scholarly journals Dynamic Secondary Borehole-Sealing Method for Gas Drainage Boreholes along the Coal Seam

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Wei Qin ◽  
Jialin Xu
Keyword(s):  
Abutment Pressure ◽  
High Water ◽  
Test Results ◽  
Gas Drainage ◽  
Gas Concentration ◽  
Working Face ◽  
Opportune Time ◽  
Sealing Device ◽  
Better Than

Under the influence of advanced abutment pressure, the tightness of a borehole is destroyed, so secondary borehole sealing is needed; however, the opportune time for a secondary borehole sealing is unclear. In addition, current borehole-sealing devices do not have a secondary borehole-sealing functionality. In this paper, an opportunity election model of secondary borehole sealing was established, and a dynamic secondary borehole-sealing device was developed. In working face 3908 of the Kaiyuan Coal Mine, an in situ dynamic secondary borehole-sealing test was conducted. The test results show that the tightness of the boreholes sealed with high-water-expansion slurry is obviously better than that of the boreholes sealed with cement mortar and polyurethane. When a borehole is destroyed by the peak of the advanced abutment pressure, the secondary borehole-sealing measures can significantly improve borehole suction pressure, gas concentration, and gas drainage amount in the advanced abutment pressure loading stage.

Experimental Study on Deep Borehole Pre-Cracking Blasting of Drilling through Strata at Low Permeability Seam

2013 ◽  
Vol 868 ◽  
pp. 339-342
Author(s):  
Jian Liu ◽  
Qian Le
Keyword(s):  
Coal Seam ◽  
Control Area ◽  
Low Permeability ◽  
Gas Extraction ◽  
Test Results ◽  
Deep Borehole ◽  
Coal Seam Gas ◽  
Gas Concentration ◽  
Working Face ◽  
Outburst Coal Seam

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.

scholarly journals Reasonable Layout of High Drainage Roadways for Jiaojiazhai Mine

2022 ◽  
Author(s):  
Dongjie Hu ◽  
Zongxiang Li
Keyword(s):  
Control Program ◽  
Simulation Software ◽  
Fluid Simulation ◽  
Gas Extraction ◽  
Tracer Gas ◽  
Element Analysis ◽  
Gas Concentration ◽  
Working Face ◽  
Deformation Law ◽  
Better Than

Abstract To ensure that the gas concentration at the top corner does not exceed the limit, a reasonable level of the high drainage roadway layout in Jiaojiazhai Mine should be determined. In this work, based on the actual conditions of the working face, an SF6 tracer gas was used to test the connectivity between the high drainage roadway and the working face. A discrete element analysis program was used to simulate the deformation law of the overlying strata in the goaf, and a corresponding caving control program for the surrounding rock was written based on the obtained parameters and “O” ring theory. A fluid simulation software was used to simulate and analyze five goaf models with different high drainage roadway layouts (10, 15, 20, 25, and 30 m). The gas drainage data for two layers (10 m and 20 m) of the high drainage roadway were measured. The results showed that the height of the caving zone in the goaf is approximately 20 m, and when the high drainage roadway is arranged along the roof (when the layout layer height is 10 m), the roadway will be directly connected to the working face, thus pumping fresh air to the working face. The gas extraction effect of the 20 m stratum was better than those of the other strata. The simulation results of the gas extraction were consistent with the measured data. The proposed scheme was practically applied, and its effect was found to be evident, thus solving the problem of high gas concentration at the top corner and increasing the mine output.

scholarly journals Disastrous Mechanism and Concentration Distribution of Gas Migration in Fully Mechanized Caving Stope in Wuyang Coal Mine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Li Chong ◽  
He Sifeng ◽  
Xu Zhijun
Keyword(s):  
Coal Mine ◽  
Concentration Distribution ◽  
Spontaneous Combustion ◽  
Concentration Field ◽  
Gas Migration ◽  
Coal Spontaneous Combustion ◽  
Gas Drainage ◽  
Gas Concentration ◽  
Research Results ◽  
Working Face

The overrunning disaster of harmful gas tends to occur in the working face in thick coal seam with high gas concentration, as the fully mechanized caving stope has the characteristics of high mining intensity, high remnant coal, and high gas content. Therefore, the disastrous mechanism and concentration distribution of gas migration in fully mechanized caving stope are the theoretical basis for gas control scheme. Based on the 7607 working face in Wuyang coal mine, the gas emission quantity in working face is comprehensively analyzed by field measurement in this paper. The gas leakage field, oxygen concentration field, and gas concentration field in 7607 working face are simulated by establishing the equal proportional numerical model. Due to the increase of air leakage in working face caused by the high alley pumping drainage, the risk of coal spontaneous combustion is also analyzed, when gas extraction in goaf is carried out. The research results show that the gas drainage technology in high drainage roadway has a remarkable effect on the gas overrunning phenomenon. The gas concentration near the upper corner of the working surface has been reduced from 0.7%-1% to 0.5%. At the same time, it is necessary to pay attention to the risk of coal spontaneous combustion in the goaf for gas drainage in the high drainage roadway. The width of the oxidation zone in the goaf is about 25 m deeper than that before the drainage. Research results provide the references for gas control technology and coal spontaneous combustion prevention in similar working faces.

scholarly journals Study on the Optimization of a Gas Drainage Borehole Drainage Horizon Based on the Evolution Characteristics of Mining Fracture

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4499
Author(s):  
Tengteng Li ◽  
Bing Wu ◽  
Baiwei Lei
Keyword(s):  
Coal Mine ◽  
Gas Drainage ◽  
Gas Concentration ◽  
Low Level ◽  
Working Face ◽  
Evolution Characteristics ◽  
Gas Disaster ◽  
Fracture Area ◽  
High Level ◽  
Initial Change

Gas disaster restricts the safety development of coal mine. The technology of high-level borehole gas drainage is an important means to reduce the gas concentration in goaf. In order to determine the best position of the end of gas drainage hole, in this paper, based on the geological conditions of Xinyuan coal mine 31009 working face, a series of numerical simulation is carried out; and through the field test, the dynamic change of gas concentration in different height of borehole is monitored. The results show that: When the working face advances to different distances, there are four characteristic distribution areas in the horizontal direction: the fracture area of the original rock stratum, fracture channel generation and development area, fracture channel mature area and fracture channel closure area. Although the drilling horizon is different, the change of gas concentration in drilling can be divided into four stages: gas stabilization stage, gas initial change stage, gas fluctuation stage and gas re-stabilization stage. The variation of borehole concentration can reflect the evolution characteristics of fracture area. The response time of gas change in different layers is also different. In the gas initial change stage and the gas re-stabilization stage, the low-level borehole first responds. The response of gas change in high-level drilling is a long process, so the effect of high-level drilling is better than that of low-level drilling. For 31009 working face, the best gas drainage layer is 32m, and the field gas drainage has achieved good practical results. This study can provide some guidance for the prevention and control of gas disaster in goaf.

Application of TiAl(CN) Metal Ceramic Coating by Reactive Nitrogen-Arc Cladding on Stubble-Cleaning Cutter

2013 ◽  
Vol 341-342 ◽  
pp. 83-87
Author(s):  
Ling Xiao Zhu ◽  
Jian Jun Hao ◽  
Liang Gao ◽  
Yue Jin Ma ◽  
Jian Guo Zhao
Keyword(s):  
Ceramic Coating ◽  
Steel Substrate ◽  
Ceramic Particle ◽  
Test Results ◽  
Simulation Test ◽  
X Ray ◽  
Metal Ceramic ◽  
Quenching And Tempering ◽  
Better Than

The metal ceramic coating of TiAl (CN) by nitrogen-arc cladding technology was produced on the surface of 45#steel.The phase composition of coating was analyzed with X-ray diffractometer; The bonding state and microstructure were observed with scanning electron microscope; The microhardness was examined and the wear resistance of the metal ceramic coating compared with that of 60Si2Mn steel treated by quenching and tempering was tested by abrasive tester as well. The results indicated that the TiAl (CN) ceramic particle synthesized in-situ is distributed dispersively in the cladding and the size is under 3 um. The excellent bonding between the coating and 45# steel substrate is strengthened by the strong metallurgical interface; the coating is uniform and continuous. The maximum microhardness of cladding is HV0.21820 and the abrasive performance is better than 60Si2Mn steel treated by quenching and tempering. The simulation test results showed that the cladding is good, and can be used to the repair and remanufacture for wearable parts of stubble-cleaning cutter.

Numerical Simulation of Gas Transportation in Mechanized Top-Coal Caving with Gob-Side Entry Retaining

2014 ◽  
Vol 577 ◽  
pp. 1170-1173
Author(s):  
Sheng Li ◽  
Jun Wen Li ◽  
Guang Yan Zheng ◽  
Nuo Nuo Ma
Keyword(s):  
Mass Conservation ◽  
In Situ Monitoring ◽  
Gas Migration ◽  
Thick Seam ◽  
Gas Concentration ◽  
Gas Accumulation ◽  
Working Face ◽  
Seepage Theory ◽  
Mining Face

To solve the problem of gas accumulation in thick-seam top-coal caving mining face, goaf gas migration equations were established based on seepage theory and the law of mass conservation. Taking No.7602 working face of Wuyang coal mine as the study object, gas migration rules of goaf in ventilation of U + I and Y+I were simulated by Fluent, and comparative analysis and verification were carried out by in-situ monitoring data. Test indicates that after gob-side entry retaining, average gas concentration value of No.7602 working face Return airway decreased by 39% compared with similar working face, decreased by 39% in gas emission roadway, decreased by 42% in upper corner. Ventilation of U + I can successfully resolve the problem of gas accumulation in upper corner and working face. The conclusion has a good instruction value to gas control in thick-seam top-coal caving mining face.

Gas Control Technology under Unstable Disturbance Stress

2015 ◽  
Vol 15 ◽  
pp. 26-34
Author(s):  
Wei Min Cheng ◽  
Lu Lu Sun ◽  
Gang Wang ◽  
Hong Yuan Qu
Keyword(s):  
Control Technology ◽  
Static Loads ◽  
Gas Drainage ◽  
Gas Concentration ◽  
Pressure Step ◽  
Working Face ◽  
Gas Control ◽  
High Level ◽  
Roadway Deformation ◽  
Surrounding Rock Deformation

Under the action of unstable disturbance stress, the stress concentration and roadway deformation are serious when tunneling along the goaf with small pillar while the adjacent working face is mining. This leads to the abnormal gas discharge and the increase of gas emission, and the effectiveness of gas drainage is reduced. In order to eliminate the threat of gas, the dynamic gas control technology of tunneling along the goaf with small pillar under unstable disturbance stress has been researched. The main sources of loads are confirmed by the analysis of dynamic and static loads. Combined with the force analysis of roadway and pillar, the stress superposition level is affected by the relative location of heading face and working face, and the regional characteristics. The measured surrounding rock deformation of A4007 return roadway heading face fits the theoretical analysis and pressure step of working face. The dynamic gas control technology is researched from the aspects of air volume, high-level gas drainage and goaf drainage, and applied in A4007 working face. The gas has been well controlled with the gas concentration of top corner of 0.62% and gas concentration of return current of 0.35%. As a result of the flow control, the gas drainage has not casused spontaneous combustion.

Measurement and Analysis for Gas Emission Characters in Fully Mechanized Caving Face

2013 ◽  
Vol 353-356 ◽  
pp. 2331-2336
Author(s):  
Xin Jian Li ◽  
Shou Song Guo ◽  
Jun He ◽  
Xiang Fan Mi
Keyword(s):  
Abutment Pressure ◽  
Coal Production ◽  
Coal Face ◽  
Gas Emission ◽  
Obvious Effect ◽  
Gas Concentration ◽  
Working Face ◽  
Measurement And Analysis ◽  
Working Resistance ◽  
The Relationship

According to the practical condition of 3401 fully mechanized caving face in Dayang coal mine, the relationship between strata behaviors, mining technology and stope gas emission are analyzed through real-time monitoring of the support working resistance, advance abutment pressure and gas concentration of working face. It shows that the change of working face abutment pressure has an obvious effect on the regularity of coal face gas emission. The crest value of gas emission falls behind periodic weighting, the lagging time is about one day. Other factors, like coal production processes, daily coal output and advance speed also have close relationships with gas emission.

scholarly journals Improvement and application of hole-sealing technology across seams in Song Zao coal mine

2018 ◽  
Vol 53 ◽  
pp. 02003
Author(s):  
Rili Yang ◽  
Xiaoxia Zhao ◽  
Lan Yu
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Field Conditions ◽  
Test Results ◽  
Pressure Relief ◽  
Gas Drainage ◽  
Working Face ◽  
Sealing Material ◽  
Drainage Effect ◽  
The Cost

Through the analysis on the drilling hole gas drainage effect(2225 working face crossing seam drainage, K2air way drilling field layout, crossing seam drainage gas in K3b coal seam),it is found that hole sealing technology directly affects gas drainage. Based on the original hole sealing technology and combining with field conditions, an improved drilling scheme for transportation roadway was proposed, considering the drilling layout, sealing material and depth, grouting time, pre-plunging depth. Test results of the scheme showed that, with a rise in the cost and drilling pressure relief time, the pressuring-relief gas drainage amount was greatly increased, the drilling field pre-pumping concentration was enhanced to 4.4times, the drainage efficiency was improved.

A High Angle, Double Tilting Cold Stage for the AEI EM7

1974 ◽  
Vol 32 ◽  
pp. 450-451
Author(s):  
P.R. Swann ◽  
A.E. Lloyd
Keyword(s):  
Habit Plane ◽  
Temperature Control ◽  
Tilt Angle ◽  
Cooling System ◽  
Thermal Drift ◽  
High Angle ◽  
Cold Stage ◽  
High Degree ◽  
Better Than

Figure 1 shows the design of a specimen stage used for the in situ observation of phase transformations in the temperature range between ambient and −160°C. The design has the following features a high degree of specimen stability during tilting linear tilt actuation about two orthogonal axes for accurate control of tilt angle read-out high angle tilt range for stereo work and habit plane determination simple, robust construction temperature control of better than ±0.5°C minimum thermal drift and transmission of vibration from the cooling system.

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