Advanced Materials Research Vols. 634-638

Abstract: For efficient analysis of mine gas monitoring data to expand monitor system function and realize effective gas pre-warning, the gas concentration pre-warning method based on monitoring data processing was studied. Studying by mine gas monitoring data, its statistical characteristics was abstracted, the intrinsic correlation characteristics of time series consisted by gas monitoring data was also analyzed by using grey relational analysis method. Further, the pre-warning indexes and its thresholds were determined, and the gas concentration abnormal situations could be analyzed, which realized timely and dynamically quantitative pre-warning. The case analysis shows that the method has a better applicability for mine-site gas concentration pre-warning, which can offer the effective decision for daily safe management.

Abstract: In order to evaluate occupational hazards comprehensively in the rolling enterprise to provide an effective reference for their improvement, this paper identifies and analyzes the existing occupational risk factors of the rolling enterprise; modeling the occupational hazards of the fuzzy comprehensive evaluation; then studies the example on the basic principles of F-AHP (Fuzzy-Analytic Hierarchy Process). The noise, toxic gas, high temperature and dust are studied respectively and noise is the worst factor. The investigation indicates that F-AHP can be used in comprehensive evaluation of various hazards instead of evaluation based on the single index so as to ensure the results to be more comprehensive, more objective and more practical.

Abstract: Spontaneous combustion of coal is an important problem in mining and storage, in terms of both safety and economics. The heat of the reaction accumulates and the reaction becomes progressively faster and thermal runaway may take place to the point of ignition. A detailed computer model has been developed to simulate a bulk-scale, one-dimensional test column. A column is used in this laboratory to conduct a practical test capable of providing reliable data on coal self-heating. Under the specific conditions considered in this study, it is shown that a subbituminous coal can reach thermal runaway in 4.5 days. The results obtained in this study indicate that there is a definite need to consider the influence of coal moisture on spontaneous combustion.

Abstract: The fuzzy Fault Tree Analysis (FTA) of mine ventilation system is set up based on thorough composition of the system, with triangular fuzzy number being used as probability of elementary event and “mine ventilation system fault” being deemed as top event. In this paper, the reliability of FTA has been analyzed and applied to a mine in Gansu Province. The result shows that the minimum cut set of fault tree is 549 and the main reason why it has a huge number of minimum cut set is Level 1，Event 7，“Monitoring feedback system failure”. The reliability of top event and Level 1 event is low, and fuzzy failure probability of top event is (0.009, 0.014, 0.009), the maximum of which is 2.3% of it. The degree of fuzzy importance of elementary event is the highest in Level 1，Event 7. The maximum of fuzzy importance is 0.0843 by the normalization and the rest vary from 0.0050 to 0.0100 mostly.

Abstract: In order to prevent the spontaneous combustion of coal efficaciously, a kind of new compound material of multi-phase foamed gel, which is based on three-phase foam, composed of foaming agent, thickener, fly ash and nitrogen and formed by physical and mechanical stirring, is proposed. It makes use of the all-around capability of gel and three-phase foam to prevent mine fire. The effects of the mass fraction of foaming agent and slurry, the quantitative ratio of polymers and concentration on foam properties had been carried out. The results show that the properties of multi-phase foamed gel are the best when the mass fraction of foaming agent, polymers and slurry were 4‰, 6‰(the quantitative ratio was 1:1) and 16.66%(water cement ratio was 5:1). In addition, the inhibition characteristic of multi-phase foamed gel was studied experimentally and theoretically.

Abstract: To further study, mesoscopic percolation evolution of gas-containing coal on loading conditions, this paper uses a self-developed loading system in seepage experiments to study the permeability changes of gas-containing coal on loading conditions, and it conducts CT reconstruction scan experiments on some pressure points. The results show that the permeability of coal samples decreases with increasing axial pressure when the air inlet pressure and confining pressure remain constant. It can be drawn by observation of the coal pore three-dimensional reconstructed images that when axial pressure increases to a certain value as well as other stress conditions remain unchanged, continue to increase the axial compression, coal pores and fissures appear contraction and even close, and the permeability of coal gets a reduction.

Abstract: In China, as popularizing the technology of fully mechanized top-coal mining and increasing the strength and depth of mining, the gutter-up gob can be formed. But the work of fire preventing and extinguishing for its coal spontaneous combustion is more complexity and difficulty. In this paper, based on geology parameters and mining practice for 93up12 fully mechanized top-coal caving face in Nantun coalmine, the form and character of gutter-up gob are analyzed. According to the hidden danger of high temperature for spontaneous combustion in the gob, we adopt the comprehension technologies of fire extinguishing and preventing which include sealing air-leakage, grouting, and injecting compound gel with fly-ash, foam of retarding oxidation, liquid carbon dioxide, and gas of nitrogen. By putting in practice the pre-controlling technology in gutter-up gob and monitoring data of target gases, it obtains a good effect and ensures the safety in production of the fully-mechanized top-coal caving face.

Abstract: Railway transportation safety management must adhere to the approach of safety and prevention first. The transport of dangerous goods should be paid more attention as a particularly important part. This paper made use of fault tree analysis to research and analyze the risk factors of dangerous goods LPG which may explode in the rail transport. The analysis was made from two aspects of chemistry and physics, then the minimal cut sets and structure importance of the specific factors which may cause explosion accidents are solved, and the importance of each factor is analyzed and sorted on the calculated results. Based on the above method, measures of LPG rail transport explosion prevention were proposed.

Abstract: In order to monitor landslide risk, GeoStudio software is frequently applied to landslide stability analysis. In this paper, Juting landslide in Shanxi was subjected by GeoStudio software, while limit equilibrium method was adopted to calculate the landslide stability in the slip surface. The solutions of stress and displacement vector were gotten through SIGMA / W module on the landslide for finite element method in sliding surface stress analysis. And it was also used to import the results obtained in SIGMA / W module into SLOPE / W module to calculate safety factor and the potential sliding surface. The result shows that the calculated safety factors which are worked out by those two ways are close to each other, and limit equilibrium method can be used in landslide stability analysis, but the finite element method is more consistent with the actual situation. GeoStudio software can calculate landslide stability coefficient conveniently, and can express potential slip surface intuitively, providing reliable foundation for landslide stability analysis.

Abstract: This paper introduces the survey of bauxite resources in China, analyses the basal principle of selective dissociation, then details dissociation process flow and selective grinding, finally prospects the future development of bauxite selective dissociation.