Hydrothermal conversion of kaolin to kalsilite (kalSiO₄): the effect of K₂CO₃ concentrations

• Main Authors: Eddy Mohd Farid Mohd Yusslee, Nur Hazwani Dahon, Mohd Azrul Abdul Rajak, Sazmal Effendi Arshad
• Format: Proceedings
• Language: English; English
• Published: Pusat e-pembelajaran, UMS 2021
• Subjects: Q1-390 Science (General); TN1-997 Mining engineering. Metallurgy
• Online Access: https://eprints.ums.edu.my/id/eprint/41631/1/ABSTRACT.pdf; https://eprints.ums.edu.my/id/eprint/41631/2/FULL%20TEXT.pdf; https://eprints.ums.edu.my/id/eprint/41631/; https://oer.ums.edu.my/handle/oer_source_files/1874

Kaolin was used as a silica and alumina precursor in the hydrothermal synthesis of kalsilite with the addition of potassium carbonate (K₂CO₃) as a potassium source. The effects of different K₂CO₃ concentrations have been studied. After a 24-hour hydrothermal reaction at 200°C, kaolin treated with 1.25M K₂CO₃ shows 28.7°, 34.2°, and 42.3° as the most significant peaks under X-ray diffraction (XRD) which corresponds to hexagonal kalsilite. In addition, Field emission scanning electron microscopy (FESEM) images also revealed hexagonal particles proving the formation of the desired kalsilite. At K₂CO₃ concentrations less than 1.0M, boehmite and bayerite were identified to be the primary products while kalsilite forms as a minor crystalline phase. Hexagonal kalsilite was observed as the major product at higher (>1.0M) K₂CO₃ concentration while the reaction kept constant at 200°C.