Method for removing manganese from molten iron

Abstract

The application discloses a method for removing manganese from molten iron, and belongs to the field of molten iron pretreatment. The method is used for reducing the pressure of removing manganese from industrial pure iron smelted by a converter, and comprises the following steps: detecting the composition of the molten iron in a tapping process; adding a certain amount of a manganese removal agent into a molten iron channel when the manganese content of the molten iron is greater than or equal to 0.2%; and the main component of the manganese removal agent is Al2O3 20-30%, SiO2 70-80%, and other impurities, and the particle size of the manganese removal agent is 1-5 mm. The process parameters such as the temperature of the molten iron, the tapping speed, and the adding speed of the manganese removal agent are synchronously controlled, and the molten iron slag is removed at a KR desulfurization station. The method can stably control the manganese content of the molten iron to be less than 0.2%, and can increase the silicon content of the molten iron and the heat source, and is worth popularizing and applying.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hot metal pretreatment, and particularly relates to a hot metal manganese removal method. BACKGROUND

[0002] Industrial pure iron is a kind of metal material with very low alloy content, and the main component is iron, and other elements are as low as possible. The manganese content has a great influence on the soft magnetic properties of the industrial pure iron, and is generally required to be ≤0.06%, and some strict products even require the manganese content in the material to be ≤0.035%. For example, patent CN115261564A non-aluminum deoxidized raw material pure iron for amorphous soft magnetic ribbon and a preparation method thereof requires that the manganese content of the industrial pure iron is ≤0.06%; patent CN113774277A ultra-low-carbon ultra-low-manganese industrial pure iron and a preparation method thereof requires that the manganese content of the industrial pure iron is ≤0.035%. The industrial pure iron is generally smelted by a converter / electric furnace, and the raw materials are mainly hot metal and scrap steel, and the manganese content in the hot metal accounts for more than 80% in the converter smelting process. In order to remove the manganese in the hot metal, a converter double-slag + end-point over-oxidation smelting method is generally used for removal, but it causes a long converter smelting cycle, and the over-oxidation of the molten steel intensifies the erosion of the furnace lining and increases the consumption of deoxidizers, thereby increasing the cost of steelmaking. In order to reduce the manganese removal pressure of the converter, some steel plants use a hot metal manganese removal method, which generally uses iron oxide as an oxidizing agent, and the actual use effect is that the silicon in the hot metal is also removed while the manganese in the hot metal is removed; in addition, the iron oxide is a cooling agent, which also greatly reduces the temperature drop of the hot metal, and is more unfavorable for steel plants with low hot metal ratio or insufficient heat.

[0003] Chinese patent CN101294233 A method for simultaneously removing silicon and manganese in hot metal pretreatment uses iron scale as a main manganese removal agent, which is sprayed into a torpedo tank or a hot metal ladle by a powder spraying method, and the silicon and manganese are removed through an oxidation reaction, and the silicon removal rate can reach 79-90%, and the manganese removal rate can reach 78-88%. Using iron scale as a manganese removal agent, it is inevitable to remove silicon during the manganese removal process. Since the oxygen potential of silicon is lower, the silicon removal reaction occurs preferentially and the silicon removal rate is generally greater than the manganese removal rate. SUMMARY

[0004] The purpose of the present application is to provide a hot metal manganese removal method, which can effectively remove the manganese content in the hot metal, and at the same time can increase the silicon content of the molten steel to a certain extent and compensate for the heat source.

[0005] The present application provides a hot metal manganese removal method, which adds a manganese removal agent mainly composed of acidic oxidizing agents SiO2 and Al2O3 during the hot metal tapping process, removes the manganese in the hot metal, increases the silicon content of the hot metal, and reduces the temperature drop. The specific method steps and control method parameters are as follows:

[0006] A method for demanganese removal from molten iron involves taking a sample of molten iron from the blast furnace trough. When the manganese content of the molten iron exceeds 0.2%, a certain amount of demanganese removal agent is added to the trough. After the molten iron reaches the KR desulfurization station, the slag is removed.

[0007] Furthermore, as a preferred embodiment, the main components of the manganese removal agent are: 20-30% Al2O3, 70-80% SiO2, with the remainder being impurities, and the particle size of the manganese removal agent is 1-5 mm.

[0008] Furthermore, as a preferred embodiment, the amount of manganese removal agent added is as follows: when the manganese content of molten iron is 0.5-0.6%, add 10-13 kg / t of manganese removal agent; when the manganese content of molten iron is 0.35-0.5%, add 7-10 kg / t of manganese removal agent; when the manganese content of molten iron is 0.2-0.35%, add 4-7 kg / t of manganese removal agent.

[0009] Furthermore, as a preferred embodiment, the manganese removal agent is added 3 minutes after each bag of iron is tapped, at a rate of 0.5–1.5 kg / t / min.

[0010] Furthermore, as a preferred embodiment, when the demanganese-removing agent is added, the temperature of the molten iron is 1500–1550°C, and the tapping speed is controlled at 3.5–4.5 t / min.

[0011] The advantages of this invention are mainly reflected in the following aspects:

[0012] 1. A method for demanganese removal from molten iron is provided. A demanganese-removing agent is added to the molten iron trough, and the molten iron temperature and tapping rate during demanganese removal are specifically specified. The method utilizes the flow of molten iron during tapping to improve kinetic conditions, as well as the kinetic conditions generated when the demanganese-removing agent floats to the surface after reaching the ladle, thereby improving the demanganese removal effect. Simultaneously, the relatively high temperature of the molten iron at tapping promotes the demanganese removal reaction. After the demanganese-removed molten iron reaches the KR desulfurization station, slag is removed through a slag removal operation to prevent the slag from being reduced and incorporated into the molten steel after being added to the converter.

[0013] 2. A manganese removal agent is provided, the main components of which are 20-30% Al2O3 and 70-80% SiO2. This manganese removal agent utilizes SiO2 to oxidize manganese in molten iron. Simultaneously, the manganese oxide product can react with silicon dioxide and aluminum oxide to reduce the activity of MnO and promote the manganese removal reaction. On the other hand, Al2O3 can increase the activity of SiO2 in the slag, further promoting the manganese removal reaction.

[0014] 3. The iron demanganese removal method of the present invention can stably control the manganese content of iron to below 0.2%, and can increase the silicon content of iron and increase the heat source, which is worth promoting and applying. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to the embodiments:

[0016] Example 1

[0017] The molten iron was sampled and analyzed in the tundish. The composition was found to be C: 4.52%, Si: 0.21%, Mn: 0.55%, P: 0.126%, and S: 0.0253%, requiring demanganese treatment. The tapping rate was controlled at 3.5 t / min, and the molten iron temperature in the tundish was maintained at 1500–1550℃. Three minutes after tapping, a demanganese-removing agent was added to the tundish. The demanganese-removing agent consisted of 25% Al₂O₃, 74% SiO₂, with the remainder being impurities. The particle size of the demanganese-removing agent was 1–5 mm, and the addition rate was 90 kg / min, with a total addition of 1450 kg. The total output of molten iron was 115t. After the molten iron arrived at the KR desulfurization station, the temperature was measured and found to be 1420℃. The slag was removed and a sample of the molten iron was taken for analysis. The composition of the molten iron was C: 4.49%, Si: 0.35%, Mn: 0.16%, P: 0.127%, and S: 0.0252%.

[0018] Example 2

[0019] Samples of molten iron were taken from the molten iron trough for analysis. The composition was found to be C: 4.55%, Si: 0.16%, Mn: 0.45%, P: 0.133%, and S: 0.0247%, requiring demanganese treatment. The tapping rate was controlled at 3.6 t / min, and the molten iron temperature in the trough was 1500–1550℃. Three minutes after tapping, a demanganese-removing agent was added to the trough. The demanganese-removing agent consisted of 22% Al₂O₃, 77% SiO₂, with the remainder being impurities. The particle size of the demanganese-removing agent was 1–5 mm, and the addition rate was 95 kg / min, with a total addition of 1130 kg. The total output of molten iron was 116t. After the molten iron arrived at the KR desulfurization station, the temperature was measured and found to be 1430℃. The slag was removed and a sample of the molten iron was taken for analysis. The composition of the molten iron was C: 4.48%, Si: 0.29%, Mn: 0.17%, P: 0.131%, and S: 0.0245%.

[0020] Example 3

[0021] Samples of molten iron were taken from the molten iron trough for analysis. The composition was found to be C: 4.48%, Si: 0.12%, Mn: 0.33%, P: 0.136%, and S: 0.0238%, requiring demanganese treatment. The tapping rate was controlled at 3.8 t / min, and the molten iron temperature in the trough was 1500–1550℃. Three minutes after tapping, a demanganese-removing agent was added to the trough. The demanganese-removing agent consisted of 20% Al₂O₃, 79% SiO₂, with the remainder being impurities. The particle size of the demanganese-removing agent was 1–5 mm, and the addition rate was 92 kg / min, with a total addition of 690 kg. The total output of molten iron was 115t. After the molten iron arrived at the KR desulfurization station, the temperature was measured and found to be 1436℃. The slag was removed and a sample of the molten iron was taken for analysis. The composition of the molten iron was C: 4.46%, Si: 0.20%, Mn: 0.14%, P: 0.133%, and S: 0.0236%.

[0022] Comparative Example 1

[0023] Samples of molten iron were taken from the molten iron trough for analysis. The composition was found to be C: 4.50%, Si: 0.22%, Mn: 0.54%, P: 0.125%, and S: 0.0252%, requiring demanganese treatment. The tapping rate was controlled at 3.5 t / min, and the molten iron temperature in the trough was 1500–1550℃. Three minutes after tapping, a demanganese-removing agent was added to the trough. The demanganese-removing agent consisted of 70% Fe2O3, 22% FeO, with the remainder being impurities. The particle size of the demanganese-removing agent was 1–5 mm, and the addition rate was 90 kg / min, with a total addition of 1450 kg. The total iron output was 115 tons. After the molten iron arrived at the KR desulfurization station, the temperature was measured at 1380℃. The slag was removed, and a sample of the molten iron was taken for analysis. The composition was: C: 4.21%, Si: 0.12%, Mn: 0.38%, P: 0.121%, S: 0.0252%. In this comparative example, iron oxide scale was used as a demanganese remover, resulting in a smaller amount of demanganese removed, but a significant amount of silicon was removed from the molten iron, leading to a large temperature drop.

[0024] Comparative Example 2

[0025] Samples of molten iron were taken from the molten iron trough for analysis. The composition was found to be C: 4.52%, Si: 0.22%, Mn: 0.54%, P: 0.128%, and S: 0.0251%, requiring demanganese treatment. The tapping rate was controlled at 3.5 t / min, and the molten iron temperature at the trough was 1500–1550℃. No demanganese agent was added during the tapping process. The total tapping volume was 115 t. After tapping, a demanganese agent was added to the ladle. The demanganese agent composition was Al₂O₃ 25%, SiO₂ 74%, with the remainder being impurities. The particle size of the demanganese agent was 1–5 mm, and the amount added was 1450 kg. After the molten iron reached the KR desulfurization station, the temperature was measured at 1422℃, and a sample of the molten iron was taken for analysis. The composition was found to be C: 4.49%, Si: 0.28%, Mn: 0.37%, P: 0.129%, and S: 0.0250%. In this comparative example, the demanganese remover was added directly to the molten iron ladle instead of being discharged into the trough, resulting in a poor demanganese removal effect.

[0026] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

[0027] This invention is not limited to the specific embodiments listed below. Those skilled in the art can implement this invention using various other specific embodiments based on the content disclosed herein. Any modifications or alterations made to the design structure and concept of this invention fall within the protection scope of this invention. It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

Claims

1. A method for demanganese removal from molten iron, characterized in that: Iron samples are taken from the blast furnace trough. When the manganese content of the molten iron exceeds 0.2%, a demanganese-removing agent is added to the trough. After the molten iron reaches the KR desulfurization station, the slag is removed. The main components of the demanganese-removing agent are: Al2O3 20-30%, SiO2 70-80%, and the rest are impurities. The particle size of the demanganese-removing agent is 1-5mm. The amount of demanganese-removing agent added is as follows: when the manganese content of the molten iron is 0.5-0.6%, add 10-13 kg / t of demanganese-removing agent; when the manganese content of the molten iron is 0.35-0.5%, add 7-10 kg / t of demanganese-removing agent; when the manganese content of the molten iron is 0.2-0.35%, add 4-7 kg / t of demanganese-removing agent.

2. The method for demanganese removal from molten iron according to claim 1, characterized in that: The manganese removal agent is added 3 minutes after each bag of iron is tapped, at a rate of 0.5–1.5 kg / t / min.

3. The method for demanganese removal from molten iron according to claim 1, characterized in that: When the demanganese agent is added, the temperature of the molten iron is 1500-1550℃, and the tapping speed is controlled at 3.5-4.0t / min.