Method for smelting vanadium-titanium ore in blast furnace

Abstract

The application discloses a method for smelting vanadium-titanium ore in a blast furnace, and comprises the following steps: determining the weight of the coke to be used and the blast volume according to constraint conditions; placing liquid slag iron and coke into the blast furnace for smelting, and providing dry air and dry oxygen-rich gas according to the blast volume; and after the smelting is completed, discharging the liquid slag and molten iron through multiple tapping holes within a preset time period. The scheme provided by the application determines the weight of the coke to be used and the blast volume according to constraint conditions, so that slag with high TiO2 content is obtained, and the liquid slag and molten iron are discharged through multiple tapping holes, so that the time for storing the slag in the furnace hearth is reduced, thereby achieving the purpose of reducing TiO2 reduction, and providing support for low-carbon smelting of a high-titanium vanadium-titanium ore blast furnace under high-grade conditions.

Description

Technical Field

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

[0002] In the smelting of high-titanium vanadium magnetite, the TiO2 content in the slag is as high as 22% or more. TiO2 in the slag is easily excessively reduced to form TiC, TiN, and their solid solutions Ti(C,N), which are insoluble under blast furnace smelting conditions. This leads to slag thickening, severely affecting the stable operation of the blast furnace process and, in severe cases, causing abnormal furnace conditions. Secondly, due to the low CaO content and low basicity of the slag, the desulfurization capacity of high-titanium blast furnace slag is extremely low. The sulfur distribution coefficient between slag and iron (w(S) / w[S]) is typically only 5-8, while in blast furnaces smelting ordinary ores it can reach 40-50 or even higher. To improve the quality of molten iron and reduce its S content, blast furnace operators must increase the smelting furnace temperature to improve the desulfurization effect. However, this increased temperature further exacerbates the reduction of TiO2. This contradiction significantly increases the technical difficulty of blast furnace smelting of high-titanium vanadium-titanium ore, exacerbates fluctuations in blast furnace conditions, results in poor stable operation of the blast furnace, and makes it impossible to further improve technical and economic indicators.

[0003] Due to the unique characteristics of vanadium-titanium ore, to appropriately reduce the TiO2 content in blast furnace slag and achieve better technical and economic indicators, it is necessary to use low-grade common ore to lower the feed grade and increase the slag-to-iron ratio. A higher slag-to-iron ratio necessitates increasing the coke and coal ratios during blast furnace smelting, leading to increased carbon emissions. In the context of low-carbon smelting, reducing the fuel ratio becomes a key aspect of reducing carbon emissions in the blast furnace process. To further reduce carbon emissions from the blast furnace process, it is essential to increase the feed grade and reduce the slag-to-iron ratio. With increased feed grade, without reducing the proportion of vanadium-titanium ore used, the TiO2 content in the slag will inevitably increase. Experimental research and production practice show that slag TiO2 content, temperature, and time are the main factors affecting TiO2 reduction, while adjusting the slag chemical composition has a relatively small effect on reducing the reduction products TiC, TiN, and titanium carbonitride. Under conditions of increased slag TiO2 content, lowering the smelting temperature and reducing the reduction time have the greatest effect on reducing TiO2 reduction and titanium carbonitride formation. As mentioned earlier, lowering the furnace temperature can lead to a deterioration in the quality of molten iron and even cause abnormal furnace operation. Secondly, actual production shows that the furnace temperature level for vanadium-titanium ore blast furnace smelting is already significantly lower than that for blast furnaces smelting ordinary ores, leaving little room for further reducing the furnace temperature level for blast furnace smelting of high-titanium vanadium-titanium ore. Summary of the Invention

[0004] In view of this, in order to overcome at least one aspect of the above-mentioned problems, embodiments of the present invention provide a method for smelting vanadium-titanium ore in a blast furnace, comprising the following steps: The weight of the coke to be used and the air volume are determined according to the constraints. Liquid slag iron and coke are put into a blast furnace for smelting, and dry air and dry oxygen-enriched gas are provided according to the blast volume. After smelting, the liquid slag and molten iron are discharged through multiple tapping ports within a preset time period.

[0005] In some embodiments, the weight of the coke to be used and the air volume are determined according to constraints, further including that the weight of the coke and the air volume satisfy the following formula: +M1× =M2；

[0006] in, The blower volume includes dry air and dry oxygen-enriched gas; This is the weight of the coke; For oxygen enrichment rate, It is an oxygen-rich body mass; The O2 content in oxygen-rich gas; M 1, M2 is a coefficient.

[0007] In some embodiments, M The value of 1 ranges from 16.5 to 18; M The value of 2 is between 2700 and 2850.

[0008] In some embodiments, the oxygen enrichment rate is 5%-10%.

[0009] In some embodiments, the oxygen-enriched gas is industrial pure oxygen with an O2 content of 99% or other oxygen-enriched gas with an O2 content higher than 21%.

[0010] In some embodiments, after smelting is completed, the liquid slag and molten iron are discharged from multiple tapping ports within a preset time, further comprising: The liquid slag and molten iron are discharged within 60-90 minutes using multiple tapping ports.

[0011] In some embodiments, after smelting is completed, the liquid slag and molten iron are discharged from multiple tapping ports within a preset time, further comprising: The volume of liquid slag and molten iron discharged per minute from multiple tapholes is controlled to be no less than the volume of molten iron and liquid slag produced per minute by the blast furnace, so as to control the residence time of liquid slag produced by the blast furnace in the hearth to be equal to the preset time.

[0012] In some embodiments, the number of iron outlets is 2-4.

[0013] In some embodiments, the Ti content in the molten iron is 0.095%–0.180%, and the sum of the Ti and Si contents is controlled within the range of 0.15%–0.30%. The TiO2 content in the liquid slag is 22.5%-28%.

[0014] The present invention has one of the following beneficial technical effects: The solution proposed in this invention determines the weight of coke to be used and the blast volume by constraining conditions, thereby obtaining slag with high TiO2 content. At the same time, it uses multiple tapping ports to discharge liquid slag and molten iron, reducing the storage time of slag in the hearth, thereby achieving the purpose of reducing TiO2 reduction, and providing support for low-carbon smelting of high-titanium vanadium-titanium ore blast furnaces under high-grade conditions. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0016] Figure 1 A schematic flow diagram of a method for smelting vanadium-titanium ore in a blast furnace, provided as an embodiment of the present invention; Figure 2 A table of chemical composition and quantity of iron-containing furnace charge provided for embodiments of the present invention; Figure 3 A table of chemical composition and quantity of iron-containing furnace charge provided for embodiments of the present invention; Figure 4 Air and furnace top gas composition tables provided for embodiments of the present invention; Figure 5 A chemical composition table of dust ash provided for embodiments of the present invention; Figure 6 Table of chemical composition and quantity of pig iron provided for embodiments of the present invention; Figure 7 A table of slag chemical composition and quantity provided for embodiments of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0018] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0019] According to one aspect of the present invention, embodiments of the present invention provide a method for smelting vanadium-titanium ore in a blast furnace, such as... Figure 1 As shown, it may include the following steps: S1, determine the weight of the coke to be used and the air volume according to the constraints; S2, molten slag iron and coke are put into the blast furnace for smelting, and dry air and dry oxygen-enriched gas are provided according to the blast volume; S3, after smelting is completed, liquid slag and molten iron are discharged through multiple tapping ports within a preset time period.

[0020] The proposed solution determines the weight of coke to be used and the blast volume by constraining conditions, thereby obtaining slag with high TiO2 content. At the same time, multiple tapping ports are used to discharge liquid slag and molten iron, reducing the storage time of slag in the hearth, thereby achieving the goal of reducing TiO2 reduction and providing support for low-carbon smelting of high-titanium vanadium-titanium ore blast furnaces under high-grade conditions.

[0021] In some embodiments, the weight of the coke to be used and the air volume are determined according to constraints, further including that the weight of the coke and the air volume satisfy the following formula: +M1× =M2；

[0022] in, The blower volume includes dry air and dry oxygen-enriched gas; This is the weight of the coke; For oxygen enrichment rate, It is an oxygen-rich body mass; The O2 content in oxygen-rich gas; M 1, M2 is a coefficient.

[0023] In some embodiments, the oxygen enrichment rate is 5%-10%.

[0024] In some embodiments, M The value of 1 ranges from 16.5 to 18. M The value of 2 is between 2700 and 2850.

[0025] In some embodiments, the oxygen-enriched gas is industrial pure oxygen with an O2 content of 99% or other oxygen-enriched gas with an O2 content higher than 21%.

[0026] Specifically, in order to increase the coke combustion rate and improve the TiO2 content, the constraint relationship between air volume and coke can be as follows: +M1× =M2； in, The oxygen enrichment rate is preferably 5%-10%, and its calculation formula is as follows:

[0027] in, For blower volume, m 3 / min, including dry air and dry oxygen-enriched gas, such as industrial pure oxygen with an O2 content of 99% or other oxygen-enriched gas with an O2 content of more than 21%; This represents the total amount of coke consumed per day by a single blast furnace, in tons per day (t / d). Oxygen enrichment rate, % For oxygen-rich body mass, m 3 / min, often expressed in m in actual production 3 / h means when compared with air volume (m³) 3 When calculating ( / min), divide by 60 to convert to m. 3 / min; This represents the O2 content in oxygen-rich gas. For example, if the oxygen content is 99%, the value is taken as 0.99, and the N2 content is 0.01.

[0028] In some embodiments, the air volume includes the oxygen enrichment value but excludes moisture (H2O). The air volume is calculated using the CN method based on the actual quantity of raw materials and fuels consumed, the chemical composition of the raw materials and fuels, the quantity and chemical composition of pig iron and slag, and the composition of the gas (CO, CO2, N2, H2, etc.).

[0029] In some embodiments, the theoretical combustion temperature refers to the temperature that can be reached when all the heat released by the fuel after incomplete combustion in the combustion zone is used to heat the resulting gas. This process is adiabatic and can be calculated using the following formula: (3) kJ / kg(4) kJ / kg(5) kJ / kg

[0030] (6) (7) (8) (9) (10) In equations (3)-(10): T f The theoretical combustion temperature within the combustion zone is given in °C. The heat released when carbon burns to produce CO, expressed in kJ / kg. The physical heat, in kJ, is brought into the combustion zone by coke, pulverized coal, pulverized coal carrier gas, and hot air. The heat consumed by the decomposition of moisture in fuel and blower air is kJ. The heat consumed by the thermal decomposition of the injected fuel is kJ; m is the amount of gas produced by the combustion of carbon in front of the vent. 3 ; The average specific heat capacity of the gas produced by combustion is given in kJ / (m³). 3 ·℃).

[0031] This represents the actual amount of pulverized coal consumed by a blast furnace per day, expressed in kg / d. In actual production, it is often expressed in t. The calculation involves multiplying by 1000 to convert it to kg. The combustion rate of pulverized coal in front of the tuyeres is 80%–100%, and the actual value used in the calculation is 0.8–1.0. Y 日 The theoretical daily production output, in kg / d, is calculated from the company's actual pig iron production (Y, kg / d) and iron content (%). Y 日 =Y / (1-iron loss / 100), where t usually represents output in actual production and is converted to kg during calculation; and The fixed carbon content on an air-dried basis for pulverized coal and coke, respectively, is %, such as 80%, which is taken as 0.8 in the calculation; This refers to the actual moisture content of the anhydrous pulverized coal entering the blast furnace. For example, if the mass of the pulverized coal is 100 kg and the corresponding moisture content is 1 kg, then the total mass of the pulverized coal entering the blast furnace is 101 kg. The value is 1%, and is taken as 1 in the calculation. However, in actual production, the moisture test result is often expressed as 1 / (100+1) = 0.99. In the patent calculation, it needs to be converted to 100kg of dry coal. It is 1%.

[0032] C b For blower heat capacity; CNT O2-b and CNT N2-b These represent the proportions of O2 and N2 in the blower air; T b The hot air temperature is in °C. O2% The O2 content in the drying blast air of 1 ton of iron, % This refers to the moisture content (H2O) corresponding to the drying air (including oxygen enrichment), such as 100m³ of drying air. 3 Moisture content is 1m 3， The total of the two is 101m 3 M t It is 1%; In order to obtain a defined theoretical combustion temperature Previously, the theoretical combustion temperature was set. Afterwards, a set furnace gas heat capacity can be obtained. Therefore, a result can be obtained from equation (3). There is a gap between this and the previous one, which needs to be continuously adjusted. To make the two the same, we obtain the final result. .

[0033] In this embodiment, the theoretical combustion temperature can be 2350-2400℃.

[0034] In some embodiments, after smelting is completed, the liquid slag and molten iron are discharged from multiple tapping ports within a preset time, further comprising: The liquid slag and molten iron are discharged within 60-90 minutes using multiple tapping ports.

[0035] In some embodiments, after smelting is completed, the liquid slag and molten iron are discharged from multiple tapping ports within a preset time, further comprising: The volume of liquid slag and molten iron discharged per minute from multiple tapholes is controlled to be no less than the volume of molten iron and liquid slag produced per minute by the blast furnace, so as to control the residence time of liquid slag produced by the blast furnace in the hearth to be equal to the preset time.

[0036] In some embodiments, the number of iron outlets is 2-4.

[0037] In some embodiments, the Ti content in the molten iron is 0.095%–0.180%, and the sum of the Ti and Si contents is controlled within the range of 0.15%–0.30%. The TiO2 content in the liquid slag is 22.5%-28%.

[0038] Specifically, if the effective volume of the blast furnace is 1000m³ 3 -2500m 3 The furnace has 2-4 tapholes, capable of continuously discharging slag and iron, ensuring a slag residence time of 60-90 minutes in the hearth. Each taphole has the same tapping capacity. When two tapholes tap simultaneously, they can completely discharge the slag and iron stored in the hearth within the specified tapping time (60-90 minutes). Furthermore, the rate of continued tapping is equal to the rate of slag and iron formation. The tapping capacity of a single taphole (m³) is [missing information]. 3 The blast furnace's tapping rate (per min) is less than the slag-iron formation rate, but the tapping capacity of the two tapholes is greater than or equal to the slag-iron formation rate, enabling uninterrupted tapping. The Ti content of the final discharged molten iron is controlled within the range of 0.095%–0.180%, and the sum of Ti and Si content is controlled within the range of 0.15%–0.30%. The TiO2 content in the slag is 22.5%–28%.

[0039] Example A certain 1750m 3 The blast furnace has a hearth diameter of 9.5m and a throat diameter of 6.9m. The composition of raw materials, blast air, top gas, pig iron, and slag, as well as the corresponding material qualities, are detailed below. Figures 2-7 .

[0040] Depend on Figures 2-7 The calculated air volume per ton of iron is 3738 m³. 3 / min, at oxygen enrichment rate f o Given a concentration of 5.04%, we can obtain: 1440 × 3738 / 1967 = 2736.51 At this point, if M1 is 17 multiplied by f o 17 × 5.04 = 85.68 Add 85.68 to 2735.84: 2736.51 + 85.68 = 2822.19, which is within the range of 2700-2850.

[0041] use Figures 2-7 Based on the data and equations (3)-(10), the theoretical combustion temperature Tf can be calculated to be 2353℃.

[0042] The average TiO2 content of the slag from all furnaces throughout the day was 23.47%.

[0043] The distance from the lower edge of the tuyeres to the center line of the taphole in this blast furnace is approximately 3.2 meters. The internal volume of this section of the furnace is 3.2 × 9.5 × 9.5 × 3.14 / 4 = 226.71 m². 3 Because the hearth is filled with a large amount of coke, occupying a significant portion of the furnace's internal volume, this 226.71m³... 3 Only about 45% of the volume is available, which is 102.02m². 3 It can be used to contain molten slag and iron dripping from the top of the blast furnace into the hearth. Figure 6 and Figure 7 It can be seen that for every ton of iron produced, 2637 / 5066 = 0.52 tons of slag are generated. The density of the slag is approximately 2.85-3.0 t / mm³. 3 The density of molten iron is approximately 7.0 g / mm³. 3 The slag density is calculated as 2.9 g / mm³. 3 The density of molten iron is 7.0 g / mm³. 3 Considering that the volume of 1 ton of molten iron and the corresponding slag is 0.1429 + 0.1793 = 0.3229 mm, 3 102.2mm 3 It can hold 102.2 / (1 / 7+0.52×1 / 2.9)=316.66t of molten iron. If the required residence time of the newly generated liquid slag in the hearth is not to exceed 70 minutes, then this 102.02m 3 The furnace contains 316.66 tons of molten iron and 164.66 tons of slag, which need to be discharged within 70 minutes. The average volume of slag and iron discharged per minute is 102.02 / 70 = 1.46 m³. 3 In the initial tapping stage immediately after the taphole opens, only molten iron is discharged, with no slag. The corresponding tapping rate is 1.46 × 7 = 10.22 t. As tapping progresses, both molten iron and slag are discharged from the taphole. For example, considering the volume, if 50% is molten iron and 50% is slag, the tapping rate is 1.46 × 7 × 50% = 5.11 t. If the tapping rate of a single taphole is 5.2 t / min, and two tapholes are used simultaneously, 316.66 t of molten iron and 164.66 t of slag will be discharged after 69 minutes. At this point, the newly generated slag has remained in the hearth for 69 minutes, thus meeting the requirement that it not exceed 70 minutes in the hearth.

[0044] Therefore, the residence time of newly generated slag in the hearth can be equated with the time set for completely discharging the slag and iron from the hearth within a specified time.

[0045] The above represents the maximum amount of slag and iron that a blast furnace hearth can hold; this phenomenon generally does not occur in actual production. In actual production, the slag and iron in the hearth are usually discharged through the taphole before reaching the maximum storage capacity. Figure 6 and Figure 7 As shown, under the current conditions, the blast furnace produces 3.52 t / min of molten iron at a rate of 5066 / 1440. Clearly, after 70 minutes, the volume of slag and iron formed is: 3.52 × 70 / 7 + 3.52 × 0.52 × 70 / 2.95 = 35.20 + 43.43 = 78.63 m³. 3 The average slag and iron volume discharged per minute is 1.123 m³. 3 In the initial stage of tapping, when only molten iron is discharged from the furnace, the tapping rate is 1.123 × 7 = 7.861 t. It is still necessary to schedule tapping from two tapholes for a period of time. At this point, one taphole can be opened first, temporarily using single-tap tapping. After tapping from this taphole for a period of time, the other taphole can be opened, and the first opened taphole can be closed. Let the tapping time of the first single taphole be t1, and the tapping times of the first and second tapholes be t2. Then the relationship between t1 and t2 is as follows: t1+t2=t(11) υ ht ×t1+2υ ht ×t2=V ht (12) In formula (11), t1, t2, and t are the tapping time of a single tapping iron outlet, the tapping time of two tapping iron outlets, and the total tapping time, respectively; ht Let m be the tapping rate of a single taphole, expressed as volume, within a specified tapping time. 3 / min, its value is the total volume of slag and iron produced within a specified time (V) ht (and the agreed time)

[0046] In this embodiment, if the iron discharge rate from a single tap is 5.2 tons of iron, this is equivalent to a discharge volume of υ per minute. ht = 5.2 / 7 = 0.743m 3 Then V ht It is 78.63m 3 If t is 70 minutes, then t1 is 34.17 minutes and t2 is 35.83 minutes. After 70 minutes of tapping time, one tap is blocked, and only one tap is used for tapping. The tapping time is then restarted, and after 34.17 minutes, the other tap is opened. Usually, the tap with the longer tapping time is blocked.

[0047] If the tapping time is 60 minutes, then V ht It is 67.40m 3t1 was 29.27 min and t2 was 30.73 min.

[0048] If the tapping time is 90 minutes, then V ht 101.10m 3 t1 was 43.90 min and t2 was 46.10 min.

[0049] Typically, a blast furnace can only use a maximum of two tapholes simultaneously. Therefore, the tapping capacity of a single taphole, i.e., the tapping rate mentioned above, is limited. That is, after specifying the tapping time per cycle, the volume of molten iron and slag produced by the blast furnace per minute cannot exceed the total molten iron and slag discharge from both tapholes (2υ). ht For example, if the daily pig iron production of this blast furnace increases to 5500t and the slag-to-iron ratio increases from 0.52 to 0.54, the slag-to-iron volume produced per minute is 5500 / 1440 / 7 + 5500 × 0.54 / 1440 / 2.95 = 1.245m³. 3 / min, then the discharge capacity of a single taphole is υ ht It should reach at least 0.6235m 3 / min, corresponding to the iron tapping rate of a single tap when only iron is tapped, is not less than 4.361t / min.

[0050] As the reduction time is shortened, the Ti and Si contents of the molten iron decrease, with the Ti content at 0.16% and the Si content at 0.12%, totaling 0.28%.

[0051] Due to the implementation of the above measures, the formation of TiC, TiN, and Ti(C,N) in the slag is reduced. Under the condition of significantly increased TiO2 content in the slag, the TiC content is less than 0.1% and the TiN content is less than 0.1%.

[0052] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0053] It should be understood that, as used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, “and / or” refers to any and all possible combinations of one or more of the associated listed items.

[0054] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0055] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for smelting vanadium-titanium ore in a blast furnace, characterized in that, include: The weight of the coke to be used and the air volume are determined according to the constraints. Liquid slag iron and coke are put into a blast furnace for smelting, and dry air and dry oxygen-enriched gas are provided according to the blast volume. After smelting, the liquid slag and molten iron are discharged through multiple tapping ports within a preset time period.

2. The method as described in claim 1, characterized in that, The weight of the coke to be used and the air volume are determined according to the constraints, further including that the weight of the coke and the air volume satisfy the following formula: +M1× =M2； in, Air volume, including dry air and dry oxygen-enriched gas, is measured in cubic meters per second (m³). 3 / min; The value is the weight of coke, expressed in tons per day (t / d). For oxygen enrichment rate, Oxygen-rich volume, unit: m 3 / min; The O2 content in oxygen-rich gas, expressed in m³. 3 / min; M 1, M 2 is a coefficient.

3. The method as described in claim 2, characterized in that, M The value of 1 ranges from 16.5 to 18.

4. The method as described in claim 2, characterized in that, M The value of 2 is between 2700 and 2850.

5. The method as described in claim 2, characterized in that, The oxygen enrichment rate is 5%-10%.

6. The method as described in claim 2, characterized in that, The oxygen-enriched gas is industrial pure oxygen with an O2 content of 99% or other oxygen-enriched gas with an O2 content higher than 21%.

7. The method as described in claim 1, characterized in that, After smelting, the molten slag and iron are discharged from multiple tapping ports within a preset time, further including: The liquid slag and molten iron are discharged within 60-90 minutes using multiple tapping ports.

8. The method as described in claim 1, characterized in that, After smelting, the molten slag and iron are discharged from multiple tapping ports within a preset time, further including: The volume of liquid slag and molten iron discharged per minute from multiple tapholes is controlled to be no less than the volume of molten iron and liquid slag produced per minute by the blast furnace, so as to control the residence time of liquid slag produced by the blast furnace in the hearth to be equal to the preset time.

9. The method as described in claim 1, characterized in that, The number of iron outlets is 2-4.

10. The method as described in claim 1, characterized in that, The Ti content in the molten iron is 0.095%–0.180%, and the sum of the Ti and Si contents is controlled within the range of 0.15%–0.30%. The TiO2 content in the liquid slag is 22.5%-28%.

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