Advanced Materials Research Vol. 868

Abstract: when explosive blasts in the rock, the stress wave of impact produced appears all kinds of phenomena, such as reflection, refraction, and transmission in the process of transmission on the joint surface because of discontinuity, heterogeneity and anisotropy of rock mass of weak plane in physics, which lead to extremely complex on rock blasting process. Through conducting on high dynamic strain test of blasting process on joint rock mass model, it researches dynamic load characteristics of joint rock mass and joint-planes effect on extension of critical raw crack and attenuation law of stress wave, analyzes the strain waveform of strain gages which locate in the different direction between initial crack of blasting and joint, and figures out the impact of joint plane on the stress wave transmission, which provide an important theoretical basis on the relevant parameters design in the process of blasting engineering of joint mass existing in actual.

Abstract: In the process of roadway excavation in the low permeability outburst coal seam, with drilling through strata in the bottom drainage roadway extracting coal seam gas of control area. In order to improve extraction effect, the method that deep borehole pre-cracking blasting is used to increase the permeability of coal in the drilling through strata seam segment is proposed. The calculation formula on crushing circle and crack circle radius of deep borehole pre-cracking blasting are derived, and the effective loosening radius of blasting is calculated in theory, the research achievements are applied to field test, the test results show that deep borehole pre-cracking blasting permeability improvement technology is carried out in the drilling through strata of the low permeability outburst coal seam, the permeability of coal seam is improved by 180 times, the gas extraction scalar is raised by 8-10 tomes, during the process of roadway excavation, gas concentration of the working face is 0.2%-0.3%, and tunneling footage is increased by 2 times.

Abstract: The coal 8210 big mining height of the Datong mine Jin hua gong face in the process of mining airport coal pillar fried state a, floor deformation intense, serious kick drum, eventually leading to rock failure .In the severe cases, easily induced by shock pressure and other disasters ,these have serious impact on the efficient production of face security in the large mining height. by the airport side of roadway roof pressure relief, combined with roadway bolting reinforcement technology effectively control the deformation of surrounding rock of roadway, Test results show that the security measures taken can meet the well production safety requirements.

Abstract: Based the analysis of the “3 zones” theory and index of spontaneous combustion in the mined out area, six measured points under which there are air sample collection probe and temperature sensor measuring the air composition and temperature of the mined out area of No 1304 face are arranged along both crossheadings of the mined out area in order to divide the “3 zones” of spontaneous combustion with the combination of the mining situation of No 1304 face in Tangkou coal mine. This present study mainly measures and analyzes the concentration of O2 and the temperature change and takes advantage of the Matlab and Excel to fit the concentration of O2 to determine the range of “3 zones”of spontaneous combustion in NO. 1304 face. Meanwhile, the concentration of CO is also measured and analyzed to determine the most prone location to fire of No. 1304.

Abstract: Apply high pressure water jet drilling and reaming integrated technique to research the technique of dip cross-cut uncovering serious outburst coal seam group; numerical simulation by FLAC^3D concludes that how much the diameters be after being reamed can get relief pressure well at different hole spacing; it shows that the technique expands pressure relief range, increases the permeability of coal and improves the drainage efficient at uncovering coal area in the experiment. Improve the craft and equipment of high pressure water jet drilling and reaming integrated technique, solve the problem of coal dust extraction difficultly at the dip hole, prolong high pressure and rotating joints life; the research indicates that high pressure water jet drilling and reaming integrated technique gets well effect on uncovering coals speed and outburst prevention effect, its of promotion application value to uncovering coal safely and efficiently in mine.

Abstract: To well develop coal gas and prevent gas outburst accidents, gas pre-drainage project has become the prerequisite of coal mining in underground collieries. Its construction quality determined drainage effect as well as touched miners lives closely. Based on the X-R_s control chart, a novel tracking and warning method for the gas pre-drainage project was proposed. Firstly, the data structure of upward cross-seam boreholes that were widely used in gas pre-drainage project was built. As time went by, the construction data of boreholes formed multivariable time series. Using the difference transformation between construction and design, the inspection data series of boreholes construction was designed. After that, the complete X-R_s control chart was implemented, in which by three types of anomaly characteristics the tracking and warning of the construction quality was accomplished.

Abstract: Coal blending is widely utilized in coal chemical industry and power plants, and ash slagging propensity, a non-additive property of the pure coals, is difficult to predict and related to its AFTs (ash fusion temperatures). A combustion experimental approach was undertaken to investigate the influence of coal blending ratio on the AFTs of three coal samples Sh-coal, Qi-coal, Que-coal from Ningdong mining areas. The results showed that a nonlinear decrease of the AFTs was obtained with the blending ratios (Sh-coal/Qi-coal or Sh-coal/Que-coal) increasing, the AFTs dropped by 30 °C from 0.5 to 0.8 ratio; the content of Al₂O₃ can be obviously lowered AFTs. Therefore, coal blending could lower the AFTs evidently. The obtained results in this research can be used in coal gasification process and further theoretical studies.

Abstract: In this paper, the regional distribution of six hazardous elements (S, Cl, Hg, Se, F and As) in Late Permian coal in southern Sichuan, China, is discussed based on the differences of the sedimentary environment. Based on the different sedimentary facies, the sedimentary environment of the southern Sichuan coal basin can be divided into three areas: fluvial or swamp (AreaI), tidal flat (AreaII) and marine carbonate platform (Area III). The content of F, Hg, Cl and Se is lower in the entire southern Sichuan coal field as compared to the average value of these hazardous elements in Chinese coal. The element S is concentrated in coal in Area III and the upper part of Area II. The element As is concentrated in coal in the upper part of Area II.

Abstract: The research on predicting gas outburst hazard on the basis of the unbalanced problem of gas monitoring samples under usual circumstances is given in this paper. Combined with outburst-preventing monitoring parameters, a new kind of method of predicting gas outburst hazard based on v-SVM algorithm through analyzing features of real-time gas monitoring data and extracting parameters of gas concentration real-time variation trend, parameters of gas variation rates and feature parameters of gas emission is put forward in this paper. And the application shows that this algorithm for the prediction of actual gas emission in coal mines is effective.

Abstract: Hydraulic classifier is widely used in the mill plant，But the design of traditional hydraulic classifier is simple，less controllable factors, cause the inaccuracy of Classifying product particle size，low classification efficiency. In order to solve these problems, the paper puts forward a new hydraulic classifier, we can improve the efficiency of classification by improving the appearance structure of hydraulic classifier and taking two pieces of top water. In the lab，the classification test was conducted with the coarse slime (0.9~0.3 mm, 0.3~0.074 mm) from Yanma coal preparation plant under the two phase of water supplying. The results of test show that by using two phase of water supplying, the new hydraulic classifier Can improve the classification effect of coarse coal slime.