Thermodynamic analysis of the influence of potassium on the thermal behavior of kaolin raw material
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INSTITUTO POLITÉCNICO NACIONAL - Unidad Profesional Interdisciplinaria de Ingeniería campus Hidalgo (UPIIH)
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Universidad Autónoma del Estado de Hidalgo (UAEH) - Instituto de Ciencias Básicas e Ingeniería
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INSTITUTO POLITÉCNICO NACIONAL - Escuela Superior de Ingeniería Química e Industrias Extractivas (ESIQIE)
Publication date: 2020-10-13
Corresponding author
Alejandro Cruz Ramírez
INSTITUTO POLITÉCNICO NACIONAL - Escuela Superior de Ingeniería Química e Industrias Extractivas (ESIQIE)
Physicochem. Probl. Miner. Process. 2021;57(1):39-52
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ABSTRACT
The mineralogy and thermal properties of two kaolin clay samples from Agua Blanca (Hidalgo-México) were determined by XRD, SEM-EDS, TGA-DSC techniques. Kaolin clay A contains a higher Al2O3 and lower impurities (K2O, TiO2, Fe2O3) amount than kaolin clay B, while the SiO2 amount is similar for both kaolin clays. A theoretical approach was carried out by a thermodynamic analysis considering the chemical composition of both kaolin clay samples with the FactSage 7.3 software. Stability phase diagrams were obtained to different K2O content from 0.1 to 3 wt % and temperatures in the range from 600 to 1600°C based on the chemical composition of the kaolin clay samples. The main mineralogical compounds predicted are andalusite (Al2O3·SiO2), K-Potash feldspar (K2O·Al2O3·6SiO2), and the SiO2 polymorphs (quartz, tridymite, and cristobalite) with small amounts of ferric-pseudobrookite (Fe2O5Ti), and rutile (TiO2). As K2O content is increased, the amounts of mullite and tridymite decrease meanwhile the potash feldspar is increased at high temperatures. A liquid phase is formed at around 1350 and 1400°C for the kaolin clay samples A and B, respectively. The viscosity of the melt is increased for the evaluated K2O additions to 1400, 1500, and 1600°C.