Iron ore beneficiation and processing technology
Our iron ore due to the lean ore and more (97.5% of total reserves) and with (total) students have integrated mine the other components of the multi (total reserves of 1/3), so most of the need for smelting before beneficiation processing .
In 1996, the country selected 219.97 million tons of iron ore, accounting for 85.2% of the country's iron ore original ore 25.22 million tons. The iron ore produced iron ore concentrate was 85.857 million tons, of which the key ore processing plant processed 10.961 million tons of ore, and produced iron ore fines of 41.58 million tons, accounting for 48.4% of the national iron concentrate powder production.
(1) Ore crushing
China's concentrating plants generally use crushing, crushing and fine-breaking three-stage crushing process to break iron ore. The coarse-breaking multi-purpose 1.2m or 1.5m rotary crusher is used in the 2.1m or 2.2m standard conical stone crusher, and the 2.1m or 2.2m short-head cone crusher is used for fine breaking. Through the coarse ore, the blockiness is not more than 1m, and then it is crushed by medium and fine, and sieved into the final product of the ore grain size less than 12mm.
(2) Grinding process
Most of China's iron ore grinding process uses two-stage grinding process, and small and medium-sized ore dressing plants use a grinding process. Due to the use of fine screening and re-grinding new processes, in recent years some concentrating plants have changed from two-stage grinding to three-stage grinding. The grinding equipment used is generally small, the largest ball mill is 3.6m×6m, the largest rod mill is 3.2m×4.5m, the largest self-grinding mill is 5.5m×1.8m, and the gravel mill is 2.7m×3.6m.
The classification after grinding is basically a spiral classifier. In order to improve efficiency, some concentrators use hydrocyclones to replace the secondary spiral classifier.
(3) Sorting technology
Magnetite ore dressing
It is mainly used to select low-grade "Anshan-style" magnetite. Due to the strong magnetic properties of the ore and good grinding, the domestic magnetic separation plant adopts stage grinding and multi-stage grinding process. For the coarse-grained magnetite, the former (a section of grinding), fine-grained and fine-grained inlays are used. The magnetite uses the latter (two or three stages of grinding). The series of permanent magnetization developed by China has made the magnetic separator realize permanent magnetization. 70 years later, due to the magnetite concentrator in the country to promote a fine sieve and then grinding the new technology, the concentrate grade increased from 62% to about 66%, to achieve the requirements of the Ministry of metallurgical industry proposed concentrate grade of 65%.
(4) Sintering pellet technology
Sintering technology is the main means of man-made rich ore in China. In 1996, a total of 196.956 million tons of man-made rich ore were produced, of which 94.859 million tons were key enterprises, accounting for 58.9%, and 63.37 million tons were local state-owned enterprises, accounting for 38.1%.
China has reached a considerable level in the technology of fine concentrate sintering. As early as the early 1950s, Angang successfully changed the acid sinter production method to the alkaline sinter production method on the sintering machine, and solved the problem of fine concentrate sintering in the world with slaked lime or quicklime as the flux.
Sintering equipment level pellets also increased, a total sintering machine 419 units with a total area of 15522m 2, wherein: 130m or more stages of sintering machine has 22 units, the total area of 4107m 2; sintering machine 24 ~ 129m 2 197 units, The total area is 9387m 2 ; 200 sets of sintering machines less than 24m2, with a total area of ​​2028m 2 . The 300m 2 sintering machine, which was put into operation at Maanshan Iron and Steel Plant on February 24, 1994, is the largest modern sintering machine designed, manufactured and constructed by China in addition to Baosteel.
The main technical and economic indicators for sintering in 1995 were: utilization factor 1.36t/(m 2 ·h), sinter grade 53.00%, sintering machine calendar operation rate 80.94%, sinter qualification rate 84.92%, worker labor productivity 2170t /(h·a).Personal Use Electric Heater,Natural Warm Wind Ac Heater,Room Heater,Electric Water Heater
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