Morphology of calcium carbonate coating on amorphous silicate powder

Abstract

The amorphous silicate powders containing sodium, calcium,barium and magnesium were prepared by sol-gel and ion-exchangemethod, and calcium carbonate was coated on the powders for thepurpose of industrial re-circulation of calcium carbonate. Thecalcium carbonate powder with micro pores was obtained bycoating on amorphous CaO-SiO₂ powder, and the pore sizedistribution would be influenced by calcium on the surface ofthe powder. The coating on amorphous MgO-SiO₂ powderresulted in a hedgehog-like powder, which allowed needle-likecrystal extended radially, and the coated powder was the mixedphase of aragonite and calcite. The use of amorphousBaO-SiO₂ and Na₂O-SiO₂ powders also led to the coatingpowder with the single phase of calcite. The morphology ofcalcium carbonate coating would be ascribed to cations on thesurface of the amorphous silicate powders, because the amount ofcations that would be dissolved in soaking solution was smalland insufficient to affect the morphology.