Method for smelting vanadium titano-magnetite in blast furnace

Abstract

The invention belongs to the field of blast furnace ironmaking, and particularly relates to a method for smelting vanadium titano-magnetite in a blast furnace, which comprises the following steps: charging iron ore and coke into the blast furnace for smelting to obtain slag and molten iron; the effective volume of the blast furnace is 1000-2500m < 3 >; the iron ore comprises two or three of alkaline sintered ore, acidic pellet ore, alkaline pellet ore and lump ore; the proportion of the iron ore with the particle size smaller than 5 mm in the iron ore is smaller than or equal to 1.8 wt%; the coke comprises large coke blocks and small coke blocks; the weight of each batch of smelted iron ore and coke meets the requirements of a formula (1)-a formula (3); the oxygen enrichment rate in the smelting process is controlled to be 4.5-10%; the TiO2 content of the slag is greater than or equal to 22wt%. According to the characteristics of blast furnace smelting of the vanadium titano-magnetite, the fuel ratio of blast furnace smelting of the high-titanium type vanadium titano-magnetite can be reduced by increasing the thickness of a coke layer of blast furnace smelting and adding small coke blocks into ore.

Description

Technical Field

[0001] This invention belongs to the field of blast furnace ironmaking, and specifically relates to a method for smelting vanadium-titanium magnetite in a blast furnace. Background Technology

[0002] In blast furnace smelting of high-titanium vanadium-titanium magnetite, the TiO2 content in the slag reaches over 22%. During smelting, TiO2 is easily reduced to form TiC, TiN, and their solid solutions Ti(C,N), which cannot be melted under blast furnace smelting conditions, thus deteriorating slag properties. To accelerate the blast furnace smelting process and reduce TiO2 reduction time, a high-volume, low-batch smelting strategy can be adopted, increasing smelting intensity and reducing TiO2 reduction. However, this strategy also has negative effects. First, the large gas volume creates a more acute conflict between the upward flow of gas and the downward movement of the burden compared to blast furnaces smelting high-grade ordinary ores, leading to a more strained relationship between blast volume and pressure. Second, the high degree of direct reduction in the blast furnace means that the iron-containing burden rapidly enters the lower section where the carbon melting reaction (CO2 + C = 2CO) is intensely occurring before the indirect reduction in the upper part of the blast furnace is complete, resulting in a high blast furnace fuel ratio.

[0003] In the context of low-carbon smelting, the need to reduce carbon emissions from blast furnaces is even more urgent. Therefore, how to reduce fuel consumption in blast furnace smelting of high-titanium vanadium-titanium magnetite, especially by reducing the blast furnace coke ratio, has become a major research direction in this field. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for smelting vanadium-titanium magnetite in a blast furnace, which can reduce the fuel ratio for smelting high-titanium vanadium-titanium magnetite in a blast furnace, and in particular, can significantly reduce the blast furnace coke ratio.

[0005] This invention provides a method for smelting vanadium-titanium magnetite in a blast furnace, comprising the following steps:

[0006] Iron ore and coke are smelted in a blast furnace to obtain slag and molten iron.

[0007] The effective volume of the blast furnace is 1000~2500m³. 3 ;

[0008] The iron ore comprises two or three of the following: alkaline sinter, acidic pellets, alkaline pellets, and lump ore; the proportion of iron ore with a particle size <5mm in the iron ore is ≤1.8wt%.

[0009] The coke includes large pieces of coke and small pieces of coke, wherein the average particle size of the large pieces of coke is >25mm and the average particle size of the small pieces of coke is 10~25mm.

[0010] The batch weight of the iron ore and coke smelted in each batch shall meet the requirements of equations (1) to (3):

[0011] Equation (1);

[0012] Equation (2);

[0013] Equation (3);

[0014] In equations (1) to (3), k1 is 0.15 to 0.22; m 焦大 The mass of large coke produced in each batch of blast furnace smelting, unit: t / batch; ρ 焦大 Bulk density of coke, unit: t / m³ 3 λ is the coke volume compressibility coefficient, ranging from 0.1 to 0.12; d is the blast furnace waist diameter, in meters; k2 is 24 to 30 mm. 焦小 The mass of small pieces of coke produced in each batch of blast furnace smelting, in t / batch; m 矿 The mass of iron ore smelted in each blast furnace batch, in tons (t / batch); liters (L) 负荷 The ratio of ore to coke mass in each batch of blast furnace is 4.3 to 5.2.

[0015] The oxygen enrichment rate during the smelting process is controlled at 4.5-10%;

[0016] The TiO2 content of the slag is ≥22wt%.

[0017] Preferably, the basic sinter has a drum index ≥77%; the acidic pellet has a binary basicity ≤0.2 and a compressive strength ≥2200N / piece; the basic pellet has a binary basicity ≥0.3 and a compressive strength ≥2200N / piece.

[0018] Preferably, the iron ore includes alkaline sinter and acidic pellets.

[0019] Preferably, the mass ratio of the alkaline sinter to the acidic pellet is 45:(50~60).

[0020] Preferably, the oxygen enrichment rate is calculated according to formula (4):

[0021] Equation (4);

[0022] In equation (4), f O Oxygen enrichment rate, unit: % Oxygen-rich volume, unit: m 3 / min;O 2O % represents the volume percentage of O2 in oxygen-rich gas, in units of %; V bAir volume, unit: m 3 / min.

[0023] Preferably, the post-reaction strength and air-dried ash content of the coke meet the following requirements:

[0024] If the effective volume of the blast furnace is ≥1000m³ 3 and <1500m 3 The post-reaction strength of the coke is 63-65%, and the air-dried ash content is ≤13.2 wt%.

[0025] If the effective volume of the blast furnace is ≥1500m³ 3 and <1800m 3 The post-reaction strength of the coke is 65-68%, and the air-dried ash content is ≤13wt%.

[0026] If the effective volume of the blast furnace is ≥1800m³ 3 And ≤2500m 3 The post-reaction strength of the coke is 66-68%, and the air-dried ash content is ≤12.8wt%.

[0027] Preferably, pulverized coal is injected into the blast furnace during the smelting process.

[0028] Preferably, the volatile matter content of the coal powder is 15~21wt%, the air-dried ash content is ≤12.5wt%, and the moisture content is ≤0.8wt%; the proportion of coal powder with a particle size <74μm in the coal powder is 70~80wt%.

[0029] Preferably, the binary basicity of the slag is 1 to 1.12.

[0030] Preferably, the molten iron has a Ti content of 0.09~0.2wt% and a total Ti and Si content of 0.15~0.38wt%.

[0031] Compared with the prior art, the present invention provides a method for smelting vanadium-titanium magnetite in a blast furnace, comprising the following steps: charging iron ore and coke into a blast furnace for smelting to obtain slag and molten iron; wherein the effective volume of the blast furnace is 1000~2500m³. 3The iron ore includes two or three of the following: alkaline sinter, acidic pellets, alkaline pellets, and lump ore; the proportion of iron ore with a particle size <5mm in the iron ore is ≤1.8wt%; the coke includes large lump coke and small lump coke, the average particle size of the large lump coke is >25mm, and the average particle size of the small lump coke is 10~25mm; the batch weight of the iron ore and coke smelted in each batch meets the requirements of formulas (1) to (3); the oxygen enrichment rate during the smelting process is controlled at 4.5~10%; the TiO2 content of the slag is ≥22wt%. This invention addresses the characteristics of blast furnace smelting of vanadium-titanium magnetite by increasing the coke layer thickness in blast furnace smelting and adding small lump coke to the ore, thereby reducing the fuel ratio in blast furnace smelting of high-titanium vanadium-titanium magnetite, and in particular, significantly reducing the blast furnace coke ratio. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] This invention provides a method for smelting vanadium-titanium magnetite in a blast furnace, comprising the following steps:

[0034] Iron ore and coke are smelted in a blast furnace to produce slag and molten iron.

[0035] In the method provided by this invention, the effective volume of the blast furnace is 1000~2500m³. 3 Specifically, it can be 1000m 3 1100m 3 1200m 3 1300m 3 1400m 3 1500m 3 1600m 3 1700m 3 1750m 3 1800m 3 1900m 3 2000m 3 2100m 3 2200m 3 2300m 3 2400m 3 or 2500m 3The preferred diameter of the blast furnace hearth is 6-12m, specifically 6m, 6.5m, 7m, 7.5m, 8m, 8.5m, 9m, 9.5m, 10m, 10.5m, 11m, 11.5m or 12m; the preferred diameter of the blast furnace waist is 8-15m, specifically 8m, 8.5m, 9m, 9.5m, 10m, 10.5m, 11m, 11.3m, 11.5m, 12m, 12.5m, 13m, 13.5m, 14m, 14.5m or 15m.

[0036] In the method provided by this invention, the iron ore includes two or three of the following: basic sinter, acidic pellets, basic pellets, and lump ore; wherein, the drum index of the basic sinter is preferably ≥77%, more preferably 77~82%, specifically 79.8%; the binary basicity (w(CaO) / w(SiO2)) of the acidic pellets is preferably ≤0.2; the compressive strength of the acidic pellets is preferably ≥2200N / piece, more preferably 2200~2300N / piece, specifically 2256N / piece; the binary basicity of the basic pellets is preferably ≥0.3; and the compressive strength of the basic pellets is preferably ≥2200N / piece.

[0037] In the method provided by this invention, the iron ore preferably comprises basic sinter and acidic pellets; the V2O5 content of the basic sinter is preferably 0.05~0.5wt%, more preferably 0.1~0.3wt%, specifically 0.2wt%; the TiO2 content of the basic sinter is preferably 1~5wt%, more preferably 2~4wt%, specifically 3.08wt%; the FeO content of the basic sinter is preferably 6~12wt%, more preferably 8~10wt%, specifically 8.92wt%; the TFe content of the basic sinter is preferably 40~55wt%, more preferably 45~50wt%, specifically 47.46wt%; the V2O5 content of the acidic pellets is preferably 0.5~0.8wt%, more preferably 0.6~0.8wt%. The preferred TiO2 content of the acidic pellets is 7-12 wt%, more preferably 9-10 wt%, specifically 9.73 wt%; the preferred FeO content of the acidic pellets is 0.6-1.2 wt%, more preferably 0.9-1 wt%, specifically 0.93 wt%; the preferred TFe content of the acidic pellets is 45-65 wt%, more preferably 50-60 wt%, specifically 54.99 wt%; the preferred mass ratio of the alkaline sinter to the acidic pellets is 45:(50-60), specifically 45:50, 45:51, 45:52, 45:53, 45:54, 45:55, 45:56, 45:57, 45:58, 45:59 or 45:60.

[0038] In the method provided by the present invention, the proportion of iron ore with a particle size <5mm in the iron ore is ≤1.8wt%, preferably 1~1.8wt%, specifically 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.42wt%, 1.5wt%, 1.6wt%, 1.7wt% or 1.8wt%.

[0039] In the method provided by the present invention, the coke includes large pieces of coke and small pieces of coke. The average particle size of the large pieces of coke is >25mm, preferably 30-80mm, specifically 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm or 80mm. The average particle size of the small pieces of coke is 10-25mm, specifically 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, 24mm or 25mm.

[0040] In the method provided by this invention, the batch weight of each batch of smelted iron ore and coke satisfies the requirements of formulas (1) to (3):

[0041] Equation (1);

[0042] Equation (2);

[0043] Equation (3);

[0044] In equations (1) to (3), k1 is 0.15 to 0.22; m 焦大 The mass of large coke produced in each batch of blast furnace smelting, unit: t / batch; ρ 焦大 Bulk density of coke, unit: t / m³ 3 λ is the coke volume compressibility coefficient, ranging from 0.1 to 0.12; d is the blast furnace waist diameter, in meters; k2 is 24 to 30 mm. 焦小 The mass of small pieces of coke produced in each batch of blast furnace smelting, in t / batch; m 矿 The mass of iron ore smelted in each blast furnace batch, in tons (t / batch); liters (L) 负荷 The ratio of ore to coke mass in each batch of blast furnace is 4.3 to 5.2.

[0045] In equations (1) to (3), k1 can specifically be 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21 or; ρ 焦大 The typical value is 0.56~0.6 t / m 3Specifically, it can be 0.56t / m 3 0.57t / m 3 0.58t / m 3 0.59t / m 3 Or 0.6t / m 3 λ can specifically be 0.1, 0.102, 0.105, 0.107, 0.11, 0.112, 0.115, 0.117, or 0.12; k2 can specifically be 24, 24.5, 25, 25.5, 26, 26.5, 27, 27.5, 28, 28.5, 29, 29.5, or 30; L 负荷 Specifically, it can be 4.3, 4.4, 4.5, 4.9, 4.7, 4.8, 4.9, 5, 5.1 or 5.2.

[0046] In the method provided by this invention, the oxygen enrichment rate during the smelting process is controlled at 4.5% to 10%, specifically 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%; the oxygen enrichment rate can be calculated according to formula (4):

[0047] Equation (4);

[0048] In equation (4), f O Oxygen enrichment rate, unit: % Oxygen-rich volume, unit: m 3 / min;O 2O % represents the volume percentage of O2 in oxygen-rich gas, expressed as %. 2O If % is 99%, then the value used in the calculation is 99; 21 is the volume percentage of O2 in the air, in units of %; V b The volume of gas pumped, including air and oxygen-enriched gas, is measured in cubic meters (m³). 3 / min.

[0049] In the method provided by this invention, the post-reaction strength (CSR) and air-dried ash (Aad) content of the coke preferably meet the following requirements:

[0050] If the effective volume of the blast furnace is ≥1000m³ 3 and <1500m 3 The post-reaction strength of the coke is 63-65%, and the air-dried ash content is ≤13.2 wt%.

[0051] If the effective volume of the blast furnace is ≥1500m³ 3 and <1800m 3The post-reaction strength of the coke is 65-68%, specifically 66.7%, and the air-dried ash content is ≤13wt%, specifically 12.5wt%.

[0052] If the effective volume of the blast furnace is ≥1800m³ 3 And ≤2500m 3 The post-reaction strength of the coke is 66-68%, and the air-dried ash content is ≤12.8wt%.

[0053] In the method provided by this invention, pulverized coal is preferably injected into the blast furnace during the smelting process; the volatile matter (Vad) content of the pulverized coal is preferably 15-21 wt%, specifically 15 wt%, 15.5 wt%, 15.6 wt%, 16 wt%, 16.5 wt%, 17 wt%, 17.5 wt%, 18 wt%, 18.5 wt%, 19 wt%, 19.5 wt%, 20 wt%, 20.5 wt%, or 21 wt%; the air-dried ash content of the pulverized coal is preferably ≤12.5 wt%, more preferably 10-12.5 wt%, specifically 10 wt%, 10.2 wt%, 10.5 wt%, 10.7 wt%, 11 wt%, or 11.2 wt%. The preferred percentages of the coal powder are 11.5 wt%, 11.7 wt%, 12 wt%, 12.2 wt%, or 12.5 wt%. The moisture (Mt) content of the coal powder is preferably ≤0.8 wt%, more preferably 0.05~0.8 wt%, specifically 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, or 0.8 wt%. The preferred percentage of coal powder with a particle size <74 μm is 70~80 wt%, specifically 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 75 wt%, 77 wt%, 78 wt%, 79 wt%, or 80 wt%.

[0054] In the method provided by the present invention, the TiO2 content of the slag is ≥22wt%, preferably 22~25wt%, specifically 22wt%, 22.5wt%, 22.76wt%, 23wt%, 23.5wt%, 24wt%, 24.5wt%, or 25wt%; the binary basicity of the slag is preferably 1~1.12, specifically 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, 1.11, or 1.12.

[0055] In the method provided by this invention, the Ti content of the molten iron is preferably 0.09~0.2wt%, specifically 0.09wt%, 0.1wt%, 0.11wt%, 0.12wt%, 0.127wt%, 0.13wt%, 0.14wt%, 0.15wt%, 0.16wt%, 0.17wt%, 0.18wt%, 0.19wt%, or 0.2wt%; the total Ti and Si content of the molten iron is preferably 0.15~0.38wt%, specifically 0.15wt%, 0.16wt%, 0.17wt%, 0.18wt%, 0.19wt%, 0.2wt%, 0.21wt%, 0.22wt%, 0.23wt%, 0.24wt%, 0.25wt%, 0.27wt%, 0.3wt%, 0.32wt%, 0.35wt%, or 0.38wt%.

[0056] In the method provided by the present invention, the blast furnace coke ratio of the smelting is preferably 360~400 kg / t, specifically 360 kg / t, 362 kg / t, 365 kg / t, 367 kg / t, 370 kg / t, 372 kg / t, 375 kg / t, 377 kg / t, 380 kg / t, 383 kg / t, 385 kg / t, 387 kg / t, 390 kg / t, 392 kg / t, 395 kg / t, 397 kg / t or 400 kg / t.

[0057] In the method provided by the present invention, the preferred pulverized coal injection ratio for smelting is 140~160 kg / t, specifically 140 kg / t, 141 kg / t, 142 kg / t, 143 kg / t, 144 kg / t, 145 kg / t, 146 kg / t, 147 kg / t, 148 kg / t, 149 kg / t, 150 kg / t, 151 kg / t, 152 kg / t, 153 kg / t, 154 kg / t, 155 kg / t, 156 kg / t, 157 kg / t, 158 kg / t, 159 kg / t, or 160 kg / t.

[0058] For clarity, the following examples will be used to provide a detailed description.

[0059] Example 1

[0060] A method for smelting vanadium-titanium magnetite in a blast furnace includes the following steps:

[0061] Iron ore and coke are smelted in a blast furnace to obtain slag and molten iron.

[0062] The effective volume of the blast furnace used is 1750m³. 3 The furnace hearth diameter is 9.5m, and the furnace waist diameter is 11.3m;

[0063] The iron ore used is alkaline sinter and acidic pellet, and its chemical composition and parameters are shown in Table 1:

[0064] Table 1 Chemical composition and parameters of iron ore fed into the furnace

[0065]

[0066] The coke used includes large and small pieces, with the large pieces having an average particle size of 50 mm and the small pieces having an average particle size of 20 mm. The post-reaction strength (CSR) of the coke used is 66.7%, and the air-dried ash (Aad) content is 12.5 wt%.

[0067] Calculate the batch quantity (i.e., batch weight) of iron ore, large coke, and small coke according to equations (1) to (3), where k1 is 0.17, λ is 0.12, and ρ is 0.12. 焦大 It is 0.58t / m 3 d is 11.3m, k2 is 25, L 负荷 The value is 4.3t / t; calculated from equations (1) to (3), m 焦大 It is 11.23t / batch, m 焦小 It is 1.568t / batch, m 矿 The yield is 62.709 tons per batch.

[0068] During the smelting process, pulverized coal is injected into the blast furnace. The air-dried ash (Aad) content of the pulverized coal is 11.2 wt%, the volatile matter (Vad) content is 15.6 wt%, the moisture (Mt) content is 0.3 wt%, and the proportion of pulverized coal with a particle size <74 μm is 77 wt%.

[0069] Gas volume (V) during smelting b ) is 4200m 3 / min, oxygen-rich body mass ( ) is 18000m 3 / h (i.e., 300m) 3 / min), the volume percentage of O2 in oxygen-rich gas (O 2O The oxygen enrichment rate (f) is 99%; according to formula (4), the oxygen enrichment rate (f) can be calculated. O The figure is 5.57%;

[0070] The resulting slag had a TiO2 content of 22.76 wt% and a binary basicity of 1.10.

[0071] The molten iron has a Ti content of 0.127 wt%, a Si content of 0.103 wt%, and a total Ti and Si content of 0.230 wt%.

[0072] The blast furnace coke ratio for smelting is 383 kg / t, and the pulverized coal injection ratio is 151 kg / t.

[0073] Compared to the traditional method of smelting vanadium-titanium magnetite in a blast furnace, the blast furnace coke ratio in this embodiment is reduced from 406 kg / t to 383 kg / t, the pulverized coal injection ratio is increased from 136 kg / t to 151 kg / t, the blast furnace coke ratio is reduced by 23 kg / t, and the fuel ratio is reduced by 8 kg / t.

[0074] 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 smelting vanadium-titanium magnetite in a blast furnace, characterized in that, Includes the following steps: Iron ore and coke are smelted in a blast furnace to obtain slag and molten iron. The effective volume of the blast furnace is 1000~2500m³. 3 ; The iron ore comprises two or three of the following: basic sinter, acidic pellets, basic pellets, and lump ore; the proportion of iron ore with a particle size <5mm in the iron ore is ≤1.8wt%. The coke includes large pieces of coke and small pieces of coke, wherein the average particle size of the large pieces of coke is >25mm and the average particle size of the small pieces of coke is 10~25mm. The batch weight of the iron ore and coke smelted in each batch shall meet the requirements of equations (1) to (3): Equation (1); Equation (2); Equation (3); In equations (1) to (3), k1 is 0.15 to 0.22; m 焦大 The mass of large coke produced in each batch of blast furnace smelting, in t / batch; ρ 焦大 Bulk density of coke, unit: t / m³ 3 λ is the coke volume compressibility coefficient, ranging from 0.1 to 0.12; d is the blast furnace waist diameter, in meters; k2 is 24 to 30 mm. 焦小 The mass of small pieces of coke produced in each batch of blast furnace smelting, in t / batch; m 矿 The mass of iron ore smelted in each blast furnace batch, in tons (t / batch); liters (L) 负荷 The ratio of ore to coke mass in each batch of blast furnace is 4.3 to 5.

2. The oxygen enrichment rate during the smelting process is controlled at 4.5-10%; The TiO2 content of the slag is ≥22wt%.

2. The method according to claim 1, characterized in that, The basic sinter has a drum index ≥77%; the acidic pellets have a binary basicity ≤0.2 and a compressive strength ≥2200N / piece; the basic pellets have a binary basicity ≥0.3 and a compressive strength ≥2200N / piece.

3. The method according to claim 1, characterized in that, The iron ore includes alkaline sinter and acidic pellets.

4. The method according to claim 3, characterized in that, The mass ratio of alkaline sinter to acidic pellets is 45:(50~60).

5. The method according to claim 1, characterized in that, The oxygen enrichment rate is calculated according to formula (4): Equation (4); In equation (4), f O Oxygen enrichment rate, unit: % Oxygen-rich volume, unit: m 3 / min; O 2O % represents the volume percentage of O2 in oxygen-enriched gas, in units of %; V b Air volume, unit: m 3 / min.

6. The method according to claim 1, characterized in that, The post-reaction strength and air-dried ash content of the coke must meet the following requirements: If the effective volume of the blast furnace is ≥1000m³ 3 and <1500m 3 The post-reaction strength of the coke is 63-65%, and the air-dried ash content is ≤13.2 wt%. If the effective volume of the blast furnace is ≥1500m³ 3 and <1800m 3 The post-reaction strength of the coke is 65-68%, and the air-dried ash content is ≤13wt%. If the effective volume of the blast furnace is ≥1800m³ 3 And ≤2500m 3 The post-reaction strength of the coke is 66-68%, and the air-dried ash content is ≤12.8wt%.

7. The method according to claim 1, characterized in that, During the smelting process, pulverized coal is injected into the blast furnace.

8. The method according to claim 7, characterized in that, The volatile matter content of the pulverized coal is 15~21wt%, the ash content on an air-dried basis is ≤12.5wt%, and the moisture content is ≤0.8wt%; the proportion of pulverized coal with a particle size <74μm is 70~80wt%.

9. The method according to claim 1, characterized in that, The binary basicity of the slag is 1 to 1.

12.

10. The method according to claim 1, characterized in that, The molten iron has a Ti content of 0.09~0.2wt% and a total Ti and Si content of 0.15~0.38wt%.

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