A method for maintaining the lining of a converter in a low-slag smelting mode

Abstract

The present application belongs to the technical field of steel smelting, and particularly discloses a furnace lining maintenance method under a converter slag-less smelting mode, which comprises optimized smelting process control and optimized slag splashing and furnace protection control; the optimized smelting process control comprises control of two stages of a smelting early stage and a smelting middle stage, wherein the control of the smelting early stage comprises slag form control and smelting raw material loading dynamic adjustment, and the control of the smelting middle stage comprises smelting gun position control and tapping temperature control; and the optimized slag splashing and furnace protection control comprises slag splashing gun position operation control and reasonable slag splashing time control. The present application performs slag splashing and furnace protection operation under a slag-less smelting process mode, and respectively performs process control in a smelting process stage and a slag splashing and furnace protection stage; the smelting stage provides high-viscosity slag for a slag splashing and furnace protection operation process, and through control of a gun position operation mode in a slag splashing process and reasonable specification of a slag splashing time, the slag is effectively attached to a furnace wall, thereby protecting the furnace lining and prolonging the service life of the furnace lining.

Description

Technical Field

[0001] This invention relates to the field of iron and steel smelting technology, and specifically to a furnace lining maintenance method under a converter slag-free smelting mode. Background Technology

[0002] Low-slag steelmaking, also known as converter steelmaking, is a steelmaking process that minimizes the total amount of slag produced during converter smelting. The main purpose of adding slag in low-slag steelmaking is to protect the furnace lining, cover the molten steel, and reduce metal splashing.

[0003] Converter slag consumption is usually high, while slag consumption is low in the low-slag smelting process mode. Slag retention is adopted, which effectively slags during smelting and retains slag after tapping, using the slag to maintain the furnace lining.

[0004] In existing technologies, even after optimizing converter slag formation, oxygen supply, temperature, and tapping processes to reduce converter slag consumption, the optimization of the slag splashing process for furnace protection has lagged behind, resulting in problems such as difficulty in slag splashing and slag adhesion to the furnace wall. These problems mainly involve poor slag morphology, low viscosity, and difficulty in adhering to the furnace wall. The slag splashing process is also prolonged, leading to poor adhesion of the slag to the furnace wall. Prolonged slag splashing also increases the erosion and scouring of the furnace lining bricks by high-temperature slag, causing furnace lining deterioration and shortening its lifespan. The slag splashing operation not only fails to protect the furnace lining but also affects the steelmaking cycle. Summary of the Invention

[0005] The purpose of this invention is to provide a furnace lining maintenance method under the low-slag smelting mode of a converter, in order to solve the problem in the prior art that, under the low-slag smelting process mode, due to the small amount of slag and the difficulty in slag formation during smelting, the final slag morphology is not conducive to slag splashing. At the same time, the slag splashing stage is long and ineffective, and it is difficult to effectively adhere the slag to the furnace wall. This makes it difficult to effectively maintain the furnace lining through slag splashing furnace protection operation, thereby indirectly shortening the service life of the furnace lining.

[0006] To achieve the above objectives, the basic solution provided by this invention is: a furnace lining maintenance method under a converter slag-less smelting mode, including optimized smelting process control and optimized slag splashing furnace protection control. The optimized smelting process control includes control in two stages: the early stage of smelting and the middle stage of smelting. The control in the early stage of smelting includes slag morphology control and dynamic adjustment of smelting raw material charging. The control in the middle stage of smelting includes smelting lance position control and tapping temperature control. The optimized slag splashing furnace protection control includes slag splashing lance position operation control and reasonable control of slag splashing time.

[0007] The principle and beneficial effects of this invention are as follows: This invention performs slag splashing furnace protection operation under the low-slag smelting process mode. In order to ensure slag quality and slag splashing effect, process control is carried out in the smelting process stage and the slag splashing furnace protection stage, and the angles such as raw material charging amount, lance position height during smelting and steel tapping temperature are optimized to ensure the smooth slag formation process and thus obtain good final slag conditions. In the smelting stage, high-viscosity slag is provided for the slag splashing furnace protection operation. By controlling the lance position operation mode and reasonably standardizing the slag splashing time during the slag splashing stage, it is ensured that the slag can effectively adhere to the furnace wall under the low-slag smelting process mode, thereby protecting the furnace lining and extending the service life of the furnace lining.

[0008] Option 2, which is a preferred option of the basic option, involves controlling the slag morphology as follows: 28 kg / t of lime is added to the converter, nitrogen is injected into the bottom of the converter and vigorously stirred; by controlling the amount of lime added, excessive lime addition is avoided to prevent an increase in FeO concentration, thus ensuring the slag-forming effect and indirectly controlling the FeO concentration.

[0009] Option 3, which is a preferred option of the basic option, is as follows: the method for dynamically adjusting the smelting raw material loading is as follows: dynamically adjust the amount of molten iron added, maintain the average temperature of the added molten iron at 1376℃, and control the Si content in the molten iron to be no higher than 0.8% and the Mn content in the molten iron to be no higher than 0.7%.

[0010] By optimizing the charging process in the early stages of smelting, heat balance is ensured. Based on the current conditions of molten iron and scrap steel, the heat balance is calculated, and the charging amounts of molten iron and scrap steel are adjusted in a timely manner according to the Si and Mn content of the molten iron to ensure heat balance, avoid excess heat, eliminate the need for blindly adding lime to cool down, and save costs.

[0011] Option 4, which is the preferred option of the basic option, is as follows during the middle stage of smelting: the position of the oxygen lance is adjusted reasonably during oxygen blowing. In the early stage of blowing, the height of the oxygen lance is controlled at 1.40m. During the blowing process, the slag formation is observed in real time and the size of the splashes at the furnace mouth is observed. During this process, the oxygen lance is lowered to 1.35m. When the slag is dried, the oxygen lance position is raised by 0.05-0.15m. In the late stage of blowing, the oxygen lance is lowered to the final position of 1.30m to ensure the lance pressing time, which is not less than 45s.

[0012] Increasing the FeO content during the blowing process helps to form slag quickly. By adjusting the oxygen lance position during the smelting process as described above, the FeO content can be increased and controlled at 21%-24%, ensuring rapid slag formation.

[0013] Option 5, which is the preferred option of Option 4, adopts the "constant pressure, variable lance" operation mode during the oxygen lance blowing process, and sets the bottom blowing pressure in the early stage, middle stage and late stage of blowing to 1.25-1.3 MPa, 1.3-1.35 MPa and 1.35-1.4 MPa respectively.

[0014] The traditional "variable lance, variable pressure" operation mode is easily limited by the operator's skill level, resulting in poor slag formation during oxygen lance blowing and causing phenomena such as slag overflow, splashing, and re-drying during smelting. By using the "constant pressure, variable lance" operation mode, while ensuring uniform stirring of the molten pool, it is possible to achieve early slag formation in the early stage, good slag formation in the middle stage, and thorough slag formation in the later stage, further reducing the slag-forming material to 18 kg / t.

[0015] Option 6, which is an optimal choice of Option 4, involves adding 300-500 kg of steel particles to each furnace in the early stage of blowing. The addition of steel particles reduces the surface activity of the slag and facilitates the discharge of CO gas from the converter.

[0016] Option 7, a preferred option of the basic option, describes the following method for controlling the tapping temperature: The tapping temperature is controlled at 1620-1645℃. When the tapping temperature exceeds 1660℃, the viscosity of the slag solution drops sharply, accelerating the damage to the furnace lining and significantly reducing its lifespan. By lowering the tapping temperature to 1620-1645℃, the average tapping temperature is maintained at around 1640℃. This lower temperature reduces the expansion stress generated by the furnace lining during heating, and the high temperature in the reaction zone softens and melts the furnace lining surface, slowing down lining damage, effectively reducing lining erosion, and simultaneously reducing slag consumption during smelting, thus improving furnace lining lifespan.

[0017] Option 8, a preferred option of the basic option, includes three gun position operation modes in the method for controlling the slag splash gun position:

[0018] Mode 1: High gun position operation, slag splash gun position is 1.4-1.7m;

[0019] Mode 2: Low gun position operation, slag splash gun position 0.9-1.1m;

[0020] Mode 3: Normal gun position operation, slag splash gun position 1.1-1.4m;

[0021] When the furnace bottom drops to a height of 100-300cm, it is too low. In this case, use mode one for gun position operation. When the furnace bottom rises to a height of 400-500cm, it is too high. In this case, use mode two for gun position operation. When the furnace bottom is at a height of 300-400cm, it is at a normal height. Use mode three for gun position operation.

[0022] During slag splashing, a variable lance position operation is adopted. At the beginning of slag splashing, the oxygen lance position is controlled at a higher level. As the slag volume and slag temperature decrease, the lance position can be appropriately lowered. This ensures that the slag is splashed up and adheres to the furnace wall in large quantities to protect the furnace lining.

[0023] Option 9, which is a preferred option of the basic option, is as follows: the slag splashing time is reasonably controlled to be no less than 2.5 minutes, and nitrogen is injected into the slag at the bottom of the furnace for 2 minutes; when the slag splashing time is about 2.5 minutes, a large amount of slag is splashed up, and the splashing height can reach the furnace cap. After observation, the slag adhesion of the furnace lining is good at about 2.5 minutes of slag splashing.

[0024] Option 10, which is the preferred option of Option 7, involves adding 28-30 tons of scrap steel to the converter in the early stage of smelting. The iron-adding speed is controlled at 1800 kg / s in the first 20 seconds of iron-adding. When the Fe0 concentration in the slag drops to 5.48% 4 seconds after the start of iron-adding, the iron-adding speed is restored to 2377.6 kg / s.

[0025] In the initial stage of molten iron addition, the molten iron is added slowly, reducing the initial addition speed to 1800 kg / s. This not only prevents smoke and splashing when the molten iron is added to the converter, but also effectively ensures that the smelting cycle time is not too long. Detailed Implementation

[0026] The present invention will be further described in detail below through specific embodiments:

[0027] A furnace lining maintenance method under a converter slag-less smelting mode includes optimized smelting process control and optimized slag splashing furnace protection control. Optimized smelting process control includes control in two stages: the early stage of smelting and the middle stage of smelting. The control in the early stage of smelting includes slag morphology control and dynamic adjustment of smelting raw material charging. The control in the middle stage of smelting includes smelting lance position control and tapping temperature control.

[0028] In the low-slag smelting process, a single-slag operation mode is adopted. After the slag retention operation of the previous furnace, scrap steel and molten iron are added to the converter for a new furnace smelting operation. Due to the unstable iron ore grade, high Si, Mn, and S content in the molten iron, and unstable temperature of various components in the molten iron, especially the fluctuation of Si and Mn content, which can easily lead to heat imbalance in the converter, a dynamic adjustment method of smelting raw material charging is adopted to ensure heat balance in the furnace, taking into account the molten iron conditions and raw material conditions.

[0029] Table 1. Data on the Dynamic Loading of Raw Materials

[0030]

[0031] Table 2. Raw Material Dynamic Loading Benchmark Data

[0032]

[0033] When the calorific value (calculated according to the industry's method for calculating the physicochemical parameters of molten iron) is low, the amount of molten iron added and the proportion of scrap steel should be adjusted in a timely manner to avoid the corrosion of the furnace lining by oxidized molten steel due to low calorific value. In particular, the Si content in the molten iron should be controlled to be no higher than 0.8%, and the Mn content in the molten iron should be no higher than 0.7%.

[0034] Table 2 shows that during steelmaking under the low-slag smelting industrial mode, adding 100 kg of scrap steel lowers the converter temperature by 1°C, with zero oxygen consumption; adding 100 kg of internal scrap steel lowers the converter temperature by 2°C, with zero oxygen consumption; and adding 100 kg of pig iron increases the converter temperature by 0.5°C, with 0.93 m³ of oxygen consumed. 3 For every 0.1% increase in the C, Si, and Mn content in the molten iron, the converter temperature increases by 12℃, 24℃, and 6.6℃ respectively, and the oxygen consumption increases by 0.93m³ / s. 3 0.8m 3 and 0.2m 3 Similarly, when 100 kg of ore, limestone, lime, lightly calcined magnesia balls, dolomite, and coke are added to the converter, the converter temperature increases or decreases as shown in Table 2.

[0035] According to Table 1, under the low-slag smelting process mode, the total loading of molten iron, internal scrap steel, scrap steel and pig iron in the raw materials for steelmaking is 81t, 5t, 15t and 8t respectively. The temperature of molten iron is controlled at 1376℃. The proportions of C, Si and Mn in molten iron are 4.41%, 0.51% and 0.64% respectively.

[0036] The oxygen supply flow rate was maintained at 26,000 m³ / h throughout the entire smelting process. 3 / h, during the oxygen lance blowing process, at the end of blowing, the contents of C, Si, and Mn in the molten iron should be reduced to 0.1%, 0.00%, and 0.26%, respectively. The total charge amount of each component in Table 1 should be charged based on the data in Table 2 until the final total charge amount is reached. Under this dynamic adjustment standard for charging, it can be ensured that the slag formation effect is better in the low-slag smelting process mode, and the final slag morphology is easy to splash slag for furnace protection.

[0037] In the early stages of smelting, during slag morphology control, 28-30 tons of scrap steel and molten iron are added to the converter, along with 28 kg / t of lime. Lime is a by-product of steelmaking; the more lime added, the more slag is formed. Nitrogen gas is blown into the bottom of the converter and the slag is vigorously stirred. At this time, the temperature of the slag drops rapidly, and the phase composition of the slag changes. A large number of solid particles precipitate out, and the amount of solid phase increases by more than double. The solid phase composition is approximately 3CaO·SiO2+CaO, which increases the viscosity of the slag and reduces its fluidity, thus slowing down its diffusion rate. Lime helps with slag formation, resulting in a better quality final slag.

[0038] The quality of lime can easily lead to an increase in FeO concentration. The O in FeO reacts with the C in the molten iron to produce a carbon-oxygen reaction, which can easily cause smoke and splashing. However, the presence of scrap steel slows down the impact of the molten iron on the slag when it is added to the furnace, which to some extent hinders the mixing of the molten iron and the slag. The reaction area between the molten iron and the slag is greatly reduced, which alleviates and inhibits the carbon-oxygen reaction rate, thus reducing the occurrence of smoke and splashing.

[0039] To further prevent safety accidents caused by splashing during molten iron addition and the emission of smoke and dust during the slag-less smelting process, the molten iron addition rate is controlled. The total addition time is controlled to approximately 1.5 minutes. During the initial 20 seconds of addition, the molten iron addition rate is controlled at 1800 kg / s. Four seconds after the initial addition, the FeO concentration in the slag has decreased to 5.48%, at which point the normal addition rate of 2377.6 kg / s can be resumed. This slow addition at the beginning effectively prevents smoke and splashing, thus reducing the possibility of safety accidents during the molten iron addition process.

[0040] During the smelting process, specifically in the middle stage, the smelting lance position needs to be properly controlled. The method for controlling the smelting lance position is as follows: To ensure rapid slag formation, an oxygen lance position of 1.40m is recommended to increase the FeO content in the early stage of blowing. Increasing the FeO content during this process can accelerate the slag formation of lime and improve the fluidity of the molten slag. If the oxygen lance position is low in the early stage, only 1.30m, it will cause metal splashing. Then, observe the size of the splashes at the furnace mouth according to the slag formation, observe whether the slag viscosity meets the final slag quality, and observe whether the splashes are severe and prone to causing accidents. During this process, gradually lower the oxygen lance position to 1.35m. When the slag is dried, the oxygen lance position should be appropriately increased by about 0.05-0.15m. At this time, the FeO content in the slag increases to about 21%-24%. At the end of the blowing process, lower the oxygen lance again to the final oxygen lance position of 1.30m. During the oxygen lance blowing process, it is necessary to ensure the lance pressing time, which should not be less than 45s.

[0041] During the early stages of oxygen lance blowing, splashing is likely to occur. The oxygen lance position cannot be changed. Adding 300-500 kg of steel particles to the converter can reduce the activity of the slag surface and facilitate the discharge of CO gas in the converter.

[0042] In the low-slag smelting process, the oxygen lance blowing process employs a "constant pressure, variable lance" operation. Traditional smelting converters use a "variable lance, variable pressure" operation, which limits the operator's skill level, resulting in poor slag formation and problems such as slag overflow, splashing, and re-drying. Under the "constant pressure, variable lance" operation, the converter's bottom blowing mode is adjusted, setting reasonable early, middle, and late-stage bottom blowing pressures. The early-stage pressure is set at 1.25-1.3 MPa, the middle-stage pressure at 1.3-1.35 MPa, and the late-stage pressure at 1.35-1.4 MPa. These pressure settings ensure uniform stirring of the molten pool, resulting in early slag formation, good slag formation in the middle stage, and thorough slag formation in the late stage.

[0043] To ensure lime quality during smelting, it is crucial to control the underburning rate. A higher underburning rate makes slag formation more difficult, reduces the solubility of CaO in the lime, and makes it less soluble in the slag. This results in lower basicity of the slag, which in turn decreases the viscosity of the slag, further complicating the slag formation process. The purpose of lime slag formation is to improve the viscosity and basicity of the final slag. However, an underburning rate exceeding 3% significantly hinders slag formation, making it difficult to form slag and resulting in insufficient viscosity in the final slag. Therefore, it is essential to ensure that the underburning rate is ≤3% during smelting monitoring.

[0044] In the final stage of smelting, after smelting is completed, the steel is tapped and slag is retained. It is necessary to reasonably control the tapping temperature. The methods for controlling the tapping temperature are: covering the ladle, shortening the smelting cycle, and adjusting and controlling the entire steelmaking production line to maintain the tapping temperature between 1620-1645℃. This is because when the tapping temperature exceeds 1660℃, the slag viscosity drops sharply, the rate of furnace lining damage accelerates accordingly, and the furnace lining life is significantly reduced. Therefore, maintaining an average tapping temperature of 1640℃ can effectively reduce the erosion of the furnace lining by the tapping temperature and improve the furnace lining's lifespan.

[0045] After steel smelting is completed and slag is left after tapping, the process of slag splashing to protect the furnace will be carried out. In the low-slag smelting process mode, the control of slag splashing to protect the furnace will be optimized, which mainly includes the operation control of the slag splashing gun position and the reasonable control of the slag splashing time.

[0046] The optimal lance position for slag splashing operation is related to parameters such as the amount of slag left. A variable lance position operation is used during slag splashing. Initially, the oxygen lance position is higher, and as the amount and temperature of slag decrease, the position can be appropriately lowered. The slag splashing lance position operation is controlled according to the following three modes:

[0047] Mode 1: High gun position operation, slag splash gun position is 1.4-1.7m;

[0048] Mode 2: Low gun position operation, slag splash gun position 0.9-1.1m;

[0049] Mode 3: Normal gun position operation, slag splash gun position 1.1-1.4m;

[0050] When the furnace bottom descends to a height of 100-300cm, the slag volume is relatively low and the furnace bottom is low. Use Mode 1 for lance operation, maintaining a lance height of 1.4-1.7m. When the furnace bottom rises to a height of 400-500cm, the furnace bottom is relatively high. Use Mode 2 for lance operation, maintaining a lance height of 0.9-1.1m. When the furnace bottom neither rises nor falls, i.e., the furnace bottom height is 300-400cm, the furnace bottom height is normal. Use Mode 3 for lance operation, maintaining a lance height of 1.1-1.4m. The lance height is selected based on the amount of slag left and the actual furnace bottom height to effectively prevent slag splashing and provide good protection for the furnace lining.

[0051] In addition, the slag splashing time also needs to be strictly regulated. Slag splashing time is an important process parameter in slag splashing operation. The reasonable method for controlling the slag splashing time is as follows: control the slag splashing time to be no less than 2.5 minutes.

[0052] The total slag splashing time is currently set at 2.5-4.0 minutes, based on the actual conditions of the converter lining. The initial slag splashing time of 0-1.5 minutes is the incubation period and slag removal time. The incubation period is mainly determined by the final slag temperature, slag phase (melting point), viscosity, and slag amount. When the final slag temperature is high, the slag phase has a low melting point, low viscosity, and large slag amount, resulting in good slag fluidity. If slag is splashed onto the furnace lining at this time, the slag will not easily adhere to the furnace wall. Therefore, the task in the early stage of slag splashing is only to reduce the slag temperature by injecting nitrogen, adjust the slag phase (magnesia balls or lightly calcined dolomite), change the slag viscosity, and adjust the slag to be easy to adhere to the furnace lining.

[0053] The actual slag splashing time, or slag raising time, is 1.5-2.5 minutes during the slag splashing process. Nitrogen is injected into the furnace bottom for approximately 2 minutes. The main purpose of blowing nitrogen is to provide power for slag splashing, and it also plays a protective role in cooling the slag. A large amount of slag begins to splash up, reaching the height of the furnace cap. During this time, the slag adhesion to the furnace lining is good. According to actual observations, if the slag splashing time is less than 2.5 minutes, the slag cannot be sufficiently cooled and mixed evenly. Even if this slag splashes onto the furnace wall, it cannot adhere well, resulting in poor furnace adhesion. Simultaneously, due to fluctuations in the quality of molten iron and scrap steel during production, the sulfur content is relatively high, affecting the slag splashing effect. To reduce the sulfur content, the injection time needs to be extended; therefore, the slag splashing and furnace protection time is extended to 3.5-4.0 minutes.

[0054] The average slag splashing time should be at least 2.5 minutes, and a supplementary blowing time of at least 60 seconds can be appropriately increased. Adding ≥100 kg / furnace of lightly calcined magnesia balls facilitates slag adhesion to the furnace lining. The nitrogen flow rate during slag splashing should be controlled at 28000±32000 m³ / h. 3 / h, the height of the gun position should be controlled between 0.9-1.8m when slag splashes.

[0055] Under this low-slag smelting process, the consumption of slag-forming material is reduced to approximately 31.2 kg / t, thereby lowering the consumption of steel raw materials. Simultaneously, the lifespan of the furnace lining is extended, significantly improving converter lining maintenance, increasing converter operating rates, and ensuring a balanced and stable production order in the converter.

[0056] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for furnace lining maintenance in a converter with low-slag smelting mode, characterized in that, This includes optimizing the smelting process control and optimizing the slag splashing furnace protection control. The optimized smelting process control includes control in two stages: the early stage of smelting and the middle stage of smelting. The control in the early stage of smelting includes slag morphology control and dynamic adjustment of smelting raw material charging. The control in the middle stage of smelting includes smelting lance position control and tapping temperature control. The optimized slag splashing furnace protection control includes slag splashing lance position operation control and reasonable control of slag splashing time. The method for controlling the slag morphology is as follows: 28 kg / t of lime is added to the converter, nitrogen is injected into the bottom of the converter and strong stirring is carried out. The method for dynamically adjusting the smelting raw material loading is as follows: dynamically adjust the amount of molten iron added, maintain the average temperature of the added molten iron at 1376℃, and control the Si content in the molten iron to be no higher than 0.8% and the Mn content in the molten iron to be no higher than 0.7%. During the mid-stage of smelting, the method for controlling the smelting lance position is as follows: The lance position during oxygen blowing is adjusted appropriately. In the early stage of blowing, the lance height is controlled at 1.40m. During the blowing process, the slag formation and the size of the splashes at the furnace mouth are observed in real time. During this process, the oxygen lance is lowered to 1.35m. When the slag is dried, the oxygen lance position is raised by 0.05-0.15m. At the end of the blowing process, the oxygen lance is lowered to the final position of 1.30m, ensuring a lance-holding time of no less than 45 seconds. The tapping temperature is controlled at 1620-1645℃. The slag-splashing gun position operation control includes three gun position operation modes: Mode 1: High gun position operation, slag splash gun position is 1.4-1.7m; Mode 2: Low gun position operation, slag splash gun position 0.9-1.1m; Mode 3: Normal gun position operation, slag splash gun position 1.1-1.4m; When the furnace bottom drops to a height of 100-300cm, it is too low. In this case, use mode one for gun position operation. When the furnace bottom rises to a height of 400-500cm, it is too high. In this case, use mode two for gun position operation. When the furnace bottom is maintained at a height of 300-400cm, it is at the normal height. Use mode three for gun position operation. The method for reasonably controlling the slag splashing time is as follows: the slag splashing time is controlled to be no less than 2.5 minutes, and nitrogen is injected into the slag at the bottom of the furnace for 2 minutes.

2. The furnace lining maintenance method in a converter with low slag smelting mode according to claim 1, characterized in that, The bottom blowing pressures for the early, middle, and late stages of refining are set to 1.25-1.3 MPa, 1.3-1.35 MPa, and 1.35-1.4 MPa, respectively.

3. The furnace lining maintenance method in a converter with low slag smelting mode according to claim 1, characterized in that, During the early stages of smelting, 300-500 kg of steel particles are added to each furnace in the converter.

4. The furnace lining maintenance method under the low-slag smelting mode of a converter as described in claim 1, characterized in that, In the early stage of smelting, 28-30t of scrap steel is added to the converter. The iron addition speed is controlled at 1800kg / s within the first 20s of the initial iron addition. When the Fe0 concentration in the slag drops to 5.48% 4s after the start of iron addition, the iron addition speed is restored to 2377.6kg / s.

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