Feasibility analysis of excavation with open full section boring machine for ultra-long distance slant in coal mine

Slant is one of the development ways to guarantee the efficient production of mine. It can realize the continuous main transport of the mine, large mining – excavation – transport equipment can use trackless rubber-tyred vehicles directly reach underground, and without the complex ground disassembly and assembly in the underground large chamber. To meet the demand of 10.0 Mt /a production capacity of Kekegai Coal Mine in Shaanxi province, this paper analyzes the influence factors of mine access development mode and geological and hydrogeological conditions of Kekegai Coal Mine. Four kinds of mine development schemes are put forward. Considering the advantages of external transportation conditions, convenient site management, trackless rubber-tyred vehicle of slant with gentle slope and no need to change equipment, the development scheme of main and auxiliary slant + intake and return air shaft in Kekegai Coal Mine is preliminary determined. Through further reviewed the development status and trend of long-distance inclined shaft drilling and blasting tunneling and mechanical rock breaking tunneling technology in coal mine. The problems of low driving efficiency, excess working procedures and high risk in drilling and blasting method and cantilever roadheader construction in existing slant construction are analyzed. The technical scheme of using full section boring machine to drive super long slant is put forward, and applicability of open-type full section boring machine construction is demonstrated. By comparing and analyzing the advantages and disadvantages of the segment support and bolt-mesh-shotcrete support in slant, the supporting mode of bolt-mesh-shotcrete near working face and adding steel arch in the section with local broken surrounding rock is selected. According to the comprehensive analysis of engineering geology and hydrogeology conditions, environmental conditions, engineering conditions, mine construction technology, equipment performance, mine construction period, investment cost and other factors, the mine design and construction technology and equipment of main and auxiliary slant + inlet and return air shaft in Kekegai Coal Mine are feasible and advanced. It can provide a basis for the selection of the same type of mine development mode and the determination of the construction technology and equipment of ultra-long slant, and lay a foundation for the safe, efficient, green, and intelligent construction and development of coal mine

System engineering and key technologies research and practice of smart mine

In order to overcome the problems existed in the construction process of complex giant system of smart mine, the overall technical framework of smart mine construction was proposed, and a detailed description was made from the aspects of smart mine system model construction, underground space reconstruction and model dynamic update, machine vision measurement technology, radio frequency explosion-proof test method of gas environment, mine safety closed-loop control system, smart mine standard system, etc. The smart mine was divided into information sensing support layer, edge computing layer, cloud data center, multi-type network, intelligent mine production management and control platform, intelligent mine production system and intelligent mine operation and maintenance management system. The smart mine technology architecture based on the deep integration of multiple systems was built. Based on the knowledge map and information extraction of smart mine, a smart mine system model driven by data innovation, based on communication network and centered on data computing power was constructed. A 3D visual space model based on machine vision perception information and supplemented by other perception information was constructed, and a 3D vision and spatial reconstruction framework of mine underground scene was proposed to realize the reconstruction and dynamic update of the 3D space of underground mine. Based on machine vision technology, the identification algorithm of downhole equipment position and coal-rock interface was developed to realize the simultaneous aerial measurement of fully mechanized mining equipment group and coal-rock interface. The limitations and shortcomings of the current explosion-proof standards on the power of 5G base stations in the underground gas environment were discussed, and a special test device for radio-frequency electromagnetic energy explosion-proof was designed and developed, which provides a method for reference to improve the power threshold of underground 5G base stations. The technical framework of mine disaster closed-loop management and control system, which integrates comprehensive perception of disaster information, independent decision-making of prevention and control plan, and coordinated control of prevention and control equipment, was proposed to realize advanced prediction and early warning and coordinated prevention and control of underground disasters. The framework of intelligent coal mine standard system was constructed, the typical cases of intelligent construction of coal mine and metal mine in China were analyzed, and the development trend and suggestions of intelligent mine construction were put forward

Intelligent and ecological coal mining as well as clean utilization technology in China: Review and prospects

Coal is an essential fossil fuel in China; however, coal mining and its utilization are being under the increasing pressure from ecological and environmental protection. Therefore, the consulting project “Technical Revolution in Ecological and Efficient Coal Mining and Utilization & Intelligence and Diverse Coordination of Coal-based Energy System,” initiated by Chinese Academy of Engineering, puts forward three stages (3.0, 4.0 and 5.0) of China’s coal industry development strategy. Aimed at “reduced staff, ultra-low ecological damage, and emission level near to natural gas,” breakthroughs should be achieved in the following three key technologies during the China Coal Industry 3.0 stage (2016–2025): including intelligent coal mining, ecological mining, ultra-low emission and environmental protection. This paper focuses on the development trends of the China Coal Industry 3.0 and its support for China Coal Industry 4.0 and 5.0 is analyzed and prospected as well, which may offer technical assistance and strategy orientation for realizing the transformation from traditional coal energy to clean energy. Keywords: Intelligent mining, Ecological mining, Clean utilization, Environmental protection, China’s coal industr

Mechanical behaviors of coal measures and ground control technologies for China's deep coal mines – A review

This paper reviews the major achievements in terms of mechanical behaviors of coal measures, mining stress distribution characteristics and ground control in China's deep underground coal mining. The three main aspects of this review are coal measure mechanics, mining disturbance mechanics, and rock support mechanics. Previous studies related to these three topics are reviewed, including the geomechanical properties of coal measures, distribution and evolution characteristics of mining-induced stresses, evolution characteristics of mining-induced structures, and principles and technologies of ground control in both deep roadways and longwall faces. A discussion is made to explain the structural and mechanical properties of coal measures in China's deep coal mining practices, the types and distribution characteristics of in situ stresses in underground coal mines, and the distribution of mining-induced stress that forms under different geological and engineering conditions. The theory of pre-tensioned rock bolting has been proved to be suitable for ground control of deep underground coal roadways. The use of combined ground control technology (e.g. ground support, rock mass modification, and destressing) has been demonstrated to be an effective measure for rock control of deep roadways. The developed hydraulic shields for 1000 m deep ultra-long working face can effectively improve the stability of surrounding rocks and mining efficiency in the longwall face. The ground control challenges in deep underground coal mines in China are discussed, and further research is recommended in terms of theory and technology for ground control in deep roadways and longwall faces

Innovation progress and prospect on key technologies of intelligent coal mining

Innovation and practice were summarized overall about intelligent fully mechanized coal mining in thin coal seam and thinner coal seam, intelligent fully mechanized coal mining of large mining height and super large mining height in thick coal seam, and intelligentization technology of fully-mechanized top coal mining in super thick coal seam, and shortcomings of the above technologies were analyzed. Five key technologies were proposed for fully mechanized coal mining equipments to adapt to surrounding rock movement and dynamic environment variety, which were intelligent height adjustment control of shearer, intelligent coupling self-adaptive control of hydraulic support units and surrounding rock, intelligent alignment control of working face, cooperative control based on multi-information fusion and intelligent control of advance support and assistant operation. The key technologies lay technical base for intelligent mining progressing to senior stage of self-learning, self-decision-making and self-adjustment from current initial stag. Technical development directions and targets of coal industry in the short term, medium term and long term were proposed, namely intelligent mining, limited unmanned mining and fluidized mining, and development route, key technologies and development direction were also prospected

Key technology and development trend of intelligent mining in complex condition working face

In complex condition coal seam, there are a large number of geological condition parameter changes and a large range of parameter changes. The intelligent mining is the difficult problem which needs to be solved urgently at present. This paper analyzes the main geological conditions and problems of coal mines in different regions of China, and points out that compared with fully-mechanized coal mining, intelligent mining requires higher geological security. The more complex the geological conditions, the more precise the perception, the faster the analysis and decision-making, and the higher the data transmission rate of the control system. Taking the mining of 'three soft' coal seam in Huainan and Huaibei areas as an example, the problems faced in the intelligent mining process are discussed. The coal wall is frequently spalling, the scraper conveyor moves up and down, the adjacent supports are dislocated and the occlusion is not tight, the guard plates are not neat, the supports are tied to the bottom, and the advance roadway is deformed. It is pointed out that the conditions of surrounding rock (roof, floor and coal wall), coal seam strike/dip angle, rock pressure and stability of advance roadway are the five factors that affecting the normal continuous mining of the working face. In order to solve the problems caused by the above five factors, it is necessary to develop the key core technologies to solve the intelligent mining of complex working face from the aspects of surrounding rock parameter perception, trend analysis, fine control, dynamic system adaptation and self-adaptive decision-making. The application status, effect and problems to be solved in the future of the intelligent mining technology of complex conditions working face, such as the precise control and rapid follow-up technology of hydraulic support guard plate, roof partition cooperative support technology, working face equipment attitude monitoring technology, working face straightening technology, moving up and down control technology, stable pressure liquid supply control technology, simulation decision-making system platform and advance support technology, are described in detail. It is pointed out that for the coal seam with many complex conditions, the main directions of follow-up researches are the electromechanical and hydraulic integrated design of key components, distributed control mode, analysis and application of big data, cooperative rapid advancement control of equipment group, and the development of real-time simulation platform and intelligent decision-making system

Research status and development trend of hydraulic support precision pushing and fast follow-up technology

The hydraulic support precise pushing and fast follow-up is the key technical support to realize intelligent mining of working face. In order to realize intelligent mining, the precise pushing of hydraulic support is equivalent to the precise position control of valve-controlled cylinder system in coal mine environment, and fast follow-up of hydraulic support need to be realized through follow-up process, liquid supply with stable pressure, fast support movement, etc. Aiming at the precise advancing technology of hydraulic support, it is pointed out that the mature precise position control technology of valve control in related fields can be used for reference. This paper summarizes the research achievements of the electro-hydraulic proportional valve, high-speed on-off valve and electromagnetic directional valve control cylinder position control technology. This paper also summarizes the problems existing in the application of above achievements in the field of coal mines. It is proposed that the precise pushing of hydraulic support can be realized by developing large-flow high-pressure water-based electro-hydraulic proportional valve suitable for the underground environment and developing the intelligent optimization control algorithm. Aiming at the fast follow-up technology of hydraulic support, it is pointed out that the current automatic follow-up of hydraulic support is slow due to unreasonable follow-up process, unstable liquid supply system, and unreasonable support moving process. It is easy to appear the situation of not moving in place and losing support. The related research achievements of improving the follow-up speed are summarized from three aspects: optimizing the follow-up process, supplying liquid with stable pressure, and fast pushing support. The following points are pointed out. At present, the follow-up process cannot be dynamically adjusted according to the speed of the shearer, and the automatic follow-up based on equipment perception is still at the theoretical stage. Optimizing the structure and control algorithm of the liquid supply system is the main way to realize the liquid supply with stable pressure in the working face. But it can not effectively solve the problem of pressure and flow stability at the end of the hydraulic support when the multi-support cooperates. Improving the structure of the hydraulic system is the main way to achieve fast support pushing. But there are some problems such as the large pressure drop when high-pressure oil is transmitted over a long distance, the pipe explosion at the high-pressure point, and the difficulty of pipeline layout caused by increasing the pipe diameter. In view of the above problems, it is proposed to realize the precise pushing and fast follow-up of hydraulic support from four aspects: the constant pressure control of the working face liquid supply system, the improvement of the control precision of hydraulic support pushing, the guarantee of the automatic follow-up effect of hydraulic support, and the improvement of the whole follow-up speed of the working face. It is pointed out that the development trends of precise pushing and fast follow-up technology of the hydraulic support are centralized-distributed agile and efficient liquid supply, improvement of the edge computing capacity of hydraulic support controller, enhancement of adaptability of follow-up control strategy to stope environment, dynamic coupling and follow-up control of stope and equipment.hancement of adaptability of follow-up control strategy to stope environment, dynamic coupling and follow-up control of stope and equipment

Research on key technologies of coal mine roadway dust cleaning robot

Roadway dust cleaning robot can effectively solve the problem of coal mine roadway dust accumulation. However, there is no relatively mature product to achieve 'automatic dust accumulation monitoring-autonomous/semi-autonomous movement-adaptive dust cleaning operation'. This paper analyzes the research status of three kinds of dust cleaning equipment developed at home and abroad, which are wheel-rail type roadway dust cleaning device, explosion-proof sprinkler and tunnel dust cleaning vehicle with chassis and hydraulic mechanical arm. It is pointed out that the wheel-rail type roadway dust cleaning device does not contain power system. The dust-cleaning effect of roadway wall dust is limited. The explosion-proof sprinkler has its own power, which can realize full section dust reduction of the trackless long roadway. However, the jet water surface is wide, and it is unable to deal with local areas with serious dust accumulation such as roadway walls and pipelines. Tunnel dust cleaning vehicle can solve the problem of dust accumulation in long-distance tunnels. However, manual driving and operation are still required, and it is impossible to realize tunnel dust accumulation monitoring and adaptive dust cleaning. Based on the above analysis, it is pointed out that in order to realize 'automatic dust accumulation monitoring-autonomous/semi-autonomous movement-adaptive dust cleaning operation', the research should be carried out from the aspects of dust accumulation monitoring, structure design and control of dust cleaning device, and optimization strategy of dust cleaning mode. It is pointed out that the main technical problems faced by the above research include the common problems of coal mine robots such as explosion-proof safety design, underground precise positioning, and long-distance wireless communication. The problems also include the characteristic problems of roadway dust cleaning robot such as dust monitoring, adaptive dust cleaning, and vehicle arm coordinative operation. In view of the characteristic problem of the roadway dust cleaning robot, this paper puts forward the corresponding key technologies. ① It is suggested to research and develop a multi-sensor fusion monitoring technology based on the weighing method, laser method and image method to realize long-term monitoring of dust cleaning in coal mine roadway and dynamic evaluation of dust cleaning effect. ② It is suggested to develop dust cleaning structure based on explosion-proof mechanical arm and 'wind-water-brush' linkage dust cleaning device to realize adaptive dust cleaning. ③ It is suggested to establish a unified workspace for vehicle chassis and mechanical arm. It is suggested to develop small deviation automatic compensation and flexible obstacle avoidance technology for roadway dust cleaning robot based on torque control. The vehicle arm coordination of the roadway dust cleaning robot in the dynamic scene is realized