Impact of Precursor Granulometry on the Synthesis of Calcium-Aluminate Phases

• Published in: Russian journal of applied chemistry 2023-03, Vol.96 (3), p.297-309
• Main Authors: Trubitsyn, M. A., Furda, L. V., Yapryntsev, M. N., Volovicheva, N. A., Mikhailyukova, M. O.
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Calcium aluminate; Carbonate rocks; Chemical composition; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Grain size; Industrial Chemistry/Chemical Engineering; Inorganic Synthesis and Industrial Inorganic Chemistry; Microstructure; Phase composition; Phase equilibria; Phases; Raw materials; Synthesis; Transitional aluminas
• ISSN: 1070-4272; 1608-3296
• DOI: 10.1134/S1070427223030059

Calcium aluminate phases were synthesized in the range 950–1450°C from available raw materials: carbonate rock and metallurgical alumina, predominantly in the γ form with different grain sizes. The calculations of the amount of raw materials were based on the requirement to ensure the chemical composition of the product: Al 2 O 3 71–72 and CaO 27–28 wt %. The designed phase composition of the samples is 65 wt % CaAl 2 O 4 and 35 wt % CaAl 4 O 7 . When alumina with a grain size of 90 μm and a spherulitic microstructure is introduced into the reaction, the formation of the CaAl 2 O 4 and CaAl 4 O 7 phases mainly occurs in the range of 1250–1350°C, and phase equilibrium is established at 1450°C. Reducing the size of γ-alumina grains to 10 μm and destroying their spherulitic microstructure shifts the formation of calcium aluminates to the temperature range below 1250°C, and also significantly increases the rate of synthesis of target products.