Practice and adaptable conditions classification of aquifer-protective mining in longwall coalface for shallow seam with thin bedrock

A set of adaptable conditions classification of aquifer-protective mining in thelongwall coalface for shallow coal seams with thin bedrock was put forward to deal withthe conflict between water protection and high efficiency for the mining field in west China.This classification was suitable for shallow coal seams with different thickness and wasbeneficial to the local environmental protection.Using the 3-Universal Distinct ElementCode (3DEC) numerical software, the height of the fractured zones for shallow coal seamswith thin bedrock was calculated and analyzed, and its predicting formula was achieved.Meanwhile, according to the lithology and the weathering degree of the shallow coal seam,the thickness of the protective layer was determined as 10 m and the overlying water bodyof loose water-bearing sand for shallow coal seams with thin bedrock was divided intothree types, namely, weak, medium and strong.Based on these, the necessary bedrockthickness of the longwall coalface for shallow coal seams with thin bedrock was confinedaccording to the different mining height and water yield nature of the overlying loose water-bearing sand.Combined with the present mining status, a set of new methods ofadaptable conditions classification of aquifer-protective mining technology in the longwallcoalface for shallow coal seams with thin bedrock was put forward.

Matter-elements model and application for prediction of ccoal and gas outburst

The theory and method of extenics were applied to establish classical field matterelements and segment field matter elements for coal and gas outburst.A matter-element model for prediction was established based on five matter-elements,which includedgas pressure,types of coal damage,coal rigidity,initial speed of methane diffusionand in-situ stress.Each index weight was given fairly and quickly through the improvedanalytic hierarchy process,which need not carry on consistency checks,so accuracy ofassessment can be improved.

Analysis of irrationality of coal susceptibility to spontaneous combustion determination method with fluid oxygen adsorption

Based on experiment results and theoretical analysis,pointed out that the method of coal susceptibility to spontaneous combustion determination with fluid oxygen adsorption can not present the essence of coal oxidation process and oxidation reaction. The method is incorrect,paying attention at one aspect and ignoring the rest.The method is not reasonable for coal susceptibility to spontaneous combustion determination.Sus- ceptibility to spontaneous combustion of coal reflects chemical property of coal oxidation with oxygen absorption and heat release at low temperature.Coal's susceptibility to spon- taneous combustion is mainly decided by the number of molecules with reaction activation energy and activation molecule production rate at certain temperature.Therefore,index of susceptibility to spontaneous combustion should adopt accumulative value or trend of heat release or oxygen adsorption during oxidation process.

Overview of the South African mine health and safety standardization and regulation systems

Outlined the South African mine health and safety regulatory framework,in- cluding the roles of government,tripartite council,service agencies,mine enterprises, rescue stations and workers unions,analyzed the institutional structures of South African mine health and safety standardization,including the South African standard and specifi- cation systems and standard development processes,and characterized the South African mine health and safety standardization and regulation systems.Intended to provide some suggestions for the transformation and improvement of mine health and safety standardi- zation and regulation systems in China or in similar situations.

Research on dynamic updating of three dimensional geological modeling based on the OO-Solid model

The dynamic updating of the model included: the change of space border,addi- tion and reduction of spatial component (disappearing,dividing and merging),the change of the topological relationship and synchronous dynamic updating of database.Firstly, arming at the deficiency of OO-Solid model in the aspect of dynamic updating,modeling primitives of OO-Solid model were modified.And then the algorithms of dynamic updating of 3D geological model with the node data,line data or surface data change were dis- cussed.The core algorithms was done by establishing space index,following the way of facing the object from bottom to top,namely the dynamic updating from the node to arc, and then to polygon,then to the face of the component and finally to the geological object. The research has important theoretical and practical values in the field of three dimen- sional geological modeling and is significant in the field of mineral resources.

Three dimensional modeling and developing of tunnel based on objectarx technique

Studied the methods of 3D modeling in tunnel of underground and realized the3D visual expression of tunnel using language Object ARX CAD.

Performance assessment of water mist applied in gas burning suppression in underground coal mine

The main objective of the present study was introduced water mist suppressiontechnology to prevent and control gas burning which occurred during drilling at Wu20160working-face in No.10 coal mine of Pingdingshan Ltd..Based on the self-developed ex-periment platform,a series of fire suppression tests to evaluate the performance of a watermist system were conducted.The detailed measurements of the spray characteristics,i.e.,the Sauter Mean Diameter(SMD),the velocity and spray angle which are the main pa-rameters considered in the Study,were obtained by using LS-2000 Sizer.The amount ofwater consumed and the water flux density distribution over the cross section downstreamthe nozzle exit were measured by cup collector method.The operating pressure of thewater mist nozzle is set to 0.5 MPa,the droplet SMD of 104 pm,the water flux density dis-tribution from 0.71 to 8.47 L/(m^2.min),the average velocity of 2.14 m/s.The experimentalresults show that the averaged time required for extinguishment is 3.14 s,and the corre-sponding amount of water used during fire test is about 0.11 kg.The gas fire suppressionsystem reduces the temperature in combustion chamber of the experimental apparatusbelow the ignition point of the gas,which can effectively avoid the occurrence of the gasfire in coal mine.

Numerical simulation of deep-level rockburst in Fuxin coalfield

On the basis of ANSYS finite element model(FEM) software, the deep-level rockburst in Fuxin coalfield was simulated numerically. Based on Haizhou Mine and Wulong Mine as two typical deep-level rockburst examples in Fuxin coalfield, the rules and characteristics of the deep-level rockburst were analyzed. And the models were es- tablished. For Haizhou mine, the relationship between mining distance and rockburst was presented when 100, 300, 600 m were mined in 3313 working face. When 300 m were mined, the rockburst began to emerge. When 600 m were mined, the rockburst was the most possible to happen and the compression stress of the working face reached to the maximum value. The effect of tectonic stress on synclinal axis is also a key factor to rockburst occurrence. This was verified by the rockburst happened when 496 m were mined. For Wulong mine, based on the 311 working face as an example, the contours of Y stress in the roof and floor were obtained when the mining distance were 100, 200, 300 and 400 m. When 100 and 400 m were mined, the high stress con- centration regions occurred in the front of working face. This shows the rockburst is easy to happen. It is confirmed by the rockburst when 91m were mined in 311 working plane. The above indicates that the numerical simulation has instructive rule to study the deep-level rockburst in Fuxin coalfield.

New method of orientation and calibration for gas detector

The software system, hardware system and performance principle of the gas detector were briefly described. A new method was developed for orientating and cali- brating the instrument. The method shows excellence in automation and intelligence, and presents simpler and more reliable new method for orientating and calibrating the nominal physical quantity of the nonlinear sensor.

Experimental study of a new multifunctional device for rock fragmentation

A new multifunctional testing device for rock fragmentation was introduced, which can conduct many experiments such as single cutting under static load, crushing under impact load, thrusting under static load and cutting-impact test under the dynamic and static load. The results of granite and concrete抯 experiments with polycrystalline diamond compact (PDC) flat cutters and carbide alloy cutters under different loadings show that the device has good performance, and the characteristics of broken rock under the combined loads are similar to that under the single static pressure or impact crushing the rock, and the combined loads can increase the effect of rock fragmentation obviously. The experimental methods and effects have the important meaning for studying new drill-ing tool on hard rock fragmentation.

Analysis on the anchor mechanism of the full length resin bolt

The purpose of this paper is to reveal the stress distribution characteristic along the full length anchor bolt. Based on the mechanic model set up, the author calculated the anchor mechanism of the full length resin rock bolt. The stress distribution characteristic is different according to different type of surrounding rock. The conclusion is important to optimize the roadway bolt support design.

STUDY ON THE SEPARATION AND UTILIZATION TECHNOLOGY OF MAGNETIC BEAD IN FLY ASH

On the basis of study on physical and chemical properties of magnetic bead (MB) in fly ash (FA), the paper gives out the separation methods of MB and results of three separating process. The result of comparative test in size, density, stability, magnetic material content, specific magnetic susceptibility (SMS), medium recovery oxidation resistance and wear resistance between MB and magnetic fines currently used in dense medium separation leads to that using MB recovered from fly ash is used as medium solids in coal cleaning in stead of magnetic fines not only have no influence upon taryests of separation, but can bring good economic and social benefits.

HIGH-RESOLUTION SEQUENCE DIVISION AND TRANSGRESSIVE EVENTS COAL FORMATIONIN SOUTHEASTERN NORTH CHINA EPICONTINENTAL BASIN

The sea level changes in the Paleozoic epicontinental basin were of high frequency and the transgressive events were episodic.This kind of sea level changes controlled both the basin filling and the coal accumulation within the basin.Coal accumulation in the transgressive process is one of the typical features of the North China epicontinental basin.High resolution sequence analysis to the Permo carboniferous coal series based on the core observation indicates that the epicontintental coal bearing succession can be divided into 1 tectonic sequence (the original type of basin filling), 3 supersequences, 12 third order sequences and about 48 parasequences.The third order sequences are of dual configuration sequences that are composed of transgressive systems tract in the lower part and highstand systems tract in the upper part.The transgressive systems tracts are relatively thin in thickness and have fewer parasequences (commonly 1 to 2), while the highstand systems tracts are thick, generally consist of several parasequences.

AN ADVANCED COAL DESULFURIZATION PROCESS──SELECTIVE FLOCCULATION

Selective flocculation is an idea separation method to separate ultrafine pyrite from coal. A number of selective flocculation separation tests under different conditions have been done and the results are very encouraging. The results also show that desulfurization and deashing can be finished simultaneously in selective fIocculation process. It is an advanced coal desulfurization process.

STUDY ON GATEWAY BOLTING EXCAVATED IN INCLINED COAL SEAM

A typical gateway is analyzed using fully-deformable discrete element method. The fractured zone around the gateway is measured in field. Based on the measurement results and theoretical analysis, a comprehensive support scheme adopting bolt and steel belt is proposed. Discrete element method is used to assess the bolting scheme, and displacement monitoring in field is also carried out. Having been put into practice, it is proved that the scheme is both successful and rational. According to theoretical analysis and monitoring in field, some important keynotes that should be noticed in gateway bolting practice are presented as well.

THE THREE DIMENSIONAL MODELS AND THEIR IDENTFICATION MINING SUBSIDENCE

The theory and method for selecting the three dimensional prediction models of mining subsidence are studied in this paper. Namely, based on system identification and statistics theory, an optimum mining subsidence prediction model can be selected. The method proved by a trpical case has a good prospect fbr detetming the physical model of rock mass for mining subsidence