Ceramics-Silikáty 59 (2) 115-124 (2015)

PROPERTIES OF CaO SINTERED WITH ADDITION OF ACTIVE ALUMINA

This work provides research and evaluation of the influence of active gama alumina addition on green and sintered CaO material properties, microstructures and mineralogical phase formation. Experimental results have shown the possibility to prepare more stable CaO with excellent properties by energy saving one-stage burning process of natural ground limestone with small addition of γ-Al₂O₃ (1 wt. %) at up to 1550°C for two hours. The additive caused increasing of the sintered density but especially significant decreasing of apparent porosity of CaO. X-ray diffraction and energy dispersive X-ray fluorescence analysis confirmed mainly the presence of 3CaO∙Al₂O₃ on the grain boundaries. Formation of other phases during sintering, more specifically 12CaO∙7Al₂O₃ and CaO∙6Al₂O₃ with lower tendency to hydration was also proved.

Keywords: CaO, Ground limestone, Active additive, Gama alumina, Sintering