Method for reducing titanium content in molten iron and application thereof

Abstract

The invention belongs to the technical field of steel smelting, and particularly relates to a method for reducing the titanium content in molten iron and application thereof. The method comprises the following steps: mixing oxidized scrap steel and molten iron, and then carrying out KR stirring treatment; the temperature of the oxidized waste steel ranges from 900 DEG C to 1150 DEG C; in the KR stirring treatment, the stirring speed ranges from 115 rpm to 125 rpm, the insertion depth of a stirring head ranges from 0.8 m to 1 m, and the treatment time ranges from 15 min to 20 min. According to the method, oxidized waste steel is adopted to replace a titanium removal agent, titanium in the molten iron can be removed at the temperature of 900-1150 DEG C, KR stirring treatment is combined, the titanium content in the molten iron is remarkably reduced, and the titanium content in the finally obtained molten iron is 0.018% or below.

Description

Technical Field

[0001] The invention belongs to the technical field of steel smelting, and particularly relates to a method for reducing titanium content in molten iron and application thereof. Background Art

[0002] High-grade electrical steel used in electric vehicles requires a titanium content of less than 0.001% in the finished product. However, the titanium content in blast furnace hot metal is generally 0.04-0.07%, which is relatively high. Therefore, it is necessary to desulfurize the hot metal in the blast furnace tapping ditch or in the KR desulfurization station, add a detitanium agent, and then remove the detitanium slag in the KR process to obtain low-titanium hot metal for converter blowing, thereby reducing the titanium content in the hot metal and achieving the smelting of low-titanium steel.

[0003] However, adding a detitanium agent to molten iron will introduce new impurities and reduce the purity of the molten iron. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a method for reducing the titanium content in molten iron and its application. The method uses oxidized scrap steel to replace the traditional titanium removal agent to remove titanium from the molten iron, which not only reduces the production cost of low-titanium molten iron, but also does not introduce new impurities. The oxidized scrap steel is used to oxidize silicon and titanium in the molten iron, thereby achieving the purpose of reducing titanium in the molten iron.

[0005] The present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a method for reducing the titanium content in molten iron, comprising the following steps:

[0007] The oxidized scrap steel and molten iron are mixed and then subjected to KR stirring treatment;

[0008] The temperature of the oxidized scrap steel is 900°C to 1150°C;

[0009] In the KR stirring process, the stirring speed is 115 rpm to 125 rpm, the insertion depth of the stirring head is 0.8 m to 1.2 m, and the processing time is 15 min to 20 min.

[0010] The method for reducing the titanium content in molten iron provided by the present invention uses oxidized scrap steel instead of a titanium removal agent, and can remove titanium from the molten iron at 900°C to 1150°C. Combined with KR stirring treatment, the titanium content in the molten iron is significantly reduced, and the titanium content in the molten iron finally obtained is less than 0.018%. The method for reducing the titanium content in molten iron provided by the present invention not only improves resource utilization, but also does not introduce new impurities.

[0011] In some possible implementations, the oxidized scrap steel is baked using a coal oxygen gun, and the baking gas flow rate is 2200m 3 / h~2600m 3 / h, oxygen flow rate is 1000m 3 / h~1200m 3 / h, the distance between the baking coal oxygen gun and the scrap steel to be oxidized is 0.5m~1.0m, and the baking time is 12min~15min.

[0012] In some possible implementations, in the scrap steel to be oxidized, the titanium content is ≤0.01%, and the silicon content is 0.15% to 0.25%.

[0013] In some possible implementations, the amount of the scrap steel to be oxidized is 30 kg / t to 50 kg / t.

[0014] In some possible implementations, the silicon content in the molten iron is 0.2% to 0.4%, and the titanium content is 0.02% to 0.04%.

[0015] In some possible implementations, the conditions for preparing the molten iron include: a blast furnace fuel ratio of 490kg / t to 510kg / t, an oxygen enrichment rate of 6% to 8%, a wind temperature of 1200°C to 1250°C, and a molten iron temperature of 1490°C to 1520°C.

[0016] In a second aspect, the present invention provides an application of the method for reducing the titanium content in molten iron provided by the present invention in the field of low-titanium steel production. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described and illustrated in conjunction with the embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0018] Obviously, the following descriptions are only some examples or embodiments of the present invention, and for those of ordinary skill in the art, the present invention can also be applied to other similar scenarios without creative work. In addition, it can also be understood that although the efforts made in such a development process may be complex and lengthy, for those of ordinary skill in the art related to the contents disclosed in the present invention, some changes in design, manufacturing or production based on the technical contents disclosed in the present invention are just conventional technical means, and should not be understood as the contents disclosed in the present invention being insufficient.

[0019] However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially the same structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the following description is provided for those skilled in the art to fully understand the present invention and is not intended to limit the subject matter described in the claims.

[0020] If not otherwise specified, all embodiments and optional embodiments of the present invention may be combined with each other to form a new technical solution, and all technical features and optional technical features of the present invention may be combined with each other to form a new technical solution.

[0021] The term "content" refers to the mass fraction.

[0022] There is a strong linear correlation between the silicon content and the titanium content in the molten iron of a large blast furnace, and the empirical ratio of the silicon content to the titanium content is 9.5 to 10.5. Therefore, during smelting, the silicon content in the molten iron can be controlled by the raw materials to control the titanium content in the molten iron. If the silicon content is low, the titanium content in the molten iron will also be reduced accordingly.

[0023] Therefore, the embodiment of the present invention provides a method for reducing the titanium content in molten iron, by controlling the content of silicon in the molten iron to control the titanium content, using oxidized scrap steel instead of a de-titaniumizing agent to reduce the titanium in the molten iron, and finally obtaining a titanium content in the molten iron of less than 0.018%. The method for reducing the titanium content in molten iron provided by the present invention not only reduces the production cost of low-titanium molten iron, but also does not introduce new impurities.

[0024] The following is a detailed description of a method for reducing titanium content in molten iron according to an embodiment of the present invention.

[0025] An embodiment of the present invention provides a method for reducing the titanium content in molten iron, comprising the following steps:

[0026] S10. The oxidized scrap steel and molten iron are mixed and then subjected to KR stirring treatment;

[0027] The temperature of oxidized scrap steel is 900℃~1150℃;

[0028] In the KR stirring process, the stirring speed is 115 rpm to 125 rpm, the insertion depth of the stirring head is 0.8 m to 1.2 m, and the processing time is 15 min to 20 min.

[0029] The method for reducing the titanium content in molten iron provided by the embodiment of the present invention adopts oxidized scrap steel instead of a de-titaniumizing agent, and can remove the titanium in the molten iron at 900°C to 1150°C. Combined with KR stirring treatment, the titanium content in the molten iron is significantly reduced, and the titanium content in the molten iron finally obtained is less than 0.018%. The method for reducing the titanium content in molten iron provided by the present invention not only reduces the production cost of low-titanium molten iron, but also does not introduce new impurities.

[0030] In the embodiment, in the KR stirring treatment, the stirring speed is 115 rpm to 125 rpm, the insertion depth of the stirring head is 0.8 m to 1.2 m, and the treatment time is 15 min to 20 min. In this case, the oxide in the scrap steel is promoted to oxidize the titanium in the molten iron, and the reaction is more complete.

[0031] In some embodiments, in the above step S10, the oxidized scrap steel is obtained by baking the scrap steel to be oxidized using a coal oxygen gun, and the baking gas flow rate is 2200m 3 / h~2600m 3 / h, oxygen flow rate is 1000m 3 / h~1200m 3 / h, the distance between the baking coal oxygen gun and the scrap steel to be oxidized is 0.5m~1.0m, and the baking time is 12min~15min. In this case, the oxidized scrap steel mainly produces iron oxide to remove silicon and titanium in the molten iron.

[0032] In some embodiments, in the scrap steel to be oxidized, the titanium content in the scrap steel to be oxidized is ≤0.01%, and the silicon content is 0.15% to 0.25%.

[0033] In some embodiments, in the above step S10, the amount of scrap steel to be oxidized is 30 kg / t to 50 kg / t.

[0034] In some embodiments, in the above step S10, the ratio of the silicon content to the titanium content in the molten iron is 9.5 to 10.5. In this case, the silicon content in the molten iron can be controlled from the raw materials, thereby controlling the titanium content in the molten iron.

[0035] In some embodiments, in the above step S10, the silicon content in the molten iron is 0.2% to 0.4%, and the titanium content is 0.02% to 0.04%. In this case, the ratio of the silicon content to the titanium content is 9.5 to 10.5, so as to control the titanium content in the molten iron to be 0.02% to 0.04%.

[0036] In some embodiments, in the above step S10, the preparation conditions of molten iron include: blast furnace fuel ratio of 490kg / t to 510kg / t, oxygen enrichment rate of 6% to 8%, wind temperature of 1200°C to 1250°C, and molten iron temperature of 1490°C to 1520°C. In this case, the silicon element of SiO2 and the titanium element of TiO2 in the ore are controlled to be reduced to the molten iron, and the reduction amount of SiO2 in the ore is reduced, so that the silicon content in the molten iron is 0.2% to 0.4%.

[0037] The silicon content in molten iron is controlled in the blast furnace. The reduction of SiO2 starts at the furnace waist or the upper part of the furnace belly. When it reaches the tuyere level, the silicon content in the molten iron is reduced. (Si) It reaches the highest value, and then [Si] is partially oxidized in the tuyere area and the slag-iron interface, and finally the silicon content in the molten iron is obtained.

[0038] Low silicon smelting is mainly carried out by reducing SiO2 reduction and increasing the reoxidation of [Si] in molten iron. The reduction of silicon is carried out step by step. The first step is the reduction of SiO2 in coke ash or SiO2 in slag to produce SiO vapor. The second step is that SiO vapor is absorbed by iron droplets during the rising process and reduced by [C]. The chemical reaction equation of silicon reduction is shown below:

[0039] SiO2+C=SiO(g)+CO (1);

[0040] SiO(g)+[C]=[Si]+CO (2);

[0041] SiO2+C+[C]=[Si]+2CO (3).

[0042] It can be seen that the partial pressure of CO can affect the reduction of silicon. When the oxygen enrichment rate is 6% to 8%, the partial pressure of CO in the coal gas is high, which can inhibit the reduction of silicon.

[0043] In the above chemical reaction equation, [C] and [Si] represent C and Si in the melt respectively; C represents coke; SiO2 represents SiO2 in coke ash or SiO2 in slag.

[0044] The wind temperature is 1200℃~1250℃, which can increase the indirect reduction reaction zone, reduce the dripping zone height, shorten the silicon reduction reaction time, and help reduce the molten iron w[Si].

[0045] The blast furnace fuel ratio is 490kg / t~510kg / t, which can prevent Si and Ti in the ore from being fully reduced to the molten iron. The reduction of SiO2 and TiO2 by carbon is an endothermic reaction. Therefore, a lower molten iron temperature can also inhibit the reduction reaction.

[0046] In some embodiments, in the above step S10, during the KR stirring process, the stirring speed is 120 rpm to 150 rpm, the depth of the stirring head inserted into the molten iron is 0.8 m to 1.2 m, and the processing time is 15 min to 20 min. In this case, the KR stirring can promote the full dissolution of the oxidized scrap steel in the molten iron, and use the oxides therein to further remove the titanium content in the molten iron.

[0047] In some embodiments, a method for reducing the titanium content in molten iron is provided, comprising the following steps:

[0048] S11. Prepare molten iron according to the following conditions: blast furnace fuel ratio is 490kg / t~510kg / t, oxygen enrichment rate is 6%~8%, wind temperature is 1200℃~1250℃, molten iron temperature is 1490℃~1520℃, silicon content in molten iron is 0.2%~0.4%, and titanium content is 0.02%~0.04%.

[0049] S21. Select scrap steel to be oxidized.

[0050] S31. Put the scrap steel to be oxidized into the iron ladle, and use a coal oxygen gun to bake the scrap steel to be oxidized to obtain oxidized scrap steel with a temperature of 900° C. to 1150° C.

[0051] S41. After the blast furnace molten iron enters the iron ladle and is mixed with oxidized scrap steel, it is treated by KR stirring. The stirring speed is 120rpm~150rpm, the depth of the stirring head inserted into the molten iron is 0.8m~1.2m, and the treatment time is 15min~20min.

[0052] The following is further described in conjunction with specific embodiments.

[0053] Example 1

[0054] Example 1 provides a method for reducing the titanium content in molten iron, the steps are as follows:

[0055] (1) Molten iron was prepared under the following conditions: the blast furnace fuel ratio was 508 kg / t, the oxygen enrichment rate was 6.2%, the wind temperature was 1210° C., the molten iron temperature was 1499° C., the silicon content in the molten iron was 0.32%, and the titanium content was 0.037%.

[0056] (2) Scrap steel to be oxidized is selected, wherein the titanium content is 0.005% and the silicon content is 0.15%.

[0057] (3) Put the scrap steel to be oxidized into the iron ladle at a dosage of 30 kg / t, and use a coal oxygen gun to bake the scrap steel to obtain oxidized scrap steel at a temperature of 1120°C; wherein, the baking gas flow rate is 2500 m 3 / h, oxygen flow rate is 1100m 3 / h, the distance between the baking coal oxygen gun and the scrap steel to be oxidized is 1.0m, and the baking time is 12min.

[0058] (4) After the blast furnace molten iron enters the iron ladle and is mixed with the oxidized scrap steel, it is treated by KR stirring. The stirring speed is 120 rpm, the depth of the stirring head inserted into the molten iron is 1.2 m, and the treatment time is 15 min.

[0059] According to the method for reducing the titanium content in molten iron of this embodiment, molten iron with a titanium content of 0.018% is obtained.

[0060] Example 2

[0061] Example 2 provides a method for reducing the titanium content in molten iron, the steps are as follows:

[0062] (1) Molten iron was prepared under the following conditions: the blast furnace fuel ratio was 502 kg / t, the oxygen enrichment rate was 6.5%, the wind temperature was 1205° C., the molten iron temperature was 1509° C., the silicon content in the molten iron was 0.38%, and the titanium content in the molten iron was 0.039%.

[0063] (2) Scrap steel to be oxidized is selected, wherein the titanium content is 0.005% and the silicon content is 0.15%.

[0064] (3) Put the scrap steel to be oxidized into the iron ladle at a dosage of 50 kg / t, and use a coal oxygen gun to bake the scrap steel to obtain oxidized scrap steel at a temperature of 1150°C; the baking gas flow rate is 2500 m 3 / h, oxygen flow rate is 1200m 3 / h, the distance between the baking coal oxygen gun and the scrap steel to be oxidized is 0.8m, and the baking time is 14min.

[0065] (4) After the blast furnace molten iron enters the iron ladle and is mixed with the oxidized scrap steel, it is treated by KR stirring. The stirring speed is 120 rpm, the depth of the stirring head inserted into the molten iron is 1.2 m, and the treatment time is 15 min.

[0066] According to the method for reducing the titanium content in molten iron of this embodiment, molten iron with a titanium content of 0.017% is obtained.

[0067] Example 3

[0068] Example 3 provides a method for reducing the titanium content in molten iron, the steps are as follows:

[0069] (1) Molten iron was prepared under the following conditions: the blast furnace fuel ratio was 502 kg / t, the oxygen enrichment rate was 6.5%, the wind temperature was 1205° C., the molten iron temperature was 1509° C., the silicon content in the molten iron was 0.38%, and the titanium content in the molten iron was 0.038%.

[0070] (2) Scrap steel to be oxidized is selected, wherein the titanium content is 0.005% and the silicon content is 0.15%.

[0071] (3) Put the scrap steel to be oxidized into the iron ladle at a dosage of 50 kg / t, and use a coal oxygen gun to bake the scrap steel to obtain oxidized scrap steel at a temperature of 900°C; wherein, the baking gas flow rate is 2500 m 3 / h, oxygen flow rate is 1000m 3 / h, the distance between the baking coal oxygen gun and the scrap steel to be oxidized is 1.0m, and the baking time is 15min.

[0072] (4) After the blast furnace molten iron enters the iron ladle and is mixed with the oxidized scrap steel, it is treated by KR stirring. The stirring speed is 120 rpm, the depth of the stirring head inserted into the molten iron is 0.8 m, and the treatment time is 15 min.

[0073] According to the method for reducing the titanium content in molten iron of this embodiment, molten iron with a titanium content of 0.015% is obtained.

[0074] Example 4

[0075] Example 4 provides a method for reducing the titanium content in molten iron, the steps are as follows:

[0076] (1) Molten iron was prepared under the following conditions: the blast furnace fuel ratio was 502 kg / t, the oxygen enrichment rate was 6.5%, the wind temperature was 1205° C., the molten iron temperature was 1509° C., the silicon content in the molten iron was 0.38%, and the titanium content in the molten iron was 0.038%.

[0077] (2) Scrap steel to be oxidized is selected, wherein the titanium content is 0.005% and the silicon content is 0.15%.

[0078] (3) Put the scrap steel to be oxidized into the iron ladle at a dosage of 40 kg / t, and use a coal oxygen gun to bake the scrap steel to obtain oxidized scrap steel at a temperature of 1150° C. The baking gas flow rate is 2200 m 3 / h, oxygen flow rate is 1200m 3 / h, the distance between the baking coal oxygen gun and the scrap steel to be oxidized is 0.5m, and the baking time is 12min.

[0079] (4) After the blast furnace molten iron enters the iron ladle and is mixed with the oxidized scrap steel, it is treated by KR stirring. The stirring speed is 120 rpm, the depth of the stirring head inserted into the molten iron is 1 m, and the treatment time is 15 min.

[0080] According to the method for reducing the titanium content in molten iron of this embodiment, molten iron with a titanium content of 0.016% is obtained.

[0081] Comparative Example 1

[0082] Comparative Example 1 provides a method for reducing the titanium content in molten iron, the steps are as follows:

[0083] (1) Molten iron was prepared under the following conditions: the blast furnace fuel ratio was 522 kg / t, the oxygen enrichment rate was 4.5%, the wind temperature was 1180° C., the molten iron temperature was 1539° C., the silicon content in the molten iron was 0.59%, and the titanium content in the molten iron was 0.062%.

[0084] (2) Select iron oxide scale as the detitanium agent.

[0085] (3) Add detitanium agent into molten iron at a dosage of 50 kg / t.

[0086] (4) KR stirring treatment was adopted, the stirring speed was 120 rpm, the depth of the stirring head inserted into the molten iron was 1.2 m, and the treatment time was 15 min.

[0087] According to the method for reducing the titanium content in molten iron of this comparative example, molten iron with a titanium content of 0.030% is obtained.

[0088] Comparative Example 2

[0089] Comparative Example 2 provides a method for reducing the titanium content in molten iron, and the steps are basically the same as those in Example 1, except that:

[0090] No KR stirring treatment was performed.

[0091] According to the method for reducing the titanium content in molten iron of this comparative example, molten iron with a titanium content of 0.042% is obtained.

[0092] The titanium content in molten iron obtained from the above examples and comparative examples can be obtained as follows:

[0093] The method for reducing the titanium content in molten iron provided by the embodiment of the present invention adopts oxidized scrap steel instead of a de-titaniumizing agent, and can remove the titanium in the molten iron at 900°C to 1150°C. Combined with KR stirring treatment, the titanium content in the molten iron is significantly reduced, and the titanium content in the molten iron finally obtained is less than 0.018%. The method for reducing the titanium content in molten iron provided by the present invention not only reduces the production cost of low-titanium molten iron, but also does not introduce new impurities.

[0094] It should be noted that the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present invention are all included in the technical scope of the present invention. In addition, without departing from the scope of the main purpose of the present invention, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present invention.

Claims

1. A method for reducing the titanium content in molten iron, characterized in that: The steps include: The oxidized scrap steel and molten iron are mixed and then subjected to KR stirring treatment; The temperature of the oxidized scrap steel is 900°C to 1150°C; In the KR stirring process, the stirring speed is 115 rpm to 125 rpm, the insertion depth of the stirring head is 0.8 m to 1.2 m, and the processing time is 15 min to 20 min.

2. The method for reducing the titanium content in molten iron according to claim 1, characterized in that: The oxidized scrap steel is baked by a coal oxygen gun, and the baking gas flow rate is 2200m 3 / h~2600m 3 / h, oxygen flow rate is 1000m 3 / h~1200m 3 / h, the distance between the baking coal oxygen gun and the scrap steel to be oxidized is 0.5m~1.0m, and the baking time is 12min~15min.

3. The method for reducing the titanium content in molten iron according to claim 2, characterized in that: In the scrap steel to be oxidized, the titanium content is ≤0.01% and not 0, and the silicon content is 0.15% to 0.25%.

4. The method for reducing the titanium content in molten iron according to claim 2 or 3, characterized in that: The amount of the scrap steel to be oxidized is 30kg / t to 50kg / t.

5. The method for reducing the titanium content in molten iron according to claim 1, characterized in that: The silicon content in the molten iron is 0.2% to 0.4%, and the titanium content is 0.02% to 0.04%.

6. The method for reducing titanium content in molten iron according to claim 1, characterized in that: The preparation conditions of the molten iron include: a blast furnace fuel ratio of 490kg / t to 510kg / t, an oxygen enrichment rate of 6% to 8%, a wind temperature of 1200°C to 1250°C, and a molten iron temperature of 1490°C to 1520°C.

7. Use of the method for reducing titanium content in molten iron as claimed in any one of claims 1 to 6 in the field of low-titanium steel production.