Chromium plays a vital role in stainless steel due to its ability to improve the corrosion resistance of the latter.However,the re-lease of chromium from stainless steel slag(SSS)during SSS stockpiling causes detrimen...Chromium plays a vital role in stainless steel due to its ability to improve the corrosion resistance of the latter.However,the re-lease of chromium from stainless steel slag(SSS)during SSS stockpiling causes detrimental environmental issues.To prevent chromium pollution,the effects of iron oxide on crystallization behavior and spatial distribution of spinel were investigated in this work.The results revealed that FeO was more conducive to the growth of spinels compared with Fe2O3 and Fe3O4.Spinels were found to be mainly distrib-uted at the top and bottom of slag.The amount of spinel phase at the bottom decreased with the increasing FeO content,while that at the top increased.The average particle size of spinel in the slag with 18wt%FeO content was 12.8μm.Meanwhile,no notable structural changes were observed with a further increase in FeO content.In other words,the spatial distribution of spinel changed when the content of iron oxide varied in the range of 8wt%to 18wt%.Finally,less spinel was found at the bottom of slag with a FeO content of 23wt%.展开更多
Steelmaking industry faces urgent demands for both steel slag utilization and CO_(2)abatement.Ca and Mg of steel slag can be extracted by acid solution and used to prepare sorbents for CO_(2)capture.In this work,the c...Steelmaking industry faces urgent demands for both steel slag utilization and CO_(2)abatement.Ca and Mg of steel slag can be extracted by acid solution and used to prepare sorbents for CO_(2)capture.In this work,the calcium-based sorbents were prepared from stainless steel slag leachate by co-precipitation,and the initial CO_(2)chemisorption capacity of the calcium-based sorbent prepared from steel slag with the Ca and Mg molar ratio of 3.64:1 was 0.40 g/g.Moreover,the effect of Ca/Mg molar ratio on the morphology,structure,and CO_(2)chemisorption capacity of the calcium-based sorbents were investigated.The results show that the optimal Ca/Mg molar ratio of sorbent for CO_(2)capture was4.2:1,and the skeleton support effect of MgO in calcium-based sorbents was determined.Meanwhile,the chemisorption kinetics of the sorbents was studied using the Avrami-Erofeev model.There were two processes of CO_(2)chemisorption,and the activation energy of the first stage(reaction control)was found to be lower than that of the second stage(diffusion control).展开更多
Plenty of flue gas desulfurization(FGD) gypsum generated from coal-fired power plants for sulfur dioxide sequestration caused many environmental issues. Preparing calcium sulfate whisker(CSW) from FGD gypsum by hydrot...Plenty of flue gas desulfurization(FGD) gypsum generated from coal-fired power plants for sulfur dioxide sequestration caused many environmental issues. Preparing calcium sulfate whisker(CSW) from FGD gypsum by hydrothermal synthesis is considered to be a promising approach to solve this troublesome problem and utilize calcium sulfate in a high-value-added way. The effects of particle size of FGD gypsum, slurry concentration,and additives on CSW were investigated in this work. The results indicated that fine particle size of FGD gypsum and moderately high slurry concentration were beneficial for crystal nucleation and growth. Three additives of magnesium chloride, citric acid, and sodium dodecyl benzene sulfonate(SDBS) were employed in this study. It was found that mean length and aspect ratio of CSW were both decreased by the usage of magnesium chloride,while a small quantity of citric acid or SDBS could improve the CSW morphology. When multi-additives of citric acid-SDBS were employed, the mean length and aspect ratio increased more than 20%. Moreover, surface morphology of CSW went better, and the particle size and crystal shape became more uniform.展开更多
As an indication of the Earth's mass distribution,the principal moments of inertia(PMOI,i.e.,A,B,C) of the Earth are the basic parameters in studies of the global dynamics of the earth,like earth nutation,and the ...As an indication of the Earth's mass distribution,the principal moments of inertia(PMOI,i.e.,A,B,C) of the Earth are the basic parameters in studies of the global dynamics of the earth,like earth nutation,and the geophysics.From the aspect of observation,the PMOI can be calculated from the spherical coefficients of observed gravity field.In this paper,the PMOI are calculated directly according to its definition with the figures of the Earth's interior derived by a generalized theory of the hydrostatic equilibrium figure of the Earth.We obtain that the angle between the principal axis of the maximum moment of PMOI and the rotational axis is 0.184°,which means that the other two principal axes are very closely in the equatorial plane.Meanwhile,B-A is 1.60 × 10^(-5) MR^2,and the global dynamical flattening(H) is calculated to be 3.29587 × 10^(-3),which is 0.67%different from the latest observation derived value H_(obs)(3.273795 × 10^(-3))(Petit and Luzum,2010),and this is a significant improvement from the 1.1%difference between the value of H derived from traditional theories of the figure of the Earth and the value of H_(obs).It shows that we can calculate the PMOI and H with an appropriate accuracy by a generalized theory of the hydrostatic equilibrium figure of the Earth.展开更多
The quality of stainless steel is closely related to the deformability of inclusions,which is significantly affected by their compositions.The present study first inve stigated the evolution of inclusion compositions ...The quality of stainless steel is closely related to the deformability of inclusions,which is significantly affected by their compositions.The present study first inve stigated the evolution of inclusion compositions in AI-killed steel with rare earth-alkali metals(Ca or Mg)combined treatme nt through four laboratory-scale experiments.The Ce contents in the final steel are 0.0080 wt%,0.015 wt%,0.016 wt%and 0.010 wt%,respectively.The Mg content is 0.0014 wt%in Ce-Mg combined treated steel,and the Ca content is0.0015 wt%in Ce-Ca combined treated steel.The deformability of inclusions in both Ce_(2)O_(3)-Al_(2)O_(3)-CaO and Ce_(2)O_(3)-Al_(2)O_(3)-MgO systems was subsequently evaluated by calculating their Young's modulus at low temperature.The results show that irregular Al_(2)O_(3)and MgAl_(2)O_(4)with poor deformability are modified to CeAlO_(3)and Ce_(2)O_(3)by Ce treatment,resulting in the decrease of Young's modulus of inclusions.The deformability of inclusions is further improved due to the transformation from lumped-like CeAlO_(3)to spherical CaO-Al_(2)O_(3)-Ce_(2)O_(3)caused by Ca treatment,and some of these inclusions are the ones with low liquidus temperature.Thermodynamic analysis was used to discuss the control condition of the formation and evolution of inclusions.Accordingly,the appropriate addition amounts of Al,Mg,Ce,and Ca are expected to control inclusion compositions and properties,including deformability and liquidus temperature,thereby improving the steel performance.展开更多
The phosphorus fixation capacity of some slag systems,such as Ce_(2)O_(3)-containing slag,has hardly been investigated from a thermodynamics view due to the lack of relevant thermodynamic data.Since the macroscopic pr...The phosphorus fixation capacity of some slag systems,such as Ce_(2)O_(3)-containing slag,has hardly been investigated from a thermodynamics view due to the lack of relevant thermodynamic data.Since the macroscopic properties are primarily determined by the microscopic structure,the correlation between phosphorus fixation capacity and slag structure was explored by spectroscopy(XPS),Raman spectroscopy,and ferromanganese dephosphorization experiments.The results show that the predominant species of P^(5+)are Q_(P)^(0)(PO_(4)^(3-))and Q_(P)^(1)(P_(2)O_(7)^(4-))units in the CaO^(-)SiO_(2)-Al_(2)O_(3)-MnO^(-)Ce_(2)O_(3)-P_(2)O_(5)quenched slag,and the phosphorus fixation capacity increases with the Q_(P)^(1)(P_(2)O_(7)^(4-))unit to Q_(P)^(0)(PO_(4)^(3-))unit transformation(the P-O^(0) bond to P-O^(-)bond transformation)since the electron cloud density between P and O atoms increases and the average radius of P-O bonds decreases.Especially,CaO or Ce_(2)O_(3) as a network modifier can release the O_(2)-and promote the P-O^(0) bond to P-O^(-)bond(connected to Ca^(2+),/Ce^(3+))transformation in the quenched slag.Furthermore,the phosphorus enrichment phases in the slow cooling slag are confirmed as nCa_(2)SiO_(3)-Ca_(3)P_(2)O_(8)(nC_(2)S-C3P)and CePO_(4) solid solutions by the scan electron microscopy(SEM),transmission electron microscopy(TEM),and energy-dispersive spectrometer(EDS)methods.The re sults show Ce_(2)O_(3) can depolymerize the polyphosphate structure partially replacing CaO after introducing Ce_(2)O_(3) into CaO based slag because of its strong ability to donate electrons.The above results not only help to understand the dependence of phosphorus fixation capacity on slag composition from a structural view,but also provide the theoretical guidance for optimizing the composition of Ce_(2)O_(3)-containing dephosphorization slag.展开更多
The lack of thermodynamic information,such as primary phase fields and liquidus temperatures,in the CaO-SiO2-Nb2O5-La2O3 quaternary system phase diagram has restricted the comprehensive utilization of the niobium(Nb) ...The lack of thermodynamic information,such as primary phase fields and liquidus temperatures,in the CaO-SiO2-Nb2O5-La2O3 quaternary system phase diagram has restricted the comprehensive utilization of the niobium(Nb) and rare earth(RE) resources.In this work,the phase equilibria in low basicity region(w(CaO)/w(SiO2)<1) of CaO-SiO2-Nb2O5-(0-15 wt%)La2O3 system at 1373-1873 K were experimentally studied by thermodynamic equilibrium experiment,and then,the results were analyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM),and energy dispersive spectrometry(EDS).Additionally,an optimized method was proposed to process the compositions of equilibrium liquid phases at different temperatures.According to the experimental results,the univariate line between CaNb2O6,SiO2 and LaNbO4 primary phase fields,interface between CaNb2O6 and SiO2 primary phase fields and isothermal liquidus surfaces in SiO2 primary phase field were determined.Finally,the spatial phase diagram of CaO-SiO2-Nb2O5-La2O3 within specific region was constructed,and furthermore,the phase diagram was also presented in CaO-SiO2-Nb2O5 pseudo-ternary system with w(La2O3)=5 wt%,10 wt% and 15 wt%.The research results have guiding significance for the improvement of related phase diagram and the comprehensive utilization of Nb and RE resources.展开更多
基金the National Natural Science Foundation of China(Nos.52074078 and 52374327)the Applied Fundamental Research Program of Liaoning Province(No.2023JH2/101600002)+2 种基金the Shenyang Young Middle-Aged Scientific and Technological Innovation Talent Support Program(No.RC220491)the Liaoning Province Steel Industry-University-Research Innovation Alliance Cooperation Project of Bensteel Group(No.KJBLM202202)the Fundamental Research Funds for the Central Universities(Nos.N2201023 and N2325009).
文摘Chromium plays a vital role in stainless steel due to its ability to improve the corrosion resistance of the latter.However,the re-lease of chromium from stainless steel slag(SSS)during SSS stockpiling causes detrimental environmental issues.To prevent chromium pollution,the effects of iron oxide on crystallization behavior and spatial distribution of spinel were investigated in this work.The results revealed that FeO was more conducive to the growth of spinels compared with Fe2O3 and Fe3O4.Spinels were found to be mainly distrib-uted at the top and bottom of slag.The amount of spinel phase at the bottom decreased with the increasing FeO content,while that at the top increased.The average particle size of spinel in the slag with 18wt%FeO content was 12.8μm.Meanwhile,no notable structural changes were observed with a further increase in FeO content.In other words,the spatial distribution of spinel changed when the content of iron oxide varied in the range of 8wt%to 18wt%.Finally,less spinel was found at the bottom of slag with a FeO content of 23wt%.
基金financially supported by the National Natural Science Foundation of China(No.52074078)the National Key R&D Program of China(No.2021YFC2901200)+4 种基金the Applied Fundamental Research Program of Liaoning Province(No.2023JH2/101600002)the Liaoning Provincial Natural Science Foundation of China(No.2022-YQ-09)the Shenyang Young Middle-Aged Scientific and Technological Innovation Talent Support Program,China(No.RC220491)the Liaoning Province Steel Industry-University-Research Innovation Alliance Cooperation Project of Bensteel Group,China(No.KJBLM202202)the Fundamental Research Funds for the Central Universities,China(Nos.N2201023,N2325009)。
文摘Steelmaking industry faces urgent demands for both steel slag utilization and CO_(2)abatement.Ca and Mg of steel slag can be extracted by acid solution and used to prepare sorbents for CO_(2)capture.In this work,the calcium-based sorbents were prepared from stainless steel slag leachate by co-precipitation,and the initial CO_(2)chemisorption capacity of the calcium-based sorbent prepared from steel slag with the Ca and Mg molar ratio of 3.64:1 was 0.40 g/g.Moreover,the effect of Ca/Mg molar ratio on the morphology,structure,and CO_(2)chemisorption capacity of the calcium-based sorbents were investigated.The results show that the optimal Ca/Mg molar ratio of sorbent for CO_(2)capture was4.2:1,and the skeleton support effect of MgO in calcium-based sorbents was determined.Meanwhile,the chemisorption kinetics of the sorbents was studied using the Avrami-Erofeev model.There were two processes of CO_(2)chemisorption,and the activation energy of the first stage(reaction control)was found to be lower than that of the second stage(diffusion control).
基金Supported by National Science Foundation of China(51374059,51304042)the Fundamental Research Funds for the Central Universities of China(N130402020)
文摘Plenty of flue gas desulfurization(FGD) gypsum generated from coal-fired power plants for sulfur dioxide sequestration caused many environmental issues. Preparing calcium sulfate whisker(CSW) from FGD gypsum by hydrothermal synthesis is considered to be a promising approach to solve this troublesome problem and utilize calcium sulfate in a high-value-added way. The effects of particle size of FGD gypsum, slurry concentration,and additives on CSW were investigated in this work. The results indicated that fine particle size of FGD gypsum and moderately high slurry concentration were beneficial for crystal nucleation and growth. Three additives of magnesium chloride, citric acid, and sodium dodecyl benzene sulfonate(SDBS) were employed in this study. It was found that mean length and aspect ratio of CSW were both decreased by the usage of magnesium chloride,while a small quantity of citric acid or SDBS could improve the CSW morphology. When multi-additives of citric acid-SDBS were employed, the mean length and aspect ratio increased more than 20%. Moreover, surface morphology of CSW went better, and the particle size and crystal shape became more uniform.
文摘As an indication of the Earth's mass distribution,the principal moments of inertia(PMOI,i.e.,A,B,C) of the Earth are the basic parameters in studies of the global dynamics of the earth,like earth nutation,and the geophysics.From the aspect of observation,the PMOI can be calculated from the spherical coefficients of observed gravity field.In this paper,the PMOI are calculated directly according to its definition with the figures of the Earth's interior derived by a generalized theory of the hydrostatic equilibrium figure of the Earth.We obtain that the angle between the principal axis of the maximum moment of PMOI and the rotational axis is 0.184°,which means that the other two principal axes are very closely in the equatorial plane.Meanwhile,B-A is 1.60 × 10^(-5) MR^2,and the global dynamical flattening(H) is calculated to be 3.29587 × 10^(-3),which is 0.67%different from the latest observation derived value H_(obs)(3.273795 × 10^(-3))(Petit and Luzum,2010),and this is a significant improvement from the 1.1%difference between the value of H derived from traditional theories of the figure of the Earth and the value of H_(obs).It shows that we can calculate the PMOI and H with an appropriate accuracy by a generalized theory of the hydrostatic equilibrium figure of the Earth.
基金supported by the National Natural Science Foundation of China-Liaoning Joint Fund (U1908224)。
文摘The quality of stainless steel is closely related to the deformability of inclusions,which is significantly affected by their compositions.The present study first inve stigated the evolution of inclusion compositions in AI-killed steel with rare earth-alkali metals(Ca or Mg)combined treatme nt through four laboratory-scale experiments.The Ce contents in the final steel are 0.0080 wt%,0.015 wt%,0.016 wt%and 0.010 wt%,respectively.The Mg content is 0.0014 wt%in Ce-Mg combined treated steel,and the Ca content is0.0015 wt%in Ce-Ca combined treated steel.The deformability of inclusions in both Ce_(2)O_(3)-Al_(2)O_(3)-CaO and Ce_(2)O_(3)-Al_(2)O_(3)-MgO systems was subsequently evaluated by calculating their Young's modulus at low temperature.The results show that irregular Al_(2)O_(3)and MgAl_(2)O_(4)with poor deformability are modified to CeAlO_(3)and Ce_(2)O_(3)by Ce treatment,resulting in the decrease of Young's modulus of inclusions.The deformability of inclusions is further improved due to the transformation from lumped-like CeAlO_(3)to spherical CaO-Al_(2)O_(3)-Ce_(2)O_(3)caused by Ca treatment,and some of these inclusions are the ones with low liquidus temperature.Thermodynamic analysis was used to discuss the control condition of the formation and evolution of inclusions.Accordingly,the appropriate addition amounts of Al,Mg,Ce,and Ca are expected to control inclusion compositions and properties,including deformability and liquidus temperature,thereby improving the steel performance.
基金Project supported by the National Natural Science Foundation of China(51874082)NSFC-Liaoning Joint Fund(U1908224)。
文摘The phosphorus fixation capacity of some slag systems,such as Ce_(2)O_(3)-containing slag,has hardly been investigated from a thermodynamics view due to the lack of relevant thermodynamic data.Since the macroscopic properties are primarily determined by the microscopic structure,the correlation between phosphorus fixation capacity and slag structure was explored by spectroscopy(XPS),Raman spectroscopy,and ferromanganese dephosphorization experiments.The results show that the predominant species of P^(5+)are Q_(P)^(0)(PO_(4)^(3-))and Q_(P)^(1)(P_(2)O_(7)^(4-))units in the CaO^(-)SiO_(2)-Al_(2)O_(3)-MnO^(-)Ce_(2)O_(3)-P_(2)O_(5)quenched slag,and the phosphorus fixation capacity increases with the Q_(P)^(1)(P_(2)O_(7)^(4-))unit to Q_(P)^(0)(PO_(4)^(3-))unit transformation(the P-O^(0) bond to P-O^(-)bond transformation)since the electron cloud density between P and O atoms increases and the average radius of P-O bonds decreases.Especially,CaO or Ce_(2)O_(3) as a network modifier can release the O_(2)-and promote the P-O^(0) bond to P-O^(-)bond(connected to Ca^(2+),/Ce^(3+))transformation in the quenched slag.Furthermore,the phosphorus enrichment phases in the slow cooling slag are confirmed as nCa_(2)SiO_(3)-Ca_(3)P_(2)O_(8)(nC_(2)S-C3P)and CePO_(4) solid solutions by the scan electron microscopy(SEM),transmission electron microscopy(TEM),and energy-dispersive spectrometer(EDS)methods.The re sults show Ce_(2)O_(3) can depolymerize the polyphosphate structure partially replacing CaO after introducing Ce_(2)O_(3) into CaO based slag because of its strong ability to donate electrons.The above results not only help to understand the dependence of phosphorus fixation capacity on slag composition from a structural view,but also provide the theoretical guidance for optimizing the composition of Ce_(2)O_(3)-containing dephosphorization slag.
基金Project supported by the National Key R&D Program of China(2017YFC0805100)the National Natural Science Foundation of China(51774087)the Fundamental Research Funds for the Central Universities China(N162506002)
文摘The lack of thermodynamic information,such as primary phase fields and liquidus temperatures,in the CaO-SiO2-Nb2O5-La2O3 quaternary system phase diagram has restricted the comprehensive utilization of the niobium(Nb) and rare earth(RE) resources.In this work,the phase equilibria in low basicity region(w(CaO)/w(SiO2)<1) of CaO-SiO2-Nb2O5-(0-15 wt%)La2O3 system at 1373-1873 K were experimentally studied by thermodynamic equilibrium experiment,and then,the results were analyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM),and energy dispersive spectrometry(EDS).Additionally,an optimized method was proposed to process the compositions of equilibrium liquid phases at different temperatures.According to the experimental results,the univariate line between CaNb2O6,SiO2 and LaNbO4 primary phase fields,interface between CaNb2O6 and SiO2 primary phase fields and isothermal liquidus surfaces in SiO2 primary phase field were determined.Finally,the spatial phase diagram of CaO-SiO2-Nb2O5-La2O3 within specific region was constructed,and furthermore,the phase diagram was also presented in CaO-SiO2-Nb2O5 pseudo-ternary system with w(La2O3)=5 wt%,10 wt% and 15 wt%.The research results have guiding significance for the improvement of related phase diagram and the comprehensive utilization of Nb and RE resources.
