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Abstract

In order to characterize the chemical reactivity and hence the mineralogical CO2 sequestration potential of carbonate minerals, laboratory fluidsiderite/ankerite CO2 exposure experiments have been performed. Experiments were conducted on a hydrothermal rocking autoclave system equipped with flexible Titanium cells allowing for isobaric and isothermal fluid sampling. Crushed siderite/ankerite separates have grain sizes between 100 and 200 μm. The minerals were reacted together with pure CO2 and 2 M NaCl brine at 80 °C and 20 or 30 MPa, respectively; run durations were one week. Approximately 120 ml NaCl brine and 5.5 g of powdered carbonate separate were filled into the Titanium cells to yield a brine to mineral weightratio of 20 to 1. Experiments were supersaturated with CO2 during entire run durations. Successive fluid samples were taken after several different time steps to determine time dependent dissolution behavior. Solid samples were recovered upon completion of each run and analyzed by XRD as well as SEM. Fluid sample compositions were determined by ICPAES.