Fault Diagnosis Approach of Local Ventilation System in Coal Mines Based on Multidisciplinary Technology

In order to reduce the probability of fault occurrence of local ventilation system in coal mine and prevent gas from exceeding the standard limit, an approach incorporating the reliability analysis, rough set theory, genetic algorithm (GA), and intelligent decision support system (IDSS) was used to establish and develop a fault diagnosis system of local ventilation in coal mine. Fault tree model was established and its reliability analysis was performed. The algorithms and software of key fault symptom and fault diagnosis rule acquiring were also analyzed and developed. Finally, a prototype system was developed and demonstrated by a mine instance. The research results indicate that the proposed approach in this paper can accurately and quickly find the fault reason in a local ventilation system of coal mines and can reduce difficulty of the fault diagnosis of the local ventilation system, which is significant to decrease gas exploding accidents in coal mines.

Division of diagenesis reservoir facies and its control——Case study of Chang-3 reservoir in Yangchang formation of Fuxian exploration area in northern Shaanxi

By dividing the diagenetic reservoir facies and studying its distribution,we can effectively evaluate reservoirs.Using an analytical method for mutual relationships among diagenesis of reservoirs,structural characteristics and the origin of types of sand,we classified the diagenetic reservoir of the Yanchang formation Chang-3 oil layer into different types and analyzed the factors controlling this high quality reservoir.The results show that:1) the catagenesis of the Chang-3 oil layer in the Fuxian region is complex and variable;2) mechanical compaction,pressure solutions and cementation of all kinds of authogenous minerals decreases porosity by 28.13% and 3) corrosion increases porosity by 3.39%.Cementation and corrosion of laumontite is a kind of catagenesis which makes this region different from other exploratory regions.The original amount and rate of corrosion of laumontite are the main factors for the increase in laumontite porosity.The Chang-3 oil layer developed four kinds of diagenetic reservoir facies,of which the weak compaction facies,i.e.,laumontite corrosion and overgrowth,of the original pore reservoir facies has the most promising diagenesis.Its distribution is controlled by a sedimentary facies zone and is widely developed in the original truncated tributary channel facies belt of the delta plain.The development of this high quality reservoir is controlled by the distribution of sedimentary sand bodies and secondarily-eroded porosity of laumontite in the Chang-3 oil layer of the Fuxian exploratory region.

Application of the catastrophe progression method in predicting coal and gas outburst

Based on catastrophe theory,we used the catastrophe progression method to predict the risk of coal and gas outbursts in coal mines.According to the major factors affecting coal and gas outbursts,we built a comprehensive evaluation index system and a coal and gas outburst prediction model.In addition,we performed a standard transformation for each index system;based on the degree the various indices affect the risk of an outburst,to make the data dimensionless.Based on the outburst data from eight mines,we determined catastrophe progression values and verified these values.The results show that:1) converting multi-dimensional problems into one-dimensional problems using this catastrophe progression method can simplify the steps of predicting coal and gas outbursts;2) when pre-determined catastrophe progression values are used to predict coal and gas outbursts,the predicting accuracy rate can be as high as 87.5%;3) the various coal mines have different factors inducing outbursts with varying importance of these factors and 4) the catastrophe progression values,calculated based on these factors,can be used effectively to predict the risk of outbursts in coal mines.

Influence of microwave treatment under a hydrogen or methane atmosphere on the flotability of the macerals in Shenfu coals

The modification of Shenfu coals by a microwave treatment carried out under a hydrogen or a methane atmosphere, and the subsequent maceral separation by flotation, are described in this paper. The surface contact angle and the Zeta potential of the coal macerals were measured both with and without the treat- ment. The results show that the surface wettability of SFF (Shenfu Fusain) and SFV (Shenfu Vitrain) can be changed by the microwave treatment. An increase in the difference in surface wettability of SFF and SFV causes in a subsequent increase in the enrichment of inertinite and vitrinite. The results of the Zeta potential measurements show that the surface potentials of SFF and SFV are also changed by the treatment.

Research on mechanism of mountain landslide due to underground mining

The basics of mining landslides were first summed up based on the analysis ofactual materials by the application of mining subsidence and landslide theories. Further,the mechanism of along-layer landslide by mining was studied with the example of theXiangshan mining landslide at Hancheng, Shaanxi Province. Meanwhile, the state ofstress, and the mechanism of deformation and destruction of the Xiangshan mining slopewere analyzed by the Finite Element Method.

Experimental research of overburden movement and subsurface water seeping in shallow seam mining

Shallow seam coal field has the largest coal reserve in China. Mining in shallow depth causes serious problems, and subsurface dewatering is a major issue. In this paper, the physical simulating models were prepared to study overburden movement and aquiclude stability in the shallow seam mining of Yushuwan Coalfield, China. According to the characteristic of clay aquiclude and bedrock in the overburden, the proper simulation materials for simulating the plastic clay aquiclude layers and brittle bedrock layers were determined by the stress-strain tests and hydrophilic tests. The physical simulating models of solid medium and two phases of solid-liquid medium were carried out to simulate the failure and caving process of the roof and overburden, as well as the subsurface water seeping. Based on the simulation, it was found that the movement of clay aquiclude follows the movement of the underlying bedrock layers. The stability of aquiclude is mainly affected by cracks in fracture zone. The tests also showed that the best way to control the stability of aquiclude is to reduce the subsiding gradient, and there is a possibility of ground water conservation under longwall mining in Yushuwan Mine. This research provides a foundation for further study on mining dewatering and water conservation.

Research on Potential Fertilization of Coal Gangue in the Weibei Coalfield,China

Based on the systematic analysis of the coal gangue in Weibei Coalfield, such as petrologic characteristics, chemical composition, nutrient elements, deleterious elements, and the transformation, and compared with the soil element content background values of Loess Plateau and national harmful materials controlling standards, we conclude that the coal gangue in the Weibei Coalfield has huge potential to be used as clay fertilizer.

Top coal flows in an excavation disturbed zone of high section top coal caving of an extremely steep and thick seam

与轻轻的剧降相比长墙的探穴，在为极其陡峭、厚的缝接的充分使机械化的最高煤的探穴的一张工作的脸的长度是短的，当它的水平节与增加高时生产。但是探穴比率是低的，在一些灾难的力量结果例如房顶下降，在煤气的累积导致的一张工作的脸和危险由最高的煤的本地、大的区域倒塌导致了它。在裂缝的发展以后并且煤身体变弱，极其陡峭的缝接的最高的煤(小粒的媒介) 的高、破节(超过 60 掳) 表演清除非线性的运动的特征。我们彻底地分析了地质的环境，挖掘的采矿条件扰乱了地区。从大规模 3D 为最高的煤鈥搘a ter 鈥揼a s 的模拟建模并且联合的一个物理实验基于结果，我们断定削弱的最高的煤能被认为是间断媒介。我们使用了一个粒子流动代码程序高比较并且分析移植进程和 30 m 的运动节在在 Weihuliang 煤矿极其陡峭的缝接变弱前后随着时间的过去超过煤。我们的模拟，实验和监视表演的结果水的那注射前并且预先切开爆炸改进探穴能力和对称的探穴，为大区域减轻空间动态倒塌超过煤，延长有害气体的迁居时间并且外面免除他们 mined 区域并且那么在采矿完成安全。

Microwave-assisted extraction of Shenfu coal and its macromolecule structure

Coals consist of some molecules trapped within an organic matrix from which some organic compounds can be extracted by solvents. The Soxhlet technique has been widely used for extracting organic compounds. Microwave heating methods may be successfully applied in the field of coal science. Acetone extraction yields and the chemical composition of the extract were investigated using a typical Chinese coal, Shenfu coal, with microwave-assisted extraction. The acetone extract and residue were analyzed by GC/MS and carbon-13 nuclear magnetic resonance spectroscopy respectively. The carbon spectra were converted into several numerical parameters, fa, Ha, Xb, which indicate the difference in macromolecular structure between Shenfu coal and its residue. Furthermore, a hybrid genetic algorithm was employed using these parameters to approximate a coal macromolecule by assembling the structural fragments or functional groups into a large and complicated structure.

Simulation experiment of AE-based localization damage and deformation characteristic on covering rock in mined-out area

The localization damage and deformation characteristics of multiple rock in mined-out area under thick soil layer were investigated by acoustic emission （AE）-based physical similar simulation experiment and damage test combined with the AE theory on rock damage. During different mining courses, the degree of wall rock suffered from mining disturbed process in mined-out area was different, so did the AE density of initial damage and fracture. Some characteristic parameters, including large events, total events, and energy rate, presented fluctuations with temporal and spatial change and take on a certain extent statistic relation. Subsequently, the percent of damage degree was defined and divided into 4 stages, and the localization damage and deformation characteristics of surrounding rock in mined-out area and coal pillars were analyzed quantitatively.

Performance evaluation methods and instrumentation for mine ventilation fans

Ventilation fans are one of the most important pieces of equipment in coal mines. Their performance plays an important role in the safety of staff and production. Given the actual requirements of coal mine production,we instituted a research project on the measurement methods of key performance parameters such as wind pressure,amount of ventilation and power. At the end a virtual instrument for mine ventilation fans performance evaluation was developed using a USB interface. The practical performance and analytical results of our experiments show that it is feasible,reliable and effective to use the proposed instrumentation for mine ventilation performance evaluation.

A nonlinear rheological model of backfill material for retaining roadways and the analysis of its stability

The long-term stability of backfill material is the key to retaining roadways successfully.In order to study the rheological deformation of backfill material and its long-term stability,given the visco-elastoplastic properties of this material,we introduced a softening and a hardening function for a new nonlinear rheological model with time-varying parameters.Based on this,we presented the instability condition of this model by using the principle of minimum potential energy.Combined with engineering practice,we calculated the unstable time period of backfill material.The results show that the time of instability of the backfill material relate to the initial parameters of the material,the coefficients decided by temperature and the ratio of the plastic zone of the backfill material.Based on the results of our analysis from the point of view of energy,we can quickly obtain the time of instability of this model from our graphical analysis.The time of instability of the backfill material obtained from our investigation coincides with an actual project.

Effect of solidification parameters on the microstructures of a single crystal Ni-based superalloy AM3

A single crystal Ni-based superalloy AM3 was processed at withdraw rates of 3.5, 10, 50, 100, 200, and 500 μm·s-1, respectively.The as-cast microstructures and solidification segregation ratio were characterized with various withdraw rates.The shape and size of carbide microstructures were determined.As expected, the primary and secondary dendrite arm spacings (PDAS and SDAS) decrease with the increase of withdraw rate.The highest volume fraction of eutectic γ/γ' is observed at the 100 μm·s-1 withdraw rate.The volume fraction of eutectic γ/γ' does not appear to be a strong function of the withdraw rate.With increasing withdraw rate, interface morphologies change in the sequence of planar, cellular, and dendrite.There is a general refinement of the microstructure as the withdraw rate increases.EPMA analysis showed that withdraw rate does not have obvious influence on the segregation of elements.

Dynamic destabilization analysis based on AE experiment of deep-seated,steep-inclined and extra-thick coal seam

No. 5 coal seam in Huating Coal Mine is a deep-seated, steep-inclined extra-thick coal seam where excavation disturbance is quite frequent. The maximum and minimum principal stresses differ widely. During mining, dynamical destabilization happens frequently and induce tragedies. Based on the comparison between the acoustic emission （AE） experiment on dynamical destabilization of coal rock and the related in situ testing results, this article provides comprehensive analysis on the regular quantificational AE patterns （energy rate, total events） of coal rock destabilization in complex-variable environment. The comparison parameters include dynamic tension energy rate, deformation resistance to compression, and shear stress.

Study on melting available silicone from coal gangue

Available silicone was melted from coal gangue samples from Hancheng diggings through calcination, digestion, and other means. The best calcination temperaturewas determined from a range of 550-1150^(。)C; and the best time, from a range of 0.5-5 hby colorimetry method. The proper ratio of coal gangue, limestone, sodium carbonate, andcaustic soda was then determined through orthogonal experiment. The results show thatthe proper extraction condition for available silicone is the ratio of coal gangue, limestone,sodium carbonate, and caustic soda at 1:0.5:0.1:0.05, calcination temperature at 700^(。)C,and calcination time at 2 h. In this condition, the available silicone content can be morethan 19.65%.