REWAS 2013 pp 133-139 | Cite as

Silver Selenide Thermodynamics for Copper Anode Slime Refining

  • Dawei Feng
  • Pekka Taskinen

Abstract

Copper anode slimes are a by-product of the electrolytic refining of anode copper, which contains significant amounts of silver, selenium, copper, and gold. Slimes are usually smelted to recover silver and gold. The thermodynamics of the smelting of such selenium-rich materials have received only little attention. In this work, the numerical values on the standard thermodynamic functions of Ag2Se (Naumannite) were determined by the electromotive force (EMF) method in a solid-state galvanic cell with superionic conductor RbAg4I5 as the solid electrolyte. Ag2Se was synthesized from pure elements in evacuated quartz glass ampoules and examined to be homogenous by SEM and EDS. According to the experimental data on the EMF versus temperature, the analytical equations were obtained for the polymorphic forms of Ag2Se. The temperature of phase transformation from α-Ag2Se to β-Ag2Se is determined experimentally to be 407.7 K by interpolation of the EMF vs. T data, and the enthalpy of phase transformation is 6.06 kJ•mol-1. The Gibbs energy of formation for Ag2Se is given by
$$\begin{gathered} \Delta {\overline G _{\alpha - A{g_2}Se}},J = - \left( {40869.14 \pm 0.58129} \right) - \left( {27.94759 \pm 1.53034} \right) \cdot T,\left( {350 < T/K < 408} \right), \hfill \\ \Delta {\overline G _{\beta - A{g_2}Se}},J = - \left( {35062.17 \pm 0.09895} \right) - \left( {42.17847 \pm 0.21827} \right) \cdot T,\left( {408 < T/K < 500} \right). \hfill \\ \end{gathered}$$

Keywords

Silver selenide Thermodynamic stability Solid state galvanic cell 

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Copyright information

© TMS (The Minerals, Metals & Materials Society) 2013

Authors and Affiliations

  • Dawei Feng
    • 1
  • Pekka Taskinen
    • 1
  1. 1.Department of Materials Science and EngineeringAalto University Vuorimiehentie 2KEspooFinland

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