수화물 소성에 의한 고순도 다공성 CaO·Al2O3클링커의 합성

Abstract

For the lower-temperature preparation of calcium monoaluminate(CA, C:CaO, A:Al₂O₃) clinker which is hard to synthesize purely within its melting point, an equimolar hydrate was obtained and then used as a starting raw material of clinker burning. The hydrate was prepared from a mixture of waste oyster shell and industrial aluminium hydroxide by heating to 1200℃, grinding and mixing with water. The hydrate was composed of amorphous aluminium hydroxide and C₃AH?(H:H₂O) formed by resolution-precipitation mechanism of the system C-A-H. By heating the hydrate, nearly pure and porous calcium monoaluminate clinker was formed at 1400℃ which is fairly lower temperature than that of its melting point. The formation of calcium monoaluminate was performed mainly by the reaction between amorphous alumina and C₁₂A? caused by the decomposition of C₃AH?. The immediate and earlier formation of C₁₂A? seemed to be accelerated by not only high surface area and instability of the thermally decomposed hydrate but also the catalytic effect of water decomposed from the hydrate. The final calcium monoaluminate clinker was very porous because of the influence of highly porous shape of the thermally decomposed hydrate.