Desulfurization of CaO–Al_(2)O_(3) particles in molten steel was observed in situ using high-temperature confocal scanning laser microscopy.The effects of the aluminum and silicon contents of molten steel on desulfur...Desulfurization of CaO–Al_(2)O_(3) particles in molten steel was observed in situ using high-temperature confocal scanning laser microscopy.The effects of the aluminum and silicon contents of molten steel on desulfurization were analyzed.When the total aluminum content in the steel increased from 6 to 1100 ppm,the CaS content in CaO–Al_(2)O_(3) particles increased from 2.1wt%to 84.84wt%after the reaction for 90 s.Furthermore,when the silicon content in the steel increased from 0.01wt%to 2.20wt%,the CaS content in CaO–Al_(2)O_(3) particles increased from 1.53wt%to 79.01wt%after the reaction for 90 s.This indicates that the increase in the aluminum and silicon contents of the steel promoted the desulfurization of CaO–Al_(2)O_(3) particles.A kinetic model was established to predict the CaO–Al_(2)O_(3) particles composition,and the diffusion coefficient of sulfur in CaO–Al_(2)O_(3) particles was 9.375×10^(−10)m^(2)·s^(−1) at 1600℃,which provided a new method for the calculation of diffusion coefficient.展开更多
Rare earth elements are widely used in steel production due to their unique metallurgical properties,which can modify inclusions,improve the cleanliness of molten steel,and optimize steel properties.However,high activ...Rare earth elements are widely used in steel production due to their unique metallurgical properties,which can modify inclusions,improve the cleanliness of molten steel,and optimize steel properties.However,high activity also makes rare earth elements prone to intense chemical reactions with refractories during the smelting process,which can not only accelerate the erosion and failure of refractories,but also reduce the cleanliness of molten steel owing to the formation of secondary inclusions.Therefore,it is essential to understand the interaction mechanisms between rare earth steels and refractories.Herein,the research progress on the interactions between rare earth steels and refractories is systematically reviewed.Based on both laboratory studies and industrial applications,emphasis is placed on the reaction mechanisms and their effects on the stability of refractories and the cleanliness of molten steel.At the same time,the prevention methods are summarized,including the refractory optimization,protective coatings for nozzles,argon blowing,and the application of external electric fields.Furthermore,the applicability and limitations of these methods are analyzed.Finally,future research directions are discussed to address the limitations of current studies,focusing on the development of novel refractories,non-contact control methods,and digitally intelligent process control.展开更多
The structural changes in the CaO-SiO_(2)-Al_(2)O_(3)-MgO slag system with varying CaO contents were investigated through molecular dynamics(MD)simulations,and its effect on the dissolution behavior of alumina inclusi...The structural changes in the CaO-SiO_(2)-Al_(2)O_(3)-MgO slag system with varying CaO contents were investigated through molecular dynamics(MD)simulations,and its effect on the dissolution behavior of alumina inclusions was characterized by the Kullback-Leibler(KL)divergence.The slag structure analysis revealed that the[AlO]tetrahedral structure was the primary network structure in the slag.With increasing the CaO content,the non-bridge oxygen(NBO)content in the slag structure increases,and the bridge oxygen(BO)content decreases,thereby reducing the complexity of the slag network structure.Raman spectroscopy detection verifies the results of the MD simulations.The results indicated that the dissolution rate of alumina inclusions accelerates with increasing the CaO content in the slag,owing to the reduced complexity of the slag network structure and the enhanced interatomic interactions.The simulation results for the dissolution of alumina inclusions were consistent with theoretical calculations based on the slag inclusion capacity and the dimensionless dissolution rate of inclusions.Radial distribution function analysis demonstrated that the interaction between atoms in the slag system and alumina inclusions strengthens,increasing the dissolution rate of alumina inclusions.The[AlO_(6)]octahedral structure of the alumina inclusions is disrupted,forming BO structures,which in turn enhances the complexity of the slag network structure,slowing the dissolution rate of alumina inclusions.In contrast,the slag system with a higher CaO content has a relatively simpler network structure,promoting faster alumina inclusion dissolution.展开更多
High-quality steel production requires superior-performance refractories.To meet the requirements of quality enhancement and efficiency improvement in the steelmaking industry,the application of the novel microporous ...High-quality steel production requires superior-performance refractories.To meet the requirements of quality enhancement and efficiency improvement in the steelmaking industry,the application of the novel microporous magnesia with high strength,remarkable slag resistance,and excellent thermal insulation is promoted.The interface reaction between H13 steel and novel microporous magnesia castable was investigated by using the crucible method,to elucidate the molten steel purification mechanism.The interface microstructure was observed by scanning electron microscopy,and the composition,size,and amount of inclusions were statistically analyzed.A thermal calculation was conducted to gain a deeper understanding of the modification process of inclusions.Fused magnesia castables were used as the blank control.The results show that the average number density and size of inclusions were reduced by 5.99 mm^(−2) and 0.28μm respectively after the same reaction time because the micropores enhanced the inclusion adsorption.The size of inclusions caused by erosion decreased.Also,more[Mg]dissolved into molten steel over 60 min reaction time and resulted in a 0.49 wt.%increase in inclusion Mg content,which modified the inclusion by decreasing their melting point.Therefore,applying novel microporous magnesia was beneficial for purifying H13 steel.展开更多
To investigate the dispersion and deposition behavior of the nanoparticles(NPs)in the molten steel under the combined effects of turbulent flow and Brownian motion,a 3D model utilizing volume of fluid-discrete phase m...To investigate the dispersion and deposition behavior of the nanoparticles(NPs)in the molten steel under the combined effects of turbulent flow and Brownian motion,a 3D model utilizing volume of fluid-discrete phase model was developed based on a small-size ingot casting process.A modified Brownian motion model was implemented into the simulation using user-defined function to more accurately predict the motion behavior and distribution of the NPs in the molten steel.The results show that the NPs tend to deposit at the bottom or disperse toward the wall under the turbulent flow.The introduction of Brownian motion increases the horizontal dispersion rate(DH)to 21.3%and reduces the bottom deposition rate by 12.8%.A reduction in the particle size and density promotes higher particle mobility,characterized by increased velocity and DH,along with diminished deposition.As the particle size decreases to 1×10^(-7)m,Brownian motion becomes a significant factor influencing the particle dynamics.Additionally,increasing the initial velocity of the molten steel results in a lower DH of the particles.However,once the velocity exceeds 0.15 m s^(-1),its influence on the particle velocity becomes negligible.展开更多
To resolve severe slag penetration and erosion in Al_(2)O_(3)-SiC-C refractories during high scrap ratio iron ladle operation,a novel strategy utilizing exogenous MgAl_(2)O_(4) spinel as a sacrificial FeO_(x) scavenge...To resolve severe slag penetration and erosion in Al_(2)O_(3)-SiC-C refractories during high scrap ratio iron ladle operation,a novel strategy utilizing exogenous MgAl_(2)O_(4) spinel as a sacrificial FeO_(x) scavenger was proposed.Al_(2)O_(3)-SiC-C refractories produced with plate-like corundum,silicon carbide,and flake graphite incorporating MgAl_(2)O_(4) additives were cured at 1400℃ in the condition of carbon embedding.The impacts of additives on phase composition,microscopic morphology,and performance of materials were studied.The results indicated that Al_(2)O_(3)-SiC-C refractories with the addition of 2 wt.%MgAl_(2)O_(4) exhibited a smaller oxidation area after oxidation tests compared to samples without MgAl_(2)O_(4),resulting in 28%improvement in oxidation resistance compared to blank samples.In the erosion test,the results informed that adding 4 wt.%MgAl_(2)O_(4) induced significant interfacial slag modification:MgAl_(2)O_(4) dynamically dissolved FeO_(x) to form protective Mg(Fe,Al)_(2)O_(4) solid solution on the slag-refractory interface.This sacrificial dissolution effectively immobilized FeO_(x),elevated local slag viscosity,and fundamentally inhibited slag penetration and matrix dissolution.The erosion index decreased from 50%in the blank group to 27.4%.展开更多
The dissolution of MgO-refractory into the slag had an obvious influence on the steel-slag reaction and the slag property,especially for high-aluminum steels.The dissolution behavior of MgO-refractory was investigated...The dissolution of MgO-refractory into the slag had an obvious influence on the steel-slag reaction and the slag property,especially for high-aluminum steels.The dissolution behavior of MgO-refractory was investigated under various conditions,including the temperature,the initial steel composition,and the initial slag composition.A steel-slag-refractory kinetic model for high-aluminum steel was developed,which incorporated the process of MgO-refractory dissolution.The dependence of the MgO mass transfer coefficient k_(MgO)^(r)on temperature T during MgO-refractory dissolution process was established,as described by ln k_(MgO)^(r)=63,754/T+24.38524.It was indicated that the MgO dissolution rate was significantly influenced by the temperature.A higher temperature increased the dissolution rate of MgO.The initial steel composition had a slight impact on the MgO dissolution rate.Additionally,the initial slag composition strongly impacted the MgO saturation concentration and the dissolution rate.A lower initial Al_(2)O_(3)/SiO_(2)ratio increased the MgO dissolution rate.The steel-slag-refractory kinetic model accurately predicted the dissolution of MgO-refractory and the influence of dissolved MgO on the viscosity and composition change during steel-slag-refractory reactions.It was suggested that a higher temperature can hardly reduce the viscosity due to the dissolution of the MgO-refractory.展开更多
基金supported by the National Key R&D Program of China(No.2023YFB3709900)the National Nature Science Foundation of China(No.U22A20171)+1 种基金the China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202315)the High Steel Center(HSC)at North China University of Technology and University of Science and Technology Beijing,China.
文摘Desulfurization of CaO–Al_(2)O_(3) particles in molten steel was observed in situ using high-temperature confocal scanning laser microscopy.The effects of the aluminum and silicon contents of molten steel on desulfurization were analyzed.When the total aluminum content in the steel increased from 6 to 1100 ppm,the CaS content in CaO–Al_(2)O_(3) particles increased from 2.1wt%to 84.84wt%after the reaction for 90 s.Furthermore,when the silicon content in the steel increased from 0.01wt%to 2.20wt%,the CaS content in CaO–Al_(2)O_(3) particles increased from 1.53wt%to 79.01wt%after the reaction for 90 s.This indicates that the increase in the aluminum and silicon contents of the steel promoted the desulfurization of CaO–Al_(2)O_(3) particles.A kinetic model was established to predict the CaO–Al_(2)O_(3) particles composition,and the diffusion coefficient of sulfur in CaO–Al_(2)O_(3) particles was 9.375×10^(−10)m^(2)·s^(−1) at 1600℃,which provided a new method for the calculation of diffusion coefficient.
基金supported by the National Natural Science Foundation of China(Nos.52450003,52025041,U2341267,and 52174294).
文摘Rare earth elements are widely used in steel production due to their unique metallurgical properties,which can modify inclusions,improve the cleanliness of molten steel,and optimize steel properties.However,high activity also makes rare earth elements prone to intense chemical reactions with refractories during the smelting process,which can not only accelerate the erosion and failure of refractories,but also reduce the cleanliness of molten steel owing to the formation of secondary inclusions.Therefore,it is essential to understand the interaction mechanisms between rare earth steels and refractories.Herein,the research progress on the interactions between rare earth steels and refractories is systematically reviewed.Based on both laboratory studies and industrial applications,emphasis is placed on the reaction mechanisms and their effects on the stability of refractories and the cleanliness of molten steel.At the same time,the prevention methods are summarized,including the refractory optimization,protective coatings for nozzles,argon blowing,and the application of external electric fields.Furthermore,the applicability and limitations of these methods are analyzed.Finally,future research directions are discussed to address the limitations of current studies,focusing on the development of novel refractories,non-contact control methods,and digitally intelligent process control.
基金supported by Special Funding Projects for Local Science and Technology Development guided by the Central Committee(No.YDZJSX2022C028)the Fundamental Research Program of Shanxi Province(Nos.20210302123218 and 202203021211187)+4 种基金Innovation and Entrepreneurship Training Program for College Students in Shanxi Province(202210109006)the National Natural Science Foundation(52474367)the Key Research and Development for University-Local Government Collaboration of Lvliang City(2024XDHZ01)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(2025Q022)the Foundation of State Key Laboratory of Advanced Metallurgy,USTB(K22-10).
文摘The structural changes in the CaO-SiO_(2)-Al_(2)O_(3)-MgO slag system with varying CaO contents were investigated through molecular dynamics(MD)simulations,and its effect on the dissolution behavior of alumina inclusions was characterized by the Kullback-Leibler(KL)divergence.The slag structure analysis revealed that the[AlO]tetrahedral structure was the primary network structure in the slag.With increasing the CaO content,the non-bridge oxygen(NBO)content in the slag structure increases,and the bridge oxygen(BO)content decreases,thereby reducing the complexity of the slag network structure.Raman spectroscopy detection verifies the results of the MD simulations.The results indicated that the dissolution rate of alumina inclusions accelerates with increasing the CaO content in the slag,owing to the reduced complexity of the slag network structure and the enhanced interatomic interactions.The simulation results for the dissolution of alumina inclusions were consistent with theoretical calculations based on the slag inclusion capacity and the dimensionless dissolution rate of inclusions.Radial distribution function analysis demonstrated that the interaction between atoms in the slag system and alumina inclusions strengthens,increasing the dissolution rate of alumina inclusions.The[AlO_(6)]octahedral structure of the alumina inclusions is disrupted,forming BO structures,which in turn enhances the complexity of the slag network structure,slowing the dissolution rate of alumina inclusions.In contrast,the slag system with a higher CaO content has a relatively simpler network structure,promoting faster alumina inclusion dissolution.
基金support of this study by the National Natural Science Foundation of China(Grant Nos.U22A20173 and U21A2058).
文摘High-quality steel production requires superior-performance refractories.To meet the requirements of quality enhancement and efficiency improvement in the steelmaking industry,the application of the novel microporous magnesia with high strength,remarkable slag resistance,and excellent thermal insulation is promoted.The interface reaction between H13 steel and novel microporous magnesia castable was investigated by using the crucible method,to elucidate the molten steel purification mechanism.The interface microstructure was observed by scanning electron microscopy,and the composition,size,and amount of inclusions were statistically analyzed.A thermal calculation was conducted to gain a deeper understanding of the modification process of inclusions.Fused magnesia castables were used as the blank control.The results show that the average number density and size of inclusions were reduced by 5.99 mm^(−2) and 0.28μm respectively after the same reaction time because the micropores enhanced the inclusion adsorption.The size of inclusions caused by erosion decreased.Also,more[Mg]dissolved into molten steel over 60 min reaction time and resulted in a 0.49 wt.%increase in inclusion Mg content,which modified the inclusion by decreasing their melting point.Therefore,applying novel microporous magnesia was beneficial for purifying H13 steel.
基金supported by the 111 Project(2.0)of China(No.BP0719037)the National Natural Science Foundation of China(No.51474065).
文摘To investigate the dispersion and deposition behavior of the nanoparticles(NPs)in the molten steel under the combined effects of turbulent flow and Brownian motion,a 3D model utilizing volume of fluid-discrete phase model was developed based on a small-size ingot casting process.A modified Brownian motion model was implemented into the simulation using user-defined function to more accurately predict the motion behavior and distribution of the NPs in the molten steel.The results show that the NPs tend to deposit at the bottom or disperse toward the wall under the turbulent flow.The introduction of Brownian motion increases the horizontal dispersion rate(DH)to 21.3%and reduces the bottom deposition rate by 12.8%.A reduction in the particle size and density promotes higher particle mobility,characterized by increased velocity and DH,along with diminished deposition.As the particle size decreases to 1×10^(-7)m,Brownian motion becomes a significant factor influencing the particle dynamics.Additionally,increasing the initial velocity of the molten steel results in a lower DH of the particles.However,once the velocity exceeds 0.15 m s^(-1),its influence on the particle velocity becomes negligible.
基金support from the project supported by the National Natural Science Foundation of China(Grant No.52402034)the Science and Technology Innovation Team Foundation of Hubei Province(Grant No.T2023001)+1 种基金the Natural Science Foundation of Hubei Province(Grant No.2023BAB106)the Natural Science Foundation of Wuhan(Grant No.2024040701010051).
文摘To resolve severe slag penetration and erosion in Al_(2)O_(3)-SiC-C refractories during high scrap ratio iron ladle operation,a novel strategy utilizing exogenous MgAl_(2)O_(4) spinel as a sacrificial FeO_(x) scavenger was proposed.Al_(2)O_(3)-SiC-C refractories produced with plate-like corundum,silicon carbide,and flake graphite incorporating MgAl_(2)O_(4) additives were cured at 1400℃ in the condition of carbon embedding.The impacts of additives on phase composition,microscopic morphology,and performance of materials were studied.The results indicated that Al_(2)O_(3)-SiC-C refractories with the addition of 2 wt.%MgAl_(2)O_(4) exhibited a smaller oxidation area after oxidation tests compared to samples without MgAl_(2)O_(4),resulting in 28%improvement in oxidation resistance compared to blank samples.In the erosion test,the results informed that adding 4 wt.%MgAl_(2)O_(4) induced significant interfacial slag modification:MgAl_(2)O_(4) dynamically dissolved FeO_(x) to form protective Mg(Fe,Al)_(2)O_(4) solid solution on the slag-refractory interface.This sacrificial dissolution effectively immobilized FeO_(x),elevated local slag viscosity,and fundamentally inhibited slag penetration and matrix dissolution.The erosion index decreased from 50%in the blank group to 27.4%.
基金support from the National Key R&D Program of China(Grant No.2023YFB3709901)the National Natural Science Foundation of China(Grant No.U22A20171)+1 种基金China Baowu Low Carbon Metallurgy Innovation Foundation(Grant No.BWLCF202315)the High Steel Center(HSC)at North China University of Technology and University of Science and Technology Beijing,China.
文摘The dissolution of MgO-refractory into the slag had an obvious influence on the steel-slag reaction and the slag property,especially for high-aluminum steels.The dissolution behavior of MgO-refractory was investigated under various conditions,including the temperature,the initial steel composition,and the initial slag composition.A steel-slag-refractory kinetic model for high-aluminum steel was developed,which incorporated the process of MgO-refractory dissolution.The dependence of the MgO mass transfer coefficient k_(MgO)^(r)on temperature T during MgO-refractory dissolution process was established,as described by ln k_(MgO)^(r)=63,754/T+24.38524.It was indicated that the MgO dissolution rate was significantly influenced by the temperature.A higher temperature increased the dissolution rate of MgO.The initial steel composition had a slight impact on the MgO dissolution rate.Additionally,the initial slag composition strongly impacted the MgO saturation concentration and the dissolution rate.A lower initial Al_(2)O_(3)/SiO_(2)ratio increased the MgO dissolution rate.The steel-slag-refractory kinetic model accurately predicted the dissolution of MgO-refractory and the influence of dissolved MgO on the viscosity and composition change during steel-slag-refractory reactions.It was suggested that a higher temperature can hardly reduce the viscosity due to the dissolution of the MgO-refractory.
