Research progress and prospect of coal-rock breaking methods in mines

Aiming at the problems of serious abrasion of cutting mechanism and low heading efficiency of heading equipment in coal roadway and rock roadway, the analysis, summary and exploration of coal-rock fragmentation methods in mines were carried out. According to the proctor's coefficient of coal and rock,the types of coal-rock are divided into coal,semi-coal-rock,hard rock and high hard rock. In view of the problems existing in the current heading equipment in coal roadway and semi-coal-rock roadway,the working principle and cutting-edge research status of mechanical rock breaking technologies such as milling,impact,rolling and rolling rock breaking,and water jet rock breaking technologies such as pure water jet,pulse jet,cavitation jet and abrasive jet are summarized. First,in view of the serious wear of the shearer cutting mechanism and the low mechanized mining efficiency caused by high hardness of the coal-rock in coal seam with gangue and hard inclusions during coal mining,the mechanism and performance of the pick breaking coal-rock,the wear mechanism of the pick and the innovative design of the drum structure are summarized,and it is revealed that the current heading operation in the coal seam and the coal seam with gangue should achieve a break through in new technologies such as coal and rock breaking and efficient cutting mechanism design. Developing a complete set of technologies and equipment for fully mechanized mining in unmanned working face is the way to solve the problem of safe and efficient mining in deep coal seams. For the semi-coal rock roadway,the mechanical model of the interaction between the pick and the coal rock,the cutting mechanism of the self-rotation of the pick to reduce the wear,the cutting mechanism and the pick arrangement theory and the optimization design method are summarized. Furthermore,the working principle and research status of various water jet impact rock breaking methods are analyzed from the aspects of theory,numerical simulation and experiment in view of the low efficiency of rock roadway driving and the serious wear of mechanical tools. It is pointed out that to improve the driving efficiency in the semi-coal and rock roadway under the complex geological conditions,the cutting mechanism and the cutting tool arrangement should be designed according to the cutting conditions,and the self-adaptive technology should be adopted to plan the driving working parameters and driving technology,so as to improve the reliability,intelligence and comprehensive driving technology level of the driving equipment system to realize the rapid driving of the semi-coal and rock roadway. For hard rock roadway,the rock breaking mechanism,rock breaking performance and cutter design criteria of hob/ disc cutter are summarized from the aspects of theory,experiment and numerical simulation,and the rock breaking technology of water jet assisted pick/ drilling/ hob/ disc cutter and rock breaking assisted by fracturing are summarized. It is proposed that hydraulic or mechanical rock breaking assisted by fracturing is an effective method to deal with hard rock at present. Making a full use of the characteristics of rock compression and non-tension to achieve efficient and economic crushing of hard rock,and combining intelligent algorithms to realize the cooperative operation of drilling and fracturing is the way to realize the efficient heading of hard rock roadway. Finally,the advantages,disadvantages and limitations of the existing rock breaking technology are analyzed,and the future development trend of the hard rock cutting technology in China is pointed out. The rock breaking technology of coal mining machinery,non-coal mining machinery and shield machinery are integrated with each other,and the multi-field coupling rock breaking technology of machinery and non-machinery and the intellectualization of mining equipment are the development direction to realize the high-efficiency rock breaking under the complex geological conditions in mines. © 2023 China Coal Society. All rights reserved.