Gibbs Energy Modeling of the Cu-S Liquid Phase: Completion of the Thermodynamic Calculation of the Cu-S System
Peter Waldner
Abstract
Abstract 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 $$ {\text{log(}}p_{{{\text{S}}2}} /{\text{bar)}} - 1 /T $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mtext>log(</mml:mtext> <mml:msub> <mml:mi>p</mml:mi> <mml:mrow> <mml:mtext>S</mml:mtext> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> <mml:mo>/</mml:mo> <mml:mtext>bar)</mml:mtext> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> <mml:mo>/</mml:mo> <mml:mi>T</mml:mi> </mml:mrow> </mml:math> diagram is calculated. A limited set of obtained model parameters reproduces a large body of data within experimental uncertainties.