Hydrous carbonate-containing brucite (HCB) in MgO/hydromagnesite blends
Authors: Alexander German, Frank Winnefeld, Rentsch Daniel, Barbara Lothenbach
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.
