Progress and development trend of open-pit mining technology (including blasting technology) in metal mines in China

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Progress and development trend of open-pit mining technology in metal mines in China

Due to the disadvantages of difficult relocation and high cost, the research and development of large mobile crushing units has achieved rapid development. The discontinuous mining process of large foreign open-pit mines such as Mount Newman Iron ore in Australia, Landvalley copper mine in Canada, and Siarita copper and molybdenum mine in the United States also uses mobile crushing stations. In 1997, Qidashan Iron Mine of Anshan Iron and Steel Co., Ltd. built the movable belt transportation system for ore and rock in stope for the first time in China. The system has been running normally since it was put into operation, which indicates that the discontinuous mining technology of deep concave open-pit mine in China has reached the world advanced level.

[1.4 Steep Slope railway Transportation System of large deep concave open pit mine] After the open pit mine enters the deep concave mining stage, the railway transportation with a mild slope degree below 30‰ and slow working help mining mode are adopted, and the efficiency is low. With the increase of mining depth, the growth of transportation lines, and the sharp rise of transportation costs, it has become a bottleneck restricting the sustainable development of mines. To this end, during the "Tenth Five-Year Plan" period of scientific and technological research, China has successfully developed a large deep-concave open-pit steep slope railway transportation system, and realized the steep slope railway transportation mining of deep open-pit mine for the first time in China, effectively solving the technical problems of steep slope railway crawling, insufficient traction of locomotive, and safe network power supply, and successfully breaking the "bottleneck" of large deep-concave open-pit steep slope railway transportation. The results were applied to Zhujiabaobao Iron Mine of Panzhihua Iron and Steel Group, extending the railway transportation depth of 45m, mining 30 million tons of iron ore, reducing the stripping ratio of 0.42 tons/ton, increasing the iron-to-transport ratio by 20.72%, extending the mine service life of 15 years, reducing the mining cost by 25.33%, and direct economic benefits of 723 million yuan. The results were extended to Waitoushan open-pit Iron Mine of Benxi Iron and Steel Group Company, extending the railway transportation depth to 72m, saving 150 million yuan of investment, reducing mining costs by 30.43%, and direct economic benefits of 560 million yuan.

[1.5 Safe and Efficient Mining Technology of Large Deep pit open pit] Safe and efficient mining technology of large deep pit open pit is a scientific and technological achievement of the "Tenth Five-Year Plan". This research is aimed at the slope stability of deep concave open pit mine and production scheduling information management. It is the first time at home and abroad to analyze and optimize the stability of open pit slope based on the combination of modern three-dimensional numerical simulation and three-dimensional limit equilibrium analysis, which provides a scientific method for the slope design of deep concave open pit mine. Developed a real-time automated production scheduling system and management platform based on GPS positioning, realized the positioning, tracking and scheduling of personnel and equipment in the production process, realized the whole process control of the entire production system, and made it always in the optimization and efficient operation, and greatly improved the production efficiency.

In view of the three major public hazards of mine blasting (blasting dust, blasting vibration and blasting flying rocks), we independently designed and established a collection, test and analysis system for blasting dust, developed a new high-efficiency gas absorber for the first time, and determined a reasonable charging structure for micro-dust poisoning. Realizing no (low) public hazard in mine blasting. At the same time, a hydraulic charging structure and a comprehensive vibration reduction blasting technology, which reasonably arranges the detonation time sequence and time difference, and adopts the cushioning soft plug layer, greatly reduces the dust and blasting vibration, and obviously improves the blasting effect. The flying stone flexible protective net system is developed for the first time, the throwing distance of blasting flying stone is reduced by 50%, and the degree of flying stone can be controlled within 100mm. The technology as a whole is at the international advanced level.

[1.7 Key Technologies for Smooth transition from Open pit to Underground Mining] "Key Technologies for smooth transition from open pit to underground Mining" is the national "11th Five-Year Plan" science and technology research topic. This topic focuses on the key technical difficulties of mining and safety in the process of open-pit mining, such as when to transition from open-pit mine to underground mine, how to smoothly connect mine development system and open-pit underground production capacity, how to realize efficient underground mining under high and steep slope, how to prevent water inrush in open-pit to underground stope, and how to establish an early warning mechanism of open-pit slope landslide and underground surrounding rock collapse caused by mining disturbance The research is carried out and the following results are obtained: the dynamic relation function of open-pit to underground mining boundary is established, and the method of determining the reasonable time of smooth transition from open-pit to underground mining is invented; In order to ensure the safety of open-pit to underground caving mining method, a formula for calculating the thickness of overburden layer is invented, and the formation technology of ore-rock composite overburden is proposed for the first time, overcoming the safety technical problems of open-pit to underground caving mining method. Based on improving the efficiency of two-step mining from open pit to underground, the double bottom structure and its technology are invented to realize safe and efficient mining. In view of the characteristics of large and concentrated catchment moment of open pit, a new idea of building emergency middle section to prevent water inrush disaster is put forward creatively, and the construction method of emergency water silo is invented to improve the ability of preventing water inrush disaster in open pit to underground mining. For the first time in China, the domestic 30-channel microseismic monitoring network system has been established, and the safety monitoring and disaster warning system for the process of open-pit to underground mining has been constructed. The new functions of surrounding rock damage and degradation evaluation and rock mass quality analysis, microseismic monitoring data and three-dimensional stress field data integration, mine stress field background early warning and forecast visual digital scene, monitoring data remote transmission and expert consultation, mine personnel positioning and emergency rescue have been developed, which have reliably prevented mine disasters.

[1.8 Super large open pit safe and efficient mining technology] This topic is the national "Twelfth Five-Year" science and technology research topic, aiming at the characteristics of super large open pit iron ore deposits in China and China's overseas, from the perspective of high efficiency, economy and safety, It has developed a dynamic optimization technology for stripping flood peak control of steeply-tilted open pit deposits, a production scale optimization technology based on economic dynamic assessment and the balance of total mining and stripping, an adaptive technology for ore loss and dilution control under the interference of multiple factors in large open pit mining, and a new level multi-zone development technology for extra-large open pit mines, breaking through key technical difficulties in efficient and low-cost mining of large open pit mines. The technical and economic system of super large open-pit mining has been established, and the overall technology is at the international leading level.

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Comparison of open pit mining technology with foreign advanced level

China's metal mine open-pit mining technology has made remarkable achievements, in the open-pit mining steep slope mining, high step mining, penetration and explosion technology has developed rapidly and has certain technical advantages, basically follow the international research trend, and even some technologies have reached the international leader. However, in the open-pit mine transportation system, large-scale equipment, automation has been close to the international advanced level, in the digital mine, mining monitoring means modernization and modern mine management and other aspects of the gap is large.

[Continuous mining process, diversified transportation mode, efficient] In terms of steep slope mining, the slope Angle of China's steep slope mining is about 40°, and the working slope Angle of the United States, Canada and Russia with more advanced open-pit mining technology has reached about 45°. As in foreign countries, the discontinuous-continuous mining technology of most mines in China realizes the movable rock crushing and belt transportation in stope; The steep slope railway can extend the railway transportation to the deeper stage of the open pit mine, increase the transportation capacity by 25%, reduce the transportation cost by 20%, and China has realized the steep slope railway slope limit of 45‰ ~ 50‰. In terms of high level mining, China has realized 18m high level production in Nanfen Iron Mine, which reduces the unit mining cost; In terms of open-pit mining technology, most of our country has reached the international advanced level.

[Large-scale mining equipment] In terms of drilling RIGS, the perforating equipment of metal open-pit mines in China includes cone drill and submerged hole drill. Large mines mainly use cone drill with drilling diameters of 250mm and 310mm, while small and medium-sized open-pit mines mainly use submerged hole drilling with drilling diameters of 200mm. Foreign drilling equipment basically uses cone drill, drilling diameter is mostly 311 ~ 381mm, 445mm, 559mm. In terms of shovel loading, electric shovel equipment accounts for an absolute advantage in foreign countries (about 48%), but the application of hydraulic shovel is constantly expanding (about 26%), and the bucket capacity is mainly 21m3, 38m3, 43m3; At present, Taiyuan Heavy Industry has developed WK-75 mining electric shovel, bucket capacity of 75m3, for the world's largest level of excavator. In terms of automobile transportation, the electric wheel vehicles used in large foreign mines at present, their carrying mass is mostly 240 tons, 320 tons, 150 tons, and the maximum can reach 363 tons, and the mass of large open-pit mining vehicles in China is mostly 120 tons and 170 tons. In November 2015, Aerospace Heavy Industry independently developed H-ton 3363 two-axis electric wheel mining dump truck, carrying mass reached 363 tons, marking the domestic open-pit mining automotive equipment into the ranks of the world's advanced level.

[Blasting technology] Foreign open-pit mines widely use the large-area multi-row differential blasting technology to increase the amount of ore and rock in each blasting, reduce the number of blasting, improve the utilization rate of equipment, and improve the blasting quality, which is a general form. The advent of new explosives and blasting equipment has great influence on improving the blasting precision, improving the blasting quality and strengthening the blasting safety.

[Production management automation] Foreign metal open-pit mines have developed a number of software platforms in terms of production management automation, computer online control and design applications, such as Gemcom's surpac, mineshed, whi Ton ton le, Micromine's micromine, fieldmarshal, gbis, etc., have made remarkable achievements. These software platforms can optimize and design the surface mine boundary, prepare production schedule, plan the surface mine development strategic planning, production simulation analysis, evaluate and develop the transportation system and select the loading equipment, prepare the vehicle dispatching system, realize the maintenance plan management of mining and loading equipment, plan the storage and supply control of spare parts, simulate the main production process and optimize the working parameters. Conduct financial analysis, etc. In recent years, China has also independently developed related software platforms, such as dimine software independently developed by the Digital Mining Research Center of Central South University and 3DMINE software developed by Beijing 3Dmine Mining Software Company, but the overall degree of automation management is not high and needs to be further strengthened.

[Open-pit to underground mining technology] Foreign open-pit to underground mines, most of the joint development system connection method, no transport system in the deep surface of the open-pit, unified use of underground roadway transportation, the common use of underground crushing station and lifting system, so as to reduce the open-pit stripping and underground mining infrastructure investment, such as Sweden Kiruna mine, Finland Pihasarmi mine; However, most of the mines in China that convert from open pit to underground mining are developed off-site, and the combination and mutual utilization of the process system of open pit and underground mining are less considered, resulting in a large amount of underground Wells and lanes, high investment and long infrastructure time. During the "Eleventh Five-Year Plan" period of scientific and technological research, many scientific research institutions in China have conducted a lot of research on the technical requirements of domestic open-pit mining and the future development trend, and have made important progress. For example, the smooth transition technology of open-pit to underground mining developed by the Maanshan Mining Research Institute of China Steel Group has been designed and studied in Hebei Shirengou, Masteel Gushan and other open-pit mines, and has achieved good application results, providing theoretical basis and practical experience for domestic open-pit to underground mining mines.

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Main development direction of open pit mining technology

In the coming period, the development trend of open-pit mining technology is mainly manifested in the following aspects.

[Mining process to continuous and intensive development] Traditional open-pit mining is after the ore and rock blasting, the shovel loading equipment is loaded into the transport vehicle (car or railway) at the working face, and then transported to the destination. For decades, open-pit mining technology continues to develop, mining equipment is increasingly large-scale, domestic open-pit mining equipment bucket capacity reached more than 15m3, large transportation equipment - electric wheel vehicle deadweight tonnage reached more than 154 tons, greatly improving the mine production capacity, but with the oil and other main raw materials prices continue to rise and CPI price index climbing, Mining costs are soaring; With the deterioration of deep-concave mining conditions in open-pit mines, the increase of transportation distance, the decrease of transportation efficiency, the increase of transportation energy consumption, and the aggravation of environmental pollution in mines are many problems restricting the development of open-pit mining technology in China. Therefore, it is necessary to explore new mining technology methods and supporting equipment from the source of open-pit mining technology to solve the problems of high cost, high pollution and high energy consumption in mines. The intensive and continuous mining technology of large open pit mine will change the concept of mining transportation, abandon the traditional concept of mobile transport, develop the new concept of transmission logistics of open pit mining, innovate the technical theory of open pit mining, and practice the establishment of a centralized mining system of ore loading - crushing - transportation of open pit working face. This will be a new open-pit mining method to comprehensively improve the level of mining technology and achieve the goals of high efficiency, environmental protection and energy saving, and is the trend of future large-scale open-pit mine technology development.

[Equipment level to large-scale, intelligent development] Looking back on the history of mining, the development of open pit mining is mainly achieved through the progress of mining equipment, in the past 20 years, the trend of large-scale mining equipment is very obvious, especially the open pit equipment without working space restrictions, the working quality of hundreds of thousands of tons or even thousands of tons of equipment. The rapid development of mining equipment has greatly changed mining methods and processes, and promoted the development of mining technology. The maximum annual output of large open pit mines abroad has reached 40 million to 50 million tons of ore, generally using more than 10m3 bucket capacity of the shovel and more than 170 tons of trucks, the largest bucket capacity of 43m3, truck load has reached 240 tons, blasting hole diameter has been generally to 400 ~ 440mm development. Each blasting scale is maintained at 600,000 tons to 1 million tons; The height of the steps generally reaches more than 15m, and some reach 20m. The largest open pit mine (single stope) in China has an annual output of only 8 million tons to 12 million tons of iron ore, most of the electric bucket capacity is 4 to 10m3, and the truck load is mostly 25 to 75 tons. Practice has proved that the application of large-scale equipment to achieve large-scale mine production will inevitably bring high benefits to enterprises.

[Large deep open-pit mining technology will be developed] At present, some open-pit mines in China have entered the stage of very deep mining, and have gained certain experience, but there are also some problems: (1) When very deep open-pit mining is carried out, the mining cost increases, the transportation distance increases, the transportation conditions deteriorate, and the production output enters the decline period; (2) In order to solve the problems of high and steep slope stability and the influence of deep water on the slope, huge investment is made when the open-pit mine enters the very deep mining; (3) For mines that enter extremely deep open pit mining, due to the slow diffusion of harmful gases such as stope blasting, mining efficiency is reduced and environmental pollution is caused. In the next 10 years, most of the open pit mines in China will gradually enter the deep and very deep mining stage. Solving the special technical problems of the deep open pit mining and safely achieving stable and increased mine production with smaller investment, shorter time is of great theoretical value and practical significance for realizing the sustainable development of mines. It is a comprehensive technical problem that needs to be solved urgently in the development of metal mining industry in China, and has a broad application prospect.

[Open-pit digital mine technology will change the traditional mining technology and process, and realize the automatic control and scientific management automation of mine operations] China's open-pit digital mine technology has made certain achievements with the support of the "eleventh Five-Year" and "Twelfth Five-Year" national science and technology plan projects, but in general, There is still a huge gap between the informatization and intelligent level of mining production in China and that of developed mining countries abroad. The technical equipment level, labor production efficiency and safety guarantee ability of mines in China are far lower than the advanced level of foreign countries, and it is urgent to further develop independent intelligent mining technology and equipment and promote its industrialization.