Advanced technology and development approach of automatic underground mining of metal deposits

1. Progress of underground automatic mining technology

Since the mid-late 1980s, Noranda Technology Center in Canada, based on the prototype design of the University of Montreal laboratory, began the research and development of automatic mining technology, and developed a variety of automatic equipment for underground mining of metal deposits. Including LHD (scraper) and truck optical navigation system, LHD remote control auxiliary loading system, LHD automatic walking system, etc. [2]. These technologies and systems were first introduced in the mid-1990s by STAS at the Bell Allard mine in Noranda and at the Brunswick Mine, where 70% of ore production was achieved by automated mining. At one point, the latter reached 80%. [3] In 2001, Noranda also piloted the automated mining system SIAM on some of its stope transport trucks at the Brunswick mine with promising results [4]. Noranda's automated mining technology and system can be used independently in different mining conditions, or in a centralized cluster multi-vehicle remote control system, which is better adapted to the actual needs of Noranda's multiple mines, different production scales and complex ore body conditions.

In the early 1990s, Helsinki University of Technology in Finland adopted a 5-year "Smart Mine Technology" program in the form of industry-university cooperation to carry out research on automatic mining technology. The content includes the information and data acquisition technology of the whole mine, high-speed bidirectional real-time monitoring communication technology, computerized information management and production planning control technology, automatic mining and equipment remote control technology, and the communication interface technology between these technical systems and public information network. The results of this research programme were applied in the subsequent three-year "Smart mine" implementation programme and in the design and production of the Kemi chrome ore at Outokumpu Oy [5,6].

In 1994, Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) launched the Mining Robotics Research Project to develop sophisticated sensing systems and advanced remote control systems for mining and loading operations. CSIRO has developed a Rotary Assist (DSA) system for "cruise" operation of the dragline and a Digital Surface Model (DTM) for accurate unloading of the dragline; An LHD automatic control system for underground mining has also been developed. The technology has been commercialized by Caterpillar to form the MINEGEMTM system, and the LHD equipped with this technology is called Smart Loader [7,8].

In 1996, Inco of Canada, Tamrock of Finland and Dyno of Norway launched a Mining Automation Initiative (MAP), investing US $22.7 million to develop, demonstrate and commercialize automated mining technologies. The purpose is to effectively develop the deep or difficult mining mineral resources, reduce the ineffective working hours such as shift change and entering and leaving the mine, improve labor productivity, reduce operating costs, and ensure the safety of miners. The program is supported by Natural Resources Canada's Mining and Mineral Sciences Laboratory (CANMET-MMSL) with a matching grant of $3.5 million and project management by the laboratory. Experts have studied the effects of diesel engine operating conditions, blowdown, underground blasting and diesel exhaust gas on unmanned mining operations under hypoxia conditions in mines, the climatic conditions of unmanned mines and their effects on the productivity of infrared remote control equipment, and the response mechanism of surrounding rock to mining, etc. [9,10].

Inco further developed new automatic mining technologies in advanced communication system, mining equipment positioning and navigation system, robot excavation and mining, advanced technology and monitoring, including remote control technology of underground LHD, drilling rig and other mobile equipment, and applied them in Stobie Mine and Creighton mine. He became a pioneer in underground mining automation [11,12]. The company applied discrete event simulation technology and QUEST simulation system to study the influence of remote control LHD running speed and control strategy on LHD productivity under a given transportation mode, taking into account LHD process parameters including loading time, unloading time, heavy vehicle running speed, empty vehicle running speed, LHD full load factor, etc. The influence of factors such as the number of LHD units operated by remote control operators at the same time, stope transportation distance and operator quality on LHD idle time, waiting time and productivity was analyzed [13]. Discrete event simulation technology and WITNESS simulation system were used to study the perforating and blasting system in the automatic mining process model [14]. In cooperation with Laurentian University, the Auto Mod simulation system was applied to study the interaction between mining methods and remote control equipment, including the interaction between perforation, blasting, loading and mining sequence [15].

Inco, in cooperation with other relevant institutions, also started research and development of an Underground Blasting Automatic Charge project (ELAP) in 2000. The prototype system passed underground industrial trials in 2002 and the technology is being further refined [16,17].

The Kiruna Mine of the Swedish mining company LKAB started to implement automatic control technology for rail transportation in the early 1970s, and since the late 1990s has successively adopted remote control drilling RIGS and remote control LHD technology [18,19].

Automated mining technology has also been successfully applied at the Finsch diamond mine in De Beers, South Africa [20]. In the engineering design of the mine's open-pit conversion to underground mining in 2000, Sandvik's Sandvik Tamrock automated mining technology system was used for an investment of US $20 million, including the design, construction, equipment acquisition and installation of automated trucking systems. The mine uses a combined caving drawing, LHD and truck loading system, in which the truck system is remotely controlled from the ground and connected to the mine backbone communication network via a radio frequency system (MineLan). The application of truck automatic control system can improve the speed of underground truck operation and equipment productivity. Surface operators can operate multiple trucks at the same time, significantly reducing the number of underground personnel, which greatly improves mine safety and increases labor productivity. Sandvik Tamrock is currently implementing the LHD automated system at the Finsch mine with a planned investment of US $41 million.

In the United States, Carnegie Mellon University, funded by NASA and Joy, conducted research on the automatic positioning and navigation technology of continuous shearer in underground coal mines, and developed research results that could be commercialized [21]. The University of Colorado studied the stereographic imaging model of underground ore burst in order to effectively control LHD automatic loading [22].

In addition, in Saskatchewan, Canada, uranium mines are operated by remote control to protect miners from radiation; At Mount Essa Mine in Australia and some deep mining mines in South Africa, miners are protected from the heat and humid air of deep Wells by remote control. In Chile, Codelco's El Teniente mine used remote control to protect miners from rockbursts. [23]

In China, companies such as Meishan Iron Mine have considered using remote control drilling RIGS to free equipment operators from the high-intensity noise generated during drilling operations.

Gu Desheng, Yun Qingxia and Wang Yunmin, when elaborating the development trend of science and technology of underground mining of metal deposits, believe that unmanned mining will be one of the important fields in the development of mining technology in China in the 21st century [24~26].

The Ministry of Science and Technology has listed underground unmanned mining technology and related equipment as one of the research directions and contents of the first batch of special topics launched in the "863" plan during the "Eleventh Five-Year Plan" period, which further indicates the development trend of unmanned mining technology in China.

2. Advanced technology of underground automatic mining

At present, the unmanned mining technology at home and abroad is still in the initial stage of "unmanned mining". At this stage, the core technology of unmanned mining is still automatic mining technology, which mainly includes key technologies such as data acquisition and supervisory control (SCADA), remote control of mining equipment and digital communication, and there is no obvious breakthrough in mining process design and roadway layout. The maintenance of underground unmanned equipment, the handling of accidents, and the interaction between surface remote control personnel and underground operators all need to be further studied. 

The progress of information and communication technology will certainly promote the development of unmanned mining technology from the current automatic mining or remote control mining with traditional mining process automation as the core to the "unmanned mining" with advanced sensors and detection and monitoring systems, intelligent mining equipment, high-speed digital communication networks, and new mining process integration as the main technical characteristics. Therefore, the cutting-edge technology of unmanned underground mining or automatic mining of metal deposits mainly includes the following four aspects.

2.1 Advanced sensing, detection and monitoring technology

Detection and monitoring technology and instruments of downhole environmental factors such as temperature, humidity, air components, stope ground pressure, roadway surrounding rock deformation and other variables; The technique and method of real-time analysis of the lumpiness and its distribution, the grade and distribution of useful minerals, etc. Spatial distance recognition, positioning and navigation technologies based on underground environment, such as buried line navigation system, passive light guide system, active light guide system, wall tracking system, inertial navigation technology and equipment, are the prerequisite for intelligent mining equipment operation and process control. Therefore, the development of underground automatic mining needs to research and develop the corresponding advanced sensing technology and detection and monitoring technology.

2.2 Remote control and intelligent technology of mining equipment

The automation degree of underground mining main equipment such as drilling rig, scraper and truck is one of the important indicators of the level of underground automatic mining. By continuously improving the automation level of mining equipment, the number of underground operators can be reduced, ineffective working hours such as underground personnel transportation can be eliminated, occupational health and safety hazards of underground personnel can be avoided, and equipment and labor productivity can be improved. Therefore, the development of underground automatic mining needs to research and develop the location and positioning of drilling RIGS, scrapers, trucks and other equipment in the stope and the remote control and intelligent control technology in the production process such as perforation, blasting, shoveling, transportation and unloading, as well as the intelligent monitoring technology, fault prevention technology and failure safety technology of underground mining equipment.

2.3 High-speed digital communication network technology

The underground communication conditions are very different from the surface communication conditions, the main problems are: the underground physical environment is bad, dark, wet, corrosive, many natural damage factors, high probability; Underground communication facilities layout space is limited; Wireless communication barriers are prevalent. Generally speaking, the existing underground communication infrastructure is uneven, and the overall technical level is relatively backward, which is difficult to meet the needs of the development of automatic mining technology. Therefore, the development of underground automatic mining needs to study the high-speed digital communication network technology suitable for underground communication. The main technical requirements include: a. In order to meet the needs of communication between underground and surface and the needs of communication between underground mining areas, it is necessary to consider the automatic adjustment of bandwidth to meet the needs of bandwidth redistribution due to the frequent increase and decrease of the number of underground mining areas, stopes or workplaces, and to adopt industrial standards or surface standards while considering the underground application environment to reduce the cost of underground communication facilities. b. To be able to achieve communication between PLC, PLC and automatic equipment communication, video image communication, local area network communication, wired telephone communication, as well as wireless voice, video and automatic equipment control signal communication; c. To meet the needs of physical extension of downhole communication network with mining progress, consider plug and play; d. Consider the standardization and standardization of underground communication technology, which is conducive to promotion and application; e. Communication physical facilities and communication effects are less sensitive to the downhole environment.

2.4 New technology of underground automatic mining

The development of mining technology is closely related to the level of mining equipment technology, and the development of high and new technology will certainly promote the innovation of mining technology. For example, sublevel caving without pillar mining technology is produced to adapt to specific underground surrounding rock conditions, but the improvement of mining equipment technology has greatly promoted the development of this mining method and its adaptation range. Therefore, the improvement of automatic mining control level will further promote the reform of mining technology and production process itself. Mining planning and design, well layout, stope parameters including section height and road spacing, number and geometric size of roadway, mining and mining methods and other technology will continue to develop with the improvement of mining equipment level. The technology, design, installation and operation management related to underground climatic conditions and auxiliary facilities such as ventilation, power supply, gas pressure and lighting need to be further explored.

3. Development approaches of underground automatic mining technology

The realization of unmanned mining or unmanned mining will be a long evolution process, but as the basic technology for the development of unmanned mining or unmanned mining - automatic mining technology, the development of foreign countries has more than 20 years of history. With the continuous improvement of China's information technology level, the strengthening of production safety standards and the worsening of mineral resources mining conditions, the development of automatic mining technology has been put on the agenda of scientific research and technological development of mineral resources development and utilization in China. The Ministry of Science and Technology of the State in the "eleventh Five-Year" period of the "Eighty-three" plan to start the first batch of thematic topics guide, the research of unmanned mining technology and related equipment as exploration oriented and goal-oriented topics one of the main research direction and content, marking the development of automatic mining technology in China has a good beginning.

The research and development of automatic mining technology and even the further development of unmanned mines need to work together in the following aspects.

3.1 The government supports relevant basic and applied basic research

The Ministry of Science and Technology has initiated the exploration and development of unmanned mining technology through the "863" plan, and other relevant government departments or institutions, such as the Ministry of Education and the National Natural Science Foundation, should also consider the development of automatic mining technology in the relevant scientific research and development plans, and vigorously support universities and scientific research institutions to carry out basic research and applied basic research. In order to form a supporting system with original innovation and technology prototype development ability in automatic mining basic research, applied basic research and interdisciplinary research.

3.2 Enterprises take the lead in relevant technological innovation

Large state-owned science and technology enterprises (relevant research institutes, etc.) related to the exploitation and utilization of mineral resources shall cooperate closely with large state-owned production enterprises, and in the process of implementing the national medium - and long-term science and technology development plan and building national technology development bases such as national engineering laboratories or engineering (technology research) centers and industrial engineering centers related to the exploitation of mineral resources, Take underground automatic mining technology as one of the main technological development directions, according to the scientific and technological development of mining enterprises, the exploitation and utilization of mineral resources and the demand of mineral products market competition, and in view of the appropriate mining conditions, actively introduce, develop and apply foreign advanced automatic mining technology and equipment, and implement simulated innovation and integrated innovation through industrial tests and production practices. And then effectively develop the independent innovation ability of enterprises in the field of automatic mining technology.

3.3 College construction related disciplines and talent security system

Colleges and universities, especially research universities with strong scientific research ability, should strengthen the construction of automatic mining discipline system, and take underground automatic mining technology and theory as one of the main discipline development directions in the process of implementing the national medium - and long-term science and technology development plan and building national research and experiment bases such as State key laboratories and departmental laboratories in the field of mineral resources development. Strengthen industry-university-research cooperation, vigorously promote interdisciplinary, through the establishment of an advanced disciplinary system and effective academic management mechanism, the implementation of teaching, the development of personnel training system conducive to improving the original innovation ability, the cultivation of interdisciplinary academic ability, to adapt to the development of automatic mining science and technology personnel team.

3.4 Attach importance to interdisciplinary integration

Automatic mining technology has a high degree of interdisciplinary nature, involving automation technology, robotics technology, sensing technology, communication technology, machinery manufacturing technology, mining technology and other disciplines, in the process of automatic mining technology research and development, we should pay attention to interdisciplinary, pay attention to the relationship between automatic mining and continuous mining, digital mining and other research directions.

3.5 Development of application system simulation technology

Automatic mining technology is a highly complex system, and the corresponding test facilities are difficult to build, poor repeatability and high cost. In the process of research and development of automatic mining technology and technology, system simulation technology should be actively developed and applied. Simulation technology and model system are used to effectively study stope planning and design, roadway layout, equipment selection, process and other related parameters of a typical automatic mining process system and their influence on the efficiency and efficiency of the automatic mining process system through multi-scheme simulation analysis. The dynamic process of a typical underground automatic mining process system is vividly displayed and its operating status is visually investigated. System process simulation technology based on discrete event simulation method and system spatiotemporal dynamic simulation technology based on 3D visualization simulation method will be important technical means to study and develop automatic mining technology, especially automatic mining process system.