Method for reducing and eliminating high-titanium vanadium titano-magnetite blast furnace smelting hearth center accumulation

Abstract

The invention provides a method for reducing and eliminating accumulation at the center of a high-titanium vanadium titano-magnetite blast furnace smelting hearth, which comprises the following steps of: during material distribution, independently adding titanium-free metallized pre-reduced pellets into the center of a blast furnace; the metalized pre-reduced pellets are prepared from the following components in percentage by mass: 75 to 90 percent of TFe, 2 to 4 percent of C, 0.005 percent of P, 0.004 percent of S, 2.5 to 4.5 percent of SiO2, 2.2 to 4 percent of Al2O3, 0.5 to 1.2 percent of MgO, 0.2 to 0.8 percent of CaO and 0.05 to 0.15 percent of Mn. The method provided by the invention not only solves the technical problem of quickly reducing and eliminating the accumulation in the center of the hearth, but also can improve the blast furnace yield and smelting strength and reduce the pig iron cost.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel metallurgy technology, and particularly relates to a method for reducing and eliminating the accumulation in the center of the hearth during blast furnace smelting of high-titanium vanadium-titanium magnetite. Background Technology

[0002] Panzhihua Iron and Steel Group (Pangang) uses high-titanium vanadium-titanium magnetite blast furnaces for smelting, resulting in blast furnace slag with a TiO2 content as high as 20-25%. During the smelting process, TiO2 in the slag is easily reduced to form high-melting-point phases such as TiC, TiN, and their solid solutions Ti(C,N), leading to viscous slag. If not removed in time, these high-melting-point substances accumulate in the center of the hearth, forming a viscous mixture and causing hearth buildup. This results in abnormal temperature field and gas flow distribution within the furnace, leading to slag-iron separation and severely affecting normal blast furnace smelting. The hearth center is the area where high-temperature gas flow is most difficult to reach, making it the most prone to hearth buildup during blast furnace smelting.

[0003] To address these issues, steel companies have explored numerous methods in practice. These include using models to assess the amount of residual slag and iron in the hearth, ensuring its normal operation; the application of inverse heat transfer boundary solutions in blast furnace hearth erosion diagnosis; and the use of mathematical models to manage the working state of the blast furnace hearth, constructing mathematical models to ensure hearth buildup and stability. Some companies also assess blast furnace hearth buildup based on water temperature difference and heat load. However, these methods primarily monitor hearth buildup. To eliminate hearth buildup, the main methods involve adding fluorite and scrap steel. Adding fluorite increases the CaF2 content in the slag, reduces slag viscosity, and improves slag flowability, gradually eliminating hearth buildup. However, fluorite entering the furnace and being discharged with the slag causes significant environmental pollution. Summary of the Invention

[0004] The purpose of this invention is to provide a method for reducing and eliminating the accumulation in the center of the hearth during blast furnace smelting of high-titanium vanadium-titanium magnetite. The method of this invention not only solves the technical problem of rapidly reducing and eliminating the accumulation in the center of the hearth, but also increases blast furnace output and smelting intensity, and reduces pig iron costs.

[0005] This invention provides a method for reducing and eliminating accumulation in the center of the hearth during blast furnace smelting of high-titanium vanadium-titanium magnetite, wherein titanium-free metallized pre-reduced pellets are added separately to the center of the blast furnace during charging.

[0006] The metallized pre-reduced pellets comprise the following components by mass fraction:

[0007] TFe75~90%, C: 2~4%, P: 0.005%, S: 0.004%, SiO2: 2.5~4.5%, Al2O3: 2.2~4%, MgO: 0.5~1.2%, CaO: 0.2~0.8%, Mn: 0.05~0.15%.

[0008] Preferably, the TiO2 content of the smelting slag of the high-titanium vanadium-titanium magnetite is 20-25%.

[0009] Preferably, the metallization rate of the metallized pre-reduced pellets is 75-95%.

[0010] Preferably, the fabric angle of the metallized pre-reduced pellets is 10~28°.

[0011] Preferably, the metallized pre-reduced pellets are added during blast furnace charging along with each batch of material, and the amount of metallized pre-reduced pellets added is 1 to 20% of the batch weight.

[0012] Preferably, the degree of accumulation in the center of the hearth of a blast furnace for high-titanium vanadium-titanium magnetite is determined based on the Ti and Si content and the matching degree of air volume and air pressure; the degree of accumulation is divided into general accumulation, medium accumulation and severe accumulation.

[0013] Preferably, the difference between the mass fraction of Ti and the mass fraction of Si in the molten iron is a%, and the air volume is bm. 3 / min, wind pressure is c kPa;

[0014] When -0.08≤a≤0 and -10≤b-10×c≤5, it is a general stacking;

[0015] When -0.08≤a≤0 and -60≤b-10×c<-10, it is a medium packing.

[0016] When -0.08≤a≤0 and -100≤b-10×c<-60, it is considered severe accumulation.

[0017] Preferably, under normal stacking conditions, the fabric angle of the metallized pre-reduced pellets is 20~28°; under medium stacking conditions, the fabric angle of the metallized pre-reduced pellets is 15~20°; and under severe stacking conditions, the fabric angle of the metallized pre-reduced pellets is 10~15°.

[0018] Preferably, under normal stacking conditions, the amount of metallized pre-reduced pellets added is 1-8% of the batch weight; under medium stacking conditions, the amount of metallized pre-reduced pellets added is 8-13% of the batch weight; and under severe stacking conditions, the amount of metallized pre-reduced pellets added is 13-20% of the batch weight.

[0019] Preferably, the metallized pre-reduced pellets are added continuously for 2 to 7 days.

[0020] This invention provides a method for reducing and eliminating accumulation in the center of the hearth during blast furnace smelting of high-titanium vanadium-titanium magnetite. During charging, titanium-free metallized pre-reduced pellets are added separately to the center of the blast furnace. The metallized pre-reduced pellets comprise the following components by mass fraction: TFe 75-90%, C: 2-4%, P: 0.005%, S: 0.004%, SiO2: 2.5-4.5%, Al2O3: 2.2-4%, MgO: 0.5-1.2%, CaO: 0.2-0.8%, Mn: 0.05-0.15%. To reduce and eliminate the accumulation in the hearth center of vanadium-titanium magnetite blast furnaces, this invention involves adding ordinary, titanium-free metallized pre-reduced pellets separately to the center of the blast furnace throat during charging. These pellets descend with the furnace charge to the hearth center without being mixed with sintered ore, pellets, or lump ore, or with coke. This eliminates the technical problem of hearth center accumulation caused by the aggregation of high-melting-point substances such as TiCN during the blast furnace smelting of high-titanium vanadium-titanium magnetite. This not only solves the technical problem of rapidly reducing and eliminating hearth center accumulation but also increases blast furnace output and smelting intensity, while reducing pig iron costs. Detailed Implementation

[0021] This invention provides a method for reducing and eliminating accumulation in the center of the hearth during blast furnace smelting of high-titanium vanadium-titanium magnetite, wherein titanium-free metallized pre-reduced pellets are added separately to the center of the blast furnace during charging.

[0022] The metallized pre-reduced pellets comprise the following components by mass fraction:

[0023] TFe75~90%, C: 2~4%, P: 0.005%, S: 0.004%, SiO2: 2.5~4.5%, Al2O3: 2.2~4%, MgO: 0.5~1.2%, CaO: 0.2~0.8%, Mn: 0.05~0.15%.

[0024] In this invention, the metallization rate of the metallized pre-reduced pellets is preferably 75-95%, more preferably 80-90%, such as 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, preferably a range of values ​​with any of the above values ​​as the upper or lower limit.

[0025] In this invention, the TiO2 content of the smelting slag of the high-titanium vanadium-titanium magnetite is 20-25%, more preferably 21-24%, such as 20%, 21%, 22%, 23%, 24%, 25%, preferably a range of values ​​with the above values ​​as the upper or lower limit.

[0026] Under the condition that the TiO2 content of the smelting slag of the high-titanium vanadium-titanium magnetite is 20-25%, this invention, based on the Ti and Si content and the matching degree of air volume and air pressure, promptly judges the accumulation status at the center of the hearth during the smelting of high-titanium blast furnaces, and determines the charging angle and addition amount of metallization pre-reduction pellets according to the accumulation status. In this invention, the charging angle is the angle between the charging chute (the chute through which the material entering the blast furnace passes, an empty semi-cylindrical shape) and the vertical line.

[0027] In this invention, the difference between the mass fraction of Ti and the mass fraction of Si in the molten iron is a%, and the air volume is bm. 3 / min, wind pressure is c kPa.

[0028] When -0.08≤a≤0 and -10≤b-10×c≤5, it is a general stacking;

[0029] When -0.08≤a≤0 and -60≤b-10×c<-10, it is a medium packing.

[0030] When -0.08≤a≤0 and -100≤b-10×c<-60, it is considered severe accumulation.

[0031] In this invention, under normal stacking conditions, the fabric angle of the metallized pre-reduced pellets is preferably 20~28°, more preferably 22~27°, such as 20°, 21°, 22°, 23°, 24°, 25°, 26°, 27°, 28°, preferably within the range of any of the above values ​​as the upper or lower limit; under medium stacking conditions, the fabric angle of the metallized pre-reduced pellets is preferably 15~20°, more preferably 16~18°, such as 15°, 16°, 17°, 18°, 19°, 19.5°, preferably within the range of any of the above values ​​as the upper or lower limit; under severe stacking conditions, the fabric angle of the metallized pre-reduced pellets is preferably 10~15°, more preferably 10~14°, such as 10°, 11°, 12°, 13°, 14°, 15°, preferably within the range of any of the above values ​​as the upper or lower limit.

[0032] In this invention, under normal stacking conditions, the amount of metallized pre-reduced pellets added is preferably 1-8% of the batch weight, more preferably 1-7%, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, preferably within the range of any of the above values ​​as the upper or lower limit; under medium stacking conditions, the amount of metallized pre-reduced pellets added is preferably 8-13% of the batch weight, more preferably 9-13%, such as 8.5%, 9%, 10%, 11%, 12%, 13%, preferably within the range of any of the above values ​​as the upper or lower limit; under severe stacking conditions, the amount of metallized pre-reduced pellets added is preferably 13-20% of the batch weight, more preferably 13.5-20%, such as 13.5%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, preferably within the range of any of the above values ​​as the upper or lower limit.

[0033] In this invention, the metallized pre-reduced pellets are added during blast furnace charging with each batch of material, and each batch of material is accompanied by the addition of metallized pre-reduced pellets. The amount of metallized pre-reduced pellets added is based on the batch weight (the weight of each batch of material during blast furnace charging). The metallized pre-reduced pellets need to be added continuously for 2 to 7 days, more preferably 3 to 6 days, such as 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, preferably within the range of any of the above values ​​as the upper or lower limit.

[0034] After adding metallized pre-reduced pellets according to the above method, the Ti, Si, average air volume and air pressure in the molten iron composition are detected each time iron is tapped. If a≥0 and b-10×c>5 for four consecutive taps, it is judged that the hearth is gradually returning to normal and the addition of metallized pellets is stopped.

[0035] This invention provides a method for reducing and eliminating accumulation in the center of the hearth during blast furnace smelting of high-titanium vanadium-titanium magnetite. During charging, titanium-free metallized pre-reduced pellets are added separately to the center of the blast furnace. The metallized pre-reduced pellets comprise the following components by mass fraction: TFe 75-90%, C: 2-4%, P: 0.005%, S: 0.004%, SiO2: 2.5-4.5%, Al2O3: 2.2-4%, MgO: 0.5-1.2%, CaO: 0.2-0.8%, Mn: 0.05-0.15%. To reduce and eliminate the accumulation in the hearth center of vanadium-titanium magnetite blast furnaces, this invention involves adding ordinary, titanium-free metallized pre-reduced pellets separately to the center of the blast furnace throat during charging. These pellets descend with the furnace charge to the hearth center without being mixed with sintered ore, pellets, or lump ore, or with coke. This eliminates the technical problem of hearth center accumulation caused by the aggregation of high-melting-point substances such as TiCN during the blast furnace smelting of high-titanium vanadium-titanium magnetite. This not only solves the technical problem of rapidly reducing and eliminating hearth center accumulation but also increases blast furnace output and smelting intensity, while reducing pig iron costs.

[0036] To further illustrate the present invention, the following detailed description of a method for reducing and eliminating the accumulation in the center of the hearth during blast furnace smelting of high-titanium vanadium-titanium magnetite is provided by the present invention in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0037] Example 1

[0038] blast furnace volume 1350m³ 3 The batch weight of the charge is 32.5t. The charge structure is sintered ore (66% by mass) + pellets (34% by mass). The coke ratio is 420kg / tp, the pulverized coal ratio is 138kg / tp, the slag TiO2 is 22.78%, the metallized pellets are TFe 85%, and the metallization rate is 85%.

[0039] During normal blast furnace production, the molten iron [Ti] < [Si] for four consecutive times (each time the iron was tested at the initial, middle, and late stages of the tapping process; the following examples are similar), and the average [Ti] - [Si] for the four times was -0.011%, with a blast volume of 3200 m³ / h. 3 When the blast pressure rose to 320.6 kPa, it indicated that there was accumulation in the hearth, and measures had to be taken, namely changing the charging system, determining the amount of metallized pellets added per batch to be 0.65t (2% of the batch weight), the charging angle to be 25°, and placing the metallized pellets in the center of the throat. As the blast furnace smelting proceeded, the metallized pellets descended to the center of the hearth, and the hearth gradually became more active. After adding metallized pellets continuously for 3 days, the [Ti] content in the molten iron was 0.246%, [Si] was 0.231%, and the blast volume was increased to 3200 m³ / min. 3 When the air volume was 100 m / min, the air pressure dropped to 316.8 kPa. The air volume and air pressure were well matched, indicating that the hearth of the blast furnace for smelting high-titanium vanadium-titanium ore had returned to normal. The addition of metallized pellets was stopped, and the original charging system was restored.

[0040] Table 1

[0041]

[0042] Note: Iron-containing material / number of rings, such as 39.5° / 3, means that the chute is arranged with 3 rings of iron-containing material at 39.5 degrees. "Coke / number of rings" and "metallized pellets / number of rings" are similar.

[0043] Example 2

[0044] blast furnace volume 1350m³ 3 The batch weight of the charge is 32.5t. The furnace charge structure is sintered ore (66% by mass) + pellets (34% by mass). The coke ratio is 418kg / tp, the pulverized coal ratio is 135kg / tp, the slag TiO2 is 22.74%, the metallized pellets are TFe 85%, and the metallization rate is 85%.

[0045] During normal blast furnace production, the molten iron [Ti] < [Si] for four consecutive times, with an average [Ti] - [Si] = -0.02%, and the blast volume reached 2800 m³ / s. 3 When the blast pressure rose to 284.7 kPa, it indicated severe buildup in the hearth, necessitating intervention. This involved changing the charging schedule, setting the metallized pellet addition to 3.25 t (10% of batch weight) per batch, with a 17° distribution angle. The metallized pellets were placed at the center of the hearth. As blast furnace smelting progressed, the metallized pellets descended to the hearth center, gradually increasing its activity. After 5 days of continuous metallized pellet addition, the [Ti] content in the molten iron was 0.251%, [Si] was 0.226%, and the blast volume was increased to 2800 m³ / min. 3 When the air volume was 100 m / min, the air pressure dropped to 271.5 kPa. The air volume and air pressure were well matched, indicating that the hearth of the blast furnace for smelting high-titanium vanadium-titanium ore had returned to normal. The addition of metallized pellets was stopped, and the original charging system was restored.

[0046] Table 2

[0047]

[0048] Example 3

[0049] blast furnace volume 1350m³ 3 The batch weight of the charge is 32.5t. The charge structure is sintered ore (66% by mass) + pellets (34% by mass). The coke ratio is 423kg / tp, the pulverized coal ratio is 121kg / tp, the slag TiO2 is 23.02%, the metallized pellets are TFe 85%, and the metallization rate is 85%.

[0050] During normal blast furnace production, the molten iron [Ti] < [Si] for four consecutive times, with an average [Ti] - [Si] = -0.08%, and the blast volume reached 2800 m³ / s. 3 When the blast pressure rose to 287.4 kPa, it indicated that there was potential for buildup and deterioration in the hearth, necessitating measures to be taken. This involved changing the charging system, determining the amount of metallized pellets added per batch to be 5.525 t (17% of the batch weight), with a charging angle of 11°. The metallized pellets were placed in the center of the furnace throat. As blast furnace smelting progressed, the metallized pellets descended to the center of the hearth, gradually increasing its activity. After two days of continuous addition of metallized pellets, the [Ti] content in the molten iron was 0.243%, and the [Si] content was 0.231%. The blast volume was increased to 2800 m³ / min. 3 When the air volume was 100 m / min, the air pressure dropped to 271.7 kPa. The air volume and air pressure were well matched, indicating that the hearth of the blast furnace for smelting high-titanium vanadium-titanium ore had returned to normal. The addition of metallized pellets was stopped, and the original charging system was restored.

[0051] Table 3

[0052]

[0053] This invention addresses the problem of accumulation in the hearth caused by the formation of high-melting-point solid solutions such as TiCN during blast furnace smelting of high-titanium vanadium-titanium magnetite. The invention employs the method of adding metallized pellets, which are directly distributed to the center of the furnace throat and move downwards with the furnace charge to the center of the hearth. This fully utilizes the metallized pellets and solves the key technical problem of insufficient accumulation in the hearth center when adding fluorite, manganese ore, etc.

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for reducing and eliminating accumulation in the center of the hearth during blast furnace smelting of high-titanium vanadium-titanium magnetite, characterized in that, During the feeding process, titanium-free metallized pre-reduced pellets are added separately to the center of the blast furnace; The metallized pre-reduced pellets comprise the following components by mass fraction: TFe75~90%, C: 2~4%, P: 0.005%, S: 0.004%, SiO2: 2.5~4.5%, Al2O3: 2.2~4%, MgO: 0.5~1.2%, CaO: 0.2~0.8%, Mn: 0.05~0.15%.

2. The method for reducing and eliminating accumulation in the center of the hearth during blast furnace smelting of high-titanium vanadium-titanium magnetite according to claim 1, characterized in that, The TiO2 content of the smelting slag of the high-titanium vanadium-titanium magnetite is 20-25%.

3. The method for reducing and eliminating accumulation in the center of the hearth during blast furnace smelting of high-titanium vanadium-titanium magnetite according to claim 1, characterized in that, The metallization rate of the metallized pre-reduced pellets is 75-95%.

4. The method for reducing and eliminating center buildup in the hearth of a blast furnace for smelting high-titanium vanadium-titanium magnetite according to claim 1, characterized in that, The fabric angle of the metallized pre-reduced pellets is 10~28°.

5. The method for reducing and eliminating accumulation in the center of the hearth during blast furnace smelting of high-titanium vanadium-titanium magnetite according to claim 1, characterized in that, The metallized pre-reduced pellets are added during blast furnace charging, along with each batch of material, and the amount of metallized pre-reduced pellets added is 1-20% of the batch weight.

6. The method for reducing and eliminating center buildup in the hearth of a blast furnace for smelting high-titanium vanadium-titanium magnetite according to claim 1, characterized in that, The degree of accumulation in the center of the hearth of a blast furnace for high-titanium vanadium-titanium magnetite is determined based on the Ti and Si content and the matching degree of air volume and air pressure; the degree of accumulation is divided into general accumulation, medium accumulation and severe accumulation.

7. The method for reducing and eliminating center buildup in the hearth of a blast furnace for smelting high-titanium vanadium-titanium magnetite according to claim 6, characterized in that, The difference between the mass fraction of Ti and the mass fraction of Si in the molten iron is a%, and the air volume is bm. 3 / min, wind pressure is ckPa; When -0.08≤a≤0 and -10≤b-10×c≤5, it is a general stacking; When -0.08≤a≤0 and -60≤b-10×c<-10, it is a medium packing. When -0.08≤a≤0 and -100≤b-10×c<-60, it is considered severe accumulation.

8. The method for reducing and eliminating center buildup in the hearth of a blast furnace for smelting high-titanium vanadium-titanium magnetite according to claim 6 or 7, characterized in that, Under normal stacking conditions, the fabric angle of the metallized pre-reduced pellets is 20~28°; under medium stacking conditions, the fabric angle of the metallized pre-reduced pellets is 15~20°; under severe stacking conditions, the fabric angle of the metallized pre-reduced pellets is 10~15°.

9. The method for reducing and eliminating center buildup in the hearth of a blast furnace for smelting high-titanium vanadium-titanium magnetite according to claim 6 or 7, characterized in that, Under normal stacking conditions, the amount of metallized pre-reduced pellets added is 1-8% of the batch weight; under medium stacking conditions, the amount of metallized pre-reduced pellets added is 8-13% of the batch weight; under severe stacking conditions, the amount of metallized pre-reduced pellets added is 13-20% of the batch weight.

10. The method for reducing and eliminating center buildup in the hearth of a blast furnace for smelting high-titanium vanadium-titanium magnetite according to claim 1, characterized in that, The metallized pre-reduced pellets are added continuously for 2 to 7 days.

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