Solubility of Gold in FeO <sub>x</sub> -SiO <sub>2</sub> -Al <sub>2</sub> O <sub>3</sub> Slags at 1300°C
2025
Avarmaa, Katri | Klemettinen, Lassi | Michallik, Radoslaw M. | Lindberg, Daniel | Geologian tutkimuskeskus | Geological Survey of Finland
Solubility of gold in copper-free alumina iron silicate slags in equilibrium with iron alumina spinel wasstudied using equilibration-quenching technique under controlled p(O2) gas atmosphere at 1300°C. Thegold concentration in slag was analyzed by laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS), which allowed elimination of the mechanical metal dispersion from the slag analyses. Thus,the data represent purely the chemically dissolved gold, and the dissolution in slag was shown to occur asAuO0.5 species at high oxygen partial pressures ≥10−7 atm. Contrary to earlier observations in (basaltic)iron-lean high-silica melts, the results indicate that gold solubility at low oxygen partial pressures, <10−7atm, was no more decreasing but maintained at a minimum (log10LAu/s(Au) = 5.6–5.7). Even at the highestpartial pressure of oxygen (=10−5 atm), the distribution coefficient was above log10LAu/s(Au) = 5.2, whichsuggests that mechanical dispersion containing gold causes by far the major source of gold loss in thecopper and nickel matte smelting as well as in the secondary copper (‘black copper’) smelting operations.
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