Method for calculating and evaluating slag aggressiveness for slag splashing in a converter

Abstract

This invention discloses a method for calculating and evaluating the erosiveness of slag used for converter slag splashing protection, relating to the field of metallurgical technology. The method includes: obtaining the chemical composition of the slag; thermodynamically calculating the Gibbs free energy of the reaction between each component and magnesia-carbon bricks, classifying components as strongly / weakly erosive; and calculating the oxidative erosion capacity Q. ox (Total oxygen content of highly corrosive components) and structural erosion ability Q st (low melting point liquid phase content × basicity coefficient); and a temperature correction factor is introduced. T Finally, the erosivity index Q is calculated. 侵蚀 = T ×[a1×Q ox +a2×Q st ]. Q 侵蚀 Compared with thresholds of 30 and 60, the slag is determined to be low, medium, or high corrosivity, and suggestions are given for direct slag splashing, adjusted slag splashing, or slag dumping. Industrial verification has confirmed that Q... 侵蚀 The corrosion rate was significantly positively correlated with the actual furnace lining corrosion rate (r=0.93), and the corrosion rate decreased by 70-80% after adjusting the slag composition. This invention fills the gap in the quantitative evaluation of slag corrosivity and provides a scientific and simple operational basis for slag splashing protection of the furnace.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, and more specifically to a method for calculating and evaluating the erosiveness of slag used for converter slag splashing protection. Background Technology

[0002] Slag splashing is a crucial furnace lining maintenance technology in converter steelmaking. Its core principle is to use high-pressure nitrogen gas after tapping to disperse and splash the remaining high-temperature molten slag onto the furnace lining surface, forming a dense protective slag layer. This layer effectively insulates against heat and resists chemical erosion and mechanical scouring by molten steel and slag during subsequent smelting processes, thus significantly extending furnace lining life, increasing converter operating rate, and reducing refractory material consumption. Researchers both domestically and internationally have conducted extensive research on slag splashing technology and disclosed numerous technological achievements. Existing patents disclose the following technologies: Patent CN110878383B discloses a converter slag splashing protection control system and method. By using a laser rangefinder to detect the thickness of the furnace lining at various points, combined with a secondary model and audio detection technology, the system can indirectly monitor and judge the slag condition and slag splashing effect, thereby reducing blind spots, improving the efficiency and effect of slag splashing, facilitating converter furnace type control, and helping to extend the converter's lifespan.

[0003] CN117025883A discloses an intelligent control method for converter slag splashing mode. It fits the control curves of various slag splashing gun positions and performs stepwise regression calculations on various slag components and weights. It calculates the slag components and weights for this furnace according to the material balance, obtains the predicted slag components and weights for this furnace through recurrent neural network calculation, and finally obtains the slag splashing mode for this furnace and performs automatic slag splashing operation.

[0004] CN206916179U discloses an automatic slag splashing device for converters. This device can automatically complete normal slag splashing mode, feeding slag splashing mode and slag retention slag splashing mode. It can realize automatic feeding and slag discharge during the slag splashing process, which significantly improves the automation level and slag splashing efficiency of converter slag splashing technology.

[0005] CN113913583A discloses a method for slag modification and slag splashing for furnace protection. After the converter blowing is completed, the method calculates the appropriate amount of reducing agent and modifying agent to be added based on the oxygen content and temperature of the molten steel obtained by the secondary lance. The appropriate slag splashing time is calculated by the process heat balance model, thereby achieving precision in slag modification and slag splashing for furnace protection. This method plays a significant role in reducing furnace lining erosion in specific areas and extending furnace lining life.

[0006] CN113122671B discloses a method for controlling the erosion of the furnace lining by high-titanium molten iron converter slag. The method reduces the erosion of the furnace lining by solidifying the slag left from the previous furnace and the TiO2 formed by the oxidation during the current furnace. At the end of the furnace, a low lance position, high flow rate, and long duration of lance pressing mode are adopted to reduce the FeO content of the final slag and control its erosion of the slag line of the furnace lining during furnace turning, slag pouring, and steel tapping. This reduces refractory material consumption and saves steelmaking costs.

[0007] CN108330243A discloses a method for reducing converter lining erosion. By using dolomite slag and adding converter waste slag to replace part of the metallurgical auxiliary materials, the TFe content in the final slag is reduced, which significantly reduces the converter lining erosion rate and increases the converter life.

[0008] While the aforementioned technologies have improved the slag splashing effect from different angles, such as equipment improvement, process parameter optimization, and slag composition adjustment, none of them have solved a core problem: how to quantitatively and comprehensively evaluate the potential erosion ability of the slag itself on the magnesia-carbon brick lining. During slag splashing, reactive components in the slag (such as FeO, MnO, and P2O5) react with carbon in the magnesia-carbon bricks through oxidation (MxOy + yC → xM + yCO↑, where MxOy is the reactive component of the slag), leading to decarburization and damage to the lining. Simultaneously, low-melting-point silicate phases in the slag can penetrate into the pores of the magnesia-carbon bricks, causing structural thermal shock damage. Currently, there is a lack of an evaluation method that can simultaneously consider both erosion mechanisms and perform quantitative calculations based on the slag's basic composition. This prevents on-site operators from quickly and scientifically determining whether the current slag is "suitable" for splashing beforehand, and also hinders precise guidance for optimizing slag composition. Decisions are often made based on experience, resulting in significant uncertainty.

[0009] Therefore, developing a method that can quantitatively calculate and evaluate the erosiveness of slag used for converter slag splashing furnace protection, filling the relevant technological gap, is of great practical significance for guiding production practices, extending furnace lining life, and reducing steelmaking costs. Summary of the Invention

[0010] The purpose of this invention is to address the lack of a quantitative and comprehensive evaluation method for the corrosivity of slag used in converter slag splashing protection. This invention provides a method for calculating and evaluating the corrosivity of slag used in converter slag splashing protection.

[0011] To achieve the above objectives, the present invention specifically adopts the following technical solution: This invention provides a method for calculating and evaluating the erosiveness of slag used for converter slag splashing protection, including the following steps: S1. Take a slag sample before the splashing point and test the content of each component in the slag sample; S2. Thermodynamic calculation of the reactivity of each component in the slag sample with magnesia-carbon bricks: The standard Gibbs free energy change ΔG of each component in the erosion reaction with magnesia-carbon bricks at the splashing temperature was determined by thermodynamic calculation. i And according to ΔG i The values ​​categorize the components into highly corrosive, weakly corrosive, and inert components. S3. Calculate the oxidative erosion ability Q of the slag sample on magnesia-carbon bricks. ox Oxidative corrosion ability Q ox The total weight of oxygen in all the highly corrosive components; S4. Calculate the structural erosion ability Q of the slag sample on magnesia-carbon bricks. st Structural erosion capability Q st w is the mass fraction of the low-melting-point liquid phase in the slag at the splashing temperature. 低熔 With structural erosion coefficient k 渗 The product; S5. Calculate the temperature correction factor β based on the slag splashing temperature T. T ; S6, Based on the aforementioned oxidation erosion ability Q ox Structural erosion capability Q st and temperature correction factor β T Calculate the comprehensive erosivity index Q of slag 侵蚀 ; S7, the comprehensive erosivity index of slag Q 侵蚀 The slag's corrosivity level and suitability for splashing are determined by comparing it with a preset threshold.

[0012] In one embodiment, in step S2, the main components of the magnesia-carbon brick are MgO and C; the calculated reaction temperature is the slag splashing temperature of 1650°C. When ΔG i When ≥0, it indicates that slag component i will not react with the magnesia-carbon bricks, and its erosion effect on the furnace lining can be ignored; when ΔG i When the value is less than 0, it indicates that slag component i has undergone an erosion reaction with the magnesia-carbon brick. The specific judgment rules are as follows: When ΔG i When the value is less than -50 kJ / mol, component i is a highly corrosive component, i.e., oxidative corrosion. The molecular formula of this component is denoted as MxOy, where M is the non-oxygen element in the component and O is the oxygen element in the component. When -50≤ΔG i When <0, component i is a weakly corrosive component, which is structural erosion; When ΔG i When the value is ≥0, component i is an inert component and does not participate in the erosion calculation.

[0013] In one embodiment, in step S3, the oxidative erosion capacity Q of the slag sample on magnesia-carbon bricks is calculated.ox The specific method is as follows: S31. Calculate the weight W of oxygen in the highly corrosive component i in the slag that can undergo an oxidation reaction with magnesia-carbon bricks (ΔG_i < -50 kJ / mol). O-i W O-i The calculation formula is as follows: W O-i =(w i / M i )×n O ×M O ×1000; In the formula, w i M represents the mass fraction (wt%) of component i in the slag sample. i n is the relative molecular mass of component i; O y represents the number of oxygen atoms in the molecular formula MxOy of component i; M O This refers to the relative atomic weight of oxygen. S32. By summing the oxygen element weights of all the highly corrosive components of the slag, the oxidative erosion ability Q of the slag on magnesia-carbon bricks can be determined. ox : Q ox =ΣW O-i ; Q ox The larger the value, the greater the degree of oxidation and erosion of carbon in the magnesia-carbon brick by the slag.

[0014] In one embodiment, in step S4, the structural erosion capability Q of the slag sample on the magnesia-carbon brick is calculated. st (The low-melting-point liquid phase in the slag permeates into the pores of the magnesia-carbon brick), specifically in the following manner: S41. Based on the thermodynamic calculation results of step S2, obtain the mass fraction w of the low-melting-point liquid phase in the slag at the slag splashing temperature. 低熔 ; S42. Determine the structural erosion coefficient k based on the slag basicity R. 渗 , where R=w CaO / w SiO2 : When R < 2.0, k 渗 =3.5 (low alkalinity, high permeability); When 2.0 ≤ R < 3.5, k 渗 =2.0 (medium alkalinity); When R ≥ 3.5, k 渗 =1.0 (high alkalinity, low permeability); S43. Calculate the structural erosion capacity of slag on magnesia-carbon bricks, Qst: Q st =w 低熔 ×k 渗.

[0015] In one embodiment, in step S41, the low-melting-point liquid phase refers to a silicate phase with a melting point below 1600°C at the slag-splashing temperature, including one or more of 2CaO·SiO2, CaO·SiO2, and FeO·SiO2.

[0016] In one embodiment, in step S5, the temperature correction factor β T Calculated using the following formula: T =exp[(T-1600) / 150]; Where T is the slag splashing temperature, in °C.

[0017] In one embodiment, in step S6, the overall erosivity index Q of the slag is... 侵蚀 The calculation formula is: Q 侵蚀 = T ×[a1×Q ox +a2×Q st ]; Where a1 is the oxidation erosion weight coefficient, with a value of 0.6; and a2 is the structural erosion weight coefficient, with a value of 0.4.

[0018] In one implementation, in step S7, the preset threshold includes a first threshold 30 and a second threshold 60; the determination rule is: When Q 侵蚀 When the temperature is less than 30°C, the slag is determined to be low-corrosive and suitable for slag splashing operation. When 30≤Q 侵蚀 If the slag content is less than 60, the slag is determined to be moderately corrosive, and the slag composition needs to be adjusted before the slag splashing operation can be carried out. When Q 侵蚀 When the temperature is ≥60, the slag is determined to be highly corrosive and should not be splashed; instead, slag should be dumped.

[0019] Among them, Q 侵蚀 The larger the value, the greater the erosion of the magnesia-carbon brick lining by the slag, and the less conducive it is to extending the lining's lifespan.

[0020] In one embodiment, the slag composition is adjusted by controlling the FeO content in the slag to ≤12%, controlling the MgO content to ≥12%, or adjusting the alkalinity to 4.0 or higher.

[0021] In one embodiment, in step S1, the chemical composition of the slag sample is detected using an X-ray fluorescence spectrometer. The slag sample amount is ≥50g, and the main components to be detected are CaO, SiO2, FeO, MnO, MgO, Al2O3, P2O5, and TiO2.

[0022] The beneficial effects of this invention are as follows: 1. This invention fills a technological gap and achieves quantitative evaluation: This invention proposes for the first time a quantitative evaluation model that comprehensively considers slag oxidation erosion and structural erosion, filling the technological gap in the quantitative evaluation of slag erosion in the field of slag splashing protection. This is achieved through a comprehensive index Q. 侵蚀 This allows for a direct and scientific reflection of the overall erosion capacity of slag on magnesia-carbon brick furnace linings.

[0023] 2. Clear Mechanism and Strong Scientific Basis: This invention is based on thermodynamic principles. By calculating the Gibbs free energy change of the reaction between different slag compositions and magnesia-carbon bricks, it fundamentally distinguishes the types of erosion and constructs an oxidative erosion capability (Q) accordingly. ox ) and structural erosion capacity (Q st A calculation model for ) was developed. Simultaneously, a correction factor (k) for the effect of alkalinity on structural erosion was introduced. 渗 ) and temperature correction factor (β) T This makes the evaluation results more closely reflect actual physicochemical processes, significantly improving their scientific rigor and accuracy.

[0024] 3. Provides clear operational guidance to reduce decision-making uncertainty: This invention sets clear Q... 侵蚀 Thresholds (30 and 60) and corresponding operational recommendations ("direct slag splashing", "adjusted slag splashing", "slag dumping treatment"). This enables on-site technicians to make quick and accurate decisions based on the calculation results, completely changing the previous extensive mode of relying on experience-based judgment, and effectively avoiding problems such as excessive furnace lining erosion or shortened furnace lining life caused by unsuitable slag splashing.

[0025] 4. Effectively guides slag composition optimization, resulting in significant cost reduction and efficiency improvement: Through model analysis, the factors affecting Q can be clearly identified. 侵蚀 Key factors. For example, examples demonstrate that highly corrosive slag typically exhibits high FeO and low MgO. Therefore, targeted guidance can be provided to convert highly corrosive slag into low-corrosive slag by controlling the final FeO content, adding magnesia materials, or adjusting basicity. Verification results show that the adjusted furnace lining erosion rate can be reduced by 70-80%, and the furnace life is expected to be extended to over 8000 heats, significantly reducing refractory consumption and steelmaking costs.

[0026] 5. Simple operation and strong applicability: All input parameters of this invention (slag composition, temperature) are routine monitoring indicators for steel enterprises, requiring no additional monitoring costs. Therefore, this method is easy to promote and apply on various converter steelmaking production lines, and has extremely strong industrial practical value.

[0027] 6. Industrial verification confirms reliability: Industrial verification tests in the specific embodiments of the specification show that the Q calculated by this invention is reliable.侵蚀 The value showed a significant positive correlation with the actual average erosion amount per furnace lining (correlation coefficient r=0.93), verifying the accuracy and reliability of the present invention. Detailed Implementation

[0028] To make the technical problems, technical solutions, and technical effects of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0030] This invention provides a method for calculating and evaluating the erosiveness of slag used for converter slag splashing protection, including the following steps: S1. Take a slag sample before the splashing point and detect the content of each component in the slag sample; use X-ray fluorescence spectrometry to detect the chemical composition of the slag sample. The slag sample amount is ≥50g, and the main components to be detected are CaO, SiO2, FeO, MnO, MgO, Al2O3, P2O5, and TiO2.

[0031] S2. Thermodynamic calculation of the reactivity of each component in the slag sample with magnesia-carbon bricks: The standard Gibbs free energy change ΔG of each component in the erosion reaction with magnesia-carbon bricks at the splashing temperature was determined by thermodynamic calculation. i And according to ΔG i The values ​​categorize the components into highly corrosive, weakly corrosive, and inert components, as detailed below: The main components of magnesia-carbon bricks are MgO and C; the calculated reaction temperature is the slag splashing temperature of 1650℃. When ΔG i When ≥0, it indicates that slag component i will not react with the magnesia-carbon bricks, and its erosion effect on the furnace lining can be ignored; when ΔG i When the value is less than 0, it indicates that slag component i has undergone an erosion reaction with the magnesia-carbon brick. The specific judgment rules are as follows: When ΔG i When the value is less than -50 kJ / mol, component i is a highly corrosive component, i.e., oxidative corrosion. The molecular formula of this component is denoted as MxOy, where M is the non-oxygen element in the component and O is the oxygen element in the component. When -50≤ΔG iWhen <0, component i is a weakly corrosive component, which is structural erosion; When ΔG i When the value is ≥0, component i is an inert component and does not participate in the erosion calculation.

[0032] S3. Calculate the oxidative erosion ability Q of the slag sample on magnesia-carbon bricks. ox Oxidative corrosion ability Q ox This is the total weight of oxygen in all the highly corrosive components; the specific method is as follows: S31. Calculate the weight W of oxygen in the highly corrosive component i in the slag that can undergo an oxidation reaction with magnesia-carbon bricks (ΔG_i < -50 kJ / mol). O-i W O-i The calculation formula is as follows: W O-i =(w i / M i )×n O ×M O ×1000; In the formula, w i M represents the mass fraction (wt%) of component i in the slag sample. i n is the relative molecular mass of component i; O y represents the number of oxygen atoms in the molecular formula MxOy of component i; M O This refers to the relative atomic weight of oxygen. S32. By summing the oxygen element weights of all the highly corrosive components of the slag, the oxidative erosion ability Q of the slag on magnesia-carbon bricks can be determined. ox : Q ox =ΣW O-i ; Q ox The larger the value, the greater the degree of oxidation and erosion of carbon in the magnesia-carbon brick by the slag.

[0033] S4. Calculate the structural erosion ability Q of the slag sample on magnesia-carbon bricks. st Structural erosion capability Q st w is the mass fraction of the low-melting-point liquid phase in the slag at the splashing temperature. 低熔 With structural erosion coefficient k 渗 The product; the specific method is as follows: S41. Based on the thermodynamic calculation results of step S2, obtain the mass fraction w of the low-melting-point liquid phase in the slag at the slag splashing temperature. 低熔 Low-melting-point liquid phases refer to silicate phases with melting points below 1600℃ at the slag-splashing temperature, including one or more of 2CaO·SiO2, CaO·SiO2, and FeO·SiO2.

[0034] S42. Determine the structural erosion coefficient k based on the slag basicity R.渗 , where R=w CaO / w SiO2 : When R < 2.0, k 渗 =3.5 (low alkalinity, high permeability); When 2.0 ≤ R < 3.5, k 渗 =2.0 (medium alkalinity); When R ≥ 3.5, k 渗 =1.0 (high alkalinity, low permeability); S43. Calculate the structural erosion capacity of slag on magnesia-carbon bricks, Qst: Q st =w 低熔 ×k 渗 .

[0035] S5. Calculate the temperature correction factor β based on the slag splashing temperature T. T Temperature correction factor β T Calculated using the following formula: T =exp[(T-1600) / 150]; Where T is the slag splashing temperature, in °C.

[0036] S6, Based on the aforementioned oxidation erosion ability Q ox Structural erosion capability Q st and temperature correction factor β T Calculate the comprehensive erosivity index Q of slag 侵蚀 The calculation formula is: Q 侵蚀 = T ×[a1×Q ox +a2×Q st ]; Where a1 is the oxidation erosion weight coefficient, with a value of 0.6; and a2 is the structural erosion weight coefficient, with a value of 0.4.

[0037] S7, the comprehensive erosivity index of slag Q 侵蚀 The slag's corrosivity level and suitability for splashing are determined by comparing it with preset thresholds. The preset thresholds include a first threshold of 30 and a second threshold of 60; the determination rule is as follows: When Q 侵蚀 When the temperature is less than 30°C, the slag is determined to be low-corrosive and suitable for slag splashing operation. When 30≤Q 侵蚀If the slag content is less than 60, the slag is considered to be moderately corrosive and the slag composition needs to be adjusted before slag splashing. The slag composition can be adjusted by controlling the FeO content in the slag to ≤12% and the MgO content to ≥12%, or by adjusting the alkalinity to 4.0 or higher.

[0038] When Q 侵蚀 When the temperature is ≥60, the slag is determined to be highly corrosive and should not be splashed; instead, slag should be dumped.

[0039] In summary, Q 侵蚀 The larger the value, the greater the erosion of the magnesia-carbon brick lining by the slag, and the less conducive it is to extending the lining's lifespan.

[0040] The furnace number in Example 1 is A, the furnace number in Example 2 is B, and the furnace number in Example 3 is C; Examples 1-3 are the erosivity evaluation and industrial verification of slags with different compositions. Based on the actual production data of a steel plant, the erosivity of the final slags of three converters with different compositions was evaluated and verified through industrial tests.

[0041] The details are as follows: (1) Slag composition analysis: ≥50g samples were taken from the final slag of each of the three converter furnaces, and the content of each component was determined using X-ray fluorescence spectrometry (XRF). The test results, alkalinity, and splashing temperature of each slag are shown in Table 1.

[0042] Table 1. Analytical results of slag composition (wt%) from three furnaces.

[0043] Slag basicity R=w CaO / w SiO2 : (2) Thermodynamic calculations and erosion type classification: Using FactSage thermodynamic software, with the reaction temperature set at 1650℃ and the pressure at 1 atm, the Gibbs free energy change ΔG of the reaction between each slag component and the main components of the MgO-C brick was calculated. i The main reactions and calculation results are shown in Table 2.

[0044] Table 2. Thermodynamic calculation results of the reaction between slag composition and MgO-C bricks.

[0045] The judgment rules are as follows: When ΔG i When the value is less than -50 kJ / mol, component i is a highly corrosive component, i.e., oxidative corrosion. When -50≤ΔG i When <0, component i is a weakly corrosive component, which is structural erosion; When ΔG i When the value is ≥0, component i is an inert component and does not participate in the erosion calculation.

[0046] According to the judgment rules: The highly corrosive components include: FeO, MnO, and P2O5; Weakly corrosive components include: SiO2 and TiO2; Inert components include: CaO, MgO, and Al2O3; (3) Calculate the oxidation erosion capacity Q ox : Calculate the weight W of oxygen in the highly corrosive component i in the slag that can undergo an oxidation reaction with magnesia-carbon bricks (ΔG_i < -50 kJ / mol). O-i W O-i The calculation formula is as follows: W O-i =(w i / M i )×n O ×M O ×1000; In the formula, w i M represents the mass fraction (wt%) of component i in the slag sample. i n is the relative molecular mass of component i; O y represents the number of oxygen atoms in the molecular formula MxOy of component i; M O This refers to the relative atomic weight of oxygen. Calculate the weight of oxygen in each of the highly corrosive components (FeO, MnO, P2O5) in the slag.

[0047] A. Slag: W O-FeO =(18.5 / 72)×1×16×1000=4111gO / kg residue; W O-MnO =(6.8 / 71)×1×16×1000=1532gO / kg residue; W O-P2O5 =(1.0 / 142)×5×16×1000=563gO / kg residue; Q ox =4111 + 1532 + 563 = 6206 gO / kg slag. For easier calculation, it is normalized by dividing by 100 to obtain Q. ox =62.06.

[0048] B slag: W O-FeO =(9.2 / 72)×1×16×1000=2044gO / kg residue; W O-MnO=(4.5 / 71)×1×16×1000=1014gO / kg residue; W O-P2O5 =(1.5 / 142)×5×16×1000=845gO / kg residue; Q ox =2044+1014+845=3903gO / kg slag. To facilitate calculation, we normalize it by dividing by 100 to obtain Q. ox =39.03.

[0049] C. Slag: W O-FeO =(24.3 / 72)×1×16×1000=5400gO / kg residue; W O-MnO =(8.2 / 71)×1×16×1000=1848gO / kg residue; W O-P2O5 =(0.5 / 142)×5×16×1000=282gO / kg residue; Q ox =5400+1848+282=7530gO / kg slag. To facilitate calculation, we normalize it by dividing by 100 to obtain Q. ox =75.30.

[0050] (4) Calculate the structural erosion capacity Q st Calculate the content of low-melting-point liquid phase w 低熔 Using the Equilib module of FactSage software, input the slag composition from Table 1, and calculate the mass fraction of the low-melting-point liquid phase (melting point <1600℃) at equilibrium under their respective splashing temperatures. The results are shown in Table 3.

[0051] Table 3 Calculation results of low-melting-point liquid phase of slag from three furnaces

[0052] Calculate the structural erosion ability Q of the slag sample on magnesia-carbon bricks. st (The low-melting-point liquid phase in the slag permeates into the pores of the magnesia-carbon brick), specifically in the following manner: The structural erosion coefficient k is determined based on the slag alkalinity R. 渗 ; When R < 2.0, k 渗 =3.5 (low alkalinity, high permeability); When 2.0 ≤ R < 3.5, k 渗 =2.0 (medium alkalinity); When R ≥ 3.5, k 渗 =1.0 (high alkalinity, low permeability); Calculate the structural erosion capacity Q of slag on magnesia-carbon bricks. st : Q st =w 低熔 ×k 渗 .

[0053] According to Table 3, we can conclude that: A. Slag: R = 3.42 (2.0 ≤ R < 3.5), k 渗 =2.0; B slag: R=3.79 (R≥3.5), k 渗 =1.0; Cslag: R = 2.74 (2.0 ≤ R < 3.5), k 渗 =2.0; Calculate the structural erosion capacity Q of three types of slag on magnesia-carbon bricks. st : According to formula Q st =w 低熔 ×k 渗 The following conclusions can be drawn: A slag: Q st =22.5 × 2.0 = 45.0; B slag: Q st =18.2 × 1.0 = 18.2; C slag: Q st =38.6 × 2.0 = 77.2; (5) Calculate the temperature correction factor β T : According to formula β T =exp[(T-1600) / 150].

[0054] A slag: T=1620℃, β T =exp[(1620-1600) / 150]=exp(0.133)=1.142; B slag: T=1650℃, β T =exp[(1650-1600) / 150]=exp(0.333)=1.395; C slag: T=1680℃, β T =exp[(1680-1600) / 150]=exp(0.533)=1.704; (6) Calculate the comprehensive erosivity index Q 侵蚀 According to formula Q 侵蚀 = T ×[a1×Q ox+a2×Q st The following results were obtained: A slag: Q 侵蚀 =1.142×(0.6×62.06+0.4×45.0)=1.142×(37.236+18.0)=1.142×55.236=63.08; B slag: Q 侵蚀 =1.395×(0.6×39.03+0.4×18.2)=1.395×(23.418+7.28)=1.395×30.698=42.83; C slag: Q 侵蚀 =1.704×(0.6×75.30+0.4×77.2)=1.704×(45.18+30.88)=1.704×76.06=129.61; (7) Suitability determination According to the threshold determination rule (Q) 侵蚀 <30 is low, 30-60 is medium, and ≥60 is high), and the results are shown in Table 4.

[0055] Table 4 Evaluation results of slag erosion in three furnaces

[0056] (8) Industrial verification test: To verify the accuracy of this invention, an industrial test of slag splashing for furnace protection was conducted on the slag from the three furnaces mentioned above. Simultaneously, control groups (A' and C') were added, and the adjusted operations were performed on each group. The slag splashing parameters were standardized as follows: nitrogen pressure 0.9 MPa, lance position 1.2 m, and time 3 minutes. After 50 consecutive furnace cycles, the furnace lining erosion was assessed, and the results are shown in Table 5.

[0057] Table 5 Verification results of furnace lining erosion after slag splashing.

[0058] Explanation of adjustment measures: A' Slag Adjustment: After slag dumping, slag is re-formed, controlling the endpoint FeO ≤ 12%, MgO ≥ 12%. After adjustment, Q is recalculated using the method of this invention. 侵蚀 It dropped to 28.5 (low corrosivity).

[0059] B. Slag Adjustment: Before slag splashing, add 8 kg / t of active lime to increase MgO to 14.8% and basicity to 4.1. After adjustment, Q is calculated... 侵蚀 It dropped to 27.3 (low corrosivity).

[0060] C' Slag Treatment: Due to excessively high FeO content (24.3%) and excessively low MgO content (4.8%), the slag was directly dumped. Subsequently, slag was re-formed, controlling FeO ≤ 10% and MgO ≥ 13%. After adjustment, Q was calculated. 侵蚀 It dropped to 25.8 (low corrosivity).

[0061] (9) Verification conclusions and correlation analysis: Q for each batch (including before and after adjustment) 侵蚀 The correlation analysis between the calculated values ​​and the actual measured average erosion per furnace was performed, and the results are shown in Table 6.

[0062] Table 6 Q 侵蚀 Correlation analysis with furnace lining erosion rate

[0063] Correlation coefficient calculation: According to statistical calculation, Q 侵蚀 The Pearson correlation coefficient between the average loss per furnace and the loss was r=0.93, indicating a significant positive correlation.

[0064] Final conclusion: Q calculated by the method of this invention 侵蚀 The value showed a significant positive correlation with the actual furnace lining erosion rate (r=0.93), proving that the method can accurately and reliably evaluate the corrosiveness of slag to magnesia-carbon brick furnace linings.

[0065] When Q 侵蚀 When the temperature is below 30°C, the average erosion per furnace is ≤1.2mm, which is suitable for slag splashing, and the furnace life can reach more than 8000 furnaces.

[0066] When 30≤Q 侵蚀 When the furnace lining erosion rate is less than 60 mm, the erosion rate is between 1.2 and 3.5 mm / furnace. The slag composition needs to be adjusted, otherwise the furnace life will be shortened.

[0067] When Q 侵蚀 When the temperature reaches ≥60°C, the furnace lining erosion rate is ≥3.5 mm / furnace, which will severely shorten the furnace life and requires slag removal or significant composition adjustment.

[0068] By directionally adjusting the slag composition (such as controlling FeO, increasing MgO, and optimizing basicity), highly corrosive slag can be successfully transformed into low-corrosive slag, and the lining erosion rate after slag splashing can be reduced by 70-80%, resulting in significant economic benefits.

Claims

1. A method for calculating and evaluating the erosiveness of slag used for converter slag splashing protection, characterized in that, Includes the following steps: S1. Take a slag sample before the splashing point and test the content of each component in the slag sample; S2. Thermodynamic calculation of the reactivity of each component in the slag sample with magnesia-carbon bricks: The standard Gibbs free energy change ΔG of each component in the erosion reaction with magnesia-carbon bricks at the splashing temperature was determined by thermodynamic calculation. i And according to ΔG i The values ​​categorize the components into highly corrosive, weakly corrosive, and inert components. S3. Calculate the oxidative erosion ability Q of the slag sample on magnesia-carbon bricks. ox Oxidative corrosion ability Q ox The total weight of oxygen in all the highly corrosive components; S4. Calculate the structural erosion ability Q of the slag sample on magnesia-carbon bricks. st Structural erosion capability Q st w is the mass fraction of the low-melting-point liquid phase in the slag at the splashing temperature. 低熔 With structural erosion coefficient k 渗 The product; S5. Calculate the temperature correction factor β based on the slag splashing temperature T. T ; S6, Based on the aforementioned oxidation erosion ability Q ox Structural erosion capability Q st and temperature correction factor β T Calculate the comprehensive erosivity index Q of slag 侵蚀 ; S7, the comprehensive erosivity index of slag Q 侵蚀 The slag's corrosivity level and suitability for splashing are determined by comparing it with a preset threshold.

2. The method for calculating and evaluating the erosiveness of slag splashing for converter furnace protection according to claim 1, characterized in that, In step S2, the main components of the magnesia-carbon brick are MgO and C; when ΔG i When ≥0, it indicates that slag component i will not react with the magnesia-carbon bricks, and its erosion effect on the furnace lining can be ignored; when ΔG i When the value is less than 0, it indicates that slag component i has undergone an erosion reaction with the magnesia-carbon brick. The specific judgment rules are as follows: When ΔG i When the value is less than -50 kJ / mol, component i is a highly corrosive component, i.e., oxidative corrosion. The molecular formula of this component is denoted as MxOy, where M is the non-oxygen element in the component and O is the oxygen element in the component. When -50≤ΔG i When <0, component i is a weakly corrosive component, which is structural erosion; When ΔG i When the value is ≥0, component i is an inert component and does not participate in the erosion calculation.

3. The method for calculating and evaluating the erosiveness of slag splashing for converter furnace protection according to claim 2, characterized in that, In step S3, the oxidative erosion capacity Q of the slag sample on the magnesia-carbon brick is calculated. ox The specific method is as follows: S31. Calculate the weight W of oxygen in the highly corrosive component i in the slag that can undergo an oxidation reaction with magnesia-carbon bricks. O-i W O-i The calculation formula is as follows: W O-i =(w i / M i )×n O ×M O ×1000; In the formula, w i M represents the mass fraction of component i in the slag sample. i n is the relative molecular mass of component i; O y represents the number of oxygen atoms in the molecular formula MxOy of component i; M O This refers to the relative atomic weight of oxygen. S32. By summing the oxygen element weights of all the highly corrosive components of the slag, the oxidative erosion ability Q of the slag on magnesia-carbon bricks can be determined. ox : Q ox =ΣW O-i ; Q ox The larger the value, the greater the degree of oxidation and erosion of carbon in the magnesia-carbon brick by the slag.

4. The method for calculating and evaluating the erosiveness of slag splashing for converter furnace protection according to claim 1, characterized in that, In step S4, the structural erosion capacity Qst of the slag sample on the magnesia-carbon brick is calculated, as follows: S41. Based on the thermodynamic calculation results of step S2, obtain the mass fraction w of the low-melting-point liquid phase in the slag at the slag splashing temperature. 低熔 ; S42. Determine the structural erosion coefficient k based on the slag basicity R. 渗 : When R < 2.0, k 渗 =3.5; When 2.0 ≤ R < 3.5, k 渗 =2.0; When R ≥ 3.5, k 渗 =1.0; S43. Calculate the structural erosion capacity of slag on magnesia-carbon bricks, Qst: Q st =w 低熔 ×k 渗 。 5. The method for calculating and evaluating the erosiveness of slag splashing for converter furnace protection according to claim 4, characterized in that, In step S41, the low-melting-point liquid phase refers to a silicate phase with a melting point below 1600°C at the slag-splashing temperature, including one or more of 2CaO·SiO2, CaO·SiO2, and FeO·SiO2.

6. The method for calculating and evaluating the erosivity of slag splashing for converter furnace protection according to claim 1, characterized in that, In step S5, the temperature correction factor β T Calculated using the following formula: T =exp[(T-1600) / 150]; Where T is the slag splashing temperature, in °C.

7. The method for calculating and evaluating the erosiveness of slag splashing for converter furnace protection according to claim 1, characterized in that, In step S6, the comprehensive erosivity index Q of the slag 侵蚀 The calculation formula is: Q 侵蚀 = T ×[a1×Q ox +a2×Q st ]; Where a1 is the oxidation erosion weight coefficient, with a value of 0.6; and a2 is the structural erosion weight coefficient, with a value of 0.

4.

8. The method for calculating and evaluating the erosiveness of slag splashing for converter furnace protection according to claim 1, characterized in that, In step S7, the preset thresholds include a first threshold of 30 and a second threshold of 60; the determination rule is: When Q 侵蚀 When the temperature is less than 30°C, the slag is determined to be low-corrosive and suitable for slag splashing operation. When 30≤Q 侵蚀 If the slag content is less than 60, the slag is determined to be moderately corrosive, and the slag composition needs to be adjusted before the slag splashing operation can be carried out. When Q 侵蚀 When the temperature is ≥60, the slag is determined to be highly corrosive and should not be splashed; slag removal should be performed instead. Among them, Q 侵蚀 The larger the value, the greater the erosion of the magnesia-carbon brick lining by the slag, and the less conducive it is to extending the lining's lifespan.

9. The method for calculating and evaluating the erosiveness of slag splashing for converter furnace protection according to claim 8, characterized in that, The method to adjust the slag composition is as follows: control the FeO content in the slag to ≤12%, control the MgO content to ≥12%, or adjust the alkalinity to 4.0 or above.

10. The method for calculating and evaluating the erosiveness of slag splashing for converter furnace protection according to claim 1, characterized in that, In step S1, the chemical composition of the slag sample is detected by X-ray fluorescence spectrometry, and the slag sample amount is ≥50g.

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