Rapid repairing process for converter bottom seam

Abstract

The invention relates to the technical field of converter steelmaking, in particular to a rapid repairing process for a joint at the bottom of a converter. After the converter tilts back and forth, a converter body is shaken to be upright and is static, a gun position is lowered to a slag splashing blowing position, nitrogen is blown, and primary slag splashing is conducted till no slag particles appear at a converter opening; then observing the state of the slag in the converter after primary slag splashing, and finishing repairing after the slag is completely splashed dry; the mass ratio of the slag to the dolomite is (7-8): (1-1.5); the alkalinity of the slag is controlled to be 3.0-3.2, and the content of magnesium oxide is controlled to be 8-10%; the tilting angle of the furnace body is controlled to be 50-60 degrees; and the distance from the gun head to the slag surface is 2-2.5 m. By controlling the dolomite and slag consumption, the furnace body tilting angle during furnace shaking, the slag splashing and nitrogen blowing gun position and other conditions, the blowing-out and fettling time is shortened, the production rhythm is stabilized, the labor intensity of workers is reduced, and the repairing effect is good.

Description

Technical Field

[0001] The invention relates to the technical field of converter steelmaking, and in particular to a rapid repairing process for a converter bottom joint. Background Art

[0002] The converter is a kind of equipment used for steelmaking, which uses a rotating furnace body to perform high-temperature heating and oxidation reactions. The converter consists of three parts: the furnace cap, the furnace body, and the furnace bottom. There are two types of furnace bottom structures, fixed dead furnace bottom and detachable live furnace bottom. In the converter with a detachable live furnace bottom, the furnace cap and the outer shell of the furnace body are a whole. After the furnace bottom and the furnace body are fixed with bolts and other parts, the joints need to be sealed with ramming materials, and the strength of the joints is insufficient. The furnace bottom is in a high-temperature, weight-bearing state during the converter smelting process. Especially under the smelting conditions of low iron ratio, due to the high oxygen content in the molten steel, not only does the furnace bottom often crack, but the joints between the furnace bottom and the furnace body are not strong enough, which makes it more prone to erosion and steel leakage and other safety accidents. Frequent repairs and maintenance are required, which is time-consuming and labor-intensive.

[0003] One of the ways to repair the furnace bottom and its joints in steel enterprises is to use large-surface repair bricks to burn oxygen and splash slag. This method requires lowering the gun to open oxygen and sinter the repair charge at high temperature. On the one hand, it is easy to damage the splash slag layer, resulting in frequent repairs; on the other hand, the repair time is long, usually more than two hours. In other words, the conventional method requires many repairs and long repair times, resulting in higher refractory costs and lower converter operating efficiency. Especially in the later stage of the furnace service, the converter bottom fluctuates frequently, affecting the safe operation of the converter body. Summary of the invention

[0004] Aiming at the problems of long repairing time and poor repairing effect at the joint of converter bottom in the prior art, the present invention provides a rapid repairing process for the joint of converter bottom, with the repairing time within 15 minutes and good repairing effect.

[0005] The technical solution of the present invention is: A rapid repair process for the joints at the bottom of a converter, wherein slag and dolomite are mixed in the converter; the converter is tilted forward and backward and then the furnace body is shaken straight to be stationary, the gun position is lowered to the slag splashing and blowing position, nitrogen is blown to splash the slag once, until no slag particles appear at the furnace mouth; then the state of the slag in the converter after the splashing is observed, and the repair is completed after the slag is completely splashed and dried; Among them, the mass ratio of slag to dolomite is 7-8:1-1.5; The basicity of the slag is controlled at 3.0-3.2, and the magnesium oxide content is controlled at 8%-10%; The furnace tilting angle is controlled at 50°-60°; The distance from the gun tip to the slag surface is 2-2.5m.

[0006] Furthermore, the mass of the slag in the converter is 7%-8% of the nominal capacity of the converter.

[0007] Furthermore, the dolomite is divided into two equal parts and added from the discharge ports on both sides of the converter.

[0008] Furthermore, the converter is tilted back and forth twice.

[0009] Furthermore, the shaking furnace body is kept stationary for 3-5 minutes to allow the dolomite and slag to be fully sintered.

[0010] Furthermore, the nitrogen pressure is controlled at 1.0-1.2MPa and the nitrogen flow rate is controlled at 28000-30000m 3 / h.

[0011] Furthermore, the slag splashing time is 4-6 minutes.

[0012] Furthermore, if the slag is not splashed dry after the first slag splashing, the converter is shaken straight and then the slag is splashed a second time.

[0013] The beneficial effects of the present invention are: The present invention provides a rapid repair process for the joints at the bottom of a converter. The cost of dolomite is lower than that of conventional repair consumables such as furnace repair bricks. By controlling the dosage ratio of dolomite and slag, the tilting angle of the furnace body when shaking the furnace, the position of the slag splashing nitrogen blowing gun and other conditions, the slag and dolomite can be evenly mixed in the converter, and quickly and effectively sintered and bonded to the joints at the bottom of the furnace. The repair time is controlled within 15 minutes, and rapid repair is achieved. The repair process shortens the furnace stoppage and repair time, stabilizes the production rhythm, reduces the labor intensity of employees, and has a good repair effect. DETAILED DESCRIPTION

[0014] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0015] Example 1 During converter operation, it was observed that the bottom joint of a 100t converter (purchased from Taiyuan Heavy Industry Co., Ltd.) was cracked, which affected the normal use of the converter. The operator quickly repaired it, including the following steps: (1) 7 tons of slag is left in the converter, the basicity of the slag is controlled at 3.0-3.2, and the magnesium oxide content is controlled at 8%-10% to ensure that the slag has appropriate viscosity and fluidity; (2) Shake the furnace body straight, add 600 kg of dolomite from the feeding ports on both sides of the rotary furnace, and tilt the furnace body forward and backward twice each, with the tilting angle of the furnace body controlled at 50°-60°; If the angle is too small, the dolomite cannot be evenly spread on the furnace bottom, causing dolomite to clump and affect the sintering effect; if the angle is too large, the dolomite will stick to the iron mixing surface and the steel tapping surface, affecting the furnace bottom repair effect; (3) After the tilting is completed, shake the furnace body and let it stand for 3 minutes to allow the dolomite and slag to be fully sintered. Then lower the gun to the slag splashing position and blow nitrogen to splash the slag. The nitrogen pressure is 1.0 MPa and the nitrogen flow rate is 30000m 3 / h, the distance from the gun tip to the slag surface is controlled to be 2.5m, and the slag splashing time is 4min (no slag particles appear at the furnace mouth); If the gun position is lower than 2m, the added dolomite will be dispersed, affecting the furnace bottom repair effect; if the gun position is higher than 2.5m, it will cause excessive impact force affecting the repair effect; (4) Tilt the furnace body to observe the state of the slag after slag splashing. If the slag is not splashed dry and is still in a flowing state, the converter needs to be shaken straight to continue the secondary slag splashing until the slag is completely splashed dry. The rapid repair of the furnace bottom joint is completed, and the repair time is 10 minutes.

[0016] After the repair is completed, the converter can continue to be used and can smelt at least 60 furnaces (there are no obvious cracks in the joints of the furnace bottom that affect the use).

[0017] Example 2 During converter operation, it was observed that the bottom joint of a 100t converter (purchased from Taiyuan Heavy Industry Co., Ltd.) was cracked, which affected the normal use of the converter. The operator quickly repaired it, including the following steps: (1) 7 tons of slag is left in the converter, the basicity of the slag is controlled at 3.0-3.2, and the magnesium oxide content is controlled at 8%-10% to ensure that the slag has appropriate viscosity and fluidity; (2) Shake the furnace body straight, add 600 kg of dolomite from the feeding ports on both sides of the rotary furnace, and tilt the furnace body forward and backward twice each, with the tilting angle of the furnace body controlled at 50°-60°; If the angle is too small, the dolomite cannot be evenly spread on the furnace bottom, causing dolomite to clump and affect the sintering effect; if the angle is too large, the dolomite will stick to the iron mixing surface and the steel tapping surface, affecting the furnace bottom repair effect; (3) After the tilting is completed, shake the furnace body and let it stand for 5 minutes to allow the dolomite and slag to be fully sintered. Then lower the gun to the slag splashing position and blow nitrogen to splash the slag. The nitrogen pressure is 1.2MPa and the nitrogen flow rate is 28000m 3 / h, the distance from the gun tip to the slag surface is controlled to be 2m, and the slag splashing time is 6min (no slag particles appear at the furnace mouth); If the gun position is lower than 2m, the added dolomite will be dispersed, affecting the furnace bottom repair effect; if the gun position is higher than 2.5m, it will cause excessive impact force affecting the repair effect; (4) The furnace body was tilted to observe the state of the slag after splashing. It was found that all the slag had splashed dry, and the joints at the bottom of the furnace were quickly repaired. The repair time was 11 minutes.

[0018] After the repair is completed, the converter can continue to be used and can smelt at least 60 furnaces (there are no obvious cracks in the joints of the furnace bottom that affect the use).

[0019] Comparative Example 1 During converter operation, it was observed that the bottom joint of a 100t converter (purchased from Taiyuan Heavy Industry Co., Ltd.) was cracked, which affected the normal use of the converter. The operator quickly repaired it, including the following steps: (1) 7 tons of slag is left in the converter, the basicity of the slag is controlled at 2.5-2.8, and the magnesium oxide content is controlled at 8%-10%; (2) Shake the furnace body straight, add 600 kg of dolomite from the feeding ports on both sides of the rotary furnace, and tilt the furnace body forward and backward twice each. The tilting angle of the furnace body is controlled at 70°-80°; (3) After the tilting is completed, shake the furnace body and let it stand for 3 minutes to allow the dolomite and slag to be fully sintered, then lower the gun to the slag splashing position and blow nitrogen to splash the slag once. The nitrogen pressure is 1.0MPa and the nitrogen flow rate is 30000m 3 / h, the distance from the gun tip to the slag surface is controlled to be 1.5m, and the slag splashing time is 6min (no slag particles appear at the furnace mouth); (4) Tilt the furnace body to observe the state of the slag after slag splashing. It is found that the slag has not been splashed dry and is still in a flowing state. After the converter is straightened, the slag is splashed for the second time until the slag is completely splashed dry. The rapid repair of the furnace bottom joint is completed. The repair time is 16 minutes.

[0020] The basicity of the final slag from converter smelting is related to the viscosity of the slag. Under the same conditions, the higher the basicity, the higher the viscosity. In step (1), if the slag basicity is low, the fluidity is high. In step (2), the converter is shaken too much, and the dolomite will stick to the iron mixing surface. In step (3), when blowing, the distance from the gun tip to the slag surface is too small, and the impact force is large. The technicians analyzed that the changes in the above conditions, such as the basicity of the slag, the shaking amplitude of the converter, and the distance from the gun tip to the slag surface, affect the repair time and repair effect. After the repair was completed, the converter continued to be used for operation. After smelting 53 furnaces, obvious cracks were found and needed to be repaired again.

[0021] Comparative Example 2 During converter operation, it was observed that the bottom joint of a 100t converter (purchased from Taiyuan Heavy Industry Co., Ltd.) was cracked, which affected the normal use of the converter. The operator repaired it with furnace repair bricks, including the following steps: (1) 7 tons of slag is left in the converter, the basicity of the slag is controlled at 3.0-3.2, and the magnesium oxide content is controlled at 8%-10% to ensure that the slag has appropriate viscosity and fluidity; (2) After slag splashing is completed, pour the slag into the slag basin; (3) Use the scrap steel hopper to pour 600 kg of furnace bricks and 1 t of magnesium furnace charge into the furnace, and tilt the furnace body forward and backward twice each, with the tilt angle of the furnace body controlled at 50°-60°; (4) After the tilting is completed, shake the furnace body and lower the gun to blow oxygen. The oxygen pressure is 0.7MPa and the oxygen flow rate is 8000m 3 / h, control the distance from the gun tip to the slag surface to 2m, until there is no black smoke at the furnace mouth; (5) The furnace body was tilted to observe the sintering status. It was found that the furnace repair bricks had been sintered. The rapid repair of the furnace bottom joint was completed. The repair time was 35 minutes.

[0022] Using conventional furnace repair bricks instead of dolomite for repair is costly, and the furnace repair bricks need to be sintered at a higher temperature, and oxygen blowing is required, which prolongs the repair time. Uneven sintering often occurs, and the converter continues to be used after the repair is completed. After smelting 50 furnaces, obvious cracks are found and need to be repaired again.

[0023] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily conceive of changes or substitutions within the technical scope disclosed by the present invention, and such changes or substitutions shall be within the scope of protection of the present invention.

Claims

1. A rapid repair process for the joints at the bottom of a converter, characterized in that: The slag and dolomite are mixed in the converter; after the converter is tilted back and forth, the furnace body is shaken straight and then stopped, the gun position is lowered to the slag splashing and blowing position, nitrogen is blown to splash the slag once, until no slag particles appear at the furnace mouth; then the slag state in the converter after splashing is observed, and the repair is completed after the slag is completely splashed; Among them, the mass ratio of slag to dolomite is 7-8:1-1.5; The basicity of the slag is controlled at 3.0-3.2, and the magnesium oxide content is controlled at 8%-10%; The furnace tilting angle is controlled at 50°-60°; The distance from the gun tip to the slag surface is 2-2.5m.

2. A rapid repair process for the joints at the bottom of a converter as claimed in claim 1, characterized in that: The mass of slag in the converter is 7%-8% of the nominal capacity of the converter.

3. A rapid repair process for the joints at the bottom of a converter as claimed in claim 1, characterized in that: The dolomite is divided into two equal parts and added from the discharge ports on both sides of the converter.

4. A rapid repair process for a converter bottom joint as claimed in claim 1, characterized in that: The converter is tilted back and forth twice.

5. A rapid repair process for the joints at the bottom of a converter as claimed in claim 1, characterized in that: The shaking furnace body should be stationary for 3-5 minutes.

6. A rapid repair process for the joints at the bottom of a converter as claimed in claim 1, characterized in that: The nitrogen pressure is controlled at 1.0-1.2MPa, and the nitrogen flow rate is controlled at 28000-30000m 3 / h.

7. A rapid repair process for the joints at the bottom of a converter as claimed in claim 1, characterized in that: The slag splashing time is 4-6 minutes.

8. A rapid repair process for a converter bottom joint as claimed in claim 1, characterized in that: If the slag is not splashed dry after the first splash, the converter should be straightened and then splashed a second time.