A systemic investigation on the hydroxylation behavior of caustic magnesia and magnesia sinter

Abstract

Caustic magnesia (CM) and magnesia sinter (MS or hard-burnt magnesia) are the main sources of MgO employed in industry. Both are obtained from the calcination of Mg(OH)2 or MgCO3, however, due to differences in their manufacture, they display significant distinct physical–chemical properties. MS is produced at temperatures above 1500°C and shows large crystal size and low inner micro–meso pores content, whereas CM is attained at lower temperatures (600–900°C) and has high specific surface area, micro–meso pores content and chemical reactivity. Their hydroxylation behavior is also different, as it takes MS several hours-days to react completely with water, while the CM reaction achieves total conversion after few minutes. Because of their technological importance, a deeper understanding of the processes involved in hydroxylation reactions and how particles׳ characteristics affect them is required. This study relates the characterization of MS and CM particles with their hydroxylation reactions in aqueous suspensions through thermogravimetry, X-ray diffraction, nitrogen adsorption, and scanning electron microscopy.