A small-scale flow-through column system to determine the rates of mineral dissolution at high temperature and pressure

- A small-scale plug-flow dissolution column is described.
- The system can simulate long-term dissolution rates at high temperature and pressure.
- The system design maximizes dissolution rates by reducing mass transfer limitations.
- The system was validated for the oxidative dissolution of arsenopyrite.

Mineral dissolution is a critical phenomenon in many geochemical systems, including those of geologic CO2 storage. It affects the mobilization, fate and transport of toxic metals in subsurface waters. A small-scale plug-flow system was designed and demonstrated for use in determining dissolution rates and simulating mineral-water interactions under a wide range of conditions, including high pressure (P, up to 300 bar) and temperature (T, up to 120 °C). The system enables rapid achievement of steady-state rates, and minimizes the experimental time to study such mineral-water systems. The performance of the system was evaluated through study of the oxidative dissolution of arsenopyrite (FeAsS (s)). Rates of arsenic release induced by dissolved Fe3 + (10− 4 M) in anoxic systems at 25 °C and pressures of 1 bar and 100 bar were measured. The performance testing confirmed the ability to obtain reproducible results under the wide range of conditions tested, and to obtain similar results to certain benchmark cases, e.g., the FeAsS (s) dissolution rate of 10− 8.09 mol As/m2 s at 25 °C and 1 bar was comparable to previously reported values. Potential mass-transfer limitations associated with the system were studied and results indicate such limitations can be avoided at flow-rates higher than 0.8 mL/min.