Hydrous carbonate-containing brucite (HCB) in MgO/hydromagnesite blends
Alexander German, Frank Winnefeld, Pietro Lura, Daniel Rentsch, Barbara Lothenbach
Abstract
The hydration of reactive MgO in presence of hydromagnesite was investigated using analyses of the solid and the liquid phase. A brucite-like phase with low crystallinity was identified as hydration product. A partial destabilization of hydromagnesite was observed and it is suggested that the carbonate was taken up by the brucite-like phase. Furthermore, it was evidenced by thermogravimetry that this phase contained loosely bound “gel water”. Thus, a hypothetical hydrous carbonate-containing brucite (HCB) phase is proposed with a tentative composition MgCO3·35Mg(OH)2·H2O derived from mass balance calculations. Based on the solution chemistry and other considerations, its thermodynamic data were determined. Thermodynamic modeling of the hydrate assemblage of MgO/hydromagnesite blends confirmed the stability of HCB in the presence of hydromagnesite and brucite.