RH refining method for reducing adhesion of cold steel in vacuum tank

Abstract

The invention discloses an RH (Ruhrstahl Heraeus) refining method for reducing adhesion of cold steel in a vacuum tank, which comprises the following steps: (1) in the RH vacuum decarburization process, if a natural decarburization process is adopted, when the vacuum degree in a furnace reaches 300 mbar and below, executing the following secondary combustion operation: controlling the oxygen blowing flow of a top lance to be 500-900 Nm < 3 > / h, the lance position to be 800-900 cm and the time to be 180-360 s; if an oxygen blowing decarburization process is adopted, after oxygen blowing decarburization is finished, the following secondary combustion operation is executed: the oxygen flow of a top lance is controlled to be 200-400 Nm < 3 > / h, the lance position is 800-900 cm, and the time is 180-360 s; and (2) after the secondary combustion operation is finished, executing the following small-flow coal oxygen combustion operation: lifting the lance position of the top lance to 900-1100cm, controlling the coke oven gas flow of the top lance to be 100-300Nm < 3 > / h, and operating for the time until the RH smelting is finished. The method can reduce the adhesion of cold steel in the vacuum tank and improve the cleanliness of molten steel.

Description

Technical Field

[0001] The invention relates to an RH refining method, in particular to an RH refining method for reducing cold steel adhesion in a vacuum tank. Background Art

[0002] In the smelting process of low-carbon and ultra-low-carbon steel, RH is a commonly used refining process, which can achieve multiple functions such as decarburization, degassing, uniform composition and temperature, and removal of inclusions.

[0003] As the RH processing volume continues to increase, the cold slag in the RH vacuum tank continues to increase, and the cold slag adheres to the inner wall of the vacuum tank and the hot bend pipe. Excessive accumulation of slag at the hot bend pipe will not only reduce the life of the hot bend pipe, but also lead to insufficient RH vacuum pumping capacity, thus affecting the efficient production of RH. At the same time, during the RH smelting process, the slag adhered to the inner wall of the vacuum tank and the hot bend pipe may fall off irregularly, causing abnormal temperature and composition of the molten steel, resulting in quality loss.

[0004] In the prior art, the lower part of the vacuum tank is generally heated and slag-melted by top gun coal-oxygen combustion between pouring times, but the improvement effect on the upper part of the vacuum tank and the hot-bent pipe part is not obvious. In addition, the cold steel that falls off the bottom of the vacuum tank will affect the composition of the next batch of molten steel.

[0005] Therefore, the art urgently needs a smelting method that can effectively reduce the cold slag in the RH vacuum tank and hot-bent pipe and improve the RH production quality and production efficiency. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a high-quality and efficient RH refining method for reducing cold steel adhesion in a vacuum tank.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention includes the following steps:

[0008] (1) During the RH vacuum decarburization process, if the natural decarburization process is used, when the vacuum degree in the furnace reaches 300 mbar or below, perform the following secondary combustion operation: control the oxygen flow rate of the top gun to 500-900 Nm 3 / h, gun position is 800-900cm, time is 180s-360s;

[0009] If oxygen blowing decarburization process is adopted, after oxygen blowing decarburization is completed, the following secondary combustion operation is performed: control the oxygen flow rate of the top gun to 200~400Nm 3 / h, gun position is 800-900cm, time is 180s-360s;

[0010] (2) After the secondary combustion operation is completed, the following small-flow coal-oxygen combustion operation is performed: the top gun position is raised to 900-1100 cm, and the top gun coke oven gas flow rate is controlled to 100-300 Nm 3 / h, the operation time is until the end of RH smelting;

[0011] (3) After the RH smelting is completed, the following high-flow coal-oxygen combustion operation is performed: the top gun position is continuously adjusted between 600 and 1100 cm, and the top gun coke oven gas flow is controlled to 300 to 500 Nm 3 / h.

[0012] Furthermore, in step (2), the oxygen-to-coal ratio is controlled within the range of 1.0 to 1.2.

[0013] Furthermore, in step (3), the oxygen-to-coal ratio is controlled at 1.2 to 1.4.

[0014] The beneficial effects of the above technical solution are as follows: the present invention reduces the temperature drop of molten steel during RH refining by controlling the top gun position and the proportion of the gas flow rate, and utilizes secondary combustion and coal-oxygen combustion technology, thereby increasing the temperature of the refractory material in the vacuum tank, reducing the adhesion of cold steel in the vacuum tank, and reducing the offline maintenance time of the vacuum tank and the hot-bending pipe, thereby improving production efficiency and reducing the labor intensity of workers. Production efficiency is improved while ensuring the cleanliness of molten steel. The present invention solves the problems of low production efficiency and poor cleanliness of molten steel caused by cold steel slag in the vacuum tank and the hot-bending pipe in the RH process, and improves production efficiency while improving the cleanliness of molten steel, with significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0016] Figure 1 It is a schematic diagram of the process structure of the present invention. DETAILED DESCRIPTION

[0017] Figure 1 As shown, the RH refining method for reducing cold steel adhesion in a vacuum tank is applicable to steel grades that require RH treatment for decarburization, especially ultra-low carbon steel, and adopts the following steps:

[0018] (1) Secondary combustion operation: During the RH vacuum decarburization process, the secondary combustion operation is performed, that is, by controlling the top gun position and oxygen blowing flow rate, the secondary combustion heat release of carbon monoxide generated by the decarburization reaction is used to increase the refractory temperature at the vacuum tank and the hot bend.

[0019] RH enters the station and evacuates the vacuum. According to the carbon and oxygen content entering the station, it is determined whether to adopt natural decarburization or oxygen blowing decarburization process:

[0020] If [O]-0.7[C] in the incoming molten steel is greater than 300ppm, a natural decarburization process is adopted; if [O]-0.7[C] in the incoming molten steel is less than 300ppm, an oxygen blowing decarburization process is adopted; the [O] is the mass percentage of oxygen in the molten steel, and [C] is the mass percentage of carbon in the molten steel.

[0021] (1.1) If the natural decarburization process is adopted, when the vacuum degree in the furnace reaches 300mbar or below, the secondary combustion operation is immediately performed; the secondary combustion operation process is: control the oxygen flow rate of the top gun to 500~900Nm 3 / h, the gun position is 800-900cm, and the time is 180s-360s; preferably, during the secondary combustion operation, the oxygen flow rate of the top gun is gradually reduced; it is best to adopt the following secondary combustion operation process according to the incoming carbon;

[0022] When the inlet carbon is ≤0.025wt%, the secondary combustion operation process is best controlled as follows: gun position 900cm; top gun oxygen flow rate 700Nm 3 / h spray for 60s, then top gun blow oxygen flow rate 600Nm 3 / h spraying for 60s, and finally the top gun blowing oxygen flow rate is 500Nm 3 / h spraying for 60s.

[0023] When 0.025wt%<incoming carbon<0.035wt%, the secondary combustion operation process is best controlled as follows: gun position 900cm; top gun oxygen flow 800Nm 3 / h spray for 60s, then top gun oxygen blowing flow rate 700Nm 3 / h spraying for 60s, and finally the top gun blowing oxygen flow rate is 600Nm 3 / h spraying for 60s.

[0024] When the inlet carbon is ≥0.035wt%, the secondary combustion operation process is best controlled as follows: gun position 900cm; top gun oxygen flow 900Nm 3 / h spray for 60s, then top gun blow oxygen flow rate 800Nm 3 / h spraying for 60s, and finally the top gun blowing oxygen flow rate is 700Nm 3 / h spraying for 60s.

[0025] (1.2) If the oxygen blowing decarburization process is adopted, the secondary combustion operation shall be performed immediately after the oxygen blowing decarburization is completed; the secondary combustion operation process is: control the oxygen flow rate of the top gun to 200~400Nm 3 / h, the gun position is 800-900cm, and the time is 180s-360s. Preferably, during the secondary combustion operation, the oxygen flow rate of the top gun is gradually reduced; it is best to use the following secondary combustion operation parameters: gun position 900cm; top gun oxygen flow rate 400Nm 3 / h spray for 60s, then top gun blow oxygen flow rate 300Nm 3 / h spraying for 60s, and finally the top gun blowing oxygen flow rate is 200Nm 3 / h spraying for 60s.

[0026] The technical principle of the secondary combustion operation is: according to the relationship between the carbon and oxygen content of the inlet station, the natural decarburization or oxygen blowing decarburization process is selected. Then, the relationship curve between the real-time volume flow rate of carbon monoxide and time after the decarburization reaction is established through the data obtained by the RH flue gas analyzer;

[0027] The real-time volume flow rate of carbon monoxide is calculated as follows:

[0028] CO V =CO m / ρ CO =Q·CO% / ρ CO (I);

[0029] Where:

[0030] CO V : Carbon monoxide volume flow rate, Nm 3 / h;

[0031] CO m : Carbon monoxide mass flow rate, kg / h;

[0032] ρ CO : Carbon monoxide density, kg / Nm 3 , 1.250kg / Nm under standard conditions 3 ;

[0033] Q: exhaust gas mass flow rate, kg / h;

[0034] CO%: gas concentration of CO in exhaust gas, vol%.

[0035] After statistical analysis of more than 3,000 furnaces, it was found that:

[0036] During natural decarburization, the CO volume flow rate in the vacuum tank drops to 100 Nm after 3 to 6 minutes. 3 / h. If oxygen is blown for secondary combustion afterwards, the oxygen content in the molten steel will increase. At the same time, the CO volume flow rate in the vacuum tank is closely related to the carbon content entering the station.

[0037] During forced oxygen decarburization, the CO volume flow rate in the vacuum tank drops to 100 Nm2 to 5 minutes after the oxygen decarburization is completed. 3 / h. If oxygen is blown for secondary combustion thereafter, the oxygen content in the molten steel will increase. At the same time, during the oxygen blowing decarburization process, the carbon monoxide produced meets the oxygen in the top gun and undergoes a partial secondary combustion first. Therefore, after the oxygen blowing is completed, the CO volume flow rate in the vacuum tank is less than that during natural decarburization.

[0038] (2) Small flow coal-oxygen combustion operation: After the secondary combustion operation is completed, the small flow coal-oxygen combustion operation is immediately performed, that is, the top gun position is raised, the flow of oxygen and coke oven gas in the top gun is controlled, and the heat released by coal-oxygen combustion is used to increase the refractory temperature at the vacuum tank and the hot bend pipe.

[0039] The small flow coal oxygen combustion operation process is as follows: after the secondary combustion operation is completed, the top gun position is raised to 900-1100cm, and the top gun coke oven gas flow is controlled to 100-300Nm 3 / h, in order to avoid excessive oxygen entering the molten steel and ensure the complete combustion and consumption of oxygen, the oxygen-coal ratio is controlled at 1.0-1.2, and the operation time is until the end of RH smelting. During the small-flow coal-oxygen combustion operation, if oxygen blowing and heating operation is required during the period, oxygen blowing and heating are performed as required, and then the small-flow coal-oxygen combustion operation is continued. It is best to adopt the following small-flow coal-oxygen combustion operation: the top gun position is raised to 1050cm, and the top gun coke oven gas flow is controlled to 200Nm 3 / h, and the oxygen-coal ratio is controlled at 1.1. The oxygen-coal ratio is: O2 flow / coal gas flow.

[0040] The technical principle of the small-flow coal-oxygen combustion operation is as follows: the small-flow coal-oxygen combustion operation utilizes the heat released by the combustion of coke oven gas to increase the temperature of the refractory in the RH vacuum tank. During the small-flow coal-oxygen combustion operation, the gun is located in the center area of ​​the hot-bending pipe. While increasing the temperature of the upper part of the vacuum tank and the refractory of the hot-bending pipe, it is away from the molten steel surface to avoid oxygenation of the molten steel. During the operation of the vacuum tank, the temperature inside is relatively high, above 1300°C. The heat released by the small-flow coal-oxygen combustion can ensure the temperature near the hot-bending pipe and reduce the cold steel in the hot-bending pipe and the upper part of the vacuum tank. In addition, to further ensure that there is no oxygenation in the molten steel, the oxygen-coal ratio is controlled at 1.0 to 1.2 so that the oxygen is completely burned and consumed.

[0041] (3) High-flow coal-oxygen combustion operation: between furnaces, high-flow coal-oxygen combustion operation is performed immediately, that is, by controlling the position of the top gun, the flow of oxygen and coke oven gas in the top gun, and utilizing the heat released by coal-oxygen combustion to increase the refractory temperature at the vacuum tank and hot bend pipe.

[0042] The high-flow coal-oxygen combustion operation process is as follows: after the RH smelting is completed, the top gun position is controlled to be continuously adjusted between 600 and 1100 cm, and the height is changed at a certain interval; the top gun coke oven gas flow is controlled to be 300 to 500 Nm 3 / h; to provide maximum heat and ensure complete combustion and consumption of coke oven gas, the oxygen-coal ratio is controlled at 1.2-1.4; the operation time is from the end of the current furnace smelting to the start of the next furnace. Preferably, the top gun position adjustment process during the large-flow coal-oxygen combustion operation is: according to the furnace interval time, every 180-600s, the gun position is raised or lowered by 50-200cm to ensure the uniformity of the refractory temperature in the vacuum tank.

[0043] It is best to use the following high-flow coal-oxygen combustion operation process according to single or double stations;

[0044] If it is single-station RH smelting, refer to the steps described in Table 1 to perform high-flow coal-oxygen combustion operation;

[0045] Table 1: High flow coal-oxygen combustion parameters for single-station RH smelting

[0046] step <![CDATA[O2 flow rate Nm 3 / h]]> <![CDATA[COG flow rate Nm 3 / h]]> Gun position cm Time 1 540 400 650 300 2 540 400 800 300 3 540 400 950 300 4 270 200 1000 Until the next furnace smelting begins

[0047] If it is a double-station RH smelting, refer to the steps described in Table 2 to perform high-flow coal-oxygen combustion operation;

[0048] Table 2: High flow coal-oxygen combustion parameters for double-station RH smelting

[0049] step <![CDATA[O2 flow rate Nm 3 / h]]> <![CDATA[COG flow Nm 3 / h]]> Gun position cm Time 1 540 400 600 600 2 540 400 800 600 3 540 400 900 600 4 540 400 850 600 5 540 400 750 600 6 540 400 650 600 7 270 200 1000 Until the next furnace smelting begins

[0050] In Table 1 and Table 2, the COG flow rate is the coke oven gas flow rate.

[0051] The technical principle of the large-flow coal-oxygen combustion operation is as follows: the large-flow coal-oxygen combustion operation also utilizes the heat released by the combustion of coke oven gas to increase the temperature of the refractory in the RH vacuum tank. In the interval between furnaces, in order to ensure that the temperature of the refractory in the vacuum tank remains above 1200°C, a large-flow coal-oxygen combustion operation is performed. During this period, the gun position is continuously adjusted to ensure the uniformity of the temperature in the vacuum tank; in order to provide maximum heat and ensure the complete combustion and consumption of the coke oven gas, the oxygen-coal ratio is controlled at 1.2 to 1.4; its operation time depends on the interval between RH furnaces. It can avoid cracking and spalling of refractory materials caused by rapid cooling and heating, so as not to affect the life of the refractory materials and the RH operating rate.

[0052] Embodiment 1:

[0053] During the smelting of a certain heat of ultra-low carbon steel, the ladle enters the station, the bottom blowing is turned on, the ladle is transported to the lifting waiting position, the circulating gas is switched to argon, and the ladle is lifted to the processing position for temperature measurement, sampling, and oxygen determination operations.

[0054] The inlet temperature is 1638℃, the inlet carbon content is 0.030wt%, the oxygen content is 600ppm, [O]-0.7[C]=600-0.7×300=390>300ppm, and the natural decarburization process is selected. Pre-vacuum, the top gun is lowered to 900cm, vacuumed to 300mbar, and the secondary combustion operation is performed. The top gun starts blowing oxygen, and the flow rate is 800Nm 3 / h oxygen blowing 60s, flow rate 700Nm 3 / h oxygen blowing 60s, flow rate 600Nm 3 / h oxygen blowing for 60s.

[0055] After the secondary combustion oxygen blowing is completed, the gun position is raised to 1050cm, and a small flow coal-oxygen combustion operation is performed, with an oxygen flow rate of 220Nm 3 / h, coke oven gas flow rate 200Nm 3 After decarburization, the temperature and oxygen are measured. The temperature of the molten steel is 1612℃, and there is no need to blow oxygen to increase the temperature. The small flow rate coal oxygen combustion operation is carried out until the furnace treatment is completed.

[0056] After RH smelting is completed, high-flow coal-oxygen combustion operation is performed. RH is a single-station smelting, the next furnace entry time is about 15 minutes, the top gun position is reduced to 650cm, and the top gun coke oven gas flow is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 300s; the top gun position is raised to 800cm, and the top gun coke oven gas flow rate is 400Nm3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 300s; the top gun position is raised to 950cm, and the top gun coke oven gas flow rate is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 250s; the next batch of smelting enters the station and starts.

[0057] Embodiment 2:

[0058] During the smelting of a certain heat of ultra-low carbon steel, the ladle enters the station, the bottom blowing is turned on, the ladle is transported to the lifting waiting position, the circulating gas is switched to argon, and the ladle is lifted to the processing position for temperature measurement, sampling, and oxygen determination operations.

[0059] The inlet temperature is 1601℃, the inlet carbon content is 0.045wt%, the oxygen content is 300ppm, [O]-0.7[C]=300-0.7×450=-15<300ppm, and the oxygen blowing decarburization process is selected. Pre-vacuum, the top gun is lowered to 600cm, vacuumed to 300mbar, and oxygen blowing decarburization operation is performed. After the oxygen blowing decarburization is completed, the secondary combustion operation is performed, the top gun is raised to 900cm, and the top gun starts to blow oxygen, with a flow rate of 400Nm 3 / h oxygen blowing 60s, flow rate 300Nm 3 / h oxygen blowing 60s, flow rate 200Nm 3 / h oxygen blowing for 60s.

[0060] After the secondary combustion oxygen blowing is completed, the gun position is raised to 1050cm, and a small flow coal-oxygen combustion operation is performed, with an oxygen flow rate of 220Nm 3 / h, coke oven gas flow rate 200Nm 3 / h. After decarburization, the temperature is measured and oxygen is determined. The temperature of the molten steel is 1580℃. Oxygen blowing is required to increase the temperature. Aluminum is added as required to increase the temperature. After the temperature is increased and oxygen is blown, the small flow rate coal-oxygen combustion operation is continued until the furnace treatment is completed.

[0061] After RH smelting is completed, high-flow coal-oxygen combustion operation is performed. RH is a single-station smelting, the next furnace entry time is about 15 minutes, the top gun position is reduced to 650cm, and the top gun coke oven gas flow is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 300s; the top gun position is raised to 800cm, and the top gun coke oven gas flow rate is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 300s; the top gun position is raised to 950cm, and the top gun coke oven gas flow rate is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 300s; the top gun position is raised to 1000cm, and the top gun coke oven gas flow rate is 200Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 80s; the next furnace enters the station and the next furnace smelting begins.

[0062] Embodiment 3:

[0063] During the smelting of a certain heat of ultra-low carbon steel, the ladle enters the station, the bottom blowing is turned on, the ladle is transported to the lifting waiting position, the circulating gas is switched to argon, and the ladle is lifted to the processing position for temperature measurement, sampling, and oxygen determination operations.

[0064] The inlet temperature is 1642℃, the inlet carbon content is 0.023wt%, the oxygen content is 550ppm, [O]-0.7[C]=550-0.7×230=389>300ppm, and the natural decarburization process is selected. Pre-vacuum, the top gun is lowered to 900cm, vacuumed to 300mbar, and the secondary combustion operation is performed. The top gun starts blowing oxygen, and the flow rate is 700Nm 3 / h oxygen blowing 60s, flow rate 600Nm 3 / h oxygen blowing 60s, flow rate 500Nm 3 / h oxygen blowing for 60s.

[0065] After the secondary combustion oxygen blowing is completed, the gun position is raised to 1050cm, and a small flow coal-oxygen combustion operation is performed, with an oxygen flow rate of 220Nm 3 / h, coke oven gas flow rate 200Nm 3 After decarburization, the temperature and oxygen are measured. The temperature of the molten steel is 1624℃. There is no need to blow oxygen to increase the temperature. The small flow rate coal oxygen combustion operation is carried out until the furnace treatment is completed.

[0066] After RH smelting is completed, high-flow coal-oxygen combustion operation is performed. RH is a double-station smelting, the next furnace entry time is about 60 minutes, the top gun position is lowered to 600cm, and the top gun coke oven gas flow is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 600s; the top gun position is raised to 800cm, and the top gun coke oven gas flow rate is 400Nm3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 600s; the top gun position is raised to 900cm, and the top gun coke oven gas flow rate is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 600s; the top gun position is reduced to 850cm, and the top gun coke oven gas flow rate is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 600s; the top gun position is reduced to 750cm, and the top gun coke oven gas flow rate is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 600s; the top gun position is lowered to 650cm, and the top gun coke oven gas flow rate is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 520s; the next furnace enters the station and the next furnace smelting begins.

[0067] Embodiment 4:

[0068] During the smelting of a certain heat of ultra-low carbon steel, the ladle enters the station, the bottom blowing is turned on, the ladle is transported to the lifting waiting position, the circulating gas is switched to argon, and the ladle is lifted to the processing position for temperature measurement, sampling, and oxygen determination operations.

[0069] The inlet temperature is 1641℃, the inlet carbon content is 0.038wt%, the oxygen content is 570ppm, [O]-0.7[C]=570-0.7×380=304>300ppm, and the natural decarburization process is selected. Pre-vacuum, the top gun is lowered to 900cm, vacuumed to 300mbar, and the secondary combustion operation is performed. The top gun starts blowing oxygen, and the flow rate is 900Nm 3 / h oxygen blowing 60s, flow rate 800Nm 3 / h oxygen blowing 60s, flow rate 700Nm 3 / h oxygen blowing for 60s.

[0070] After the secondary combustion oxygen blowing is completed, the gun position is raised to 1050cm, and a small flow coal-oxygen combustion operation is performed, with an oxygen flow rate of 220Nm 3 / h, coke oven gas flow rate 200Nm 3 After decarburization, the temperature and oxygen are measured. The temperature of the molten steel is 1615℃. There is no need to blow oxygen to increase the temperature. The small flow rate coal oxygen combustion operation is carried out until the furnace treatment is completed.

[0071] After RH smelting is completed, high-flow coal-oxygen combustion operation is performed. RH is a double-station smelting, the next furnace entry time is about 55 minutes, the top gun position is reduced to 650cm, and the top gun coke oven gas flow is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 600s; the top gun position is raised to 850cm, and the top gun coke oven gas flow rate is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 600s; the top gun position is raised to 950cm, and the top gun coke oven gas flow rate is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 600s; the top gun position is lowered to 800cm, and the top gun coke oven gas flow rate is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 600s; the top gun position is lowered to 700cm, and the top gun coke oven gas flow rate is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 600s; the top gun position is lowered to 600cm, and the top gun coke oven gas flow rate is 400Nm 3 / h, the coal-oxygen ratio is 1.35, and the coal-oxygen combustion heating at this gun position is 350s; the next batch of smelting enters the station and starts.

[0072] After the implementation of this method, the service life of the hot-bent pipe was increased from 800 furnaces to 1500 furnaces, the phenomenon of cold slag in the vacuum chamber and the hot-bent pipe was effectively controlled, and the proportion of abnormal furnaces with RH refining carbon content exceeding the upper limit was reduced by 83%. This method provides a strong guarantee for high-quality and efficient production of RH refining.

Claims

1. A RH refining method for reducing cold steel adhesion in a vacuum tank, characterized in that: The steps include: (1) During the RH vacuum decarburization process, if the natural decarburization process is used, when the vacuum degree in the furnace reaches 300 mbar or below, perform the following secondary combustion operation: control the oxygen flow rate of the top gun to 500-900 Nm 3 / h, gun position is 800-900cm, time is 180s-360s; If oxygen blowing decarburization process is adopted, after oxygen blowing decarburization is completed, the following secondary combustion operation is performed: control the oxygen flow rate of the top gun to 200~400Nm 3 / h, gun position is 800-900cm, time is 180s-360s; (2) After the secondary combustion operation is completed, the following small-flow coal-oxygen combustion operation is performed: the top gun position is raised to 900-1100 cm, and the top gun coke oven gas flow rate is controlled to 100-300 Nm 3 / h, operation time until the end of RH smelting; (3) After the RH smelting is completed, the following high-flow coal-oxygen combustion operation is performed: the top gun position is continuously adjusted between 600 and 1100 cm, and the top gun coke oven gas flow is controlled at 300 to 500 Nm 3 / h.

2. The RH refining method for reducing cold steel adhesion in a vacuum tank according to claim 1, characterized in that: In the step (2), the oxygen-to-coal ratio is controlled at 1.0 to 1.

2.

3. A RH refining method for reducing cold steel adhesion in a vacuum tank according to claim 1 or 2, characterized in that: In the step (3), the oxygen-to-coal ratio is controlled at 1.2 to 1.4.

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