Gas control technology for coal and gas outburst mines based on new sealing materials

Abstract

In order to solve the problem of gas overlimit in corner corners of coal and gas prominent mines, through the combination of air leakage mechanism in the goaf, near-field fissure expansion and rich area division, blocking material development and optimization, performance measurement of blocking materials and on-site test, we started to study the causes of gas concentration in corner corners, analysis of roof collapse and transparency in corners and performance test of blocking materials, and optimized the blocking materials by combining laboratory test and engineering test. Considering the thickness of the sealing film, the attenuation ratio of the sealing film thickness, the gelation time, and the gelation viscosity under different ratios, we designed a multi factor orthogonal experiment to optimize the optimal ratio suitable for the engineering site. Factors affecting blocking effectiveness, such as gel water retention and gel flame resistance, were also tested. The sealing scheme was implemented in the 2109 working face of a coal and gas outburst mine in Gansu, China. Through on-site monitoring of the changes in temperature, gas concentration, and air leakage at each monitoring point before and after the use of sealing materials, the analysis of the detection results shows that the temperature changes at each monitoring point after the use of sealing materials do not exceed 0.2°C; The change in oxygen concentration is less than 0.27 %; The gas concentration has decreased by more than 60 %, with a decrease of 71.32 % in the gas concentration in the upper corner. The air leakage has decreased by more than 53 %, and the proportion of decrease in air leakage at the upper corner is as high as 56.83 %. This air leakage control technology has remarkable blocking effect, meets the requirements of corner near-field fissure blocking material, and is easy to prepare, inexpensive, non-toxic, tasteless and green, providing a successful experience for the treatment of similar coal and gas outburst mines that can be referenced.

Keywords

Coal and gas outburst / Air leakage in goaf / Near-field fissure / Gas concentration / Air leakage

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

The authors gratefully acknowledge the financial support of the S&T Program of Hebei (Grant No. 23567602H).

References

[1] G.X. Jing, L.L. Mu, Study on statistical analysis and emergency management of coal mine gas explosion accident, J. Saf. Environ. 23 (10) (2023) 3657-3665.

[2] C. Zhai, Y.X. Cong, et al., Reflection and prospect on the prevention of gas outburst disasters in China’s coal mines, J. China Inst. Min. Technol. 52 (6) (2023) 1146-1161.

[3] L.C. Wang, B.M. Shi, et al., Experimental study on evolution characteristics of coal body spallation during coal and gas outburst, J. Safet. Sci. Technol. 19 (3) (2023) 67-72.

[4] J. Wang, X.L. Wang, Seepage characteristic and fracture development of protected seam caused by mining protecting strata, J. Min. Strata Cont. Eng. 3 (3) (2021) 62-70.

[5] J.F. Ju, Q.S. Li, et al., Permeability reduction test of CaCO3/Fe(OH) 3 repairing single fractured rock specimens, J. Min. Safet. Eng. 41 (1) (2024) 151-159.

[6] Y.Q. Liu, L.J. Xu, et al., Research on development characteristics of overburden fracture in lower protective layer mining of high-gas coal seams, Min. Res. Dev. 44 (2) (2024) 66-73.

[7] R. Tx, J.S. E d wands, R. Jozefowicz,CFD ode ling of methane flow around longwall coal faces, in:Proceedings of the 6th International Mine Ventilation Congress Pittsburgh, 1997, pp. 17-22.

[8] M. W Endt, R. Balusu, CFD Modeling of Longwall Goaf Gas Flow Dynamics, Coal Safety, 2002, pp. 17-34.

[9] N. Yao, X.M. Deng, et al., Strength and failure mode of expansive slurry-inclined layered rock mass composite based on mohr-coulomb criterion, Rock Mech. Rock Eng. 56 (2023) 3679-3692.

[10] J.X. Zhang, W.B. Song, et al., Experimenta1-study and application of new polymer foam plugging material, J. China Coal Soc. 43 (S1) (2018) 158-166.

[11] S.J. Yu, H. Zhao, et al., Research on gelling and fire extinguishing characteristic of a-new-style foamed gel, Fire Saf. Sci. 22 (4) (2013) 219-225.

[12] B.S. Nie, Y.K. Ma, et al., Micro-scale mechanism of coal and gas outburst: a preliminary study, J. China Inst. Min. Technol. 51 (2) (2022) 207-220.

[13] X.B. Zhang, P. Wang, H. Wang, Study on gas migration law in goaf under the influence of small faults, Coal Sci. Technol. 1-18 ( 2024), 02-07.

[14] P.X. Zhao, X.B. An, et al., Coupling mechanism of pseudo-slope length change and gas concentration in upper corner of fully mechanized caving surface of inclined thick coal seam in Xinjiang, Coal Sci. Technol. 51 (S1) (2023) 73-85.

[15] C.J. Fan, X.F. Lai, et al., Coal and gas outburst prediction model based on principal component analysis and improved support vector machine, Geohazard Mech. 1 (2023) 319-324.

[16] D.K. Wang, L.Y. Zhang, et al., Analysis of dynamic failure characteristics and gas seepage law of gas-bearing coal under impact loads, J. China Coal Soc. 1-16 (2024). -02-08].

[17] A.I. Wen jia, Mechanism of the Binding of Alkaline Earth Metal Ions to Alginate, Hubei University of Technology, 2015, pp. 1-4.

[18] B. Isabelle, P. Serge, Molecular basis of Ca2t-induced gelation in alginates and pectins: the egg-box model revisited, Biomacromolecules 2 (4) (2001).

[19] Z.B. Peng, C. Zhang, et al., A laboratory study on a PVA gel plugging agent, Nat. Gas. Ind. 37 (6) (2017) 72-78.

[20] F.C. Sun, Study on the Preparation and Properties of New Polyvinyl Alcohol Gel Sealing Material for Mining, CUMT, 2022.

[21] Y.Q. Liu, L.J. Xu, Research on development characteristics of overburden fracture in lower protective layer mining of high-gas coal seams, Min. Res. Dev. 44 (2) (2024) 66-73.