Hydraulic flushing in soft coal sublayer: Gas extraction enhancement mechanism and field application

Zhang, Hao; Wang, Chenghao; Yuan, Liang; Wang, Liang; Pan, Zhejun

doi:10.1002/ese3.405

Cited by 19 publications

(13 citation statements)

References 46 publications

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“…China is currently faced with the most severe gas disaster in coal mines in the world (Yuan 2016;Zhang et al 2019a; Xue and Yuan 2017). Gas pre-drainage is effective for coal mine gas control, and the the performance of sealing material is the key to ensuring drainage e ciency.…”

Section: Introductionmentioning

confidence: 99%

WITHDRAWN: Strength Analysis and Ratio Optimization of New Sealing Materials With Response Surface Method

Xue

Guo

et al. 2020

Preprint

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The influence of the interaction among water-cement ratio, content of expansion agent, water reducing agent, and retarder on the compressive strength of new sealing material was studied. The Design-Expert software was used to design experiments, establish a quadratic polynomial regression model, draw response surface, and optimize parameters. The microstructure morphology of the sample is explored by scanning electron microscope (Hereinafter referred to as SEM). The research results show that the interaction between water-cement ratio and expansion agent content is the most crucial factor affecting the compressive strength of the new sealing material. Under the optimal condition of 0.4% water reducing agent, 0.04% retarder, 0.8 water-cement ratio, and 8% expansion agent, the compressive strength of the sealing material cured for 3 d and 7 d is 39.247 MPa and 41.044 MPa, with the maximum absolute error of 1.71% and 2.81%, which proves the high accuracy of the model. The main hydration products of the new sealing material are ettringite and C-S-H gel, interlacing each other to form a dense structure, which contributes to the high strength of the new sealing material.

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Section: Introductionmentioning

confidence: 99%

WITHDRAWN: Strength Analysis and Ratio Optimization of New Sealing Materials With Response Surface Method

Xue

Guo

et al. 2020

Preprint

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“…However, when the soft and hard coals coexist in the coal seam, the prediction of coal and gas outburst is carried out according to these critical values, and it is found that the prediction index is not sensitive and the critical value is unreliable sometimes. − Many coal seams in mines often contain soft and hard coal stratification. There are significant differences in mechanical characteristics and permeability between soft and hard coal. − The mechanical strength of soft coal stratification is low, which is a prominent breakthrough point. − Therefore, based on the difference of adsorption structure between soft and hard coal, it is of great significance to study the critical value of the inspection index for the regional outburst risk caused by the residual gas content when soft and hard coals coexist.…”

Section: Introductionmentioning

confidence: 99%

Study on the Critical Value of Residual Gas Content Based on the Difference of Adsorption Structure between Soft and Hard Coal

Liang

Lin

et al. 2021

ACS Omega

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In view of the difference of the adsorption structure between soft and hard coal, there is a big difference in the critical value of the inspection index for the regional outburst risk caused by the gas content. For the coal seams with soft and hard coal stratification, the model of gas content in the equilibrium state was established first, and the microscopic parameters of different rank coals were determined by the low-temperature liquid nitrogen adsorption test and mercury intrusion test. Then, the adsorption capacity of coal samples was determined by the adsorption test. Finally, the residual gas content of the coal seam in the equilibrium state was calculated based on the adsorbed gas content, and the critical value of prediction indexes of regional outburst based on the residual gas content was studied. The results show that for the same metamorphic degree, the specific surface area of soft coal is larger than that of hard coal. However, under the same gas pressure, the residual gas content of hard coal of anthracite and lean coal is greater than that of soft coal with the same metamorphic degree, while that of meager-lean coal and gas-fat coal is opposite. It is suggested to adopt the small value (rounded) of the measured gas content of soft and hard coal at 0.74 MPa as the critical value of the residual gas content in the regional effect test from the economic perspective. It is of great significance to determine the critical standard of the residual gas content in the regional effect test according to local conditions for reducing the cost of outburst prevention work.

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“…China is currently faced with the most severe gas disaster in coal mines in the world [1][2][3]. Gas predrainage is effective for coal mine gas control, and the performance of sealing material is the key to ensuring drainage efficiency.…”

Section: Introductionmentioning

confidence: 99%

Response Surface Method for Strength Analysis and Proportion Optimization of New Type Sealing Materials

et al. 2021

View full text Add to dashboard Cite

The influence of the interaction among water-cement ratio, content of expansion agent, water reducing agent, and retarder on the compressive strength of new sealing material was studied. The Design-Expert software was used to design experiments, establish a quadratic polynomial regression model, draw response surface, and optimize parameters. The microstructure morphology of the sample is explored by a scanning electron microscope (hereinafter referred to as SEM). The research results show that the interaction between the water-cement ratio and expansion agent content is the most crucial factor affecting the compressive strength of the new sealing material. Under the optimal condition of 0.4% water reducing agent, 0.04% retarder, 0.8 water-cement ratio, and 8% expansion agent, the compressive strength of the sealing material cured for 3 d and 7 d is 39.247 MPa and 41.044 MPa, with the maximum absolute error of 1.71% and 2.81%, which proves the high accuracy of the model. The main hydration products of the new sealing material are ettringite and C-S-H gel, interlacing each other to form a dense structure, which contributes to the high strength of the new sealing material.

show abstract

Hydraulic flushing in soft coal sublayer: Gas extraction enhancement mechanism and field application

Cited by 19 publications

References 46 publications

WITHDRAWN: Strength Analysis and Ratio Optimization of New Sealing Materials With Response Surface Method

WITHDRAWN: Strength Analysis and Ratio Optimization of New Sealing Materials With Response Surface Method

Study on the Critical Value of Residual Gas Content Based on the Difference of Adsorption Structure between Soft and Hard Coal

Response Surface Method for Strength Analysis and Proportion Optimization of New Type Sealing Materials

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