Experimental research on increasing effect of water injection in coal seam with chelating agent

ABSTRACT

Coal seam water injection has a significant effect on the prevention and control of coal mine rock burst, and the pore characteristics of the coal seam is an important factor affecting the effect of coal seam water injection. With the deep mining of coal mine, the physical and mechanical properties of coal body change, the porosity of the coal seam decreases, and the injectability of the coal seam becomes worse. With the passage of time the minerals and CO2 in coal makes it more difficult to inject water. In order to obtain the reason why the water injection in coal seam becomes worse, the water injection additive with excellent performance is found, and a series of experiments on the impact tendency of coal body are carried out. The results show that the mine water used for coal seam water injection was liable to precipitate more ions, which may react with CO₂ dissolved in water to form precipitates, plug coal pore and reduce the fluidity of water in the coal seam, resulting in poor water injection effect. Adding chelating agent IDS in aqueous solution can effectively prevent precipitation formed by the combination of easily precipitated ions and carbonate ions in it. At the same time, the chelating agent IDS can decompose precipitated ions from the surface of coal particles, change from insoluble to soluble, promote pore development, increase the effect of water injection and the pore diameter of the coal, and reduce hydrophobic groups on the coal surface. IDS can reduce the impact tendency of coal, and it is an environmental protection additive that can increase permeability. It can provide reference for prevention and control of composite power disasters by coal seam water injection.

KEYWORDS:

• Water injection in coal seam
• chelating agent
• effect of water injection
• precipitable ions

Acknowledgments

The authors gratefully acknowledge Pingdingshan No.11 Mine for the financial resources provided, Liaoning University for the performed instrumental analysis. This paper was supported by the State Key Research Development Program of China (Grant No. 2017YFC0804208).

Additional information

Funding

This work was supported by the National Key Research and Development Project [2017YFC0804208],The National Natural Science Foundation of China[51904141], the Educational Commission of Liaoning Province of China [LQN201705].