A contribution to the thermodynamics of high-temperature digenite Cu2−y S

Sick, Georg; Schwerdtfeger, Klaus

doi:10.1007/bf02657300

Cited by 10 publications

(5 citation statements)

References 18 publications

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“…Although related only to Cu-S solid phases, the publications from Sudo, [20] Brooks, [21] Sadakane et al [22] and Brunetti et al [23] are considered in the section for experimental data on thermodynamic properties because they have not been treated yet in the preceding publications of Waldner [13,14] but are relevant in this study for a comprehensive comparison with modeling results. The studies of Wehefritz, [24] Luquet et al, [25] Peronne et al, [26] Dumon et al, [27] Nagamori, [28] Peronne and Balesdent [29] and Sick and Schwerdtfeger have the same relevance [30] ; selected data points from these will appear in the subsequent figures. However, since these seven publications were already described in detail in the corresponding sections of the preceding publications of Waldner, [13,14] their treatment will not be repeated here.…”

Section: Experimental Data From the Literaturementioning

confidence: 96%

Gibbs Energy Modeling of the Cu-S Liquid Phase: Completion of the Thermodynamic Calculation of the Cu-S System

Waldner

2020

Metall Mater Trans B

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A thorough review and critical evaluation of all experimental sulfur potential and phase diagram data available from the literature has been made for optimizing the Gibbs energy of the copper-sulfur liquid phase at 1 bar total pressure. The extended modified quasichemical model serves as a basis for the mathematical expression of the Gibbs energy of binary Cu-S solutions over the complete composition range. A structurally versatile molten phase ranging from highly metallic via sulfur-rich to pure sulfuric is described simultaneously by a single Gibbs energy function. In combination with the recently published Gibbs energies of all Cu-S solid phases, the complete T-x phase diagram as well as for the first time the log(p S2 =bar) À 1=T diagram is calculated. A limited set of obtained model parameters reproduces a large body of data within experimental uncertainties.

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Section: Experimental Data From the Literaturementioning

confidence: 96%

Gibbs Energy Modeling of the Cu-S Liquid Phase: Completion of the Thermodynamic Calculation of the Cu-S System

Waldner

2020

Metall Mater Trans B

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“…1 The desulphurization occurs via the reaction (1) In the temperature range 650-800°C, the equilibrium pressure ratios PH 2 S/PH 2 are between 0·0005 and 0·0011 (Ref. 2). After the copper has been converted to sulphide, regeneration is performed by oxidation of the sulphide with air and reduction of the oxide.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…The molar flux of H 2 S N H2S to the surface of the sphere is given, in a binary H 2 S-H 2 gas mixture, by N H2S = kH2S-H2C(X~2S -X~2S) (2) where k H2 S-H2 is the mass transfer coefficient, c is the molar density of the gas, X H2S is the mole (or volume) fraction of…”

Section: Control By Gaseous Diffusionmentioning

confidence: 99%

“…The concentration of vacancies does not appear either in rate equation (25) or in the law of mass action because of the large excess of copper vacancies (interstitial type) in the sulphide. 2,20 The copper activity of the sulphide is established by the H2S/H2 ratio of the gas phase at the sulphide/gas interface (reaction (1) The elimination of X~2S/X~2 by coupling equation (28) with the equations for gaseous transport (second part of equations (18) and (19)) is not as straightforward as for the other model because of the square root of X~2S/X~2' However, since the effect of gaseous diffusion is not great in most experiments, the ratio X~2S/X~2 is rather close to the bulk ratio X~2S/X~2' By inspection of the data in Table 1 it can be seen that very different rates are obtained with the same X~2S/X~2 ratio using the binary or the ternary gas mixtures. That is, the sulphidation rate is not a unique function of X~2S/X~2' Consequently, it would appear to be unlikely that the transfer of copper at the metal/sulphide interface could impede the rate of sulphidation of copper by H 2 S at elevated temperatures.…”

Section: )mentioning

confidence: 99%

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Kinetics of formation at 800°C of ‘Cu₂S’ on copper under gases containing H₂S

Sick¹,

Schwerdtfeger²

1986

Materials Science and Technology

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“…In Figs. 2(b) and 2(c), calculated composition dependences of sulfur activity in digenite and in Cu and Cu 2 S-rich liquid are compared with corresponding experimental data 31,28) in the form of the ratio between partial pressures of H 2 S and H 2 . It is shown that all thermodynamic properties are correctly reproduced by the present thermodynamic description.…”

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confidence: 99%

Thermodynamic Calculations on the Stability of Cu2S in Low Carbon Steels

et al. 2007

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Thermodynamic stability of Cu 2 S sulfide in low carbon steels has been investigated using a CALPHAD type thermodynamic calculation method. Thermodynamic properties of the Cu-S binary and Fe-Cu-S ternary systems were critically assessed. By combining the newly assessed thermodynamic parameters to an existing thermodynamic database for steels, a thermodynamic description for low carbon steels involving sulfur and Cu could be obtained and be used to calculate phase equilibria and thermodynamic stability of precipitating phases such as AlN, MnS, and Cu 2 S. It was predicted that the Cu 2 S sulfide often observed in low carbon steels is actually a thermodynamically unstable phase and can precipitate when thermodynamic equilibrium state is not reached during steel making processes. Probable reasons and conditions for the formation of this unstable phase are discussed.KEY WORDS: thermodynamic calculation; low carbon steel; Cu 2 S; MnS. © 2007 ISIJThe calculated phase diagrams and thermodynamic properties were in good agreement with corresponding experimental information. Unfortunately however, the model used for Cu 2 S could not be reconcilable to the current steel database which is based on the compound energy formalism. 17,18) Later, the Cu-S system was assessed again by Sundman 19) using a more friendly thermodynamic model (sublattice model) for the Cu 2 S phase. In this assessment, the liquid phase was not involved and more critically, the calculated enthalpies of formation of sulfide phases showed somewhat too large differences from corresponding experimental information. In the present study, a reassessment of the Cu-S binary system was carried out using the same thermodynamic model for Cu 2 S with that by Sundman, including also the liquid phase. The resultant thermodynamic parameter set for the Cu-S system was combined with those of 20) and to assess the Fe-Cu-S ternary system. Thermodynamic ModelsIn the CALPHAD method 12,13) the Gibbs energy of individual phases is described using thermodynamic models. Then, the calculations of phase equilibria are performed based on the minimum-of-Gibbs-energy criterion, for example, the Hillert's equilibrium condition.22) An ordinary substitutional subregular solution model was used for the Gibbs energy of fcc and bcc solid solutions in Cu-S and Fe-Cu-S systems. For liquid, an associate solution model was used assuming the existence of an associate, Cu 2 S. The liquid Fe-S phase had also been described using the same model with an associate, FeS.19) With the above two associates, the Gibbs energy per mol of the Fe-Cu-S liquid phase can be described as follows: where x and °G represent mol fraction and Gibbs energy of individual component, respectively, and L parameters represent interactions between components. The L parameters can be expressed as a function of composition and temperature.The Cu 2 S phase (digenite) shows a rather wide composition range and is often expressed as Cu 2Ϫy S. In his assessment, Sundman 19) described this phase using a three-sublattice model wi...

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A contribution to the thermodynamics of high-temperature digenite Cu2−y S

Cited by 10 publications

References 18 publications

Gibbs Energy Modeling of the Cu-S Liquid Phase: Completion of the Thermodynamic Calculation of the Cu-S System

Gibbs Energy Modeling of the Cu-S Liquid Phase: Completion of the Thermodynamic Calculation of the Cu-S System

Kinetics of formation at 800°C of ‘Cu₂S’ on copper under gases containing H₂S

Thermodynamic Calculations on the Stability of Cu2S in Low Carbon Steels

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A contribution to the thermodynamics of high-temperature digenite Cu2−y S

Cited by 10 publications

References 18 publications

Gibbs Energy Modeling of the Cu-S Liquid Phase: Completion of the Thermodynamic Calculation of the Cu-S System

Gibbs Energy Modeling of the Cu-S Liquid Phase: Completion of the Thermodynamic Calculation of the Cu-S System

Kinetics of formation at 800°C of ‘Cu2S’ on copper under gases containing H2S

Thermodynamic Calculations on the Stability of Cu2S in Low Carbon Steels

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Kinetics of formation at 800°C of ‘Cu₂S’ on copper under gases containing H₂S