Study on the Response Law of Coal Pore Structure and Permeability Affected by Acidification Time

Xinglin Qin; Yaolin Cao; Xianfeng Liu; Longkang Wang; Baisheng Nie

doi:10.1021/acsomega.3c02923

Study on the Response Law of Coal Pore Structure and Permeability Affected by Acidification Time

ACS Omega. 2023 Aug 8;8(33):30213-30220. doi: 10.1021/acsomega.3c02923. eCollection 2023 Aug 22.

Authors

Xinglin Qin^{1

2}, Yaolin Cao^{1

2}, Xianfeng Liu^{2

3

4}, Longkang Wang⁵, Baisheng Nie³

Affiliations

¹ China Coal Technology and Engineering Group Corp. China Coal Science Research Institute, Beijing 100013, China.
² State Key Laboratory of Coal Mine Safety Technology, China Coal Technology and Engineering Group Shenyang Research Institute, Shenfu Demonstration Zone 113122, China.
³ State Key Laboratory of Coal Mine Disaster Dynamics and Control, School of Resources and Safety Engineering, Chongqing University, Chongqing 400044, China.
⁴ Hubei Key Laboratory for Efficient Utilization and Agglomeration of Metallurgic Mineral Resources, Wuhan University of Science and Technology, Wuhan 430081, China.
⁵ China Center for Information Industry Development, Beijing 100048, China.

Abstract

In order to study the pore alteration and permeability of coal affected by acid liquor, samples were collected from the Yuwu coal mine in the Qinshui basin, Shanxi Province, and taken as the study object. Hydrochloric acid (HCl) with a 10% volume concentration was used to treat these coal samples. The pore structure characteristics and gas permeability of this coal with different treatment times were measured by laboratory experiments. The fractal theory was introduced to analyze the complexity of the sample pore and the changing rules of coal permeability. The research results show that acid liquor has a significant influence on the pore structure of YW coal. Under the effect of acid treatment, the micropore volume of the coal sample is reduced, but both the mesopore and macropore volume are increased. The fractal dimension of acidulated coal samples changes in the range of 2.57-2.81, and it is exponentially decreased with the increase of the treatment time. This indicates that the acid treatment can make the YW coal surface become smooth, and the pore structure tends to be smooth. The acidification method is able to effectively enhance the coal permeability with a maximum increment of about 9.43 times. After 30 h of acid treatment, the total pore volume, fractal dimension, and gas permeability of this coal tend to be stable. The acid treatment time should be controlled at around 30 h.