Application of coke dicing in blast furnace ironmaking

Abstract

The invention relates to the technical field of blast furnace ironmaking, and discloses a method for applying coke diced in blast furnace ironmaking, which comprises the following steps: (1) setting a screen surface with screen holes of 25 mm, 14 mm, 12 mm and 10 mm respectively during coke screening, wherein particles with a particle size of ≥25 mm are coke, particles with a particle size of 10 mm≤<25 mm are coke diced, and particles with a particle size of <10 mm are coke powder; the minimum particle size of coke diced added to the blast furnace includes 14 mm, 12 mm and 10 mm; (2) adding coke diced to iron-containing raw materials, uniformly mixing to form an ore mixture, and alternately feeding the ore mixture and coke into the blast furnace to form a layered structure of alternating ore layers and coke layers in the blast furnace; (3) the blast furnace adopts large-scale ore batch smelting. The invention enables the blast furnace to have the ability to receive low-particle coke diced, reduces the amount of coke powder transported, increases the amount of coke diced recovered, reduces the loss of coke discount, and achieves the technical effect of reducing fuel costs.

Description

Technical Field

[0001] The invention relates to the technical field of blast furnace ironmaking, and in particular to an application method of diced coke in blast furnace ironmaking. Background Art

[0002] Blast furnace ironmaking is the main method of modern ironmaking and an important link in steel production. It is a continuous production process of reducing iron ore into pig iron. Solid raw materials such as iron ore, coke and flux are fed into the blast furnace in batches by the furnace top charging device according to the prescribed proportions, and the throat material surface is kept at a certain height. Coke and ore form an alternating layered structure in the furnace. The ore is gradually reduced and melted into iron and slag during the descent process, which gather in the furnace and are regularly discharged from the iron mouth and slag mouth.

[0003] The coke returned from the ironmaking plant first passes through a 25mm coke screen. Coke with a particle size of ≥25mm is used as coke for blast furnaces. It then passes through a 14mm coke diced screen. Coke with a particle size of <25mm and ≥14mm is used as coke diced, and coke with a particle size of <14mm is used as coke powder. It is mainly transported to the sintering plant for fuel use. Among them, the price of coke is about 2,500 yuan / ton, and the price of coke powder is about 1,460 yuan / ton. At present, the 14mm coke diced screen is used, and about 330 tons of coke powder is transported to the sintering plant every day, which contains A large proportion of large-size coke pieces are not utilized. If the use range of coke particle size is increased and the amount of coke powder transported is reduced, the production cost of the ironmaking plant can be reduced. However, as the use range of blast furnace coke particle size becomes wider, the particle size difference increases, the blast furnace skeleton function weakens, and furnace conditions fluctuate easily. Moreover, when the average coke particle size is reduced, the permeability of the material column may deteriorate, especially the air and liquid permeability of the dead material column in the lower part of the blast furnace may decrease, which may easily cause high and fluctuating pressure differences in the blast furnace, abnormal furnace conditions, suspended materials, increased coke ratio, and decreased output. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention aims to provide a method for applying diced coke in blast furnace ironmaking, so as to reduce the amount of coke powder transported and reduce the production cost of the ironmaking plant.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions.

[0006] A method for applying diced coke in blast furnace ironmaking comprises the following steps:

[0007] (1) In the coke screening process, sieve surfaces with sieve openings of 25 mm, 14 mm, 12 mm and 10 mm are set respectively; coke is ≥25 mm in size, coke is 10 mm≤ in size and <25 mm in size, and coke powder is ≤10 mm in size; the minimum size of coke diced added to the blast furnace includes 14 mm, 12 mm and 10 mm, preferably 10 mm;

[0008] (2) adding diced coke to an iron-containing raw material, uniformly mixing the mixture to form an ore mixture, and alternately feeding the ore mixture and coke into a blast furnace to form a layered structure of alternating ore layers and coke layers in the blast furnace;

[0009] (3) Blast furnaces use large batches of ore for smelting.

[0010] Furthermore, the above application method also includes controlling the blast furnace top pressure to be ≥210KPa.

[0011] In some embodiments of the present invention, the iron-containing raw materials include lump ore, sintered ore, and pelletized ore.

[0012] Preferably, the mass ratio of the lump ore, sintered ore and pelletized ore is 2:(3-5):1.

[0013] Furthermore, the ore batch in the large ore batch smelting is 60-65t.

[0014] Furthermore, the cross-sectional shape of the ore layer and the coke layer is "V"-shaped, and the opening of the "V"-shaped increases as the position of the ore layer and the coke layer in the blast furnace decreases.

[0015] Furthermore, the thickness of the ore layer is 300-500 mm, and the thickness of the coke layer is 300-500 mm.

[0016] The present invention classifies coke with a particle size of ≥25mm and coke pieces with a particle size of 10mm-25mm into the furnace. The coke with a particle size of ≥25mm mainly plays the role of a skeleton and a heat-generating agent in the blast furnace, and the coke pieces with a particle size of 10mm-25mm mainly play the role of a carburizing agent and a heat-generating agent, thereby avoiding the adverse effect of the addition of low-particle coke pieces on the air permeability of the blast furnace; the present invention gradually reduces the particle size of coke pieces from 14mm to 12mm and then to 10mm through theoretical practice, so that the blast furnace gradually adapts to the increase in the coke particle size difference and avoids furnace condition fluctuations; the present invention mixes coke pieces with a particle size of 10mm-25mm in sintered ore and adds them to the blast furnace together with ore raw materials, so that the coke pieces can better play a carburizing role; the present invention adjusts the distribution method, relates the cross-sectional shape of the ore layer and the coke layer to a "V" shape, and the opening of the "V" shape is changed as it is in the blast furnace. The blast furnace of the present invention adopts large ore batch smelting, and the ore batch is increased to 60-65t. The increased batch weight can stabilize the upper coal gas flow, improve the coal gas utilization, increase the thickness of the coke interlayer in the soft melting zone, facilitate the air flow through the soft melting zone, reduce the lower pressure difference, and improve the permeability; the present invention improves the coal gas utilization rate by increasing the blast furnace top pressure, prolonging the time that the coal gas stays in the furnace, promoting indirect reduction, and facilitating the stability of the air flow; the present invention adjusts the air supply system, maintains a reasonable wind speed and blast kinetic energy, makes the initial distribution of the coal gas flow reasonable, and makes the furnace work evenly and actively; develops the central coal gas flow, facilitates the smooth flow of the furnace charge, and limits the edge air flow.

[0017] In summary, the present invention provides a method for applying diced coke in blast furnace ironmaking, which increases the particle size difference of coke used in blast furnace ironmaking while ensuring smooth operation of the blast furnace, enables the blast furnace to receive low-particle-size diced coke, reduces the amount of coke powder transported, increases the amount of diced coke recovered, reduces the loss of coke discount, and achieves the technical effect of reducing fuel costs. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] The present invention provides a method for applying diced coke in blast furnace ironmaking, which comprises the following steps:

[0020] (1) In the coke screening process, sieve surfaces with sieve openings of 25 mm, 14 mm, 12 mm and 10 mm are set respectively; coke is ≥25 mm in size, coke is 10 mm≤ in size and <25 mm in size, and coke powder is ≤10 mm in size; the minimum size of coke diced added to the blast furnace includes 14 mm, 12 mm and 10 mm, preferably 10 mm;

[0021] (2) adding diced coke to an iron-containing raw material, uniformly mixing the mixture to form an ore mixture, and alternately feeding the ore mixture and coke into a blast furnace to form a layered structure of alternating ore layers and coke layers in the blast furnace;

[0022] (3) The blast furnace adopts large-scale ore batch smelting and controls the blast furnace top pressure ≥210KPa.

[0023] In some embodiments of the present invention, the iron-containing raw materials include lump ore, sintered ore, and pelletized ore.

[0024] Preferably, the mass ratio of the lump ore, sintered ore and pelletized ore is 2:(3-5):1.

[0025] Furthermore, the ore batch in the large ore batch smelting is 60-65t.

[0026] Furthermore, the cross-sectional shape of the ore layer and the coke layer is "V"-shaped, and the opening of the "V"-shaped increases as the position of the ore layer and the coke layer in the blast furnace decreases.

[0027] Furthermore, the thickness of the ore layer is 300-500 mm, and the thickness of the coke layer is 300-500 mm.

[0028] The specific embodiments of the technical solution of the present invention are as follows:

[0029] The ore raw material for blast furnace smelting in this embodiment is vanadium-titanium magnetite in the Panxi area. The ore is mixed in a mass ratio of lump ore: sintered ore: pelletized ore = 2:4:1 to obtain an iron-containing raw material. From July 4, 2023, the coke screened with a 12mm sieve is added to the blast furnace as blast furnace fuel, wherein 12-25mm coke pieces are added to the iron-containing raw material and evenly mixed, and then alternately fed into the blast furnace with coke ≥25mm, to form a layered structure of alternating ore layers and coke layers in the blast furnace, the cross-sectional shape of the ore layer and the coke layer is "V" shaped, and the The "V"-shaped opening becomes larger as its position in the blast furnace decreases. The thickness of the ore layer is controlled to be 300-500mm, and the thickness of the coke layer is controlled to be 300-500mm. The blast furnace adopts large ore batch smelting, with an ore batch of 62t, and the furnace top pressure is increased to above 210KPa. This production mode will be used until November 30, 2023, and the coke screened with a 10mm sieve will be added to the blast furnace as blast furnace fuel, among which 10-25mm coke pieces are added to the iron-containing raw materials and evenly mixed, and then alternately fed into the blast furnace with coke ≥25mm.

[0030] According to this production model, from July 4 to November 30, 2023, the minimum particle size of coke entering the furnace will be reduced from 14mm to 12mm, and the average coke powder production will be reduced from 330t / day to 310t / day; from November 30, the minimum particle size of coke entering the furnace will be reduced from 12mm to 10mm, and the average coke powder production will be reduced to 280t / day. It can be seen that the present invention increases the particle size difference of coke used in blast furnace ironmaking under the premise of ensuring the smooth operation of the blast furnace, enables the blast furnace to have the ability to receive low-particle coke, reduces the amount of coke powder transportation, increases the amount of coke recovery, reduces the loss of coke discount, and achieves the technical effect of reducing fuel costs.

[0031] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for applying diced coke in blast furnace ironmaking, characterized in that: The following steps are involved: (1) In the coke screening process, the screens with mesh sizes of 25 mm, 14 mm, 12 mm and 10 mm are set respectively. The particle size ≥ 25 mm is coke, 10 mm ≤ and < 25 mm is coke diced, and the particle size < 10 mm is coke powder; the minimum particle size of coke diced added to the blast furnace includes 14 mm, 12 mm and 10 mm; (2) adding diced coke to an iron-containing raw material, uniformly mixing the mixture to form an ore mixture, and alternately feeding the ore mixture and coke into a blast furnace to form a layered structure of alternating ore layers and coke layers in the blast furnace; (3) Blast furnaces use large batches of ore for smelting.

2. The method for applying diced coke in blast furnace ironmaking according to claim 1, characterized in that: It also includes controlling the blast furnace top pressure ≥210KPa.

3. The method for applying diced coke in blast furnace ironmaking according to claim 1, characterized in that: The minimum particle size of coke diced fed into the blast furnace is 10 mm.

4. The method for using diced coke in blast furnace ironmaking according to claim 1, characterized in that: The iron-containing raw materials include lump ore, sintered ore and pelletized ore.

5. The method for using diced coke in blast furnace ironmaking according to claim 4, characterized in that: The mass ratio of the lump ore, sintered ore and pelletized ore is 2:(3-5):

1.

6. The method for using diced coke in blast furnace ironmaking according to claim 1, characterized in that: The ore batch in the large ore batch smelting is 60 to 65 tons.

7. The method for using diced coke in blast furnace ironmaking according to claim 1, characterized in that: The cross-sectional shape of the ore layer and the coke layer is "V"-shaped, and the opening of the "V"-shaped becomes larger as the position thereof in the blast furnace is lowered.

8. The method for using diced coke in blast furnace ironmaking according to claim 1, characterized in that: The thickness of the ore layer is 300-500 mm, and the thickness of the coke layer is 300-500 mm.