Carbonation of Natural Wollastonite at Non-Ambient Conditions Relevant for CCS—the Possible Use as Cementitious Material in Wellbores

The reaction of wollastonite with CO 2 accompanied by SO 2 and NO 2 in the presence of a chloride-rich brine (230 g/L NaCl, 15 g/L CaCl 2, 5 g/L MgCl 2) at temperatures relevant to injection conditions (333 K) in carbon capture and storage (CCS) were investigated within the joint BMWi (Federal Ministry for Economic Affairs and Energy) research project CLUSTER. The reaction which describes the formation of wollastonite during metamorphism is reversed and shows a strong temperature dependence. Wollastonite reacts in the presence of CO 2 ( C ˉ ) in aqueous conditions to form calcium carbonate and amorphous silicon oxide. At 333 K and 2 MPa the carbonation reaction of wollastonite ( C ˉ C S ) is fast (<24 h). To determine the conversion rate of the reaction quantitatively different methods were used and compared: Powder X-ray diffraction (PXRD) with the Rietveld method and differential scanning calorimetry with thermogravimetry, coupled with a mass spectrometer (DSC-TG/MS) for quantitative phase analysis and for determination of the carbonation. The carbonation (CO 2 accompanied by SO 2 and NO 2) of natural wollastonite at 333 K in presence of chloride-rich brine was rather fast (almost complete after 24 h reaction time). View Full-Tex