A method for eliminating the central accumulation in blast furnace smelting of vanadium-titanium ore

Abstract

The present invention discloses a method for eliminating the central accumulation in blast furnace smelting of vanadium-titanium ore. Aiming at the central accumulation in the hearth caused by the formation of TiC, TiN and their solid solutions with high melting point and high viscosity during the blast furnace smelting of vanadium-titanium ore, scrap steel is added into the blast furnace separately as an iron-containing burden. When adding scrap steel into the furnace, the scrap steel is distributed at the center of the furnace throat; for the bell-less top, the charging angle of the scrap steel adopts the central charging angle or a charging angle smaller than the central charging angle; the weight of each batch of scrap steel added centrally is calculated according to the ratio of the TFe weight of each batch of scrap steel to the theoretical TFe weight of each batch of iron-containing burden without adding scrap steel being 30-100%; the weight and number of batches of scrap steel added centrally are determined according to the set comprehensive charging grade. By changing the use mode of scrap steel, the present invention eliminates the hearth accumulation while increasing the charging grade, thereby increasing the output and smelting intensity.

Description

Technical Field

[0001] The present invention belongs to the technical field of blast furnace ironmaking, and particularly relates to a method for eliminating central accumulation in the smelting of vanadium-titanium ore in a blast furnace. Background Art

[0002] Panzhihua Iron and Steel uses the vanadium-titanium magnetite concentrate in the Panxi area as the main iron-containing raw material, and the TiO2 content in the blast furnace slag exceeds 20%. During the smelting process, TiO2 in the slag is extremely easy to be reduced to form high-melting point phases such as TiC, TiN and their solid solution Ti(C, N) that cannot be melted under the blast furnace smelting conditions, resulting in viscous slag and increasing the difficulty of blast furnace smelting. Seriously, TiC, TiN and their solid solution Ti(C, N) are mixed with the slag in the blast furnace, especially in the hearth, and cannot be discharged from the iron notch in time. When this mixture rich in TiC, TiN and their solid solution Ti(C, N) gradually accumulates and the volume gradually increases, an extremely viscous mixture is formed in the blast furnace, thus forming a hearth accumulation.

[0003] During the smelting process of blast furnaces smelting ordinary ores without TiO2, hearth accumulation will also be formed, but most of this hearth accumulation is due to the abnormal temperature field and gas flow distribution in the blast furnace. In the areas where heat and coal gas flow cannot be effectively transmitted, the mixture of slag, hot metal and fine-grained coke cannot be melted due to temperature reduction. The hearth accumulation formed in the blast furnace smelting high-titanium vanadium-titanium ore is mainly a mixture rich in TiC, TiN and their solid solution Ti(C, N), which has a high melting point and high viscosity. It is very difficult to reduce or eliminate it only by means of adding coke to increase the temperature in the hearth and improve the gas and liquid permeability of the hearth. Especially during the process of eliminating this kind of hearth accumulation, TiO2 in the slag will further react with coke to generate more TiC, TiN and their solid solution Ti(C, N), exacerbating the formation of viscous deposits. If the elimination rate of the hearth accumulation is less than its generation rate, the hearth accumulation will further develop. If the elimination rate of the hearth accumulation is greater than its generation rate, the hearth accumulation will gradually decrease until it disappears.

[0004] Discharging these deposits rich in TiC, TiN and their solid solution Ti(C, N) out of the furnace is the basis for restoring the normal production of the blast furnace smelting vanadium-titanium ore. According to the experimental study on the deposits in the hearth of the blast furnace when it is shut down for smelting vanadium-titanium ore, liquid iron can absorb TiC, TiN and their solid solution Ti(C, N) in the slag. Secondly, the density of liquid iron is large and the scouring force is strong. Therefore, these deposits can be gradually eliminated through the erosion and scouring of liquid iron. Research shows that affected by the distribution of the coal gas flow and the top charging system of the furnace, the slag and iron dripping from the softening-melting zone mainly drip into the hearth through the annular zone between the center and the edge of the blast furnace. When deposits form in the center of the hearth, the liquid iron entering the hearth can only scour the deposits from the edge. Therefore, in production practice, the elimination effect of liquid iron, including high-temperature slag, on the hearth deposits is not obvious, and it takes a long time to slowly eliminate the deposits in the center of the hearth.

[0005] In recent years, adding scrap steel to the blast furnace has gradually become one of the effective measures to increase the output and smelting intensity of blast furnaces with low-grade ores. For blast furnaces smelting vanadium-titanium ore, changing the way of using scrap steel can not only increase the charging grade, thereby increasing the output and smelting intensity, but also play a role in eliminating the hearth deposits. Summary of the Invention

[0006] In order to overcome the defects existing in the above-mentioned prior art, the present invention adds scrap steel as an iron-containing burden alone into the blast furnace, without mixing it with iron-containing burdens such as sinter, pellet or lump ore, or mixing it with coke; it solves the technical problem that in the production practice of the traditional process, the elimination effect of liquid iron, including high-temperature slag, on the hearth deposits is not obvious.

[0007] In order to achieve the above-mentioned invention purpose, the present invention provides a method for eliminating the central deposits in the blast furnace smelting vanadium-titanium ore, including the following steps:

[0008] ① Judge the phenomenon of hearth deposits during the process of smelting vanadium-titanium ore in the blast furnace; the judgment method includes: the ability of the blast furnace to receive air volume weakens, the air volume gradually decreases, and it cannot be restored to the normal level for a long time; the output decreases.

[0009] ② Add scrap steel as an iron-containing burden alone into the blast furnace, without mixing it with iron-containing burdens such as sinter, pellet or lump ore and then adding it into the furnace, nor mixing it with coke and adding it into the furnace together.

[0010] ③ When loading scrap steel into the furnace, distribute the scrap steel at the center of the throat; for the bell-less top of the furnace, the charging angle of the scrap steel adopts the center charging angle or a charging angle smaller than the center charging angle; for example, for the ore charging angle, from the outside of the throat to the center, the maximum angle is 40°, and the minimum angle is 35°; the maximum coke charging angle is 41°, and the minimum is 26°. Then the charging angle of the scrap steel is 26° or smaller, such as 20°, 12°.

[0011] ④ Calculate the weight of scrap steel added in batches according to the ratio of the TFe weight of each batch of scrap steel to the theoretical TFe weight of each batch of iron-bearing burden without adding scrap steel, which is 30%-100%; for example, the ore batch weight is 41 tons, the charging grade is 51.5%, and the theoretical TFe weight is 21.115 tons. If the Fe content in hot metal is 94.5%, the theoretical pig iron output can be 22.344 tons. According to the TFe weight of 21.115 tons per batch of burden, if the TFe content of scrap steel is 90%, the weight of each batch of scrap steel added in batches is 7.038-23.461 tons.

[0012] ⑤ Determine the weight and number of batches of scrap steel added in batches according to the set comprehensive charging grade. The calculation formula is:

[0013] a = [TFe0×(1–TFe1 / TFe F )×β] / (TFe1–TFe0)

[0014] In the formula, a is the number of ore batches to be spaced when adding scrap steel in batches, TFe0 is the charging grade before adding scrap steel, TFe1 is the charging grade after adding scrap steel, TFe F is the TFe content of scrap steel, and β is the ratio of the set TFe weight of scrap steel to the TFe weight in the original batch of ore.

[0015] For example, the ore batch weight is 41 tons and the charging grade is 51.5%; after the blast furnace uses scrap steel, it is expected to increase the charging grade to 52.5%; if the TFe content of scrap steel is 90%, the TFe amount of scrap steel added in one-time concentration is 50% of the theoretical TFe weight of the original ore batch. Then, according to the above formula, it can be calculated that a batch of scrap steel should be added in concentration after every a batches of ore, and a is obtained as 10.73 batches; in this way, about every 11 batches of ore are added, scrap steel can be added in concentration once.

[0016] An application of the above method in blast furnace smelting.

[0017] Compared with the prior art, the beneficial effects of the present invention:

[0018] Aiming at the hearth center accumulation caused by the formation of a mixture rich in TiC, TiN and their solid solutions with high melting point and high viscosity during the smelting of high-titanium vanadium-titanium ore in a blast furnace, the present invention adopts a unique process method to add scrap steel as an iron-bearing burden into the blast furnace alone, without mixing with iron-bearing burdens such as sinter, pellet or lump ore or with coke; and adopts the method of adding in batches to distribute the scrap steel at the center of the furnace throat; solves the technical problem that the elimination effect of the traditional process on the hearth accumulation by liquid iron water including high-temperature slag is not obvious. Specific embodiments

[0019] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited in any way. To avoid repetition, the raw materials in the following embodiments are all commercially available unless otherwise specified, and the methods used are all conventional methods unless otherwise specified.

[0020] Example 1

[0021] A blast furnace with an effective volume of 1750 m 3 has a burden distribution system as shown in Table 1, the quality of coke and pulverized coal injection is shown in Table 2, and the burden structure and chemical composition are shown in Table 3.

[0022] Table 1 Burden distribution system of a 1750 m 3 blast furnace

[0023] Angle (°) 39 38 36.5 34.5 32.5 26.5 Weight (t) Stockline (m) Ore (number of rings) 2 3 3 2 41.50 1.9 Coke (number of rings) 4 2 1 1 1 4 9.10 1.9

[0024] Table 2 Fuel composition and quality

[0025] Fuel name <![CDATA[A d > <![CDATA[S td > <![CDATA[V daf > CRI CSR <![CDATA[M 10 > <![CDATA[M 40 > Coke 13.70 0.66 1.11 25.84 66.83 4.90 89.70 Pulverized coal injection 12.70 0.69 10.71

[0026] Table 3 Burden structure and chemical composition

[0027] Raw material name Ratio TFe FeO <![CDATA[SiO2]]> CaO MgO <![CDATA[Al2O3]]> <![CDATA[TiO2]]> <![CDATA[V2O5]]> Sinter 63.0 50.61 8.25 5.61 11.51 2.56 3.09 5.06 0.377 Pellet 37.0 52.95 3.28 5.61 0.73 3.57 3.88 9.50 0.662

[0028] A method for eliminating the central accumulation of vanadium-titanium ore in blast furnace smelting includes the following steps:

[0029] ① Judge the central accumulation phenomenon in the hearth during the smelting of vanadium-titanium ore in the blast furnace; due to the accumulation in the hearth, the blast volume of the blast furnace decreases from 4100 m 3 / min to 3800 m 3 / min, and the output decreases from 4424 tons / day to 3775 tons / day. It is thus judged that central accumulation in the hearth has occurred and measures should be taken to eliminate it.

[0030] ② Add scrap steel as an iron-containing burden separately into the blast furnace, without mixing it with iron-containing burdens such as sinter, pellet or lump ore before adding it into the furnace, nor mixing it with coke before adding it into the furnace together.

[0031] ③ When loading scrap steel into the furnace, distribute the scrap steel at the center of the throat; for a bell-less top, the charging angle of the scrap steel adopts the center charging angle or a charging angle smaller than the center charging angle.

[0032] ④ Calculate the weight of each batch of scrap steel added concentratedly according to the ratio of the TFe weight of each batch of scrap steel to the theoretical TFe weight of each batch of iron-containing burden without adding scrap steel being 30 - 100%.

[0033] ⑤ Determine the weight and number of batches of scrap steel added concentratedly according to the set comprehensive charging grade, and the calculation formula is:

[0034] a = [TFe0×(1 – TFe1 / TFe F )×β] / (TFe1 – TFe0).

[0035] Steps ② to ⑤ above are shown in Table 4, and the chemical composition of the scrap steel is shown in Table 5. The measure of adding one batch of scrap steel every 10 batches of burden materials at the center of the furnace throat is adopted. The change of the burden distribution system is specifically shown in Table 4. After adding the scrap steel, the in-furnace grade is increased from the original 51.48% to 52.98%.

[0036] Table 4 The burden distribution system of a 1750 m 3 blast furnace

[0037] Angle (°) 39 38 36.5 34.5 32.5 26.5 20 Weight (t) Stockline (m) Ore (number of rings) 2 3 3 2 41.50 1.9 Coke (number of rings) 4 2 1 1 1 4 9.10 1.9 Scrap 4 9.34 1.9

[0038] Table 5 Chemical composition of scrap steel (wt%)

[0039] TFe FeO S P CaO MgO 91.49 6.56 0.024 0.012 0.81 0.98

[0040] Using the above method, after about 1 week with the addition of scrap steel, the blast furnace air volume is restored to 4078 m 3 / min, and the output is increased to 4587 tons per day, indicating that the accumulation at the center of the hearth has been eliminated.

[0041] Example 2

[0042] For a blast furnace with an effective volume of 2000 m 3 , the burden structure and chemical composition are shown in Table 6, the fuel quality is shown in Table 7, and the burden distribution system of the blast furnace is shown in Table 8.

[0043] Table 6 Burden structure and chemical composition of a 2000 m 3 blast furnace

[0044] Raw material name Ratio TFe FeO <![CDATA[SiO2]]> CaO MgO <![CDATA[Al2O3]]> <![CDATA[TiO2]]> <![CDATA[V2O5]]> Sinter 76.0 50.41 7.95 5.62 10.60 2.72 3.26 5.85 0.315 Pellet 23.0 52.81 2.10 6.52 1.55 3.01 4.19 9.41 0.628 Ordinary lump ore 1.0 45.31 0.79 21.28 1.55 0.70 4.74 0.30 0.023

[0045] Table 7 Fuel composition and quality

[0046] Fuel name <![CDATA[A d > <![CDATA[S td > <![CDATA[V daf > CRI CSR <![CDATA[M 10 > <![CDATA[M 40 > Coke 12.88 0.65 115 24.89 64.12 4.98 91.86 Pulverized coal injection 12.62 0.69 10.31

[0047] Table 8 Burden distribution system of the blast furnace

[0048] Angle (°) 42 41.5 40.5 38.5 36.5 34.0 28.0 Batch weight (t) Stockline (m) Ore + fluorite (number of circles) 3 3 3 2 2 46.69 1.8 Coke (number of circles) 2 1 2 2 2 2 4 10.23 1.8

[0049] A method for eliminating the accumulation at the center of the blast furnace during the smelting of vanadium-titanium ore includes the following steps:

[0050] ① Judging the accumulation phenomenon at the center of the hearth during the smelting of vanadium-titanium ore in the blast furnace; due to the accumulation in the hearth, the ability of the blast furnace to receive air volume is weakened, and the air volume decreases significantly from 4487 m 3 / min to 4120 m 3 / min and cannot be restored to 4500 m for a long time3 to a level of around / min, and the output decreased from approximately 4,900 tons per day to 4,170 tons per day. It was thus determined that a build-up had occurred in the center of the hearth, and measures should be taken to eliminate it.

[0051] ② Add scrap steel as a single iron-bearing charge to the blast furnace, without mixing it with other iron-bearing charges such as sinter, pellets, or lump ore before adding it to the furnace, nor mixing it with coke before adding them together to the furnace.

[0052] ③ When loading scrap steel into the furnace, distribute the scrap steel at the center of the furnace throat; for a bell-less top, use the center charging angle or an angle smaller than the center charging angle for the scrap steel charging angle.

[0053] ④ Calculate the weight of each batch of scrap steel added in a concentrated manner based on the ratio of the TFe weight of each batch of scrap steel to the theoretical TFe weight of each batch of iron-bearing charges without adding scrap steel, which is 30 - 100%.

[0054] ⑤ Determine the weight and number of batches of scrap steel added in a concentrated manner according to the set overall furnace charge grade. The calculation formula is:

[0055] a = [TFe0 × (1 – TFe1 / TFe F ) × β] / (TFe1 – TFe0).

[0056] The above steps ② to ⑤ are shown in Table 10. Adopt the technical measure of adding 50% of the theoretical TFe weight of the original ore batch in a concentrated manner every 10 batches at the center of the furnace throat. After adding the scrap steel, the furnace charge grade increased from the original 50.46% to 51.56%. The changes in the charging system are shown in Table 10.

[0057] Table 10 Blast furnace charging system

[0058] Angle (°) 42 41.5 40.5 38.5 36.5 34.0 28.0 20 Batch weight (t) Stockline (m) Ore (number of circles) 3 3 3 2 2 46.00 1.8 Coke (number of circles) 2 1 2 2 2 2 4 10.20 1.8 Scrap (number of circles) 4 12.68 1.8

[0059] Using the above method, with the addition of scrap steel, about 10 days after adding the scrap steel, the blast furnace air volume recovered to 4,450 m 3 / min, and the output reached approximately 5,000 tons per day, indicating that the build-up in the center of the hearth had been eliminated.

[0060] Example 3

[0061] A blast furnace with an effective volume of 12,000 m 3 has a furnace charge structure as shown in Table 11, fuel quality as shown in Table 12, and blast furnace charging system as shown in Table 13.

[0062] Table 11 Furnace charge structure and chemical composition of a 1,200 m 3 blast furnace

[0063] Raw material name Ratio TFe FeO <![CDATA[SiO2]]> CaO MgO <![CDATA[Al2O3]]> <![CDATA[TiO2]]> <![CDATA[V2O5]]> Sinter 75 49.92 8.27 5.68 10.96 2.52 3.39 6.08 0.320 Pellet 25 52.81 2.10 6.52 1.55 3.01 4.19 9.41 0.628

[0064] Table 12 Fuel Composition and Quality Indexes

[0065] Fuel name <![CDATA[A d > <![CDATA[S td > <![CDATA[V daf > CRI CSR <![CDATA[M 10 > <![CDATA[M 40 > Coke 12.70 0.68 1.11 30.64 60.78 5.78 90.43 Pulverized coal injection 12.65 0.69 11.36

[0066] Table 13 Blast Furnace Charging System

[0067] Angle (°) 39.5 38.5 37 35.5 34 28.5 Batch weight (t) Stockline (m) Ore (number of circles) 2 3 2 3 27.50 1.8 Coke (number of circles) 2 2 2 2 3 6.00 1.8

[0068] A method for eliminating the center accumulation in the blast furnace smelting of vanadium-titanium ore, comprising the following steps:

[0069] ① Judge the center accumulation phenomenon in the hearth during the blast furnace smelting of vanadium-titanium ore; as the center accumulation in the hearth forms, the blast furnace air volume gradually decreases from 2934 m 3 / min to 2300 m 3 / min, and the pig iron output decreases from 3438 tons per day to 2580 tons per day. It is thus judged that the center accumulation in the hearth has occurred and measures should be taken to eliminate it.

[0070] ② Add scrap steel as an iron-bearing burden into the blast furnace alone, without mixing it with iron-bearing burdens such as sinter, pellet or lump ore and adding it into the furnace, nor mixing it with coke and adding them into the furnace together.

[0071] ③ When loading scrap steel into the furnace, distribute the scrap steel at the center of the furnace throat; for the bell-less top, the charging angle of the scrap steel adopts the center charging angle or a charging angle smaller than the center charging angle.

[0072] ④ Calculate the weight of each batch of scrap steel added centrally according to the ratio of the TFe weight of each batch of scrap steel to the theoretical TFe weight of each batch of iron-bearing burden without adding scrap steel being 30 - 00%.

[0073] ⑤ Determine the weight and number of batches of scrap steel added centrally according to the set comprehensive charging grade, and the calculation formula is:

[0074] a = [TFe0×(1 – TFe1 / TFe F )×β] / (TFe1 – TFe0).

[0075] The above steps ② to ⑤ are shown in Table 14, and technical measures are taken to centrally add 30% of the scrap steel with the theoretical TFe weight of the original ore batch every 10 batches at the center of the furnace throat. After adding the scrap steel, the charging grade into the furnace is increased from the original 50.40% to 51.07%. The corresponding charging system is shown in Table 14.

[0076] Table 14 Blast Furnace Charging System

[0077] Angle (°) 39.5 38.5 37 35.5 34 28.5 18 Batch weight (t) Stockline (m) Ore (number of circles) 2 3 2 3 27.50 1.8 Coke (number of circles) 2 2 2 2 3 6.00 1.8 Scrap (number of circles) 4 4.54 1.8

[0078] Using the above method, about 4 days after adding the scrap steel, the blast furnace air volume is restored to 2900 m 3Around / min, the output reaches about 3,450 tons per day, indicating that the accumulation at the center of the hearth has been eliminated.

[0079] For any person skilled in the art, without departing from the scope of the technical solution of the present invention, many possible changes and modifications can be made to the technical solution of the present invention by using the technical content disclosed above, or it can be modified into equivalent embodiments with equivalent changes. Therefore, all contents that do not depart from the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for eliminating the central accumulation of vanadium-titanium ore in blast furnace smelting, characterized in that, The method comprises the following steps: ① Judging the phenomenon of hearth center accumulation during the process of blast furnace smelting vanadium-titanium ore; The judging method includes that the blast furnace's ability to receive air volume weakens, the air volume gradually decreases, and it cannot be restored to the normal level for a long time; the output decreases; The blast furnace with an effective volume of 1750 m 3 has its blast volume reduced from 4100 m 3 / min to 3800 m 3 / min, and its output decreased from 4424 t / d to 3775 t / d. It is thus judged that the accumulation at the center of the hearth has occurred; A blast furnace with an effective volume of 2000 m 3 has its blast volume reduced from 4487 m 3 / min to 4120 m 3 / min, and its output reduced from 4900 t / d to 4170 t / d. It is thus judged that a hearth center accumulation has occurred; A blast furnace with an effective volume of 12,000 m 3 has its blast volume reduced from 2,934 m 3 / min to 2,300 m 3 / min, and the pig iron output reduced from 3,438 t / d to 2,580 t / d. It is thus judged that a hearth center build-up has occurred; ② Adding scrap steel as an iron-containing burden into the blast furnace alone, without mixing it with sinter, pellet or lump ore and adding it into the furnace, nor mixing it with coke and adding it into the furnace together; ③ When loading scrap steel into the furnace, distributing the scrap steel at the center of the furnace throat; for the bell-less top, the charging angle of the scrap steel adopts the center charging angle or a charging angle smaller than the center charging angle; ④ Calculating the weight of each batch of scrap steel added centrally according to the ratio of the TFe weight of each batch of scrap steel to the theoretical TFe weight of each batch of iron-containing burden without adding scrap steel being 30% - 100%; ⑤ Determining the weight and batch number of the scrap steel added centrally according to the set comprehensive burden grade, and the calculation formula is: a = [TFe0×(1–TFe1 / TFe F )×β] / (TFe1–TFe0) Wherein, a is the number of ore batches to be spaced when adding scrap steel centrally, TFe0 is the grade charged into the furnace before adding scrap steel, TFe1 is the grade charged into the furnace after adding scrap steel, TFe F is the TFe content of the scrap steel, and β is the proportion of the set TFe weight of the scrap steel in the TFe weight of the original ore per batch.

2. Application of the method according to claim 1 in blast furnace smelting.