Coal and gas outburst prevention using new high water content cement slurry for injection into the coal seam

作     者：Zhou Peiling Zhang Yinghua Huang Zhi'an Gao Yukun Wang Hui Luo Qiang 

作者机构：State Key Laboratory of High-Efficient Mining and Safety of Metal Mines University of Science and Technology Beijing Ministry of Education 

出 版 物：《International Journal of Mining Science and Technology》 (矿业科学技术学报（英文版）)

年 卷 期：2017年第27卷第4期

页      面：669-673页

核心收录：

学科分类：0819[工学-矿业工程] 0709[理学-地质学] 0808[工学-电气工程] 081903[工学-安全技术及工程] 08[工学] 0818[工学-地质资源与地质工程] 0708[理学-地球物理学] 0807[工学-动力工程及工程热物理] 0815[工学-水利工程] 0813[工学-建筑学] 0814[工学-土木工程] 

基　　金：financial support of the National Natural Science Foundation of China (No. 51474017) the Natural Science Foundation of Xinjiang Uygur Autonomous Region of China (No. 2014211B013) 

主　　题：Gas outburst Setting liquid Reinforce coal High-water solidified materials Rapid setting and early strength cement Retarder 

摘      要：As coal and gas outburst is one of the most serious mine disasters, it is very important to at least control it if not prevent it from occurring. Injecting cement slurry or grouting into the coal seam can strengthen the seam, increase its rigidity coefficient(f), and reduce the volumetric expansion due to gas energy release.This paper reports the results of laboratory experiments on cement-based high water content slurry having different water-cement ratios(W/C) to be used for coal injection. The results show that as the W/C increases, the mobility of the slurry and its setting time increase. The compressive strength and rupture strength, however, are reduced. Furthermore, high W/C grout shows early strength after 7 days, which can be 80% of its 14-day compressive strength. To achieve rapid setting and early strength, the addition of Na_2SiO_3has proven to give the best result, when the concentration of the additive is 3%. The initial and final setting times are 13 and 21 min shorter than samples without Na_2SiO_3, while the compressive strength is more than double. As a retarder, the initial setting time can be extended to 83 min when tartaric acid of 0.4% concentration is added. Through the orthogonal experiment, the optimum recipe of the new high water content slurry has been determined to be: W/C = 2, tartaric acid = 0.2%, Na_2SiO_3= 3%, and12% bentonite. Reinforcement by injection simulation experiments show that the grouting radius of the new slurry mix is 250 mm when the applied grouting pressure is 60 k Pa, 7-day rupture strength and compressive strength are 5.2 and 6.4 MPa, respectively, and are 37% and 88% higher than ordinary cement grout. It can be concluded that the newly developed slurry mix is more effective than the ordinary mix for reinforcing coal and controlling gas outburst.