Slag splashing furnace protection method for steelmaking converter
By optimizing the formation of the slag splash layer through thermal condition assessment and dynamic tempering, the problem of insufficient bonding strength and density of the slag splash layer in converter steelmaking was solved, achieving long-term protection and service life extension of the converter lining.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HANZHONG STEEL LTDRP OF SHAANXI STEEL GRP
- Filing Date
- 2026-01-27
- Publication Date
- 2026-04-10
AI Technical Summary
In existing converter steelmaking, the bonding strength and density between the slag splash layer and the furnace lining are weak and insufficient, resulting in a short service life of the converter furnace lining. Frequent maintenance and replacement of refractory materials increase production costs.
By introducing slag splashing timing decision-making based on thermal state assessment and dynamic segmented tempering, the performance and adhesion conditions of molten slag are optimized, including endpoint assessment and basic tempering, thermal state decision-making before slag splashing, dynamic tempering and operation during the slag splashing process, and differentiated nitrogen operation and tempering agent use, a slag splashing protective layer with high bonding strength and dense uniformity is formed.
It significantly extends the service life of converter lining, reduces refractory material consumption and maintenance frequency, and improves production stability and efficiency.
Smart Images
Figure CN121826281A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of steel metallurgy, and particularly relates to a method for slag splashing and protecting a converter. BACKGROUND
[0002] Converter steelmaking is the main process of modern steel production, and the service life of the furnace lining, as the core component of the converter, is directly related to the production efficiency, cost control and production stability; slag splashing and protection is the key technology to prolong the service life of the furnace lining, and the principle is to use high-pressure nitrogen to splash the final slag at the end of steelmaking onto the surface of the furnace lining to form a protective slag layer.
[0003] The existing slag splashing and protection technology mainly relies on the direct operation of the original final slag after the end of converter smelting; however, according to industry data such as “Converter Steelmaking Process and Equipment”, the chemical composition of the original final slag is not ideal, and the basicity (CaO / SiO2) is usually only 2.5-3.0, and the MgO content is generally less than 8%; the slag with such composition has a low melting point and poor viscosity characteristics, resulting in weak bonding strength, poor compactness and insufficient erosion resistance of the slag splashing layer formed with the magnesite-carbon brick furnace lining, and limited protection effect; secondly, the traditional operation process is to perform slag splashing immediately after the end of tapping; at this time, the high-temperature molten slag (temperature is usually higher than 1600℃) is splashed onto the furnace lining (the inner surface temperature is usually lower) which has a relatively reduced temperature due to the tapping process, and the huge temperature difference causes the splashing layer to bear extremely high thermal stress in the instant of solidification; such thermal stress is extremely easy to induce microcracks in the splashing layer, or to cause the splashing layer to peel off in the subsequent cooling and heating cycles, forming local weak points, and thus accelerating the loss under the erosion of molten steel and slag.
[0004] Therefore, under the existing technology, the average service life of the converter furnace lining is usually about 10000 heats, and frequent shutdown for maintenance and replacement of refractory materials restricts the production rhythm and increases the production cost; in order to solve the above problems, the industry has tried to add light-burned dolomite and other modifiers into the furnace before slag splashing to adjust the slag composition, but the addition is usually one-time, which is easy to cause uneven slag composition and viscosity, and does not fundamentally solve the physical contradiction of the mismatch between the “high-temperature slag” and the “medium-temperature lining” in the instant of slag splashing, and the process stability and protection effect are limitedly improved.
[0005] Therefore, in view of the above problems, the present application proposes a method for slag splashing and protecting a converter, which introduces a slag splashing timing decision based on thermal state evaluation, and combines dynamic segmented conditioning in the slag splashing process, to synergistically optimize the molten slag performance and adhesion conditions, thereby significantly improving the bonding strength, uniformity and durability of the splashing layer, and achieving the purpose of greatly prolonging the service life of the converter furnace lining. SUMMARY
[0006] In order to overcome the problem that the average service life of the converter lining in the prior art stays at about 10000 heats, frequent shutdown maintenance and refractory replacement restrict the production rhythm.
[0007] The technical scheme of the present application is as follows: a method for splashing slag to protect a converter lining in steelmaking, comprising the following steps:
[0008] S1: endpoint evaluation and basic conditioning: in the converter tapping process, a magnesium-containing conditioning agent is added to the residual slag in the furnace for the first composition conditioning; S2: decision of pre-splashing heat state: the heat state parameters of the molten slag and the lining before the splashing slag operation are obtained or calculated, and based on the comparison result of the heat state parameters and the preset threshold value, the starting time of the splashing slag operation is determined; the starting time includes immediately starting the splashing slag or starting the splashing slag after performing a controlled waiting and regulating program; S3: dynamic conditioning and operation during the splashing slag process: starting the splashing slag at the determined starting time and blowing nitrogen into the furnace; in different stages of the splashing slag operation, differential nitrogen operation and slag performance regulation operation are performed according to the preset process logic.
[0009] Preferably, in step S2, the heat state parameters include molten slag superheat (ΔT_superheat) and / or slag-lining temperature difference (ΔT_gap); The process of determining the starting time based on the comparison result is as follows: If ΔT_superheat ≤ the first threshold value and ΔT_gap ≤ the second threshold value, it is determined to immediately start the splashing slag; If ΔT_superheat > the first threshold value or ΔT_gap > the second threshold value, it is determined that the controlled waiting and regulating program needs to be performed.
[0010] Preferably, the controlled waiting and regulating program includes: The converter is shaken to a predetermined angle to make the molten slag converge; Waiting for a preset time, and at least one of the following operations is performed during the waiting period: adding a cooling agent to the molten slag surface, locally heating the lining of a specific area, and introducing a small flow of gas into the molten slag for stirring; After the waiting period ends or based on the re-evaluation of the heat state parameters, the splashing slag operation is started.
[0011] Preferably, in step S3, the differential operations performed in different stages of the splashing slag operation include: First stage: a first nitrogen operation system is used, and a first type of conditioning agent is added at the same time, which is used to adjust the fluidity and wettability of the molten slag; Second stage: switching to a second nitrogen operation system with higher gas kinetic energy than the first nitrogen operation system, and stopping adding the conditioning agent; Third stage: switching to a third nitrogen operation system with lower gas kinetic energy than the second nitrogen operation system, and selectively adding a second type of conditioning agent according to the slag state.
[0012] As a preference, in the first stage, the first nitrogen operation system adopts a lower lance position and a medium gas supply intensity; and the first type of conditioning agent is a composite powder containing fluxing and wetting functional components.
[0013] As a preference, in the second stage, the second nitrogen operation system adopts a high lance position and a high gas supply intensity.
[0014] As a preference, in the third stage, the third nitrogen operation system adopts a low lance position and a low gas supply intensity; and the selective addition of the second type of conditioning agent means that, according to the observation and judgment of the flame at the furnace mouth, the sound of splashing slag, or the consistency of molten slag, it is determined whether to add a powder for fine-tuning the viscosity of molten slag into the furnace.
[0015] As a preference, in step S1, the end-point evaluation includes obtaining the MgO content, basicity, and slag amount of the end-point slag; and the amount of the magnesium-containing conditioning agent added is calculated based on the increase of the MgO content of the end-point slag to a target range and the increase of the basicity to a target range.
[0016] As a preference, in step S3, after the dynamic conditioning and operation step of the splashing slag process, the method further includes: S4: end-point judgment of splashing slag and end of operation: observing the coverage state of the furnace lining surface, and when a uniform solid slag shell is formed, stopping the nitrogen blowing and ending the splashing slag operation.
[0017] As a preference, the method is completed within the period from the start of the converter tapping to the start of the smelting of the next furnace.
[0018] The beneficial effects of the present application are: In the method, basic conditioning is performed at tapping to quickly adjust the slag composition (MgO, basicity) to a suitable range, laying a chemical foundation for forming a high-melting-point protective layer; a hot state decision-making link is introduced, the superheat of the molten slag and the temperature difference of the slag lining are measured and calculated, and compared with the threshold value, and the starting time of the slag splashing is scientifically decided; when the hot state risk is high, a regulation program including waiting, adding coolant, local preheating and other operations is executed, and the hot state of the "slag-lining" system is actively adjusted to a well-matched window period, thereby reducing the risk of cracking and peeling of the slag splashing layer caused by thermal stress from the source; three-stage dynamic conditioning is implemented during the slag splashing process: in the slagging stage, nitrogen system and functional conditioning agent are used to optimize the fluidity of the molten slag and the wettability of the brick lining; in the high-speed sputtering stage, a high-energy nitrogen system is used to ensure that the optimized molten slag is uniformly and firmly splashed and adhered; in the covering sintering stage, a low-energy nitrogen system is used and adjusted according to the situation to promote the densification and metallurgical bonding of the protective layer; the method can stably form a long-acting slag splashing protective layer with high bonding strength, dense and uniform, and strong erosion resistance without significantly increasing the complexity of the equipment and the difficulty of the operation, thereby prolonging the service life of the converter lining, reducing the consumption of refractory materials and the frequency of maintenance. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 A simple step flowchart of the method of the present application is shown. Figure 2 A detailed step flowchart of the method of the present application is shown. DETAILED DESCRIPTION
[0020] The present application will be further described below in conjunction with the drawings and examples.
[0021] Example 1 Please refer to Figure 1 and Figure 2 , the present application provides an embodiment: a method for slag splashing protection of a steelmaking converter, comprising the following steps: S1: end evaluation and basic conditioning: during the tapping process of the converter, magnesium-containing conditioning agent is added to the residual molten slag in the furnace for the first composition conditioning; S2: hot state decision before slag splashing: the hot state parameters of the molten slag and the lining before the slag splashing operation are obtained or calculated, and based on the comparison result of the hot state parameters and the preset threshold value, the starting time of the slag splashing operation is determined; the starting time includes immediately starting the slag splashing, or starting the slag splashing after executing a controlled waiting and regulation program; S3: dynamic conditioning and operation during the slag splashing process: the slag splashing is started at the determined starting time, and nitrogen is blown into the furnace; in different stages of the slag splashing operation, according to the preset process logic, differential nitrogen operation and slag performance regulation operation are executed.
[0022] Further, in step S2, the thermal state parameters include the superheat degree of the slag (ΔT_superheat) and / or the slag-liner temperature difference (ΔT_gap); The process of determining the starting timing based on the comparison result is: If ΔT_superheat ≤ the first threshold value and ΔT_gap ≤ the second threshold value, it is determined that the slag splashing is started immediately; If ΔT_superheat > the first threshold value or ΔT_gap > the second threshold value, it is determined that the controlled waiting and regulation procedure needs to be performed.
[0023] The superheat degree of the slag (ΔT_superheat) is defined as the difference between the actual temperature of the slag and its liquidus temperature (which can be estimated according to the slag composition), which directly affects the flowability and solidification behavior of the slag; the slag-liner temperature difference (ΔT_gap) is the difference between the temperature of the slag and the inner surface temperature of the furnace lining, which is the direct cause of the interfacial thermal stress; by setting reasonable threshold values (for example, the first threshold value can be 80°C, and the second threshold value can be 250°C), a quantifiable decision-making standard is established; when the thermal state parameters are within the threshold values, it indicates that the flowability of the slag is suitable and the temperature difference with the furnace lining is small, and the thermal matching is good, so the slag can be splashed immediately to take advantage of the optimal state; otherwise, it indicates that there is a risk of cracking or poor adhesion of the splashed slag layer due to overheating or excessive temperature difference, and active intervention must be performed; this decision-making logic changes the operation from relying on experience to being regularized control based on clear physical parameters, fundamentally solving the problem of physical defects at the bonding interface caused by ignoring thermal matching in traditional processes, and improving the scientificity and stability of the process.
[0024] Further, the controlled waiting and regulation procedure includes: The converter is rocked to a predetermined angle to make the slag converge; The waiting is static for a preset time, and at least one of the following operations is performed during the waiting: adding a cooling agent to the surface of the slag, locally heating the furnace lining in a specific area, and introducing a small flow of gas into the slag for stirring; After the waiting ends or based on the re-determination of the thermal state parameters, the slag splashing operation is started; Wherein, tilting the converter to a certain angle (e.g. 60-70 degrees) can concentrate the slag and reduce the heat dissipation area, which is conducive to temperature homogenization; waiting (e.g. 2-8 minutes) provides a time window for natural cooling and temperature equalization of the slag; during this period, various active control means can be combined: adding a small amount of clean and dry coolant (such as waste magnesium carbon brick particles, fine magnesia), which can gently reduce the slag temperature through its sensible heat absorption and latent heat of fusion, avoiding drastic changes in composition; using gas or hot air to preheat the local low-temperature area of the lining (such as the sides of the trunnion), which can actively reduce ΔT_gap and reduce local weak points; introducing a small amount of nitrogen gas (about 10-20% of the normal splashing slag gas amount) for light agitation, which can prevent the formation of crust on the surface of the slag and promote internal temperature uniformity and the melting of the coolant; this procedure actively adjusts the thermal state of the "slag-lining" system in a gentle and controllable manner, making it enter a "temperature window" that is more conducive to the formation and combination of the splashing slag layer, realizing the transition from "passive acceptance of thermal state" to "active creation of suitable thermal conditions", thereby effectively reducing the thermal stress of the splashing slag layer and improving its integrity and bonding strength.
[0025] Further, in step S3, differentiated operations are performed at different stages of the slag splashing operation, including: First stage: a first nitrogen gas operation system is used, and a first type of conditioning agent is added synchronously, the first type of conditioning agent being used to adjust the flowability and wettability of the slag; Second stage: switching to a second nitrogen gas operation system, and stopping the addition of conditioning agents, the gas kinetic energy of the second nitrogen gas operation system being higher than that of the first nitrogen gas operation system; Third stage: switching to a third nitrogen gas operation system, and selectively adding a second type of conditioning agent according to the state of the slag, the gas kinetic energy of the third nitrogen gas operation system being lower than that of the second nitrogen gas operation system; In the first stage, the slag is fully foamed and homogenized by nitrogen blowing with a lower lance position (e.g. 1.0-1.5 m from the slag surface) and a medium gas flow rate (e.g. 0.8-1.2 Nm³ / t·min), and a functional first type of conditioning agent (e.g. a composite powder containing a small amount of B2O3 and other fluxing and wetting components) is added to reduce the surface tension of the slag and improve its wetting and spreading ability on the magnesia-carbon brick, creating chemical conditions for firm adhesion.
[0026] Further, in the first stage, the first nitrogen operating system uses a lower lance position and a medium gas flow rate, and the first type of conditioning agent is a composite powder containing fluxing and wetting functional components. The lower lance position helps the nitrogen jet to impact the molten bath, promoting agitation and foaming, and the medium gas flow rate ensures sufficient agitation while avoiding excessive splashing. The composite powder containing fluxing and weting functional components (e.g. specific calcium-magnesium-silicate or controlled amount of B2O3) mainly acts by adsorbing on the surface or interface of the molten slag, reducing the slag-gas surface tension and slag-brick interfacial tension, thereby significantly enhancing the wetting ability of the molten slag on the refractory material, which is a key chemical factor for improving the bonding strength of the splashed slag layer.
[0027] Further, in the second stage, the second nitrogen operating system uses a high lance position and a high gas flow rate. The high lance position allows the nitrogen jet to fully expand when it reaches the slag surface, resulting in a large acting area that can break the molten slag into small droplets and splash them onto a higher and more extensive area of the furnace lining. The high gas flow rate provides sufficient kinetic energy for transporting the slag droplets to the surface of the furnace lining. This system ensures the coverage and uniformity of the splashed slag.
[0028] Further, in the third stage, the third nitrogen operation system is to use low lance position and low gas supply intensity; the selective addition of the second type of conditioning agent means that whether to add a powder for fine adjustment of the molten slag viscosity to the furnace is determined according to the observation and judgment of the furnace mouth flame, the splashing sound of the slag or the consistency of the molten slag; Among them, the soft blowing of low lance position and low gas volume aims to smoothly lay the last part of the relatively thick slag slurry on the surface of the furnace lining without blowing it away; the operator determines by experience: if the furnace mouth flame is bright and the splashing sound of the slag is crisp, it indicates that the slag is still relatively thin, and a small amount of fine magnesia powder or the like can be added to increase its viscosity, so as to facilitate the formation of a good covering layer; otherwise, no addition is needed; this fine adjustment based on real-time state ensures the quality of the final covering layer.
[0029] Further, in step S1, the end point evaluation includes obtaining the MgO content, the basicity and the amount of slag of the end point slag; the addition amount of the magnesium-containing conditioning agent is calculated based on the promotion of the MgO content of the end point slag to the target range and the promotion of the basicity to the target range; for example, the target range can be set as MgO content 10-12% and basicity 3.2-3.5; the addition amount can be estimated by the formula: Conditioning agent addition amount (kg) = [slag amount (T.S) × (target MgO% - end point MgO%)] / (MgO content in conditioning agent × efficiency) Wherein the efficiency is 0.7-0.9 according to the temperature. This pre-conditioning based on quantitative calculation ensures that the slag before splashing has a basically suitable high melting point and suitable basicity.
[0030] Further, in step S3, after the dynamic conditioning and operation steps in the splashing process, the method further includes: S4: splashing end point judgment and operation end: observing the covering state of the furnace lining surface, when it is judged that a uniform solid slag shell is formed, stopping blowing nitrogen and ending the splashing operation; by observing the reduction of the splashing material at the furnace mouth, the formation of a dark blue or dark red solid slag shell on the surface of the furnace lining, and the relatively uniform solid slag shell, the expected effect of splashing is directly judged, so as to stop the operation in time, save nitrogen and avoid over operation.
[0031] Further, the method is completed in the period from the start of the converter tapping to the start of the next smelting; the specific production period of the method is completed in the tapping and splashing stage after smelting in a smelting cycle, which does not occupy extra production time, and ensures good compatibility with the existing converter production rhythm.
[0032] Through the above steps, in the method of the present application, the basic conditioning is carried out at the time of tapping, the slag composition (MgO, basicity) is quickly adjusted to the appropriate range, and the chemical basis for forming a high-melting-point protective layer is laid; a hot state decision-making link is introduced, the superheat of the molten slag and the temperature difference of the slag lining are measured and calculated, and compared with the threshold value, and the starting time of the slag splashing is scientifically decided; when the hot state risk is high, the regulation program including waiting, adding coolant, local preheating and the like is executed, and the hot state of the "slag-lining" system is actively adjusted to the well-matched "window period", so that the risk of cracking and peeling of the slag-splashing layer caused by thermal stress is reduced from the source; a three-stage dynamic conditioning is implemented during the slag splashing: in the slagging stage, the nitrogen system and functional conditioning agent are matched to optimize the flowability of the molten slag and the wettability to the brick lining; in the high-speed sputtering stage, a high kinetic energy nitrogen system is adopted to ensure that the optimized molten slag is uniformly and firmly splashed and adhered; in the covering sintering stage, a low kinetic energy nitrogen system is adopted and adjusted according to the situation, so as to promote the densification and metallurgical bonding of the protective layer; the method of the present application can stably form a long-acting slag-splashing protective layer with high bonding strength, dense and uniform, and strong erosion resistance without significantly increasing the complexity of the equipment and the difficulty of the operation, thereby prolonging the service life of the converter lining, reducing the consumption of refractory materials and the frequency of maintenance.
[0033] Example 2 Optionally, the present embodiment provides a basic implementation process of a slag-splashing method for a steelmaking converter.
[0034] A method for slag-splashing of a steelmaking converter, which is implemented on a converter with a capacity of 120 tons, and the core steps include: End point evaluation and basic conditioning (S1): the converter smelting is finished, and the tapping is started; when about one-third of the total amount of molten steel flows out, the required amount of magnesium-containing conditioning agent (light-burned dolomite powder is used in the present embodiment) is calculated according to the end point slag composition (MgO content, basicity) and slag amount estimated value obtained by rapid detection, and is injected into the remaining slag in the furnace through the post-furnace lance; this is aimed at preliminarily optimizing the composition of the slag.
[0035] S2: After tapping, the temperature of the molten bath (T melt) is obtained by the lance temperature measurement system, and the average temperature of the inner surface of the lining (T lining) is estimated by the infrared scanning temperature measurement device at the furnace mouth; the liquidus temperature of the slag (T liquid) is estimated according to the rapid analysis result of the obtained slag composition; the superheat of the slag (ΔT superheat = T melt - T liquid) and the slag-lining temperature difference (ΔT gap = T melt - T lining) are calculated; the calculation results are compared with the preset threshold values, so as to decide the starting time of the slag splashing operation; if the comparison result indicates good thermal matching, the slag splashing is started immediately; if the comparison result indicates the risk of thermal matching, a control program including delay and active intervention is started.
[0036] S3: According to the starting time decided by the decision result, the slag splashing and furnace protection operation is started; high-pressure nitrogen gas is blown into the furnace; the whole slag splashing operation is not fixed, but is divided into at least two different functional stages; for example, a low-energy blowing stage aiming at homogenizing the slag condition and adjusting the performance is carried out first, and then a high-energy blowing stage aiming at splashing and adhering the molten slag is carried out; in different stages, the operation parameters (such as lance position, flow) of nitrogen gas are adjusted accordingly, and different slag performance adjustment operations (such as adding a special functional modifier or stopping charging) may be carried out in different stages according to the preset logic.
[0037] Embodiment 3 Optionally, the embodiment is further refined on the basis of embodiment 2, the specific parameters of the thermal state decision and the calculation logic of the basic conditioning.
[0038] A method for slag splashing and furnace protection of a steelmaking converter, the specific steps are as follows: S1: End point evaluation and basic conditioning: at the end point of the converter smelting, the oxygen content is determined by the lance temperature measurement, and the slag sample is taken, the MgO content of the end point slag is obtained by rapid analysis as 7.5%, the basicity R is 2.8, and the slag amount (T.S) is estimated as 12 tons; the target is set to increase the MgO content of the furnace slag to 11% and the basicity to 3.4; the magnesium-containing conditioning agent used is light-burned dolomite powder, the MgO content of which is 38% and the CaO content is 55%; the A agent addition amount is calculated: Addition amount (kg) = [T.S × (target MgO% - end point MgO%)] / (MgO% in A agent × efficiency) Wherein, the efficiency is valued as 0.8 according to the current molten bath temperature (about 1680℃); Substitute the numerical value: addition amount = [12000 × (0.11 - 0.075)] / (0.38 × 0.8) ≈ 1382kg; About 1380 kg of light-burned dolomite powder is sprayed into the furnace during tapping; S2: Pre-slag splashing thermal state decision: Data acquisition: molten pool temperature T_melt = 1680℃; average temperature of inner surface of furnace lining T_lining = 1150℃; liquidus temperature T_liquid ≈ 1580℃ estimated according to the composition of the adjusted slag; Calculation parameters: ΔT_superheat = 1680 - 1580 = 100℃; ΔT_gap = 1680 - 1150 = 530℃; Decision: The preset first threshold is 80℃, and the second threshold is 250℃; since ΔT_superheat (100℃) > 80℃, and ΔT_gap (530℃) > 250℃, it is determined as “hot matching risk”, and the controlled waiting and regulation program needs to be executed; S3: Dynamic adjustment and operation during slag splashing process: (subsequent steps are connected with Example 2 or subsequent examples).
[0039] Example 4 Optionally, this embodiment is based on Example 3, and the specific operation of the controlled waiting and regulation program is described in detail.
[0040] A method for slag splashing and furnace protection of a steelmaking converter, after executing the S2 step and determining “hot matching risk”, the following program is operated: Controlled waiting and regulation program: The converter is shaken to about 65 degrees, so that the molten slag is gathered on one side of the furnace bottom, reducing the heat dissipation area; Rest and active intervention: rest for Δt = 5 minutes. During this period, the following combined intervention is performed: Micro-cooled slag addition: about 100 kg (about 0.83 kg / t of steel) of clean and dry waste magnesium carbon brick crushed particles (particle size 1-5 mm) are uniformly added to the gathered slag surface through the high-position bin; the material acts as a cooling agent, which gently and uniformly reduces the temperature of the molten slag by absorbing sensible heat and part of the latent heat of surface melting, while slightly changing the main chemical composition of the slag; Nitrogen gas with low flow rate stirring: nitrogen gas is passed through the slag layer at a very low flow rate (about 15% of the normal slag splashing initial flow rate) for slight stirring, which aims to prevent slag surface crust and promote heat exchange between the cooling agent and the high-temperature molten slag, so that the temperature distribution is more uniform; Rejudgment and start: after waiting for 5 minutes, according to the experience model estimation or the experience judgment of the operator, the molten slag temperature has been reduced, and the superheat and the slag lining temperature difference have tended to be mild; at this time, the converter is shaken to be vertical, and the slag splashing operation (S3) is prepared to start.
[0041] Example 5 Optionally, the present embodiment integrates the foregoing embodiments to show a complete and optimized implementation process.
[0042] A method for slag splashing and protecting the furnace of a steelmaking converter is applied to a smelting cycle, and the specific implementation steps are as follows: S1: endpoint evaluation and basic conditioning: same as embodiment 3, about 1380 kg of light-burned dolomite powder is added during tapping; S2: pre-slagging state decision and control: same as embodiments 3 and 4, it is determined by calculation that the controlled program needs to be executed, and after 5 minutes of waiting and intervention, the furnace condition tends to be stable; S3: dynamic conditioning and operation during slag splashing: Close the tapping hole, shake the furnace body, and start slag splashing. The whole process is divided into three stages: First stage (slagging and homogenizing conditioning stage, about 50% of time): Nitrogen operation system (first system): lower the oxygen lance (or special slag splashing lance) to a lance position about 1.2 m away from the static slag surface, and blow nitrogen at a gas supply intensity of 0.9 Nm³ / t·min; this system aims to fully stir the molten slag to make it foam and homogenize; Conditioning operation: simultaneously start the addition of functional enhancer B (composition: more than 95% high-purity magnesia powder, 3% specific calcium-magnesium silicate mineral as fluxing and wetting component); through an independent metering and conveying system, it is continuously sprayed at a stable small flow, and the total addition amount is controlled at about 200 kg (about 1.8% of the estimated basic conditioning slag weight); the goal of this stage is to obtain a foam slag with good fluidity and excellent wetting property to the furnace lining; Second stage (high-speed splashing and adhering stage, about 30% of time): Nitrogen operation system conversion (second system): quickly raise the lance position to 2.5 m, and increase the gas supply intensity to 1.8 Nm³ / t·min; Conditioning operation: immediately stop the addition of all conditioning agents; Process purpose: use high-energy nitrogen to fully break and splash the molten slag optimized in the first stage at high speed into the entire inner wall of the furnace lining to form an initial uniform adhering layer; stopping charging ensures the stability of the splashing flow field; Third stage (low-temperature covering and sintering stage, about 20% of time): Nitrogen operation system conversion (third system): lower the lance position to about 1.5 m, and significantly reduce the gas supply intensity to 0.4 Nm³ / t·min; Conditioning operation: the operator observes that the flame at the furnace mouth is dark red and the sound of slag splashing becomes dull, judging that the slag has become thick; to promote the formation of the final covering layer, about 30 kg of finely ground magnesia powder (second type of conditioning agent) is selectively pulsed and sprayed for viscosity fine-tuning; Process purpose: low energy purging makes the remaining viscous slag slurry in the furnace gently cover on the attached slag layer, and under the action of the residual heat of the furnace lining, promotes the further densification and low temperature sintering of the entire slag splashing layer, and strengthens the metallurgical combination with the magnesia carbon brick.
[0043] S4: splashing end judgment and operation end: continuous observation, when the surface of the furnace lining is basically covered with a layer of dark green solid slag shell, and only a small amount of fine splashing is left at the furnace mouth, it is determined that the splashing is completed; the nitrogen valve is closed, the lance is removed, and the furnace is shaken to check and confirm that the covering effect is good; at this time, the splashing and furnace protection operation of the present furnace is completed in the period from the beginning of tapping to the beginning of charging and smelting of the next furnace.
[0044] The embodiments of the application are described in detail above in combination with the drawings, but the application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the application.
Claims
1. A method for slag splashing protection in a steelmaking converter, characterized in that: Includes the following steps: S1: Endpoint assessment and basic tempering: During the tapping process of the converter, magnesium-containing tempering agent is added to the residual slag in the furnace for the first composition tempering; S2: Thermal state decision before slag splashing: Obtain or calculate the thermal state parameters of the molten slag and furnace lining before the slag splashing operation, and determine the starting time of the slag splashing operation based on the comparison results of the thermal state parameters and the preset threshold; the starting time includes starting slag splashing immediately, or starting slag splashing after executing a controlled waiting and adjustment procedure; S3: Dynamic conditioning and operation of slag splashing process: Slag splashing begins at a determined start time, and nitrogen is blown into the furnace; at different stages of the slag splashing operation, differentiated nitrogen operation and slag performance adjustment operation are performed according to the preset process logic.
2. The method for slag splashing protection of a steelmaking converter according to claim 1, characterized in that: In step S2, the thermal state parameters include slag superheat (ΔT_superheat) and / or slag-lining temperature difference (ΔT_gap). The process of determining the starting point based on the comparison results is as follows: If ΔT_superheat ≤ the first threshold and ΔT_gap ≤ the second threshold, then it is determined that slag splashing will begin immediately; If ΔT_superheat > the first threshold or ΔT_gap > the second threshold, then it is determined that the controlled waiting and regulation procedure needs to be executed.
3. The method for slag splashing and furnace protection in a steelmaking converter according to claim 2, characterized in that: The controlled waiting and control procedures include: The converter is tilted to a predetermined angle to allow the molten slag to converge. Set aside for a preset time, and perform at least one of the following operations during the waiting period: add coolant to the surface of the molten slag, locally heat the furnace lining in a specific area, or introduce a small flow of gas into the molten slag for stirring; After the waiting period ends or based on a reassessment of thermal state parameters, the slag splashing operation begins.
4. The method for slag splashing protection of a steelmaking converter according to claim 1, characterized in that: In step S3, performing differentiated operations at different stages of the slag splashing operation includes: Phase 1: The first nitrogen operation system is adopted, and the first type of conditioning agent is added simultaneously. The first type of conditioning agent is used to adjust the fluidity and wettability of the slag. Second stage: Switch to the second nitrogen operation regime and stop adding conditioning agent. The gas kinetic energy of the second nitrogen operation regime is higher than that of the first nitrogen operation regime. The third stage involves switching to the third nitrogen operation system and selectively adding a second type of conditioning agent based on the slag condition. The gas kinetic energy of the third nitrogen operation system is lower than that of the second nitrogen operation system.
5. A method for slag splashing and furnace protection in a steelmaking converter according to claim 4, characterized in that: In the first stage, the first nitrogen operation regime is to use a lower gun position and a medium gas supply intensity; the first type of conditioning agent is a composite powder containing fluxing and wetting functional components.
6. The method for slag splashing protection of a steelmaking converter according to claim 4, characterized in that: In the second stage, the second nitrogen operation system adopts a high nozzle position and a high gas supply intensity.
7. A method for slag splashing and furnace protection in a steelmaking converter according to claim 4, characterized in that: In the third stage, the third nitrogen operation system is to use a low gun position and a low gas supply intensity; the selective addition of the second type of conditioning agent refers to deciding whether to add powder to the furnace to finely adjust the viscosity of the molten slag based on observation and judgment of the furnace flame, slag splashing sound or molten slag consistency.
8. A method for slag splashing and furnace protection in a steelmaking converter according to claim 1, characterized in that: In step S1, the endpoint assessment includes obtaining the MgO content, alkalinity, and slag quantity of the endpoint slag; the amount of magnesium-containing conditioning agent added is calculated based on increasing the MgO content and alkalinity of the endpoint slag to the target range.
9. A method for slag splashing and furnace protection in a steelmaking converter according to claim 1, characterized in that: In step S3, after the dynamic conditioning and operation steps of the slag splashing process, the following is also included: S4: Judgment of the endpoint of slag splashing and end of operation: Observe the surface coverage of the furnace lining. When it is determined that a uniform solid slag shell has been formed, stop nitrogen blowing and end the slag splashing operation.
10. A method for slag splashing protection of a steelmaking converter according to any one of claims 1-9, characterized in that: The method is performed during the period from the start of steel tapping in the converter to the start of the next heat of smelting.