Tricalcium Aluminate Hexahydrate (TCA) Synthesis and Characterization

Abstract

Tricalcium aluminate hexahydrate (TCA) is an important filter-aid for Bayer's liquor (BL) polishing in addition to a few other applications. It can be prepared by reaction of CaO or Ca(OH)(2) in NaAlO(4) solutions preferably at low temperatures, [NaOH] and [CO(3)(2-)], however, various TCA sample properties influence efficiency of controlling the BL impurities. So the preparation of desired TCA samples under the synthetic conditions needs to be ascertained. In this study a synthesis approach for TCA was attempted using Ca(OH)(2) and Al(OH)(3) (gibbsite) at low temperature and [NaOH] under atmospheric pressure. To control it's synthesis process and the physicochemical properties further, a few simple surface active agents and ammonia-carbonate releasing reagents are tested. The effect of temperature, particle dispersion, NaOH and time on TCA particle size and morphology, reactant surface coating and product phase formation were analyzed using various analytical techniques. This kinetic study provides some insight into the TCA formation mechanism and interaction of various synthesis parameters influencing the TCA physicochemical properties.