Improving the blast furnace charge needs to increase the amount of pellets in the charge, the quality of the pellet has a very important impact on smelting, and the expansion of the blast furnace has higher and higher requirements for the quality of the pellet. The international standard is: in the case of long-distance transportation, the compressive strength of the pellet should reach 2500N/pc, which can be appropriately lowered when directly used for blast furnace ironmaking, not less than 2000N/pc. In order to better reflect the superior metallurgical properties of pellet ore, it is necessary to pay attention to the strength of pellet ore, and improve the compressive strength and pass rate of finished pellets in order to meet the needs of blast furnace production.
Factors affecting the compressive strength of the pellet:
Constraints on raw materials, raw pellet quality, thermal parameters, equipment structure, pellet adhesive quality, etc
Measures to improve the compressive strength of the pellet:
One. Improve the quality of raw balls
The quality index of raw balls has a direct impact on the compressive strength of pellets, and the ball making process mainly controls the following indicators of raw balls: falling strength, wet ball moisture, and grain size pass rate.
The particle size of the raw ball basically determines the productivity of the ball machine and the falling strength of the raw ball. The particle size is small, the productivity is high; the particle size is large, the ball making time is long, the productivity is low, and the lower the fall intensity.
The compressive strength of the finished product also has a certain relationship with the raw ball, the better the strength, the better the compressive strength of the finished product. Ensuring the quality of raw balls is a prerequisite for obtaining high-quality pellet ore.
Two. Find out why
(1) The quality of fine powder varies from place to place, and it is difficult to pile up, which brings difficulties to the batching process; (2) the quality change of bentonite that plays a bonding role also has a certain impact on the strength; (3) the physical and chemical performance index of the fine powder is low, the particle size is coarser, the impurities are more, the taste is low, and the FeO content is high; (4) the operation technology is uneven, and the technical accuracy cannot be judged.
Three. Improve gradation and improve technology
(1) Optimize the structure of raw materials, implement point stacking of concentrate powder, and optimize ore distribution. (2) Add the appropriate particle size, suitable moisture, and uniform chemical composition according to the proportion. Since the strength of the pellets mainly comes from the recrystallization and consolidation of iron trioxide, the taste of iron concentrate should be improved as much as possible to reduce the amount of bentonite. (3) Iron ore concentrate should have a certain fineness, the finer the particle size, the larger the specific surface area of the ore powder, and the greater the molecular force between the surface of the particles, which is conducive to globules. (4) According to the changes in the structure of raw materials, develop and produce suitable pellet adhesives to maximize resource utilization.