CN113265504A

CN113265504A - Operation method for splashing double slag of converter

Info

Publication number: CN113265504A
Application number: CN202110548127.7A
Authority: CN
Inventors: 韩雨亮; 吴军; 张�浩
Original assignee: Xinjiang Bayi Iron and Steel Co Ltd
Current assignee: Xinjiang Bayi Iron and Steel Co Ltd
Priority date: 2021-05-19
Filing date: 2021-05-19
Publication date: 2021-08-17
Anticipated expiration: 2041-05-19
Also published as: CN113265504B

Abstract

The invention discloses an operation method for splashing double slag of a converter, which comprises the following steps of: firstly, lowering an oxygen lance to a lower limit position to blow and stir slag, wherein the slag amount left at the bottom of the furnace is continuously reduced along with the splashing of a large amount of slag, the lance position is gradually increased and increased by 400-600 mm, the slag splashing is finished when less slag particles fly out of a furnace mouth, the slag splashing time is controlled to be 2-2.5 minutes, and the average MgO content in slag is controlled to be 7-8.5%; and (3) performing secondary slag splashing furnace protection operation: adding a hardening and tempering agent into the slag for the second slag splashing: magnesite 5-8 kg/ton steel and part of slag charge needed by the smelting of the next furnace: 1/3-1/2 of lime, increasing the viscosity of the slag, controlling the oxygen lance to gradually descend to the lower limit, and controlling the slag splashing time to be 1.5-2.0 minutes and the average MgO content in the slag to be 9.5-10 percent, wherein the slag amount remained on the furnace bottom is continuously reduced along with the slag splashing.

Description

Operation method for splashing double slag of converter

Technical Field

The invention relates to an operation method for splashing double slag of a converter.

Background

The furnace age is a comprehensive technical and economic index of converter steelmaking. The improvement of the furnace life can not only reduce the consumption of refractory materials, improve the operation rate and reduce the production cost, but also be beneficial to the balanced tissue production and promote the virtuous cycle of the production. Therefore, it is a goal of steelmaking workers to greatly increase the campaign of the converter for many years.

The converter lining works under the conditions of high temperature and high oxidizability, and is usually eroded at the speed of 0.2-0.8 mm/furnace. In order to ensure the normal production of the converter and prolong the service life of a furnace lining, a plurality of works are carried out by the metallurgical workers in China, for example, the furnace age is gradually improved to more than 1000 furnaces by adopting measures such as tar dolomite bricks, light-burned oil-immersed dolomite bricks, patching, spray-repairing, slag hanging by shaking and the like, the converter is generally built by adopting magnesia carbon bricks in the 80 s, the slag is formed by using active lime, the operation is improved, and the furnace protection method combining slag hanging and spray-repairing is adopted, so that the furnace age of the converter is obviously improved to more than 10000 furnaces.

At the present stage, the magnesia carbon brick is used as a furnace lining of the converter, and the important measure for reducing the corrosion of the furnace lining is to improve the MgO content in slag. When MgO in the slag is saturated, the dissolving amount of MgO in the furnace lining is reduced, thereby prolonging the service life of the furnace lining. The slag splashing furnace protection technology of the converter is characterized in that the slag of the steelmaking end point with the MgO content reaching saturation or supersaturation is utilized, the slag is blown and splashed by high-pressure nitrogen, cooled and solidified to form a high-melting-point slag layer on the surface of a furnace lining, the MgO content in the slag is related to the alkalinity of the slag, and the final slag alkalinity (CaO/SiO) of some factories₂) About 3 percent and the MgO content of about 8 percent can ensure that the MgO reaches the mixing degree. The MgO content of the converter slag splashed at home and abroad is generally controlled to be 8-l 4%. The slag splashing layer formed by the converter slag splashing has better corrosion resistance, can inhibit oxidation and decarburization on the surface of the lining brick, and simultaneously lightens the erosion and the scouring of high-temperature steel slag on the lining brick, thereby protecting the magnesia carbon brick of the lining, reducing the loss speed of refractory materials of the lining, reducing the consumption of furnace repairing materials, lightening the labor intensity of workers, prolonging the service life of the lining, improving the operation rate of the converter and lowering the production cost. However, in the actual production process, the traditional furnace repairing and slag splashing furnace protecting mode has weak maintenance capability on the joint of the furnace bottom and the molten pool, the spray repairing mode needs time consumption, and the continuous maintenance needs to be carried out for multiple times, so that the converter operation rate is greatly influenced, and therefore, the novel slag splashing method needs to be invented for furnace condition maintenance.

The traditional converter slag splashing is that slag drops are splashed up by using the reaction force generated by impacting liquid slag by high-speed nitrogen jet flow and splashed onto the converter lining. The amount of slag spattering is therefore dependent primarily on the amount of stirring energy that the top-blown nitrogen jet impacts the bath. The slag splashing is related to factors such as a gun position, nitrogen flow, slag quantity, an included angle of a spray hole and the like. In the slag splashing parameters of various current plants, the nitrogen flow and the included angle of the spray nozzle are fixed due to equipment and steel making requirements, so the slag amount and the gun position of the slag splashing are controlled under the current conditions to the greatest extent. After the factors such as nitrogen flow, slag quantity, nozzle included angle and the like are determined, it is very critical how to determine the optimal slag splashing gun position. The slag quantity obtained at the position above the lowest lance position slag splashing molten pool is the most, the slag quantity left at the bottom of the furnace is relatively less, and the slag quantity obtained by a high lance position slag splashing furnace cap and the molten pool is less, so that the furnace condition maintenance is not favorable. The traditional slag splashing lance position control concept is to splash slag at the lowest lance position, but a furnace cap is easy to rise so that molten steel is not easy to drain out, and the refractoriness and slag splashing frequency of slag are forced to be adjusted in order to reduce the thickness of the furnace cap, so that the furnace type and the operation rate of a converter are influenced by reinforced spray repair at a joint of a furnace bottom and below a trunnion. The slag splashing control mode can adapt to steel types with not very strong molten steel oxidability, can not meet the requirements of smelting low-carbon steel by a converter, has strong molten steel oxidability and higher erosion speed at the joint of a molten pool and a furnace bottom, and basically can not continuously maintain the joint of the molten pool and the furnace bottom by adopting a furnace repairing and gunning mode.

Disclosure of Invention

In order to overcome the defects of the traditional slag splashing, the invention provides an operation method for splashing double slag by a converter, which can effectively maintain the joint between a molten pool and a furnace bottom and make up for the short plate for splashing double slag by the converter.

The technical scheme adopted by the invention is as follows: an operation method for splashing double slag by a converter is implemented according to the following steps: the first slag splashing furnace protection operation: firstly, lowering an oxygen lance to a lower limit position to spray and stir slag, reducing the temperature of the slag and improving the viscosity of the slag, wherein the amount of slag left on a furnace bottom is continuously reduced along with the splashing of a large amount of slag, the position of the lance is gradually increased at the moment, the position of the lance is increased by 400-600 mm to act, the splashing is finished when less slag particles fly out of a furnace mouth, the slag splashing time is controlled to be 2-2.5 minutes, and the average content of MgO in the slag is controlled to be about 7-8.5%; and (3) performing secondary slag splashing furnace protection operation: adding a hardening and tempering agent into the slag for the second slag splashing: magnesite 5-8 kg/ton steel and part of slag charge needed by the smelting of the next furnace: 1/3-1/2 of lime, improve the slag viscosity, control the oxygen lance to descend the lance step by step to the lower limit, because the slag viscosity increases some slag mixture slag can not be hit above the trunnion by the high-pressure nitrogen at this moment, spread evenly in the junction of furnace bottom and molten bath, the slag mixture slag in the slag not merely has effects of improving the slag-splashing melting point, can also produce the solid mass point of dispersion in the slag, have improved the binding capacity of slag and furnace lining; the amount of slag splashed by the slag and left on the furnace bottom is continuously reduced, the gun position is gradually increased at the moment, the gun position is increased by 600-800 mm to act, the slag is fully cooled, the slag is guaranteed to be splashed in a short time, a large amount of slag is guaranteed to be splashed to the position below a trunnion, the effect of maintaining a molten pool and the furnace bottom is achieved, the slag splashing time is controlled to be 1.5-2.0 minutes, and the average MgO content in the slag is controlled to be about 9.5-10%.

Through the novel operation method for splashing double slag, the slag regulator and the slag charge are added into the furnace in advance to splash the slag, and dispersed solid phase particles are formed between the slag and the slag charge by utilizing the slag splashing time and the charging time, so that the bonding capacity of the slag and a furnace lining is improved, a slag splashing layer has enough refractoriness, and the lithofacies research of the slag shows that the converter final slag C is added into the furnace₂S+C₃The sum of S can reach 70-75%, and the two compounds are high-melting-point substances (C)₂S: 2130 degree, C₃S, 2070 degrees).

The improvement effect is as follows: 1. by using the novel operating method for splashing the double slag, the slag is splashed by stages by reasonably controlling the slag splashing gun position, so that the converter bottom, the molten pool, the trunnion and the furnace cap can obtain better slag splashing effect, and the condition that the joint of the converter bottom and the molten pool is corroded and cannot be maintained is avoided. 2. The novel operating method for splashing double slag reduces the times of furnace repairing and spray repairing, improves the effective operation rate of the converter, and has strong scientific research value, environmental protection, safety and economic significance. 3. The novel operation method for splashing the double slag has certain popularization value due to convenient operation.

Detailed Description

An operation method for splashing double slag by a converter is implemented according to the following steps:

the first slag splashing furnace protection operation: firstly, lowering an oxygen lance to a lower limit position to spray and stir slag, reducing the temperature of the slag and improving the viscosity of the slag, wherein the slag quantity left at the bottom of the furnace along with a large amount of slag splashed is continuously reduced, the position of the lance is gradually increased at the moment, the position of the lance is increased by 400-600 mm to act, the slag splashing is finished when less slag particles fly out of a furnace opening, the slag splashing time is controlled to be 2-2.5 minutes, and the average content of MgO in the slag is controlled to be about 7-8.5%;

and (3) performing secondary slag splashing furnace protection operation: adding a hardening and tempering agent into the slag for the second slag splashing: magnesite 5-8 kg/ton steel and part of slag charge needed by the smelting of the next furnace: 1/3-1/2 lime, improving the viscosity of the slag, controlling the oxygen lance to descend to the lower limit step by step, and at the moment, because the viscosity of the slag is increased, part of slag mixed slag materials cannot be hit above the trunnion by high-pressure nitrogen and are uniformly spread at the joint of the furnace bottom and the molten pool, the slag mixed slag materials in the slag not only have the function of improving the melting point of splashed slag, but also can generate dispersed solid phase particles in the slag, thereby improving the binding capacity of the slag and the furnace lining.

The amount of slag left at the bottom of the furnace along with the slag splashed is continuously reduced, the gun position is gradually increased, the gun position is increased by 600-800 mm, and the slag is fully cooled to ensure that the slag is splashed in a short time. Ensures that a large amount of slag is splashed to the part below the trunnion, and achieves the effect of maintaining a molten pool and a furnace bottom. The slag splashing time is controlled to be 1.5-2.0 minutes, and the average MgO content in the slag is controlled to be about 9.5-10%.

Claims

1. An operation method for splashing double slag by a converter is characterized by comprising the following steps: the first slag splashing furnace protection operation: firstly, lowering an oxygen lance to a lower limit position to spray and stir slag, reducing the temperature of the slag and improving the viscosity of the slag, wherein the slag amount left on the bottom of the furnace is continuously reduced along with the splashing of a large amount of slag, the position of the lance is gradually increased at the moment, the position of the lance is increased by 400-600 mm to act, the slag splashing is finished when less slag particles fly out of a furnace mouth, the slag splashing time is controlled to be 2-2.5 minutes, and the average content of MgO in the slag is controlled to be 7-8.5%; and (3) performing secondary slag splashing furnace protection operation: adding a hardening and tempering agent into the slag for the second slag splashing: magnesite 5-8 kg/ton steel and part of slag charge needed by the smelting of the next furnace: 1/3-1/2 of lime, improve the slag viscosity, control the oxygen lance to descend the lance step by step to the lower limit, because the slag viscosity increases some slag mixture slag charge of slag can not be hit above the trunnion by high-pressure nitrogen at this moment, spread evenly in the junction of furnace bottom and molten bath, the slag mixture slag charge in the slag not merely has effects of improving the slag-splashing melting point, can also produce the solid phase particle of dispersion in the slag, have improved the binding capacity of slag and furnace lining; the amount of slag splashed by the slag and left on the furnace bottom is continuously reduced, the gun position is gradually increased at the moment, the gun position is increased by 600-800 mm, the slag is fully cooled, the slag is guaranteed to be splashed in a short time, a large amount of slag is guaranteed to be splashed to the position below a trunnion, the effect of maintaining a molten pool and the furnace bottom is achieved, the slag splashing time is controlled to be 1.5-2.0 minutes, and the average MgO content in the slag is controlled to be 9.5-10%.