CN113637843A

CN113637843A - Method for producing composite flux pellet ore by grate rotary kiln

Info

Publication number: CN113637843A
Application number: CN202110317554.4A
Authority: CN
Inventors: 许贵宾
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-03-18
Filing date: 2021-03-18
Publication date: 2021-11-12

Abstract

The invention discloses a significant technical method for solving the ring formation problem of a rotary kiln of a chain grate machine during the production of fluxed pellets, which breaks through the technical bottleneck which troubles the steel industry at home and abroad for decades. The method is technically characterized in that magnesium ash or quicklime powder is added into fine iron powder to complete first pelletizing; then, after screening and compacting, extruding and dispersing capillary moisture of the pellets to the surfaces of the pellets, and carrying out secondary pelletizing; so that the magnesium ash or quicklime powder is uniformly wrapped on the surfaces of the pellets again and then is sent into a roasting system. The process enlarges the equipment limitation of the production of the fluxed pellets, and enlarges the SiO content of the fine iron powder required by the production of the fluxed pellets₂The requirements of (1). The composite fluxed pellets produced by secondary pelletizing can not form rings in the rotary kiln. By the mode, the desulfurization capacity of the pellet is enhanced, and the pellet is used in a blast furnace with a high proportionPellet smelting can obviously reduce the Cao/SiO of the charging materials of the blast furnace₂Therefore, the energy consumption is reduced, and the yield is improved.

Description

Method for producing composite flux pellet ore by grate rotary kiln

The technical field is as follows:

the invention belongs to the production field of fluxed pellets of iron-making raw materials in the smelting industry. Is suitable for manufacturing high-quality ironmaking pellets.

Background art:

at present, the SiO of the iron mineral of the melt pellets is produced at home and abroad₂The content generally needs not to exceed 2.5 percent, and the theoretical basis is as follows: if the magnetite powder is not oxidized sufficiently in the roasting process, SiO₂Feo can form a low temperature bond, thereby deteriorating production; if the Cao in the pellet is too much, calcium ferrite formed firstly finally forms calcium silicate when contacting with silicon dioxide, and the excessive formation of the calcium silicate not only reduces the reducibility of the pellet, but also reduces the strength of the pellet; the molten pellets are rotatedThe falling material in the kiln causes severe ring formation, thereby deteriorating the production.

The production mode of the composite fluxed pellet is two-time pelletizing, namely, the first pelletizing (Cao/SiO)₂More than 0.6 times), and then the mixture enters a second pelletizing system after being screened and compacted. The second pelletizing is to coat one layer of lime powder or magnesia powder to the pellet surface, and the thickness of the outer coating is determined by the water content in the pellet surface and can increase the binary alkalinity of the pellet by 0.05-0.15 times.

The technology is characterized in that the single-ball three-layer alkalinity is a simple quicklime or magnesium ash layer-calcium ferrite or magnesium ferrite layer-fluxed pellet core from outside to inside. Therefore, the distribution of the fusing agent on different parts of the single pellet solves the problem that the fusing agent pellet cannot be produced due to high silicon content and also solves the ring formation problem of the fusing agent pellet produced by the grate rotary kiln.

The invention content is as follows:

1. mixing materials: adding magnesium ash or quicklime powder into the fine iron powder, wherein the adding amount is determined by the binary alkalinity required by production. In general, Cao/SiO₂More than 0.6 times, more than 2.5 percent of Mgo and about 7.5 percent of water content of the mixture.

2. Pelletizing for the first time: the first pelletizing is completed in a disc pelletizer, and the moisture of the pelletized pellets is controlled to be 8.2-8.5%.

3. And (3) screening and compacting for the first time: the pellets manufactured for the first time enter a round roller screening and compacting system, and capillary moisture of the screened and compacted pellets is extruded and dispersed to the surfaces of the pellets.

4. And (3) pelletizing for the second time: and the pelletizing finished for the first time is screened and compacted and then enters a pelletizing system for the second time. The second pelletizing equipment may be cylinder pelletizer or roller screen, and is aimed at uniformly coating a layer of quicklime powder or magnesium ash powder on the surface of the first pelletized pellet, and the quantity of the quicklime powder or magnesium ash powder coated on the surface of the pellet is determined by the quantity of water on the surface of the pellet after the first screening.

5. After the second pelletizing is finished, the pellets are screened and compacted by a roller screen and then are sent into a roasting system to be roasted. The total water content of the pellets produced for the second time is controlled to be 8.1-8.3%.

Description of the drawings:

the attached figure 1 shows the process route of the secondary pelletizing method for producing the composite fluxed pellets by the grate rotary kiln of the invention, and according to the figure, related equipment can be designed and installed, and the production technology method provided by the invention can be used for producing the non-ring-forming composite fluxed pellets.

The specific implementation mode is as follows:

1. the technological process includes the first pelletizing, the roller screen sieving, extruding the capillary water to the surface of the pellet, and the second pelletizing. Namely, the binary alkalinity of the first pelletizing is more than 0.6 times, and the alkalinity of the second pelletizing is increased to be more than 0.7 times. The surface of the roasted pellet is a layer of calcium ferrite (or magnesium ferrite) and a layer of simple substance Cao or Mgo.

2. The total moisture of the pellets after the first pelletizing, including the capillary water extruded to the surfaces of the pellets, should be less than 8.5%. After the quicklime powder or the magnesium ash powder is wrapped outside, the total water content is controlled to be 8.1-8.3%.

3. After the second pelletizing, the pellets are screened by a roller screen and then enter a rotary kiln behind a chain grate machine for drying, preheating and roasting.

Has the advantages that:

1. the elemental Cao or Mgo falling from the composite fluxed pellet in the rotary kiln after twice pelletizing has a melting temperature higher than 2000 ℃ and cannot melt and form rings after the conventional roasting temperature of the pellet is 1250 ℃, so that the shutdown cleaning of the rotary kiln caused by the ring forming can be greatly prolonged.

2. The compression strength of the preheated pellets completed from the two stages of the chain grate can be more than 700N. The strength of the oxidized pellets after the preheating stage is less than 600N.

3. The composite fluxed pellets have high porosity (generally more than 20 percent) because the reducing agent co in the blast furnace easily enters the pellets and the surfaces of the pellets are provided with uniformly distributed Cao, the S removal capacity is greatly enhanced. The proportion of the composite fluxed pellets is increased in the blast furnace smelting, so that the composite fluxed pellets can be obviously smeltedThe binary alkalinity required by blast furnace smelting is obviously reduced. If the blast furnace completely uses the composite fluxed pellets to smelt the molten iron with Si less than 0.5 percent, the binary alkalinity of the blast furnace smelting slag of the blast furnace is Cao/SiO₂Can be controlled to be 0.85-1.05 times, thereby improving the grade of the iron entering the furnace, saving the fuel and increasing the yield.

4. The technology only needs 22kg energy consumption when roasting 1 ton of fluxed pellets, and 23kg energy consumption is reduced compared with the production of sintered ore. If the pellet ore production does not use solid fuel, dioxin pollutants are not generated.

5. The fuel ratio of the blast furnace can be controlled to be 460 kg/ton pig iron in global lump smelting, and compared with the current fuel ratio of 520kg per ton iron in China, the energy consumption of 60kg can be reduced in global lump smelting of 1 ton pig iron.

6. Full pellet smelting pig iron with binary basicity of blast furnace slag Cao/SiO₂The blast furnace slag can be controlled below 1.0, the blast furnace slag can be directly converted into glass ceramic granules, the comprehensive calculation value is calculated according to 300kg of slag generated by smelting 1 ton of pig iron, and the energy consumption of 180kg can be saved by smelting 1 ton of pig iron theoretically.

Claims

1. The present invention features that the fluxed pellet ore is produced through twice mixing and pelletizing of iron ore powder. Firstly, before the iron ore powder is pelletized, firstly, the magnesium ash powder or limestone powder is mixed into the iron ore powder according to a certain proportion, and the first pelletizing is started, and the ingredient index of the pellets can reach Cao/SiO₂> 0.6 times. And screening and compacting the mixture and then entering a second pelletizing system. And in the second pelletizing, a layer of magnesium ash powder or quicklime powder is wrapped on the surface of the pellet finished for the first time, the binary alkalinity of the pellet is increased by 0.05-0.15 time, and the problems that the raw material has high silicon content and cannot produce the fluxed pellet can be solved. Also solves the ring formation problem of the flux pellets produced by the rotary kiln of the chain grate machine.

The invention claims the process method for producing the composite fluxed pellets.