After more than 40 years of basic construction, China has built 204 iron mines. Among them: 44 key mines and 160 local state-owned mines, with a total iron ore mining capacity of 197.19 million tons. Fan Motor,Box Fan Motor,Exhaust Fan Motor,Electric Fan Motor Foshan kanasi electrical co.,ltd , https://www.fskanasifan.com
There are two major categories of open pit mining and underground mining (flat, inclined, and shaft). During the period from 1949 to 1957 in China, more than 80% of the mines were underground mining, and less than 20% of open-pit mining. Subsequently, as a batch of open-pit mines were completed and put into production, the proportion of underground mining declined sharply. By the early 1990s, the proportion of open-pit mining rose to 80%, and the proportion of underground mining fell to 20%.
(I) Open-pit mining In 1996, the amount of iron ore ore in the open-pit mining in the country was 185.38 million tons, accounting for 73.5% of the national iron ore production. There are 27 key open-pit mines, with a total of 91.06 million tons of ore-bearing iron ore, accounting for 85.6% of the ore's ore output of 106.37 million tons. Economic and technical indicators of key open pit mines: The average ore content of the produced ore is 27.67%, the recovery rate is 97.07%, the depletion rate is 4.39%, the stripping ratio is 2.74t/t, and the falling rate is 7.50m/a. Technical equipment such as piercing, shovel loading and transportation in open pit mines are constantly updated. At present, the structure of the roller drill and the down-hole drill has been formed in the perforation of key mines nationwide, and the impact drill has been completely eliminated. In 1996, the annual comprehensive efficiency of the cone drilling rig was 23787m, the highest was 31611m (water plant iron ore); the comprehensive efficiency of the downhole drilling rig was 14066m, the highest was 25279m (Lanjian iron ore). Shovel equipment is developing in the direction of large-scale and modernization. In 1996, the most used open-pit mines were 4~4.6m3 electric shovel. The average annual comprehensive efficiency was 1.333 million tons, and the largest capacity 16m3 electric shovel. The average annual efficiency was 3.475 million tons, and the highest was 48.21 million tons (Qidashan Iron Mine) ). The transportation mode is mainly for automobile and rail transportation, and some are transported by tape. Since the 1980s, some mines of Benxi Iron and Steel Company and Anshan Iron and Steel (Group) Co., Ltd. have gradually replaced other cars with electric wheels of 108-154t, realizing the large-scale and modernization of transportation vehicles. In 1996, the average annual efficiency of 108t cars was 359,000 tons; the 154t cars were 895,000 tons, the highest was 1.23 million tons (Qidashan Iron Mine); the most used 42t cars, the average annual efficiency was 276,000 tons, the highest was 44.3 Wan t (Baiyun Obo Iron Mine). After 1965, some key mines were transported by railway electric vehicles. In 1996, the average annual efficiency of key open-pit mining electric locomotives was 791,800 tons for 80t electric vehicles, 549,900 tons for 100t electric vehicles and 88.26 for 150t electric vehicles. Wan t. [next]
The mining technology of open-pit mining has long been adopted throughout the whole process, and the stripping process of wide-step slow-moving operations has now turned to steep mining and horizontally advancing new processes. Since the 1980s, many large-scale open-pit mines have been converted from open-pit mining to deep-concave mining, which has constrained the increase in production capacity due to deteriorating operating conditions and transportation problems. In 1994, the “Eighth Five-Year Plan†project of “Integrated Technology Research on Deep Open-pit Mining†was implemented, and preliminary results have been achieved.
In the blasting equipment and technology, there have also been developments, including rock explosives, ammonium explosives, ammonium nitrate explosives, emulsified explosives, etc., and large-area multi-hole fine blasting technology has been applied in production.
(II) Underground Mining In 1996, the country's underground mining of iron ore was 66.9 million tons, accounting for 26.5% of the national iron ore production. Among them, there are 17 key underground mines, with a total of 15.36 million tons of ore ore, accounting for 14.4% of the output of key mines. Key economic and technical indicators of underground mines: the average grade of ore mined is 36.9%, the recovery rate is 76.2%, the depletion rate is 19.8%, and the annual decline rate is 6.98m.
At present, the underground mining method is mainly the bottomless column mining method, accounting for about 72%, followed by shallow hole retention method, accounting for 9%, room and column mining method accounting for 8%, and empty field method accounting for 7 %, with a bottom column sublevel caving mining method accounting for 3%, filling method accounting for 1%. Underground mine roadway support has been developed from the wood support in the 1950s to the current coexistence of three support methods: wood support, concrete support and spray anchor support. Rock drilling shipments have also gradually developed towards mechanization. Nowadays, rock drilling rigs, shiploading, and electric motor transportation have been widely used. Due to continuous improvement in mining methods, technical equipment, and support methods, the labor productivity of underground mines has been greatly improved. In 1949, when the new China was founded, the labor productivity of key underground mines nationwide was only 19.9t/ (People a), by 1995, has reached 561t/(person•a), an increase of nearly 30 times.