A method for on-line repair of the lining of a converter during tapping

Abstract

The present application relates to the technical field of steel metallurgy, and particularly relates to a method for online repairing of a furnace lining in a converter tapping process, 1) smelting and end point control; 2) shaking the converter to zero position; 3) within 20s after the converter is shaken to zero position, lime is added to the surface layer of the slag; 4) the lime is added while the bottom argon blowing of the converter is started; 5) tapping and automatic slag hanging repair, the weak bottom argon blowing is maintained during the tapping process, in the tilting process, the thickened high-viscosity slag adheres to the surface of the furnace lining which is most seriously eroded on the tapping side, after the tapping is completed, the adhered slag layer is rapidly solidified to form a dense repair layer. The present application makes the slag actively adhere and solidify in the eroded part on the tapping side during the tapping process, and the best slag hanging repair effect is achieved in the shortest process time.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel metallurgy technology, and specifically relates to a method for online repair of furnace lining during converter tapping. Background Technology

[0002] The converter is the core equipment in steelmaking. Its furnace lining is constantly eroded under high temperature, high oxidation environment and mechanical erosion, especially on the tapping side, where it is subjected to intense erosion by molten steel and slag, resulting in a faster erosion rate. Excessive erosion of the furnace lining will shorten the converter's lifespan, affect production safety, and may cause fluctuations in the quality of molten steel.

[0003] Currently, the maintenance of converter linings mainly relies on slag splashing protection technology and spraying repair technology. Slag splashing protection is carried out after each heat of steelmaking, using high-pressure nitrogen gas to splash slag onto the furnace wall to form a protective layer, but its repair effect on the area below the tapping side is limited. Spraying repair technology, on the other hand, requires specialized equipment, is complex to operate, and is time-consuming, usually needing to be carried out during furnace shutdown or planned maintenance, thus affecting the production schedule.

[0004] Therefore, existing technologies suffer from low repair efficiency, limited targeting of the tapping side, and impact on converter operating rates. There is an urgent need for a method that can quickly and effectively repair the tapping side lining without interrupting normal production, and even during production breaks. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for online repair of furnace lining during the steel tapping process of a converter, so as to achieve fast and low-cost online repair of furnace lining without affecting normal steel tapping operations.

[0006] To achieve the above objectives, the present invention employs the following technical solution: A rapid repair method for the tapping side of a converter includes the following steps: 1) Smelting and endpoint control: After the converter completes the blowing of the molten steel in this furnace and reaches the endpoint composition and temperature requirements, the oxygen lance is lifted. 2) Shake the converter to the zero position, i.e., the upright position; 3) Feeding and bottom blowing: Within 20 seconds after the converter is shaken to zero, add lime to the surface layer of the slag. The amount of lime added is calculated according to the following formula: Lime addition amount = final oxygen value (%) × 0.5 kg / t × steel output (t) × 10000 4) Stirring and mixing stage: When adding lime, start the bottom blowing argon gas stirring in the converter. The total blowing time is controlled at 40-90s; the argon flow rate is controlled at 0.03-0.08Nm³ / min·t; the viscosity of the thickened slag reaches 0.5-2.0Pa·s. 5) Steel tapping and automatic slag repair: After completing the above steps, steel tapping is carried out immediately. During the steel tapping process, a weak bottom-blowing argon gas of 0.02 to 0.04 Nm³ / min·t is maintained. During the tilting process, the thickened high-viscosity slag adheres to the furnace lining surface that is most severely eroded on the steel tapping side. After steel tapping is completed, the adhered slag layer solidifies rapidly to form a dense repair layer.

[0007] The lime is active quicklime, and its composition by mass percentage is required to be: CaO≥85%, MgO≤4%, SiO2≤2%, P≤0.020%, S≤0.020%, and the particle size range is 5~30mm.

[0008] The lime is added through a chute and falls onto the surface of the slag.

[0009] Compared with existing technologies, the beneficial effects of this invention are: 1. By quantitatively adding thickening agent lime based on the endpoint oxygen value, precise batching is achieved, avoiding the problems of "too thick" affecting steel tapping or "too thin" resulting in ineffective repair caused by fixed feed amount.

[0010] 2. The introduction of bottom blowing agitation completely solves the problems of uneven lime mixing and insufficient reaction caused by feeding through the chute, ensuring the uniformity and reliability of slag viscosity improvement, and making the repair effect stable and predictable each time.

[0011] 3. Without affecting normal steel tapping operations, this invention utilizes the brief time before tapping to increase slag viscosity by adding lime, a thickening agent, into the furnace. This causes the slag to actively adhere to and solidify on the eroded areas on the tapping side during the steel tapping process. Through precise control, the invention achieves optimal slag repair results with minimal material consumption within the shortest process time, enabling rapid, online, and low-cost furnace lining repair with significant overall benefits. Detailed Implementation

[0012] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. The reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0013] A rapid repair method for the tapping side of a converter includes the following steps: 1) Smelting and endpoint control: After the converter completes the blowing of the molten steel in this furnace and reaches the endpoint composition and temperature requirements, the oxygen lance is lifted. 2) Shake the converter to the zero position, i.e., the upright position; 3) Feeding and bottom blowing: Within 20 seconds after the converter is shaken to zero, add lime to the surface layer of the slag. The amount of lime added is calculated according to the following formula: Lime addition amount = final oxygen value (%) × 0.5 kg / t × steel output (t) × 10000 Since lime does not contain carbonaceous materials and the calcium silicate produced by the reaction exists stably in the slag, it will not cause the molten steel to increase carbon, silicon, or phosphorus.

[0014] 4) Stirring and mixing stage: Simultaneously with the addition of lime, bottom-blowing argon gas is activated for stirring, with the total blowing time controlled at 40–90 seconds; the argon flow rate is controlled at 0.03–0.08 Nm³ / min·t; the uniform stirring of the bottom-blowing gas promotes the rapid melting, diffusion, and reaction of lime particles in the slag, preventing lime agglomeration and causing the slag viscosity to increase rapidly and uniformly; the lime reacts with SiO₂ and FeO in the slag to form a high-melting-point calcium silicate phase, achieving slag thickening; the viscosity of the thickened slag reaches 0.5–2.0 Pa·s; 5) Steel tapping and automatic slag repair: After completing the above steps, steel tapping is carried out immediately. During the tilting process, the thickened high-viscosity slag adheres to the furnace lining surface that is most severely eroded on the tapping side. After the steel tapping is completed, the adhered slag layer quickly solidifies to form a dense repair layer. During the tapping process, a weak bottom-blowing argon gas flow of 0.02–0.04 Nm³ / min·t is maintained. This serves two purposes: first, to maintain the uniformity of the molten steel composition within the ladle; and second, to create a slight positive pressure at the furnace bottom, preventing the molten steel eddies from "sucking" the repair layer off.

[0015] The lime is active quicklime, and its composition by mass percentage is required to be: CaO≥85%, MgO≤4%, SiO2≤2%, P≤0.020%, S≤0.020%, and the particle size range is 5~30mm.

[0016] The lime is added through a chute and falls onto the surface of the slag.

[0017] To make the objectives, technical solutions, and technical effects of this invention clearer, the technical solutions in the embodiments of this invention are now described clearly and completely. However, the embodiments described below are only some embodiments of this invention, not all embodiments. All other embodiments obtained by those skilled in the art in conjunction with the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0018] Example: A rapid repair method for the tapping side of a 260-ton converter in a steel plant, including the following steps: 1) The current furnace blowing is finished. The final temperature is 1680℃ and the final oxygen value is 0.045%. The carbon and temperature meet the standards. The oxygen lance is raised.

[0019] 2) Shake the converter to the zero position (vertical position).

[0020] 3) The amount of lime to be added is calculated according to the formula: Lime addition amount = Endpoint oxygen value (%) × 0.5 kg / t × Steel output (t) × 10000. The lime composition is as follows: CaO: 88%, MgO: 3.5%, SiO2: 1.8%, P: 0.015%, S: 0.018%, Particle size: 5~30mm. The lime is added into the converter through the feeding chute within 15 seconds and falls onto the slag surface.

[0021] 4) When adding lime, simultaneously start the bottom blowing argon gas stirring of the converter, and control the gas flow rate at 0.05 Nm³ / min·t. The total duration should be controlled at 60 s.

[0022] 5) Immediately after completing the above steps, the steel tapping operation will be carried out. During the tapping process, the slag, which becomes viscous due to the addition of lime, will adhere to the wall surface of the furnace lining on the tapping side as the molten steel swirls and the furnace body tilts, forming a repair layer.

[0023] After tapping, and following the slag splashing protection process, the furnace lining thickness detector showed that the thickness of key parts on the tapping side was on average 5-10 mm thicker than in furnaces that did not use this method. The slag coating on the furnace wall on the tapping side was good, the slag layer was uniform, and the repair effect was obvious.

[0024] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A rapid repair method for the tapping side of a converter, characterized in that, Includes the following steps: 1) Smelting and endpoint control: After the converter completes the blowing of the molten steel in this furnace and reaches the endpoint composition and temperature requirements, the oxygen lance is lifted. 2) Shake the converter to the zero position, i.e., the upright position; 3) Feeding and bottom blowing: Within 20 seconds after the converter is shaken to zero, add lime to the surface layer of the slag. The amount of lime added is calculated according to the following formula: Lime addition amount = final oxygen value (%) × 0.5 kg / t × steel output (t) × 10000 4) Stirring and mixing stage: When adding lime, start the bottom blowing argon gas stirring in the converter. The total blowing time is controlled at 40-90s; the argon flow rate is controlled at 0.03-0.08Nm³ / min·t; the viscosity of the thickened slag reaches 0.5-2.0Pa·s. 5) Steel tapping and automatic slag repair: After completing the above steps, steel tapping is carried out immediately. During the steel tapping process, a weak bottom-blowing argon gas of 0.02 to 0.04 Nm³ / min·t is maintained. During the tilting process, the thickened high-viscosity slag adheres to the furnace lining surface that is most severely eroded on the steel tapping side. After steel tapping is completed, the adhered slag layer solidifies rapidly to form a dense repair layer.

2. The rapid repair method for the tapping side of a converter according to claim 1, characterized in that, The lime is active quicklime, and its composition by mass percentage is required to be: CaO≥85%, MgO≤4%, SiO2≤2%, P≤0.020%, S≤0.020%, and the particle size range is 5~30mm.

3. The rapid repair method for the tapping side of a converter according to claim 1, characterized in that, The lime is added through a chute and falls onto the surface of the slag.