A method for semi-steel steelmaking continuous slagging

Abstract

The application discloses a method for continuous slagging of semi-steel smelting, comprising: blowing the vanadium-extracted semi-steel liquid in a furnace, tapping and leaving slag after the blowing is completed; adding carbonaceous material into the furnace after the tapping is completed, and smelting by blowing oxygen to heat the slag; adding a deoxidizing and dephosphorizing agent into the furnace after the oxygen blowing is completed, adjusting the nitrogen blowing intensity after the deoxidizing and dephosphorizing agent is added, and performing deoxidizing and dephosphorizing treatment on the steel slag; leaving the slag in the furnace and pouring the vanadium-extracted semi-steel liquid into the furnace for secondary smelting, adding active lime to adjust the composition and basicity of the slag, and performing blowing; and repeating the above steps until at least four furnaces are continuously smelted, and then pouring out all the slag. The method can better promote the rapid formation of the steel slag by leaving the slag after smelting and continuously forming the slag, is beneficial to dephosphorization of the converter, controls the sulfur return of the converter, and can utilize the heat of the steel slag, increase the scrap steel consumption of the steel smelting converter, reduce energy loss, and be beneficial to the improvement of the economic and technical indexes of the semi-steel smelting.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgy, more particularly to a method for continuous slagging of semi-steel. BACKGROUND

[0002] The semi-steel for extracting vanadium has the characteristics of low carbon (average at about 3.6%), low silicon (0.01% or less), low manganese (0.05% or less), insufficient heat source, low content of slag-forming elements, higher temperature than molten iron, low early-stage oxidation of slag, and difficulty in initial slagging.

[0003] Due to the low content of slag-forming elements in the semi-steel, the formation of initial slag in semi-steel smelting is greatly related to FeOn in the initial slag. In order to make lime quickly dissolve and slag, FeOn in the initial slag must reach a certain reasonable value. When the content of FeOn in the initial slag is lower than the reasonable value, the following adverse effects on the dissolution of lime are caused: due to the effect of FeOn on reducing the melting point of lime to form a low-melting compound, the low content of FeOn changes the thermodynamic conditions of lime dissolution; the effect of FeOn on reducing the viscosity of the slag is also very significant, and the slag will be dry again in a semi-solid state and lose the ability of dephosphorization if the content of FeOn is too low, so the positive dissolution of lime by FeOn is first related to its effect on the viscosity of the slag. Due to the great difficulty in slagging in semi-steel smelting, the batch of slag material added during on-site smelting operation is large, which causes a large amount of flue gas dust, and the control of oxygen lance position and the control of carbon reduction speed are very difficult.

[0004] Patent CN102312037A discloses a method for steelmaking and slagging, which comprises: adding semi-steel after extracting vanadium into a steelmaking furnace, and blowing oxygen for blowing and smelting; within 2 minutes after the start of blowing and smelting, adding 6-8.5 kg of lime, 4-7.5 kg of high-magnesium lime, 5-11.5 kg of fluxing agent, and 11-16 kg of acid composite slag into the steelmaking furnace for each ton of semi-steel after extracting vanadium; within 8 minutes after the formation of initial slag to the start of blowing and smelting, adding 6-8.5 kg of lime and 4-7.5 kg of high-magnesium lime into the steelmaking furnace for each ton of semi-steel after extracting vanadium; continuing to blow and smelt to obtain molten steel and final slag; the fluxing agent is a refining ladle slag. The method has the problems of high consumption of auxiliary materials for slagging and difficulty in initial slagging.

[0005] Patent CN101921891A discloses a method for semi-steel smelting and slagging with machine-burned tailings, which recovers machine-burned tailings generated in the sintering process, and screens the machine-burned tailings with a particle size of 5-30 mm as a semi-steel smelting and slagging agent. During semi-steel smelting, the machine-burned tailings are added into the furnace at 5-10 kg / t of steel within 0-2 minutes after the start of blowing and smelting to assist in rapid slagging in the early stage of blowing and smelting. The method also has the problem of high consumption of auxiliary materials for slagging, and has difficulty in slagging and increases the temperature loss in the steelmaking process, which is not conducive to the reduction of steel material consumption.

[0006] Therefore, it is necessary to improve the existing slagging technology to promote the rapid formation of steelmaking slag. SUMMARY

[0007] The present application aims to provide a semi-steel smelting continuous slagging method to solve at least one of the above problems in the prior art.

[0008] To achieve the above technical purposes, the technical solutions adopted by the present application are as follows:

[0009] According to one aspect of the present application, a semi-steel smelting continuous slagging method is provided, comprising the following steps:

[0010] Step S1: The vanadium-extracted semi-steel molten steel in the furnace is blown, and after the blowing is completed, the steel is tapped and the slag is left;

[0011] Step S2: After the tapping is completed, carbonaceous material is added to the furnace, and oxygen blowing is performed to heat the slag in the furnace;

[0012] Step S3: After the oxygen blowing is completed, deoxidizing and dephosphorizing agent is added to the furnace, and after the deoxidizing and dephosphorizing agent is added, the nitrogen gas blowing intensity is adjusted, and the steel slag is deoxidized and dephosphorized;

[0013] Step S4: The slag in the furnace is left and the vanadium-extracted semi-steel molten steel is poured in for secondary smelting, active lime is added to adjust the composition and basicity of the slag, and blowing is performed;

[0014] Step S5: Steps S1 to S4 are repeated until at least 4 furnaces are continuously smelted, and the slag is completely poured out.

[0015] According to one embodiment of the present application, in step S1, the slag is left completely.

[0016] According to one embodiment of the present application, in step S2, the carbonaceous material includes one or more of coke butter, graphite, and coke.

[0017] According to one embodiment of the present application, the amount of carbonaceous material added is 3% to 5% of the weight of the slag.

[0018] According to one embodiment of the present application, in step S2, the oxygen blowing time is 1 to 2 minutes, the oxygen pressure is 0.3 to 0.8 MPa, and the steel slag temperature is raised to 1350 to 1500°C.

[0019] According to one embodiment of the present application, in step S3, the deoxidizing and dephosphorizing agent includes at least one of ferrosilicon powder and aluminum particles, and the amount of deoxidizing and dephosphorizing agent added is 20% to 30% of the weight of the steel slag.

[0020] According to one embodiment of the present application, when the deoxidizing and dephosphorizing agent is a mixture of ferrosilicon powder and aluminum powder, the weight ratio of ferrosilicon powder to aluminum powder is 3 to 6:1.

[0021] According to one embodiment of the present application, in step S3, the intensity of the nitrogen bottom blowing is controlled to be above 500 Nm 3 / min, and the reaction time is controlled to be above 5 min.

[0022] According to one embodiment of the present application, in step S4, the alkalinity is controlled to be between 2.5 and 3.5.

[0023] According to one embodiment of the present application, in step S5, after smelting 4-7 furnaces, the slag is completely poured out.

[0024] With the above technical solution, the method for continuous slagging of semi-steel smelting provided by the present application has the following beneficial effects compared with the prior art: the method of the present application can better promote the rapid formation of smelting slag by smelting and continuously slagging, which is beneficial to the dephosphorization of the converter, the control of the converter sulfur return, and the utilization of the heat of the steel slag, the increase of the scrap steel consumption of the smelting converter, the reduction of energy loss, and the improvement of the economic and technical indicators of semi-steel smelting. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, and together with the specific embodiments described below, serve to explain the present application, but do not constitute a limitation on the present application. In the drawings:

[0026] Figure 1 A flowchart of the method for continuous slagging of semi-steel smelting according to one embodiment of the present application is shown. DETAILED DESCRIPTION

[0027] The specific embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustration and explanation of the present disclosure, and do not limit the present disclosure.

[0028] In addition, the phrase "embodiment" mentioned herein means that the specific features, structures or characteristics described in conjunction with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it independent or alternative to other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0029] Figure 1 A flowchart of the method for continuous slagging of semi-steel smelting according to one embodiment of the present application is shown. The method of the present application will be described in detail below in conjunction with the figure.

[0030] The method for continuous slagging of semi-steel smelting according to the present application generally includes the following steps:

[0031] Step S1: The vanadium-containing semi-steel liquid in the furnace is blown, and after the blowing is completed, the steel is tapped and the slag is left;

[0032] Step S2: After the tapping is completed, carbonaceous material is added to the furnace, and oxygen is blown to heat the slag;

[0033] Step S3: After the oxygen blowing is completed, deoxidizing and dephosphorizing agents are added to the furnace, the nitrogen gas blowing intensity is adjusted after the deoxidizing and dephosphorizing agents are added, and the steel slag is deoxidized and dephosphorized;

[0034] Step S4: The slag is left in the furnace and the vanadium-containing semi-steel liquid is poured into the furnace for secondary smelting, active lime is added to adjust the composition and basicity of the slag, and the liquid is blown;

[0035] Step S5: Steps S1 to S4 are repeated until at least 4 furnaces are continuously smelted, and the slag is completely poured out.

[0036] The specific operation of each step is described in detail below.

[0037] In step S1: The vanadium-containing semi-steel liquid in the furnace is blown, and after the blowing is completed, the steel is tapped and the slag is left. The liquid smelted in this step is a semi-steel obtained after special converter vanadium extraction, and the carbon content in the semi-steel obtained after desulfurization and vanadium extraction is generally 3.0% to 4.0%, and the contents of silicon and manganese, which are heat-generating slag-forming elements, are trace amounts. Therefore, the semi-steel smelting has the characteristics of late slag formation, poor dephosphorization effect, and insufficient heat. In this step, if it is the first furnace liquid and there is no steel slag left by the previous furnace smelting, slag forming material needs to be added during smelting, and the slag forming material can be selected, for example, high-magnesium lime, active lime, etc. The blowing can be conventional top and bottom combined blowing. The slag is left as a whole. Since the slag leaving operation is adopted, it is beneficial to form the initial slag as soon as possible, and can improve the efficiency of removing P and S in the early stage.

[0038] In step S2, carbonaceous material is added to the furnace after tapping is completed, and oxygen is blown to heat the slag. The carbonaceous material includes one or more of coke breeze, graphite, and coke. The amount of carbonaceous material added is 3-5% by weight of the slag. The oxygen is blown for 1-2 minutes at a pressure of 0.3-0.8 MPa, and the temperature of the slag is increased to 1350-1500°C. By adding carbonaceous material and blowing oxygen, carbon reacts with oxygen to produce carbon monoxide and carbon dioxide, which are exothermic reactions that heat the slag to ensure that the slag has good fluidity and an appropriate temperature, creating conditions for dephosphorization of the slag. Unlike dephosphorization by adding carbonaceous reducing agent to the slag, dephosphorization using carbonaceous reducing agent requires nitrogen to be introduced, and the temperature of the slag should be controlled to be above 1500°C to facilitate reduction of phosphorus oxides by carbon. In the method of the present application, the carbonaceous material is mainly used to react with the oxygen introduced to release heat, thereby heating the slag to modify the slag. Therefore, the time and pressure of the oxygen blowing should also be controlled in the method of the present application to control the temperature of the slag to be at an appropriate temperature that has good fluidity and is suitable for subsequent dephosphorization.

[0039] In step S3, dephosphorization and deoxidation agent is added to the furnace after the oxygen blowing is completed, and the intensity of the bottom nitrogen blowing is adjusted after the dephosphorization and deoxidation agent is added to perform dephosphorization and deoxidation of the slag. The dephosphorization and deoxidation agent can include at least one of ferrosilicon powder and aluminum particles, and when the dephosphorization and deoxidation agent is a mixture of ferrosilicon powder and aluminum powder, the weight ratio of the ferrosilicon powder to the aluminum powder is 3-6:1. The amount of the dephosphorization and deoxidation agent added is 20-30% by weight of the slag. The dephosphorization and deoxidation agent can be directly added using a high-position bin, and after the dephosphorization and deoxidation agent is added, the intensity of the bottom nitrogen blowing is increased to 500 Nm 3 / min or more, and the reaction time is controlled to be 5 minutes or more.

[0040] In step S4, the slag is left in the furnace and is poured into the vanadium-containing semi-steel molten steel for secondary smelting, active lime is added to adjust the composition and basicity of the slag, and the slag is blown. Oxygen is blown using an oxygen lance during the blowing, the basicity can be controlled to be between 2.5 and 3.5, nitrogen is bottom blown, and the molten steel is tapped when the end point temperature reaches 1600°C, and the slag is left in the furnace for continued recycling after the molten steel is tapped.

[0041] In step S5, steps S1-S4 are repeated for continuous smelting of at least 4 heats, and the slag is completely poured out after the continuous smelting. In some embodiments, the slag can be completely poured out after 4-7 heats of smelting.

[0042] The following are specific test examples of the method for continuous slagging of semi-steel smelting according to the present application. Unless otherwise specified, the raw materials, equipment, consumables, etc. used in the following examples can be obtained by conventional commercial means.

[0043] Example 1

[0044] In the process of 120t converter semi-steel smelting, the process of continuous slagging of multiple furnaces is adopted, that is, after the blowing of the first furnace is completed, the steel is normally tapped and the slag is left. After the end of tapping, 5% of the weight of the slag of coke butter and other carbonaceous materials is added, and oxygen is blown for 2 minutes to raise the temperature, so that the steel slag has good fluidity and appropriate temperature, and creates conditions for steel slag reduction and dephosphorization. At this time, the oxygen pressure is controlled at 0.3MPa, and the steel slag temperature is raised to 1500℃. After the oxygen blowing is completed, silicon iron powder is added for steel slag deoxidization and dephosphorization, the amount of which is 30% of the weight of the steel slag, and the adding method is direct adding from the high-position bin. After adding, the nitrogen gas intensity of bottom blowing is increased to 600Nm 3 / min, and the reaction time is controlled at 7 minutes. The slag is left in the furnace, and the semi-steel molten steel is poured into the furnace for secondary smelting, active lime is added to adjust the composition of the slag, and the basicity is controlled at 3.5. After the smelting is completed, the steel is tapped and the slag is left, and the same steel slag temperature-raising-deoxidization and dephosphorization operation of adding carbonaceous materials and oxygen and adding deoxidizing and dephosphorizing agents is adopted. After the operation of slag temperature-raising-dephosphorization-smelting is repeated for 7 furnaces, the steel is tapped and the slag is discharged. The end point phosphorus content of the smelted molten steel is between 0.006% and 0.012%. This method not only can better promote the rapid formation of steelmaking slag, is conducive to the dephosphorization of the converter, and controls the sulfur return of the converter, but also can utilize the heat of the steel slag, increase the scrap steel consumption of the steelmaking converter, and reduce energy loss.

[0045] Example 2

[0046] In the process of 120t converter semi-steel smelting, the process of continuous slagging of multiple furnaces is adopted, that is, after the blowing of the first furnace is completed, the steel is normally tapped and the slag is left. After the end of tapping, 5% of the weight of the slag of coke butter and other carbonaceous materials is added, and oxygen is blown for 2 minutes to raise the temperature, so that the steel slag has good fluidity and appropriate temperature, and creates conditions for steel slag reduction and dephosphorization. At this time, the oxygen pressure is controlled at 0.3MPa, and the steel slag temperature is raised to 1500℃. After the oxygen blowing is completed, silicon iron powder is added for steel slag deoxidization and dephosphorization, the amount of which is 30% of the weight of the steel slag, and the adding method is direct adding from the high-position bin. After adding, the nitrogen gas intensity of bottom blowing is increased to 600Nm 3 / min, and the reaction time is controlled at 7 minutes. The slag is left in the furnace, and the semi-steel molten steel is poured into the furnace for secondary smelting, active lime is added to adjust the composition of the slag, and the basicity is controlled at 3.5. After the smelting is completed, the steel is tapped and the slag is left, and the same steel slag temperature-raising-deoxidization and dephosphorization operation of adding carbonaceous materials and oxygen and adding deoxidizing and dephosphorizing agents is adopted. After the operation of slag temperature-raising-dephosphorization-smelting is repeated for 7 furnaces, the steel is tapped and the slag is discharged. The end point phosphorus content of the smelted molten steel is between 0.006% and 0.012%. This method not only can better promote the rapid formation of steelmaking slag, is conducive to the dephosphorization of the converter, and controls the sulfur return of the converter, but also can utilize the heat of the steel slag, increase the scrap steel consumption of the steelmaking converter, and reduce energy loss.

[0047] Example 3

[0048] In the 200t converter semi-steel smelting process, the multi-furnace continuous slagging process is adopted, that is, after the blowing of the first furnace is completed, the steel is normally tapped and the slag is left. After the tapping is completed, 3% of the coke butter and other carbonaceous materials are added, and oxygen is blown for 1.5min to increase the temperature, so that the steel slag has good fluidity and appropriate temperature, and conditions are created for steel slag reduction and dephosphorization. At this time, the oxygen pressure should be 0.8MPa, and the steel slag temperature is increased to 1350. After the oxygen blowing is completed, aluminum particles are added for steel slag deoxidization and dephosphorization, and the addition amount is 20% of the weight of the steel slag. The addition method is high-position bin direct addition. After the addition, the nitrogen gas blowing intensity is increased to 900Nm 3 / min, and the reaction time is controlled to 8min. The slag is left in the furnace, and the semi-steel molten steel is mixed to carry out secondary smelting, active lime is added to adjust the composition of the slag, and the basicity is controlled to 2.5. After the smelting is completed, the steel is tapped and the slag is left, and the same steel slag temperature increasing-deoxidization and dephosphorization operation is adopted. After the steel is tapped and the slag is left for 4 furnaces, the steel is tapped and the slag is left. The end point phosphorus content of the smelted molten steel is between 0.007% and 0.010%. This method not only can better promote the rapid formation of the steel slag, is beneficial to the dephosphorization of the converter, and controls the sulfur return of the converter, but also can utilize the heat of the steel slag, increase the scrap steel consumption of the steel smelting converter, and reduce the energy loss.

[0049] The preferred embodiments of the application are described in detail above, but the application is not limited to the specific details in the above-described embodiments. Within the technical concept range of the application, various simple modifications can be made to the technical solutions of the application, and these simple modifications all belong to the protection range of the application.

[0050] In addition, it should be noted that various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combination manners are not described again in the application.

[0051] Furthermore, various different embodiments of the application can also be combined in any manner, as long as it does not deviate from the idea of the application, and it should be considered as disclosed by the application.

Claims

1. A method for continuous slag formation in semi-steelmaking, characterized in that, Includes the following steps: Step S1: Blow the vanadium-extracting semi-steel in the furnace. After blowing, tap the steel and leave the slag. Step S2: After tapping, carbonaceous material is added to the furnace and oxygen is blown to heat the slag. The amount of carbonaceous material added is 3% to 5% of the slag weight, the oxygen blowing time is 1 to 2 minutes, the oxygen pressure is 0.3 to 0.8 MPa, and the steel slag temperature is raised to 1350 to 1500℃. Step S3: After oxygen blowing is completed, add deoxidizing and dephosphorizing agent into the furnace. After adding the deoxidizing and dephosphorizing agent, adjust the bottom blowing nitrogen intensity to carry out deoxidation and dephosphorization treatment of steel slag. The deoxidizing and dephosphorizing agent includes at least one of ferrosilicon powder and aluminum particles. The amount of the deoxidizing and dephosphorizing agent added is 20% to 30% of the weight of steel slag. Step S4: Leave slag in the furnace and add vanadium-extracting semi-steel molten steel for secondary smelting. Add quicklime to adjust the slag composition and alkalinity, and then carry out blowing. Step S5: Repeat steps S1 to S4 until at least 4 furnaces have been smelted consecutively, then pour out all the slag.

2. The method according to claim 1, characterized in that, In step S1, the residue retention is complete residue retention.

3. The method according to claim 1, characterized in that, In step S2, the carbonaceous material includes one or more of coke, graphite, and coke.

4. The method according to claim 1, characterized in that, When the deoxidizing and dephosphorizing agent is a mixture of ferrosilicon powder and aluminum granules, the weight ratio of ferrosilicon powder to aluminum granules is 3~6:

1.

5. The method according to claim 1, characterized in that, In step S3, the intensity of bottom-blown nitrogen is controlled at 500 Nm. 3 The reaction rate should be above 1000 m / min, and the reaction time should be controlled above 5 min.

6. The method according to claim 1, characterized in that, In step S4, the alkalinity is controlled between 2.5 and 3.

5.

7. The method according to claim 1, characterized in that, In step S5, after smelting 4 to 7 furnaces, all the slag is poured out.

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