Comparative Experiments on the Role of CO2 in the Gold Distribution between Pyrite and a High-Salinity Fluid

Experimental studies were conducted to identify the physical and chemical features of gold’s behaviour in hydrothermal processes linked ore formation involving CO2 oxidized deposits. With aid autoclave method, a temperature range between 200 400 °C, isochoric dependences PVT parameters concentrated sulphate chloride fluids plotted, both presence absence CO2. Our experiments established that sulphate–chloride (22 wt % Na2SO4 + 2.2 NaCl) lack are characterized by wide supercritical range, with homogenization temperatures 250 325 °C. In CO2, same type showed heterogenization at molar fraction XCO2 = 0.18 (t 192 P 176 bar). The process for these low-density high-salinity was impossible 375 °C pressures 600 700 bar. gold studied during its interaction basic composition fluid sulphate–chloride. We applied method under conditions simultaneous synthesis pyrite dissolution (metallic Au), 340 pressure 440 High Au concentrations (up 4410 ppm CO2-bearing fluids) attained high solubilities 13.5 CO2), owing reprecipitation within phase. did not detect when we used XRD or SEM methods, which suggested it might be present as invisible gold. values distribution coefficient (KD CAu(solid)/CAu(solution)) lacking 62) bearing 327) empirically confirmed possibility concentrates structurally non-binding forms.