Thermodynamic Model

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Anthony S Wexle - One of the best experts on this subject based on the ideXlab platform.

  • Thermodynamic Model of the system h nh4 na so42 no3 cl h2o at 298 15 k
    Journal of Physical Chemistry A, 1998
    Co-Authors: Simo L Clegg, Pete Imblecombe, Anthony S Wexle
    Abstract:

    A multicomponent mole-fraction-based Thermodynamic Model of the H+−NH4+−Na+−SO42-−NO3-−Cl-−H2O system is used to represent aqueous-phase activities, equilibrium partial pressures (of H2O, HNO3, HCl, and NH3), and saturation with respect to 19 solid phases ((NH4)2SO4(cr), (NH4)3H(SO4)2(cr), NH4HSO4(cr), NH4NO3(cr), NH4Cl(cr), Na2SO4·10H2O(cr), Na2SO4(cr), Na3H(SO4)2(cr), NaHSO4·H2O(cr), NaHSO4(cr), NaH3(SO4)2·H2O(cr), NaNO3(cr), NaCl(cr), NH4HSO4·NH4NO3(cr), (NH4)2SO4·2NH4NO3(cr), (NH4)2SO4·3NH4NO3(cr), (NH4)2SO4·Na2SO4·4H2O(cr), Na2SO4·NaNO3·H2O(cr), 2NaNO3·NH4NO3(cr)). The Model is valid for concentrations from infinite dilution to saturation (with respect to the solid phases) and to about 40 mol kg-1 for acid sulfate systems which can remain liquid to concentrations approaching the pure acid. Parameters for H2SO4−H2O interactions were adopted from a previous study, and values for other binary (water−electrolyte) and ternary (water and three ions) interactions were determined from extensive literature da...

  • Thermodynamic Model of the system h nh4 so42 no3 h2o at tropospheric temperatures
    Journal of Physical Chemistry A, 1998
    Co-Authors: Simo L Clegg, Pete Imblecombe, Anthony S Wexle
    Abstract:

    A multicomponent mole-fraction-based Thermodynamic Model is used to represent aqueous phase activities, equilibrium partial pressures (of H2O, HNO3, and NH3), and saturation with respect to solid phases (H2SO4 and HNO3 hydrates, (NH4)2SO4(cr), (NH4)3H(SO4)2(cr), NH4HSO4(cr), (NH4)2SO4·2NH4NO3(cr), (NH4)2SO4·3NH4NO3(cr), and NH4HSO4·NH4NO3(cr)) in the system H+−NH4+−SO42-−NO3-−H2O. The Model is valid from 328 to <200 K, dependent upon liquid-phase composition. Parameters for H2SO4−H2O, HNO3−H2O, and (NH4)2SO4−H2O interactions were adopted from previous studies, and values for NH4NO3−H2O obtained from vapor pressures (including data for supersaturated solutions), enthalpies, and heat capacities. Parameters for ternary interactions were determined from extensive literature data for salt solubilities, electromotive forces (emfs), and vapor pressures with an emphasis upon measurements of supersaturated H2SO4−(NH4)2SO4−H2O solutions. Comparisons suggest that the Model satisfactorily represents partial pressures...

Pete Mullne - One of the best experts on this subject based on the ideXlab platform.

  • a Thermodynamic Model for the stacking fault energy
    Acta Materialia, 1998
    Co-Authors: Paulo J Ferreira, Pete Mullne
    Abstract:

    Abstract A general Thermodynamic Model for calculating the energy of stacking faults is presented and applied to f.c.c. Fe–Cr–Ni alloys. A distinction is made between ideal stacking faults and real stacking faults which are associated with an ideal stacking-fault energy (SFE) and an effective SFE, respectively. The ideal SFE is characterized by a chemical energy volume term and an interphase surface energy term, whereas the effective SFE is defined by an additional strain energy volume term. The chemical and strain energy terms are evaluated from theoretical considerations. The interphase surface energy is calculated based on a comparison with experimental values obtained from Transmission Electron Microscopy (TEM) measurements. The results of this analysis show a good agreement between the calculated and experimental values. The Model enables the determination of the ideal and effective stacking fault energies as a function of the Cr and Ni contents. The SFE dependence on the Cr vs Ni contents has the shape of a hyperbola.

Simo L Clegg - One of the best experts on this subject based on the ideXlab platform.

  • Thermodynamic Model of the system h nh4 na so42 no3 cl h2o at 298 15 k
    Journal of Physical Chemistry A, 1998
    Co-Authors: Simo L Clegg, Pete Imblecombe, Anthony S Wexle
    Abstract:

    A multicomponent mole-fraction-based Thermodynamic Model of the H+−NH4+−Na+−SO42-−NO3-−Cl-−H2O system is used to represent aqueous-phase activities, equilibrium partial pressures (of H2O, HNO3, HCl, and NH3), and saturation with respect to 19 solid phases ((NH4)2SO4(cr), (NH4)3H(SO4)2(cr), NH4HSO4(cr), NH4NO3(cr), NH4Cl(cr), Na2SO4·10H2O(cr), Na2SO4(cr), Na3H(SO4)2(cr), NaHSO4·H2O(cr), NaHSO4(cr), NaH3(SO4)2·H2O(cr), NaNO3(cr), NaCl(cr), NH4HSO4·NH4NO3(cr), (NH4)2SO4·2NH4NO3(cr), (NH4)2SO4·3NH4NO3(cr), (NH4)2SO4·Na2SO4·4H2O(cr), Na2SO4·NaNO3·H2O(cr), 2NaNO3·NH4NO3(cr)). The Model is valid for concentrations from infinite dilution to saturation (with respect to the solid phases) and to about 40 mol kg-1 for acid sulfate systems which can remain liquid to concentrations approaching the pure acid. Parameters for H2SO4−H2O interactions were adopted from a previous study, and values for other binary (water−electrolyte) and ternary (water and three ions) interactions were determined from extensive literature da...

  • Thermodynamic Model of the system h nh4 so42 no3 h2o at tropospheric temperatures
    Journal of Physical Chemistry A, 1998
    Co-Authors: Simo L Clegg, Pete Imblecombe, Anthony S Wexle
    Abstract:

    A multicomponent mole-fraction-based Thermodynamic Model is used to represent aqueous phase activities, equilibrium partial pressures (of H2O, HNO3, and NH3), and saturation with respect to solid phases (H2SO4 and HNO3 hydrates, (NH4)2SO4(cr), (NH4)3H(SO4)2(cr), NH4HSO4(cr), (NH4)2SO4·2NH4NO3(cr), (NH4)2SO4·3NH4NO3(cr), and NH4HSO4·NH4NO3(cr)) in the system H+−NH4+−SO42-−NO3-−H2O. The Model is valid from 328 to <200 K, dependent upon liquid-phase composition. Parameters for H2SO4−H2O, HNO3−H2O, and (NH4)2SO4−H2O interactions were adopted from previous studies, and values for NH4NO3−H2O obtained from vapor pressures (including data for supersaturated solutions), enthalpies, and heat capacities. Parameters for ternary interactions were determined from extensive literature data for salt solubilities, electromotive forces (emfs), and vapor pressures with an emphasis upon measurements of supersaturated H2SO4−(NH4)2SO4−H2O solutions. Comparisons suggest that the Model satisfactorily represents partial pressures...

Meng Zhang - One of the best experts on this subject based on the ideXlab platform.

  • a Thermodynamic Model for prediction of iron oxide activity in some feo containing slag systems
    Steel Research International, 2012
    Co-Authors: Xuemin Yang, Meng Zhang, Jian Zhang
    Abstract:

    A Thermodynamic Model for calculating the mass action concentrations of structural units in CaOSiO2MgOFeOMnOAl2O3CaF2 slags, i.e., the IMCT-Ni Model, has been developed based on the ion and molecule coexistence theory (IMCT). The calculated comprehensive mass action concentration of iron oxides $N_{{\rm Fe}_{t} {\rm O}} $ has been compared with the reported activity of iron oxide $a_{{\rm Fe}_{t} {\rm O}} $ in 14 FeO-containing slag systems from literatures. The good agreement between the calculated $N_{{\rm Fe}_{t} {\rm O}} $ and reported $a_{{\rm Fe}_{t} {\rm O}} $ indicates that the developed IMCT-Ni Model can be successfully applied to predict the activity of iron oxide $a_{{\rm Fe}_{t} {\rm O}} $ as well as the slag oxidation ability of CaOFeO (s1), SiO2FeO (s2), CaOSiO2FeO (s3), CaOFeOAl2O3 (s4), SiO2MgOFeO (s5), SiO2FeOAl2O3 (s6), CaOSiO2FeOAl2O3 (s7), CaOSiO2MgOFeOAl2O3 (s8), SiO2FeOMnO (s9), SiO2FeOMnOAl2O3 (s10), FeOMnO (s11), FeOMnOAl2O3 (s12), CaOFeOCaF2 (s13), and CaOSiO2FeOCaF2 slags (s14) in a temperature range of 14731973K.

  • a Thermodynamic Model of sulfur distribution ratio between cao sio2 mgo feo mno al2o3 slags and molten steel during lf refining process based on the ion and molecule coexistence theory
    Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2011
    Co-Authors: Xuemin Yang, Guoming Chai, Meng Zhang, Fei Wang
    Abstract:

    A Thermodynamic Model for calculating the sulfur distribution ratio between ladle furnace (LF) refining slags and molten steel has been developed by coupling with a developed Thermodynamic Model for calculating the mass action concentrations of structural units in LF refining slags, i.e., CaO–SiO2–MgO–FeO–MnO–Al2O3 hexabasic slags, based on the ion and molecule coexistence theory (IMCT). The calculated mass action concentrations of structural units in CaO–SiO2–MgO–FeO–Al2O3–MnO slags equilibrated or reacted with molten steel show that the calculated equilibrium mole numbers or mass action concentrations of structural units or ion couples, rather than mass percentage of components, in the slags can represent their reaction abilities. The calculated total sulfur distribution ratio shows a reliable agreement with the measured or the calculated sulfur distribution ratio between the slags and molten steel by other Models under the condition of choosing oxygen activity based on (FeO)–[O] equilibrium. Meanwhile, the developed Thermodynamic Model for calculating sulfur distribution ratio can quantitatively determine the respective contribution of free CaO, MgO, FeO, and MnO in the LF refining slags. A significant difference of desulfurization ability among free component as CaO, MgO, FeO, and MnO has been found with approximately 87–93 pct, 11.43–5.85 pct, 0.81–0.60 pct and 0.30–0.27 pct at both middle and final stages during LF refining process, respectively. A large difference of oxygen activity is found in molten steel at the slag–metal interface and in bulk molten steel. The oxygen activity in molten steel at the slag–metal interface is controlled by (FeO)–[O] equilibrium, whereas the oxygen activity in bulk molten steel is controlled by [Al]–[O] equilibrium. Decreasing the high-oxygen-activity boundary layer beneath the slag–metal interface can promote the desulfurization reaction rate effectively or shorten the refining period during the LF refining process.

  • a Thermodynamic Model of phosphate capacity for cao sio2 mgo feo fe2o3 mno al2o3 p2o5 slags equilibrated with molten steel during a top bottom combined blown converter steelmaking process based on the ion and molecule coexistence theory
    Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2011
    Co-Authors: Xuemin Yang, Meng Zhang, Jianping Duan, Jian Zhang
    Abstract:

    A Thermodynamic Model for predicting the phosphate capacity of CaO-SiO2-MgO-FeO-Fe2O3-MnO-Al2O3-P2O5 slags at the steelmaking endpoint during an 80-ton top–bottom combined blown converter steelmaking process has been developed based on the ion and molecule coexistence theory (IMCT). The phosphate capacity has a close relationship with the phosphate capacity index, whereas the logarithm of phosphate capacity is 12.724 greater than that of phosphate capacity index at 1873 K (1600 °C). The developed phosphate capacity prediction Model can be also used to predict the phosphate capacity index with reliable accuracy compared with the measured and the predicted phosphate capacity index of the slags by other Models in literatures. The results from the IMCT phosphate capacity prediction Model show that the comprehensive effects of iron oxides and basic components control the dephosphorization reaction with an optimal ratio of (pct FeO)/(pct Fe2O3) as 0.62. The determined contribution ratio of FetO, CaO + FetO, MgO + FetO, and MnO + FetO to the phosphate capacity or phosphate capacity index of the slags is approximately 0.0 pct, 99.996 pct, 0.0 pct, and 0.0 pct, respectively. The generated 2CaO·P2O5, 3CaO·P2O5, and 4CaO·P2O5 as products of dephosphorization reactions accounts for 0.016 pct, 96.01 pct, and 3.97 pct of the phosphate capacity or phosphate capacity index of the slags, respectively.

  • a Thermodynamic Model of phosphorus distribution ratio between cao sio2 mgo feo fe2o3 mno al2o3 p2o5 slags and molten steel during a top bottom combined blown converter steelmaking process based on the ion and molecule coexistence theory
    Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2011
    Co-Authors: Xuemin Yang, Meng Zhang, Jianping Duan, Yongliang Zhang, Jianchang Wang
    Abstract:

    A Thermodynamic Model for calculating the phosphorus distribution ratio between top-bottom combined blown converter steelmaking slags and molten steel has been developed by coupling with a developed Thermodynamic Model for calculating mass action concentrations of structural units in the slags, i.e., CaO-SiO2-MgO-FeO-Fe2O3-MnO-Al2O3-P2O5 slags, based on the ion and molecule coexistence theory (IMCT). Not only the total phosphorus distribution ratio but also the respective phosphorus distribution ratio among four basic oxides as components, i.e., CaO, MgO, FeO, and MnO, in the slags and molten steel can be predicted theoretically by the developed IMCT phosphorus distribution ratio prediction Model after knowing the oxygen activity of molten steel at the slag-metal interface or the Fe (t) O activity in the slags and the related mass action concentrations of structural units or ion couples in the slags. The calculated mass action concentrations of structural units or ion couples in the slags equilibrated or reacted with molten steel show that the calculated equilibrium mole numbers or mass action concentrations of structural units or ion couples, rather than the mass percentage of components, can present the reaction ability of the components in the slags. The predicted total phosphorus distribution ratio by the developed IMCT Model shows a reliable agreement with the measured phosphorus distribution ratio by using the calculated mass action concentrations of iron oxides as presentation of slag oxidation ability. Meanwhile, the developed Thermodynamic Model for calculating the phosphorus distribution ratio can determine quantitatively the respective dephosphorization contribution ratio of Fe (t) O, CaO + Fe (t) O, MgO + Fe (t) O, and MnO + Fe (t) O in the slags. A significant difference of dephosphorization ability among Fe (t) O, CaO + Fe (t) O, MgO + Fe (t) O, and MnO + Fe (t) O has been found as approximately 0.0 pct, 99.996 pct, 0.0 pct, and 0.0 pct during a combined blown converter steelmaking process, respectively. There is a great gradient of oxygen activity of molten steel at the slag-metal interface and in a metal bath when carbon content in a metal bath is larger than 0.036 pct. The phosphorus in molten steel beneath the slag-metal interface can be extracted effectively by the comprehensive effect of CaO and Fe (t) O in slags to form 3CaO center dot P2O5 and 4CaO center dot P2O5 until the carbon content is less than 0.036 pct during a top-bottom combined blown steelmaking process.

A Ebel - One of the best experts on this subject based on the ideXlab platform.

  • temperature dependent Thermodynamic Model of the system h nh4 na so42 no3 cl h2o
    Journal of Physical Chemistry A, 2010
    Co-Authors: E Friese, A Ebel
    Abstract:

    A Thermodynamic Model of the system H+−NH4+−Na+−SO42−−NO3−−Cl−−H2O is parametrized and used to represent activity coefficients, equilibrium partial pressures of H2O, HNO3, HCl, H2SO4, and NH3, and saturation with respect to 26 solid phases (NaCl(s), NaCl·2H2O(s), Na2SO4(s), Na2SO4·10H2O(s), NaNO3·Na2SO4·H2O(s), Na3H(SO4)2(s), NaHSO4(s), NaHSO4·H2O(s), NaNH4SO4·2H2O(s), NaNO3(s), NH4Cl(s), NH4NO3(s), (NH4)2SO4(s), (NH4)3H(SO4)2(s), NH4HSO4(s), (NH4)2SO4·2NH4NO3(s), (NH4)2SO4·3NH4NO3(s), H2SO4·H2O(s), H2SO4·2H2O(s), H2SO4·3H2O(s), H2SO4·4H2O(s), H2SO4·6.5H2O(s), HNO3·H2O(s), HNO3·2H2O(s), HNO3·3H2O(s), and HCl·3H2O(s)). The enthalpy of formation of the complex salts NaNH4SO4·2H2O(s) and Na2SO4·NaNO3·H2O(s) is calculated. The Model is valid for temperatures ≲263.15 up to 330 K and concentrations from infinite dilution to saturation with respect to the solid phases. For H2SO4−H2O solutions the degree of dissociation of the HSO4− ion is represented near the experimental uncertainty over wide temperature and co...

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