China after 40 years of infrastructure have been built of iron mines 204.

China after 40 years of infrastructure have been built of iron mines 204. Of which: focus mine 44, 160 local state-owned mines, iron ore mining capacity to form a total of 197.19 million t.Way to develop iron mine open pit mining and underground mining (flat Cave, slope, shaft) two categories. China in the period 1949 to 1957, more than 80% of the mine is underground mining, open-pit mining of less than 20%. Subsequently, the number of open pit have been put into operation, a sharp decline in the proportion of underground mining, to the early 1990s, the proportion of open-pit mining rose 80%, the proportion of underground mining dropped by 20%.Open-pit miningIn 1996 the country's iron ore mining equipment open-pit mining the amount of 185.38 million t, accounting for 73.5% of iron ore production. Focus on open pit mine 27, the amount of 91.06 million communist iron ore t, accounting for key mining ore production 106 370 000 t of 85.6%. Focus on open pit economic and technical indicators: the average iron ore mined 27.67%, 97.07% recovery rate, dilution rate of 4.39%, stripping ratio 2.74t / t, decreased rate of 7.50m / a.Open-pit hole, shovel loading, transportation and other technical equipment constantly updated. Currently, the focus of mining in the country has formed a cone drill hole and drill hole and use the structure, completely eliminated the impact of drilling. In 1996, the cone drill platform was integrated efficiency 23787m, up to 31611m (water iron); hole drilling platform in overall efficiency 14066m, up to 25279m (blue tip iron). Shovel loading equipment toward large-scale, modern direction. In 1996, the focus on the most used open-pit mine is 4 ~ 4.6m3 shovel, Taiwan, the average overall efficiency of 1.333 million t, the maximum capacity of 16m3 shovel, Taiwan, the average efficiency of 3.475 million t, up to 4,821,000 t (Qidashan Iron .) Mode of transport for the automotive and rail transport, some with tape transport. Since the 1980s, Benxi Steel and Anshan Iron and Steel (Group) Company of some of the mines gradually with 108 ~ 154t electric wheel cars instead of the other car, a transport vehicle to achieve large-scale, modern. In 1996, 108t car units an average of 359,000 annual efficiency t; 154t vehicle was 89.5 million t, up to 1.23 million t (Qidashan Iron); use the 42t car sets up an average annual efficiency of 27.6 million t, up to 443 000 t (Bayan Obo iron ore). After 1965, some key mines using rail transport motor vehicles in 1996, focusing on open-pit mine average annual motor vehicle platform efficiency: 80t motor vehicle for the 791 800 t, 100t motor vehicle for the 549 900 t, 150t motor vehicle for the 88.26 Wan t.Open-pit mining process, to promote long-term use of the whole territory, wide steps to help ease the job of the stripping process, help is now turning to steep mining, horizontal to promote new technology. Since the 1980s, many large open-pit mining from the hills open into the furrow, the deterioration of working conditions and transport problems, which restricted the increase in capacity. 1994, implemented the "Comprehensive Deep open-pit mining technology research" and "85" research project, has achieved initial results.iron ore beneficiation plant and technology has also grown, with a rock after another explosive, ANFO, ammonium nitrate explosives, emulsion explosives, etc., applied in the production of large area multi-row millisecond blasting hole technology.Underground mining1996 National Underground mining iron ore 66.9 million t, accounting for 26.5% of iron ore production. 17 of which focus on underground mining, ore 15.36 million communist ore t, emphasis mine production accounted for 14.4%. Focus on economic and technical indicators underground mines: the average grade of ore mined was 36.9%, 76.2% recovery rate, dilution rate of 19.8%, the annual rate of decline 6.98m.At present, mining, underground mining methods is Pillarless mining method, which accounts for 72%, followed by shallow hole Shrinkage method, accounting for 9%, room and pillar mining method and the wall, 8%, 7% empty field method There Sublevel caving mining method, 3%, 1% filling method. Underground mining mine roadway of wood from the 1950s to the present supporting the development of supporting wood, concrete and shotcrete shoring shoring shoring three kinds of methods coexist. Shipping is also gradually mechanized drilling direction, is now widely used in rock drilling trolley, machine loading shovel equipment, motor vehicle transport. As the mining methods, technical equipment, methods, supporting the continuous improvement of the overall labor productivity of underground mines has been greatly improved, the new China was founded early 1949, the focus of the overall labor productivity in underground mines only 19.9t / (person a), 1995 has reached 561t / (person a), increased nearly 30 times.