Clean and efficient RH vacuum tank heat preservation and residual steel treatment method

Abstract

The invention discloses a clean and efficient RH vacuum tank heat preservation and residual steel treatment method which comprises the following steps: inserting a top lance into a vacuum tank after the last heat of smelting is finished, blowing mixed gas of coke oven gas and oxygen into the vacuum tank, burning the mixed gas in the vacuum tank to release heat so as to heat the vacuum tank until the temperature in the tank is greater than or equal to 1200 DEG C; and the residual steel on the refractory material on the inner wall of the vacuum tank is melted. The method can promote the melting of residual steel on the refractory material on the inner wall of the vacuum tank, can reduce the chemical reaction between oxygen and the residual steel on the inner wall of the tank, relieves smoke dust, and prevents the smoke dust from overflowing to pollute the environment. According to the method, heat released by combustion of coke oven gas and oxygen is utilized for heat preservation of the vacuum tank, meanwhile, a residual steel mixture left on a refractory material on the inner wall of the vacuum tank is efficiently removed, the influence of residual steel on subsequent heat is reduced, and production loss and mass loss are effectively reduced; red smoke generated by reaction of residual steel and oxygen in the vacuum tank is effectively weakened, and pollution of smelting to the environment is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, in particular to a clean and efficient RH vacuum tank heat preservation and residual steel treatment method. Background Art

[0002] RH cycle degassing method is a special refining method. Under vacuum, molten steel is circulated to achieve molten steel refining, thereby achieving the functions of dehydrogenation, decarbonization, deoxidation, improvement of molten steel purity and alloying. The RH process can shorten the converter smelting cycle, improve the yield, save deoxidizers and alloy materials, and improve the quality of steel. At present, it is widely used in the production of high-quality steel such as ultra-low carbon steel, silicon steel, pipeline steel, etc. During RH treatment, the molten steel reacts in a vacuum tank lined with refractory materials. After the molten steel rises with the lifting gas, it falls into the vacuum tank under the action of gravity. The tiny steel droplets contact the refractory material on the inner wall of the vacuum tank and cool down, causing part of the molten steel to solidify on the inner wall of the vacuum tank to form residual steel. The residual steel in the vacuum tank gradually accumulates and increases, and will randomly fall into the molten steel during the smelting process, causing the temperature of the molten steel to drop and the composition to change, which increases the difficulty of controlling the RH smelting process. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a clean and efficient RH vacuum tank heat preservation and residual steel treatment method.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: after the last furnace smelting is completed, a top gun is inserted into the vacuum tank and a mixture of coke oven gas and oxygen is blown into the vacuum tank. The mixture burns and releases heat in the vacuum tank to heat the vacuum tank to a temperature ≥1200°C, thereby melting the excess steel remaining on the refractory material on the inner wall of the vacuum tank.

[0005] Furthermore, the vacuum tank is processed within 1 hour after the last smelting heat is completed.

[0006] Furthermore, the top gun is inserted into the vacuum tank until the gun mouth is 8 to 5 meters away from the bottom of the vacuum tank.

[0007] Furthermore, the volume ratio of coke oven gas to oxygen in the mixed gas is 1:2.

[0008] Furthermore, the speed of the top gun blowing into the coke oven gas is 700Nm 3 / h, oxygen blowing speed is 1400Nm 3 / h.

[0009] The beneficial effect produced by adopting the above technical scheme is that after the RH production is completed, the present invention uses a top gun to blow a mixed gas of coke oven gas and oxygen in an appropriate proportion at a certain position. The mixed gas burns in the vacuum tank to release a large amount of heat, ensuring that the temperature of the vacuum tank is ≥1200°C, and promoting the melting of the residual steel remaining on the refractory material on the inner wall of the vacuum tank; at the same time, the small amount of O2 blown in will come into contact with the residual steel in the tank to react chemically, produce Fe3O4, and form smoke. In the exothermic environment of coke oven gas and oxygen, it quickly decomposes into a mixture of stable FeO and Fe2O3, reducing the chemical reaction between oxygen and the residual steel on the inner wall of the tank, alleviating the appearance of smoke, and avoiding smoke overflow to pollute the environment.

[0010] The present invention can promote the melting of excess steel remaining on the refractory material on the inner wall of the vacuum tank, and can also reduce the chemical reaction between oxygen and excess steel on the inner wall of the tank, alleviate the appearance of smoke, and avoid the overflow of smoke and dust to pollute the environment. The present invention uses the heat released by the combustion of coke oven gas and oxygen to insulate the vacuum tank, and at the same time efficiently removes the excess steel mixture remaining on the refractory material on the inner wall of the vacuum tank, reduces the impact of excess steel on subsequent furnaces, and effectively reduces production losses and quality losses; it efficiently reduces the red smoke generated by the reaction of excess steel and oxygen in the vacuum tank, and reduces the pollution of smelting to the environment. DETAILED DESCRIPTION

[0011] The present invention is further described in detail below in conjunction with specific implementation modes.

[0012] The clean and efficient RH vacuum tank insulation and residual steel treatment method is as follows: within 1 hour after the last heat of smelting is completed, the vacuum tank is inserted into the vacuum tank by a top gun, and the top gun is inserted into the vacuum tank until the gun mouth is 8 to 5 meters away from the bottom of the vacuum tank; then a mixed gas of coke oven gas and oxygen is blown into the mixed gas through the top gun, the volume ratio of coke oven gas to oxygen in the mixed gas is 1:2, and the speed of blowing the coke oven gas into the top gun is 700Nm 3 / h, oxygen blowing speed is 1400Nm 3 / h, the total amount of coke oven gas blown in is 110~230Nm 3 , the total amount of oxygen blown in is 220~460Nm 3; The mixed gas burns and releases heat in the vacuum tank, and the chemical equation is 2H2+O2=2H2O, CH4+2O2=CO2+2H2O. The released heat can reduce the cooling rate of the vacuum tank, increase the temperature in the tank to ≥1200℃, and melt the residual steel remaining on the refractory material on the inner wall of the vacuum tank; in the vacuum tank, the small amount of O2 blown in will react chemically with the residual steel in the tank to produce Fe3O4, forming smoke, which will quickly decompose into a stable mixture of FeO and Fe2O3 in the heat release environment of coke oven gas and oxygen, thereby avoiding overflow. The coke oven gas is mainly composed of hydrogen and methane, accounting for 56% and 27% by volume respectively; during the process of the top gun blowing the mixed gas, the top gun position can move up and down within a range of 8 to 5m from the bottom of the vacuum tank. During the process of the top gun blowing the mixed gas, the nitrogen flow rate of the circulating gas in the RH vacuum tank riser is adjusted to 60 to 100Nm 3 / h, which can avoid blockage of the circulation pipe on the one hand and help control costs on the other.

[0013] Example 1: This clean and efficient RH vacuum tank insulation and residual steel treatment method adopts the following process steps.

[0014] (1) Vacuum tank age is 10 furnaces. RH vacuum steel production ends 26 minutes later, and the vacuum tank temperature is 1305°C.

[0015] (2) The top gun is in the standby position with the muzzle 8.94m away from the bottom of the tank, the ladle car is parked in the slag-melting position, and the nitrogen flow rate of the riser circulation gas is adjusted to 100Nm 3 / h.

[0016] (3) Set the top lance coke oven gas flow rate to 700 Nm 3 / h, oxygen blowing flow rate is 1400Nm 3 / h,.

[0017] (4) After the conditions are confirmed, start the operation. Carry out the coke oven gas and oxygen blowing operations: the top gun is lowered from the standby position to a position 8m from the bottom of the tank, and the coke oven gas blowing volume is 100Nm 3 , oxygen volume 200Nm 3 .

[0018] (5) Lower the gun position to blow coke oven gas and oxygen: the top gun is lowered from 8m to 5m from the bottom of the tank, and the coke oven gas volume is 60Nm 3 , oxygen volume 120Nm 3 .

[0019] (6) After the coke oven gas and oxygen are blown, the oxygen gun moves from the 5m position to the standby position where the gun mouth is 8.94m from the bottom of the tank. The total amount of coke oven gas is 160Nm 3 , total oxygen volume 320Nm 3; The nitrogen flow rate of the circulating gas is adjusted to 60Nm 3 / h.

[0020] (7) After observation and verification, the vacuum tank temperature was 1300°C and the residual steel in the vacuum tank was completely removed.

[0021] Example 2: This clean and efficient RH vacuum tank insulation and residual steel treatment method adopts the following process steps.

[0022] (1) Vacuum tank age 80 furnaces. RH vacuum steel production ended 35 minutes later, and the vacuum tank temperature was 1256°C.

[0023] (2) The top gun is in the standby position with the muzzle 8.94m away from the bottom of the tank, the ladle car is parked in the slag-melting position, and the nitrogen flow rate of the riser circulation gas is adjusted to 100Nm 3 / h.

[0024] (3) Set the top lance coke oven gas flow rate to 700 Nm 3 / h, oxygen blowing flow rate is 1400Nm 3 / h,.

[0025] (4) After the conditions are confirmed, start the operation. Carry out the coke oven gas and oxygen blowing operations: the top gun is lowered from the standby position to a position 8m from the bottom of the tank, and the coke oven gas volume is 150Nm 3 , oxygen volume 300Nm 3 .

[0026] (5) Lower the gun position to blow coke oven gas and oxygen: the top gun is lowered from 8m to 7m from the bottom of the tank, and the coke oven gas volume is 50Nm 3 , oxygen content 100Nm3.

[0027] (6) After the coke oven gas and oxygen are blown, the oxygen gun moves from the 7m position to the standby position where the gun mouth is 8.94m from the bottom of the tank. The total amount of coke oven gas is 200Nm 3 , total oxygen 400Nm 3 ; The nitrogen flow rate of the circulating gas is adjusted to 60Nm 3 / h.

[0028] (7) After observation and verification, the temperature of the vacuum tank was 1267°C and the residual steel in the vacuum tank was completely removed.

[0029] Example 3: This clean and efficient RH vacuum tank insulation and residual steel treatment method adopts the following process steps.

[0030] (1) Vacuum tank age 44 furnaces. RH vacuum steel production ended 55 minutes later, and the vacuum tank temperature was 1211°C.

[0031] (2) The top gun is in the standby position with the muzzle 8.94m away from the bottom of the tank, the ladle car is parked in the slag-melting position, and the nitrogen flow rate of the riser circulation gas is adjusted to 100Nm 3 / h.

[0032] (3) Set the top lance coke oven gas flow rate to 700 Nm 3 / h, oxygen blowing flow rate is 1400Nm 3 / h,.

[0033] (4) After the conditions are confirmed, start the operation. Carry out the coke oven gas and oxygen blowing operations: the top gun is lowered from the standby position to a position 8m from the bottom of the tank, and the coke oven gas blowing volume is 200Nm 3 , oxygen volume 400Nm 3 .

[0034] (5) Lower the gun position to blow coke oven gas and oxygen: the top gun is lowered from 8m to 6m from the bottom of the tank, and the coke oven gas volume is 30Nm 3 , oxygen content 60Nm 3 .

[0035] (6) After the coke oven gas and oxygen are blown, the oxygen gun moves from the 7m position to the standby position where the gun mouth is 8.94m from the bottom of the tank. The total amount of coke oven gas is 230Nm 3 , total oxygen 460Nm 3 ; The nitrogen flow rate of the circulating gas is adjusted to 60Nm 3 / h.

[0036] (7) After observation and verification, the vacuum tank temperature was 1235°C and the residual steel in the vacuum tank was completely removed.

[0037] Example 4: This clean and efficient RH vacuum tank insulation and residual steel treatment method adopts the following process steps.

[0038] (1) Vacuum tank age 62 furnaces. RH vacuum steel production ended 15 minutes later, and the vacuum tank temperature was 1311°C.

[0039] (2) The top gun is in the standby position with the muzzle 8.94m away from the bottom of the tank, the ladle car is parked in the slag-melting position, and the nitrogen flow rate of the riser circulation gas is adjusted to 100Nm 3 / h.

[0040] (3) Set the top lance coke oven gas flow rate to 700 Nm 3 / h, oxygen blowing flow rate is 1400Nm 3 / h,.

[0041] (4) After the conditions are confirmed, start the operation. Carry out the coke oven gas and oxygen blowing operations: the top gun is lowered from the standby position to a position 8m from the bottom of the tank, and the coke oven gas blowing volume is 100Nm 3, oxygen volume 200Nm 3 .

[0042] (5) Lower the gun position to blow coke oven gas and oxygen: the top gun is lowered from 8m to 5m from the bottom of the tank, and the coke oven gas volume is 30Nm 3 , oxygen content 60Nm 3 .

[0043] (6) After the coke oven gas and oxygen are blown, the oxygen gun moves from the 7m position to the standby position where the gun mouth is 8.94m from the bottom of the tank. The total amount of coke oven gas is 130Nm 3 , total oxygen 260Nm 3 ; The nitrogen flow rate of the circulating gas is adjusted to 60Nm 3 / h.

[0044] (7) After observation and verification, the vacuum tank temperature was 1310°C and the residual steel in the vacuum tank was completely removed.

[0045] Example 5: This clean and efficient RH vacuum tank insulation and residual steel treatment method adopts the following process steps.

[0046] (1) The age of the vacuum tank is 28 furnaces. RH vacuum steel production ended 43 minutes later, and the vacuum tank temperature was 1269°C.

[0047] (2) The top gun is in the standby position with the muzzle 8.94m away from the bottom of the tank, the ladle car is parked in the slag-melting position, and the nitrogen flow rate of the riser circulation gas is adjusted to 100Nm 3 / h.

[0048] (3) Set the top lance coke oven gas flow rate to 700 Nm 3 / h, oxygen blowing flow rate is 1400Nm 3 / h.

[0049] (4) After the conditions are confirmed, start the operation. Carry out the coke oven gas and oxygen blowing operations: the top gun is lowered from the standby position to a position 8m from the bottom of the tank, and the coke oven gas blowing volume is 145Nm 3 , oxygen content 290Nm 3 .

[0050] (5) Lower the gun position to blow coke oven gas and oxygen: the top gun is lowered from 8m to 5m from the bottom of the tank, with a coke oven gas volume of 40Nm3 and an oxygen volume of 80Nm 3 .

[0051] (6) After the coke oven gas and oxygen are blown, the oxygen gun moves from the 7m position to the standby position where the gun mouth is 8.94m from the bottom of the tank. The total amount of coke oven gas is 185Nm 3 , total oxygen 370Nm 3 ; The nitrogen flow rate of the circulating gas is adjusted to 60Nm 3 / h.

[0052] (7) After observation and verification, the vacuum tank temperature was 1275°C and the residual steel in the vacuum tank was completely removed.

[0053] Statistical case: The method was used to analyze the temperature of the vacuum tank and the removal of residual steel in the tank. A random sampling of 100 times revealed that each time the temperature of the vacuum tank was kept constant and slightly increased, and the residual steel in the tank was effectively and completely removed; the removal success rate reached 100%.

Claims

1. A clean and efficient RH vacuum tank insulation and residual steel treatment method, characterized by: After the last smelting heat is completed, a top gun is inserted into the vacuum tank and a mixture of coke oven gas and oxygen is blown into the vacuum tank. The mixture burns and releases heat in the vacuum tank to heat the vacuum tank to a temperature ≥1200°C, thereby melting the excess steel remaining on the refractory material on the inner wall of the vacuum tank.

2. A clean and efficient RH vacuum tank heat preservation and residual steel treatment method according to claim 1, characterized in that: The vacuum tank is processed within 1 hour after the last smelting is completed.

3. A clean and efficient RH vacuum tank heat preservation and residual steel treatment method according to claim 1, characterized in that: The top gun is inserted into the vacuum tank until the gun mouth is 8 to 5 meters away from the bottom of the vacuum tank.

4. A clean and efficient RH vacuum tank heat preservation and residual steel treatment method according to claim 1, characterized in that: The volume ratio of coke oven gas to oxygen in the mixed gas is 1:

2.

5. A clean and efficient RH vacuum tank heat preservation and residual steel treatment method according to any one of claims 1 to 4, characterized in that: The top gun blows coke oven gas at a speed of 700 Nm 3 / h, oxygen blowing speed is 1400Nm 3 / h.