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

[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.