SOLUBILITY OF GOLD IN SULFIDE-ARSENIDE SOLUTIONS AT 200-300°C

Abstract

Experiments were carried out in autoclaves made of titanium alloy, VT-8, by the suspended-charge method. Before charging, the autoclaves were blown through with argon. Then they were filled with a solution of 0.1n HCl, saturated with 0.08-0.1 mole H3S, which was analytically controlled before the experiment. With respect to chlorine and sulfur contents the solution corresponded to that under natural geochemical conditions, and these contents were confirmed by the analysis of fluid inclusions. A titanium vessel with natural or synthetic crystals of As2S3; weighed with a precision of 0.0001 was suspended from an obturator. Flakes of Au-99.999, calcined at 750-800° C to eliminate mechanical stress, were used as a source of gold. These were suspended above the solution in the container. The pressure in the autoclaves was not measured, but was estimated on the basis of the coefficient of filling of the container and amounted to 1.0 ± 0.05 kbar. Additional aspects of the study methods are discussed, along with the study results.