure in the center occurs earlier and is stronger than those on both ends. Then, the results above are verified by in situ measurement, which may provide a basis for safe mining under similar conditions. © 2014 Published by Elsevier B.V. on behalf of China University of Mining & Technology. Source


Wang T.,Tsinghua University | Wang T.,Huadian Coal Industry Group Co. | Tang X.,Huadian Coal Industry Group Co. | Huang X.,Huadian Coal Industry Group Co. | And 5 more authors.
Catalysis Today | Year: 2014

Conversion of methanol to aromatics (MTA) was conducted over a fresh or a spent Zn/ZSM-5 catalyst in single stage fluidized bed (SSFB) and two stage fluidized bed (TSFB). Sampling at different stages of TSFB and operation in the temperature range of 250, 275, 300, 325, 350, 380 and 475 °C revealed the consecutive reaction mode from methanol to DME, C1-C4 hydrocarbons, C5+ nonaromatics to aromatics finally. High weight ratio of para-xylene (PX) in xylene in wide temperature range suggested that PX was the primary product of MTA, and other xylenes are produced by the iosmerization of PX. Other aromatics such as benzene, toluene and trimethylbenzene are finally produced by the dealkylation, alkylation or disproportionation of xylene. The adoption of TSFB reactor was effective to increase the yield of aromatics, compared to that using SSFB, due to the inhibition of backmixing of gases. Combination of TSFB and highly active catalyst with strong acids was effective to get high yield of aromatics under high space velocity of methanol. © 2014 Elsevier B.V. Source

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