Environment-friendly aluminum-based steel slag modifier, preparation method and application method

Abstract

This invention discloses an environmentally friendly aluminum-based steel slag modifier, its preparation method, and its application method. The preparation method includes: crushing and grinding calcium aluminate pre-melted slag and industrial cryolite, then slurrying them to form hollow granular balls; heating aluminum rods and drawing them into wires in air, then cutting them into aluminum wires; thoroughly mixing the hollow granular balls, aluminum wires, acidified graphite, and binder to form the modifier. The application method includes: pressing the modifier into elliptical modifier balls; adding the modifier balls to the surface of the ladle slag when the LF (sulfuric acid) slag exits the station; adding the modifier balls to the surface of the ladle slag when the RH (sulfuric acid) slag exits the station. The raw materials for preparing the modifier in this invention are simple and readily available. Furthermore, the calcium aluminate pre-melted slag, a low-nitrogen aluminum ash, and the industrial cryolite used are both solid wastes from aluminum plants, which helps to reduce the pressure on metallurgical solid waste recycling. The slag conditioning process is virtually dust-free, improving dust problems and enhancing environmental friendliness.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel metallurgy technology, and particularly relates to an environmentally friendly aluminum-based steel slag modifier, its preparation method, and its application method. Background Technology

[0002] In the refining process of aluminum-containing steel, to achieve slag modification, deoxidation, and inclusion adsorption in steel slag, the industry currently widely uses slag conditioning agents containing metallic aluminum for ladle refining. The mainstream on-site slag conditioning methods are mainly divided into two categories: The first type is premixed slag conditioner, such as aluminum slag balls and calcium aluminum balls. These are made by premixing metallic aluminum with auxiliary slag agents such as lime, calcium aluminate, and fluorite to form powder or pellets, which are then added to the ladle at once to complete the slag conditioning. This method is simple to operate and has a short feeding process, but it has the following obvious drawbacks: First, it produces a lot of smoke and dust and poses a high environmental risk. Specifically, the aluminum in the slag conditioner is mostly aluminum powder or small-sized aluminum particles, which have extremely high reactivity. When added to the ladle, it oxidizes violently and instantly, accompanied by a large amount of smoke and dust, causing serious pollution on site. At the same time, the powdery material is prone to generating dust during the feeding process, which will further worsen the operation. Secondly, the product has poor timeliness and is prone to failure. Specifically, aluminum powder or small-sized aluminum particles have strong chemical activity, and they are prone to react with other components in advance during storage and transportation, which leads to premature passivation of metallic aluminum and a decrease in slag conditioning ability, thus affecting the performance. Third, the slag conditioning effect is difficult to control. Specifically, small-particle aluminum reacts too quickly and participates in the reaction in a short period of time, resulting in large fluctuations in the slag conditioning process. It is impossible to achieve stable and continuous quality improvement, which is not conducive to the stable control of molten steel quality. The second type is the step-by-step addition process, which involves adding metallic aluminum separately from auxiliary slag agents such as alumina and fluorite. Although this method can avoid premature reaction between aluminum and auxiliary slag agents, it is cumbersome to operate and requires multiple additions, which will prolong the refining cycle. At the same time, when metallic aluminum is added directly, the burn-off rate is high and the utilization rate is low, which increases the cost of slag adjustment. In addition, the dust problem still exists in the process of adding auxiliary slag agents, and the environmental risks cannot be fundamentally solved.

[0003] In summary, current aluminum-containing slag conditioners and slag conditioner processes generally suffer from problems such as high levels of smoke and dust, poor environmental performance, easy deactivation of aluminum particles, and unstable slag conditioner effects, making it difficult to meet the requirements of green, efficient, and stable production in modern steelmaking. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides an environmentally friendly aluminum-based steel slag modifier, its preparation method, and its application method, which can improve the dust problem and slag conditioning effect during slag conditioning.

[0005] The objective of this invention is achieved through the following technical solution: Firstly, an environmentally friendly aluminum-based steel slag modifier is provided. The chemical composition of the modifier, by mass fraction, includes: CaO: 20%~30%, Al2O3: 15%~25%, metallic Al: 35%~45%, Na2O: 1%~3%, N≤0.5%, MgO: 4%~10%, FeO≤2%, SiO2: 3%~8%, S≤0.2%, P≤0.2%, activated carbon≤2.5%, H2O≤1.5%, the remainder being unavoidable impurities.

[0006] Secondly, a preparation method is provided for preparing an environmentally friendly aluminum-based steel slag modifier, comprising the following steps: The calcium aluminate pre-melted slag and industrial cryolite are crushed, ground, and then slurried to form hollow granular balls; The aluminum rod is heated and then drawn into wire in the air, and then cut into aluminum wire. Hollow granules, aluminum wire, acidified graphite, and binder are thoroughly mixed to form a modifier.

[0007] Furthermore, the crushing and grinding of calcium aluminate premelted slag and industrial cryolite includes: The calcium aluminate pre-melted slag and industrial cryolite are crushed and ground to particles below 80 mesh.

[0008] Furthermore, the particle size of the hollow granules is 0.5mm~1.5mm.

[0009] Further, the process of heating the aluminum rod and drawing it into wire in the air, then cutting it into aluminum wire includes: Aluminum rods with an aluminum content ≥99.5% are heated to 450℃~550℃; Then it is drawn into wires in the air, with the wire diameter being 1mm to 1.5mm; Then cut the thread into aluminum wires 3mm to 5mm long.

[0010] Furthermore, the adhesive is an organic and environmentally friendly adhesive, and the proportion of adhesive added is 1% to 2%.

[0011] Thirdly, an application method is provided, which utilizes an environmentally friendly aluminum-based steel slag modifier for slag conditioning, and includes the following steps: The modifier is pressed into oval-shaped modifier balls; When LF leaves the station, add modifier balls to the surface of the ladle slag; When RH leaves the station, add modifier balls to the surface of ladle slag.

[0012] Furthermore, compressing the modifier into elliptical modifier spheres includes: The modifier is pressed into elliptical modifier balls of 20mm to 50mm.

[0013] Furthermore, the addition of modifier balls to the surface of the ladle slag during LF discharge includes: When LF leaves the station, use 3~5 kg / t 钢 Add modifier balls to the surface of ladle slag.

[0014] Furthermore, the addition of modifier balls to the ladle slag surface during RH discharge includes: When RH leaves the station, apply 0.5~1.5 kg / t. 钢 Add modifier balls to the surface of ladle slag.

[0015] The beneficial effects of this invention are as follows: The raw materials for preparing the modifier in this invention are simple and readily available. At the same time, the calcium aluminate pre-melted slag, a low-nitrogen aluminum ash, and industrial cryolite used are all solid wastes from aluminum plants, which helps to reduce the pressure of metallurgical solid waste recycling. Moreover, the slag conditioning process is basically free of smoke and dust, which can improve the smoke and dust problem during slag conditioning and enhance environmental protection. Because the modifier of this invention is a fully pre-melted material, it melts quickly during the steelmaking process. By adding this modifier during the refining process, slag can be formed quickly, effectively improving the slag state. At the same time, it reduces the oxidizability of steel slag, which is beneficial for desulfurization and removal of adsorption of inclusions in steel, thereby improving the slag conditioning effect. Attached Figure Description

[0016] The invention will now be described in more detail with reference to embodiments and the accompanying drawings. Figure 1 A flowchart of the preparation method in this invention is shown; Figure 2 A flowchart of the application method in this invention is shown; Figure 3 The graph shows the dust and smoke situation when using an environmentally friendly aluminum-based steel slag modifier; Figure 4 The diagram shows the dust and smoke conditions when using the original high-alumina slag conditioner. Detailed Implementation

[0017] The invention will now be further described with reference to the accompanying drawings.

[0018] This invention provides an environmentally friendly aluminum-based steel slag modifier. The chemical composition of the modifier, by mass fraction, includes: CaO: 20%~30%, Al2O3: 15%~25%, metallic Al: 35%~45%, Na2O: 1%~3%, N≤0.5%, MgO: 4%~10%, FeO≤2%, SiO2: 3%~8%, S≤0.2%, P≤0.2%, activated carbon≤2.5%, H2O≤1.5%, the remainder being unavoidable impurities.

[0019] This invention provides a preparation and application method, such as... Figure 1 and Figure 2 As shown, it includes the following steps: The calcium aluminate pre-melted slag and industrial cryolite are crushed and ground to particles below 80 mesh, and then pulped to form hollow granular balls with a particle size of 0.5mm~1.5mm. Aluminum rods with an aluminum content of ≥99.5% are heated to 450℃~550℃; then drawn into wires in air, with a wire diameter of 1mm~1.5mm; and then the wires are cut into aluminum wires of 3mm~5mm in length. Hollow granular balls, aluminum wire, acidified graphite and binder are thoroughly mixed and pressed into elliptical modified agent balls of 20mm~50mm. When LF leaves the station, use 3~5 kg / t 钢 Add modifier balls to the surface of ladle slag; When RH leaves the station, apply 0.5~1.5 kg / t. 钢 Add modifier balls to the surface of ladle slag.

[0020] It should be noted that the calcium aluminate pre-melted slag mainly uses 12CaO.7Al2O3, which can melt slag quickly and also has a strong ability to adsorb Al2O3 inclusions. Because cryolite has the ability to break down the crystal structure of other components and lower the melting point, it mainly serves as a flux and facilitates rapid slag formation. At the same time, cryolite is structurally stable at steelmaking temperatures and does not decompose, and it does not cause environmental pollution due to its fluorine content. Metallic aluminum is used to remove oxygen from slag.

[0021] It is understood that the raw materials for preparing the modifier in this invention are simple and readily available. At the same time, the calcium aluminate pre-melted slag, a low-nitrogen aluminum ash, and industrial cryolite used are all solid wastes from aluminum plants, which helps to reduce the pressure of metallurgical solid waste recycling. Moreover, the slag conditioning process is basically free of smoke and dust, which can improve the smoke and dust problem during slag conditioning and enhance environmental protection. Because the modifier of this invention is a fully pre-melted material, it melts quickly during the steelmaking process. By adding this modifier during the refining process, slag can be formed quickly, effectively improving the slag state. At the same time, it reduces the oxidizability of steel slag, which is beneficial for desulfurization and removal of adsorption of inclusions in steel, thereby improving the slag conditioning effect.

[0022] Specifically, the adhesive is an organic and environmentally friendly adhesive, and the proportion of adhesive added is 1% to 2%.

[0023] The present invention provides three embodiments and three comparative examples below. All three embodiments and three comparative examples are used to produce IF7 ultra-low carbon steel, and the process is converter-LF furnace-RH furnace-continuous casting. In the examples, the modifier of the present invention was used, and the original high-alumina slag conditioner was used in the comparative examples. The components of the original high-alumina slag conditioner are shown in Table 1.

[0024] Table 1

[0025] The amount of modifier balls added at the LF and RH outlets in the three embodiments and the amount of the original high-alumina slag conditioner added at the LF and RH outlets in the three comparative examples are shown in Table 2. Table 2

[0026] The metallurgical effects of the three embodiments and three comparative examples are shown in Table 3 and Table 3 (continued); Table 3

[0027] Continued from Table 3

[0028] Table 4 shows the particulate matter concentrations (including PM2.5) of three examples and three comparative examples without dust removal treatment. Table 4

[0029] And by Figure 3 It can be seen that no obvious smoke or dust was observed when using the environmentally friendly aluminum-based steel slag modifier; from Figure 4 It can be seen that obvious smoke and dust were visible when the original high-alumina slag conditioner was used.

[0030] Therefore, it can be seen that the slag conditioning process of the present invention is basically smokeless, which can improve the smoke and dust problem during slag conditioning and improve environmental protection. The addition of this modifier in the refining process can effectively improve the slag state, reduce the oxidizability of steel slag, and help remove the adsorption of inclusions in steel, thereby improving the slag conditioning effect.

[0031] In the description of this invention, it should be understood that the terms "upper", "lower", "bottom", "top", "front", "rear", "inner", "outer", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0032] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. An environmentally friendly aluminum-based steel slag modifier, characterized in that, The chemical composition of the modifier, by mass fraction, includes: CaO: 20%~30%, Al2O3: 15%~25%, metallic Al: 35%~45%, Na2O: 1%~3%, N≤0.5%, MgO: 4%~10%, FeO≤2%, SiO2: 3%~8%, S≤0.2%, P≤0.2%, activated carbon≤2.5%, H2O≤1.5%, the remainder being unavoidable impurities.

2. A preparation method for preparing the environmentally friendly aluminum-based steel slag modifier of claim 1, characterized in that, Includes the following steps: The calcium aluminate pre-melted slag and industrial cryolite are crushed, ground, and then slurried to form hollow granular balls; The aluminum rod is heated and then drawn into wire in the air, and then cut into aluminum wire. Hollow granules, aluminum wire, acidified graphite, and binder are thoroughly mixed to form a modifier.

3. The preparation method according to claim 2, characterized in that, The process of crushing and grinding calcium aluminate premelted slag and industrial cryolite includes: The calcium aluminate pre-melted slag and industrial cryolite are crushed and ground to particles below 80 mesh.

4. The preparation method according to claim 3, characterized in that, The particle size of the hollow granules is 0.5mm~1.5mm.

5. The preparation method according to claim 4, characterized in that, The process of heating an aluminum rod, drawing it into wire in air, and then cutting it into aluminum wire includes: Aluminum rods with an aluminum content ≥99.5% are heated to 450℃~550℃; Then it is drawn into wires in the air, with the wire diameter being 1mm to 1.5mm; Then cut the thread into aluminum wires 3mm to 5mm long.

6. The preparation method according to claim 5, characterized in that, The adhesive is an organic and environmentally friendly adhesive, and the proportion of adhesive added is 1% to 2%.

7. An application method, comprising using the environmentally friendly aluminum-based steel slag modifier of claim 1 for slag conditioning, characterized in that, Includes the following steps: The modifier is pressed into oval-shaped modifier balls; When LF leaves the station, add modifier balls to the surface of the ladle slag; When RH leaves the station, add modifier balls to the surface of ladle slag.

8. The application method according to claim 7, characterized in that, The process of pressing the modifier into elliptical modifier spheres includes: The modifier is pressed into elliptical modifier balls of 20mm to 50mm.

9. The application method according to claim 8, characterized in that, The addition of modifier balls to the ladle slag surface during LF discharge includes: When LF leaves the station, use 3~5 kg / t 钢 Add modifier balls to the surface of ladle slag.

10. The application method according to claim 9, characterized in that, The addition of modifier balls to the ladle slag surface during RH discharge includes: When RH leaves the station, apply 0.5~1.5 kg / t. 钢 Add modifier balls to the surface of ladle slag.

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