Numerical simulation on the movement law of overlying strata in the stope with a fault and analysis of its influence on the ground gas drainage boreholes

In order to study the influence of a fault on the movement law of the overlying strata as well as its effect on the gas drainage boreholes, based on the practical situation of 1242（1） panel at Xieqiao Mine in Huainan, the Finite Element Method （FEM） model was built up, and the distribution of the stress field and the displacement field of the overlying strata in the stope with a fault were simulated by using the FEM software ANSYS. The results indicate that because of the existence of the fault, the horizontal displacement of overlying strata near the gas drainage borehole becomes larger than that in the stope without a fault, and the distribution of the stress field of the overlying strata changes greatly. When the working face is far away from the fault, the distribution of the stress field is approximately symmetrical. As the working face advances to the place 50 m away from the fault, the stress range at the right side goaf area is as twice as that at the left side. Here, the stress distribution area of goaf area and the fault plane run through, the fracture-connected-zone is formed. It can be presumed that the gas adsorbed in the coal and rock will flow into the fault zone along the fracture-connected-zone, which causes the quantity of gas drainage reduce remarkably.     

Investigation on displacement field characteristics of tunnel＇s surrounding rock and coal seam at FMTC face

The change rules of displacement field characteristics of coal seam and tunners surrounding rock were obtained by means of numerical simulation-FLAC^3D and site observation, and according to engineering geology and exploitation technology of 1151 （3） fully mechanized top coal caving （FMTC） face in Xieqiao colliery. The research＇s results show that the top coal displacement on the top of FMTC face is apparently larger than those of the middle and the bottom, the top coal begins to move in the front of the face＇s wall, and the sub-level top coal-rock moves ahead of the low-level top coal-rock, the vertical displacement of top coal-rock increases gradually as the decreasing of distance to face Top coal and overlying strata in vertical direction are always in compressed state in the front of face, then the top coal begins to separate from the overlying strata at the upside of face. The support loading at face is mainly the deformation pressure due to top coal and main roof＇s movement, and it is not suitable for the FMTC face with traditional support design. Surrounding rock movement of the face is of near-field effect, the surrounding rock deformation is acute greatly near to the face, the ideas of supporting design for the tailentry and headentry should be changed from loading control to deformation control.     

Research on application of rockmass breaking and inversion stress distribution by MS monitoring in Iongwall face

Brought forward the conception of conventional MS monitoring, and described the different monitoring ranges of frequencies and magnitude about earthquake and conventional MS monitoring and MS monitoring in detail. The monitoring results received by the Polish ARAMIS M/E monitoring system and the monitodng instrument designed by the author＇s research group in the same colliery show that the events amount received by conventional MS monitoring instrument which is only about 1/20 of the MS monitoring events, and it can only describe violent activity in larger range and be only applied to monitor hard and thick surrounding rock under mine. Meanwhile the small scale and high precision MS monitoring instrument can receive a lot of low rock fracturing signals, which can actualize the rock movement inversion and precisely descdbe 4-D changes of stress fields, and depend on the observed results we can determine the upper limits of mining and describe S-shaped strata spatial structure and high stress field in Iongwall face surrounded by two sides mined areas.     

A CUSP CATASTROPHE, PRECURSORS PATTERN ANDEVOLUTION PROCESS OF ROCKBUST OF COAL PILLARUNDER A HARD ROCK SUBJECT TO ELASTIC SUPPORT

The rockburst of the coal pillar under a thick hard roof stratum is modelled as the instability failure problem of coal pillars under strata subject to elastic support. The instability mechanism of rockburst is studied by applying cusp catastrophic theory. The effects of the stiffness ratio of the system and loads imposed on the system on the rockburst are explicated.The factors affecting rockbursts are discussed. Based on them, the “evolution process, the forewarning regularity and forewarning sings of rockbursts are studied. It is indicated that the subsidence velocity of roof stratum, which increases quickly and tends to infinity, is the forewarning measurable signs of the rockbursts of coal pillar.     

The depth effect of geological mechanics and hydraulic behaviors of rock mass

Significant changes of geological and hydraulic behaviors of rock mass with depth was studied. The general regulation and the critical depth of qualitative change of rock mass geological and hydraulic changes with depth were studied. Preliminary research show that the mechanical properties of rock mass gradually change from solid to plastic with the increasing of its buried depth. The critical depth of this tendency was controlled by geological properties of rock mass and its overlying rock. The critical depths are different in different regions because of its different geological condition. The general change depth of rock mass from rigid property to plastic property in coal mine regions of North China is about 1 800-2 300 m. The hydraulic permeability of rock mass will change significantly with depth because of the geological and hydraulic mechanics changes from solid to plastic and the groundwater circulation condition in karst and fractured aquifer will also change. The results reflact that the stability, deformation, failure, permeability and groundwater hazardous condition of rock mass during deep mining process are quite different from that of shallow mining＇s.     

Study on relation between tectonic stress and coal-mining subsidence with similar material simulation

Using a minitype and stress-type test device for similar material simulation of coal-mining subsidence, the relation between tectonic stress and coal-mining subsidence was successfully simulated, furthermore, the test period of similar material simulation was obviously shortened and the test process was more dexterous and convenient. To do similar material simulation with the minitype and stress-type test device was feasible and high-efficient. Bringing two models with the same geological and mining conditions to bear lateral compressive stress and tensile stress respectively and simulating the process of underground mining, the test results indicate that： under the compressive stress, the collapse of the coal roof occurs belatedly and the damaged range in cover of coal seam is smaller, therefore the movement and deformation of the cover and its damage to the ground geological environment are not evident; whereas under tensile stress, the situation is contrary to which mentioned above. A conclusion was obtained from the test that the ground environment hazards in coal mining areas were controlled by the regional geological tectonic stress field.     

Investigation into the surface active groups of coal

The oxidation heat of coal is the direct reason leading to coal spontaneous combustion. When coal is exposed in oxygen atmosphere, the physical adsorption and chemisorption happened, and then which resulting chemical reaction followed heat between coal and oxygen. Owing to the complexity and uncertain of molecular structure of coal, it was only reduced that bridge bonds, side chains and O2-containing functional groups in coal may be prone to oxidation in last year, but not to deeply investigate into the structures and the type of the active radicals. In this paper, according to the last achievements in coal structure research, the hypomethylether bond, hypoalkyl bond of (z-carbon atom with hydroxyl and α-oarbon atom with hypomethy side chain andhypomethyl bonds linking up two aromatic hydrocarbon in bridge bonds, and methoxy, aldehydeand alkyls of α-carbon atom with hydroxy in side bonds are inferred to be free radical easily to lead to oxidize coal under the ambient temperature and pressure. The order from strong to weak of oxide activation of the seven surface active groups is aldehyde side chains, hypomethylether bonds, hypoalkyl bonds of α-carbon atom with hydroxyl, hypoalkyl bonds of α-carbon atom with hypomethyl, hypomethyl bonds linking up two aromatic hydrocarbon, methoxy, alkyls side chains of α-carbon atom with hydroxyl. Because of the two unsaturated molecular tracks of O2 unpaired electron clouds of the part of surface active groups of coal enter molecular tracks of O2 to lead to chemisorb on the conjugate effect and induced effect of surface active groups, and then chemical reaction followed heat happens in them. On the basis of change of bond energy, weighted average method is adopted to count the reaction heat value of each tool CO, CO2 and H2O. The property of coal spontaneous combustion is different for the different number and oxidability of the active structure in the coal resulting in the different oxidation heat.     

FEASIBILITY ANALYSIS OF SAFETY SIMULTANEOUS EXTRACTION OF COAL AND COALBED METHANE

Coalbed methane is of great value to extract and utilize in China, but the result of such research is not satisfied yet today. The paper analyzed the storage characteristics of coalbed methane, and then studied the behavior of coalbed methane using the key stratum theory of strata control. According to the features related to coalbed methane accumulations and delivery, the technique for safely simultaneous extraction of coal and coalbed methane is proposed, and benefit analysis is made too.     

Correlation between coal characteristics and methane adsorption on China＇s coals

It is highly important to investigate relationship between coal characteristics and methane adsorption on coal in the fields of coalbed methane recovery. Based on data examination of coal quality indexes collected from the literatures, regression equations for Langmuir adsorption constants, VL or VLIPL, and coal quality indexes for selected coal samples were developed with multiple linear regression of SPSS software according to the degree of coal metamorphosis. The regression equations built were tested with data collected from some literatures, and the influences of coal quality indexes on CH4 adsorption on coals were studied with investigation of regression equations, and the reasons of low accuracy to Langmuir constants calculated with regression equation for a few coal samples were investigated. The results show that the regression equations can be employed to predict Langmuir constants for methane adsorption isotherms on coals obtained using volumetric gas adsorption experiments, which are conducted at 30 ℃ on a wet or dried coal samples with less than 30% ash content in coal. The influence of same coal quality index with various coal rank or influence of various coal quality indexes for same coal rank on CH4 adsorption is not consistent. The regression equations have different accuracy to different coal rank, in which the VL equations supply better prediction accuracy for anthracite and higher prediction error for lower metamorphosis coal, and the PL prediction error with VL and VL/PL equations is lower to bituminous coal and higher to anthracite.     

Study on safe thickness of overlying thin bedrock in fully-mechanized top-coal caving face with thick coal seam

To prevent support crush, the overlying strata safe thickness and its influential elements were studied by the adoption of theoretical analysis, numerical simulation and in-situ measurement. According to the production and geological condition of first face in Sima coal mine, the results indicate that the clay contains large permissible bearing ability and has better arching force. After mining destruction, stable structure is formed in bedrock to ensure face safety. The clay thickness ＆ bedrock thickness are the key influential elements to stable structure. The minimal bedrock thickness is about 40 m to ensure safe mining under loose surface soil condition. When surface soil contains mainly thick clay, it forms steady structure with the composition of thin bedrock, so that it can reduce minimal thickness of bedrock and to ensure safe mining. When clay thickness is 40 m, minimal bedrock thickness is 20 m. When clay thickness is 30 m, minimal bedrock thickness is 30 m. Bearing pressure peak ranges from 5 to 15 m in the front face under thin bedrock condition. The bearing pressure distribution range is 15 m. Main roof break distance is small, and initial weighting of main roof is not distinctive, while first periodic weighting of main roof is quite distinctive.     

稀散金属产业的观察与思考

分析了近年来国内外稀散金属产业的生产、应用、资源与市场状况.铟锡氧化物靶材、砷化镓晶片、锗红外材料、铼高温合金和硒在电解锰及玻璃的应用等已成为稀散金属的主要应用领域.稀散金属的产量快速增长达到历史高位而导致了市场的失衡.以GaInP_2/GaAs/Ge,CIGS和CdTe为代表的非硅系太阳能电池是稀散金属的新兴应用领域,将给稀散金属带来日益增长的需求.     

China rare earth market review

正November 21~30,2014Due to weak demand from downstream industries,transactions of rare earth in Chinese domestic market were inactive.It was difficult to sell any rare earth products except for dysprosium oxide and terbium oxide.Suppliers lost confidence in recent market.Demand for rare earth products was soft.Consumers continued to take a wait-and-see attitude.Rare earth export market remained slow.     

Current situation and future trend of China rare earth luminescent materialindustry(continued)

<正>Developing ecological lighting source The world is facing the big problem of energy shortage today and the contradiction between economy development and environmental protection is worsened.Therefore,people are more likely to choose an ecological light source that is more energy efficient and environmental friendly.The choice provides great opportunity for the development of rare earth optical material industry in China.The concept of green lighting positions rare earth luminescent material as a leading player in illumination market.The light source of both rare earth luminescent lamp and LED lamp is ecological and energy saving.This is why     

Galaxy Magnets achieved the net profit of 34.02 million yuan in the first six months of 2014

正Galaxy Magnet announced its financial results for the first half of 2014 on August 14.For the first six months ended on 30 June 2014,Galaxy Magnet achieved operation income of RMB 182.3 million,up8.40% over the same period of 2013,and the net profit attributable to the shareholders of the listed company of 34.02 million yuan,increasing 35.49% over the same period of last year.Stable performance increase was led by development of new customers and application market of magnets.     

Rare Earth Application in Steel in China

<正>China has rich rare earth resources.Output of rare earth and steel in China ranks the top first in the world.However,there is still certain distance between the steel produced in China and developed countries from the point of varieties and quality.China still has to import some types of steel.Improving the quality should be emphasiZed in future development of steel industry in China.Rare earth can be used to upgrade traditional steel     

Brief news

正Corun invested another 50 million yuan in power battery for HEV Hunan Corun announced on 27 June that they had signed the cooperation agreement to jointly built Corun(Shaoxing)Autos Power Battery System Co.,Ltd.in Shaoxing Binhai New City.According to the announcement,total registered     

铜熔炼中锍品位对杂质元素分配行为的影响

借助于多相、多成分系统中平衡计算的手段，开发出微量元素砷、锑、铋及伴生元素铅、锌等在铜熔炼中分配行为的计算机模型。利用该模型对铜熔炼过程进行计算机模拟，分析了冰铜品位对砷、锑、铋、铅和锌等杂质元素的分压、活度系数及它们在冰铜、炉渣和气相中分配率的影响，并讨论其热力学分析结果对生产实践的指导意义。     

减震防磨损溜槽在山东京杭水铁联运中的应用

溜槽作为煤炭运输中连接运输设备和储煤设施的重要部件，其设计的合理性直接影响到整个生产系统。尤其落差大的溜槽在使用过程中，不仅噪声大，磨损快，而且还会对下一级胶带冲击很大。实际生产中，溜槽维护成本高，严重影响煤炭运输正常作业。结合山东京杭水铁联运项目中溜槽运量大、落差高的特点，阐述了常用的防冲击、减震防磨损的方法以及在实际使用中的优缺点。并结合设计经验，提出了新的应用设计，通过计算机头落煤曲线，得出机头溜槽物料大概落煤点，设计堆煤网格，形成集料槽；在溜槽底板设置阻尼层，并用螺栓固定，起到缓冲减震降噪的作用。同时也起到了保护下一级胶带和落煤点缓冲托辊的作用。     

重型结构件快速标准化定位在液压支架生产中的应用

随着工业自动化的快速发展，机器人在加工过程中的利用率越来越高。但由于工业机器人对定位精度的要求非常高，往往会因为不能准确定位而对机器人接下来的加工操作造成一定的误差影响。而这种误差导致的最直接的结果就是焊接机器人无法准确定位到正确的焊缝位置，出现焊偏、焊漏或者熔深不够等焊接缺陷。以液压支架生产过程中对重型结构件的定位为实例，对旧式的定位块进行改进，在一定程度上增加了定位方式的灵活程度和精确程度。经过测试，新的定位方法极大地提高了定位的精确度，降低了定位过程中的操作难度，缩短了定位活件的时间。     

庐枞矿集区地震资料干扰波分析与压制研究

庐枞矿集区地表条件及地质构造非常复杂,导致地震资料波场关系复杂,有效反射信号弱,干扰波种类多及特征在时间与空间方向上差异大。通过对干扰波特征及压制技术的分析研究,确定了适合矿集区复杂地表条件下的干扰波压制方法和流程。庐枞矿集区地震资料处理的实际应用显示,使用该方法压制干扰波效果明显,提高了资料的信噪比。