Differential Thermal Calorimetric Determination of the Thermodynamic Properties of Kaolinite |
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| Authors: | PATRICK S. NICHOLSON RICHARD M. FULRATH |
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| Affiliation: | Inorganic Materials Research Division, Lawrence Radiation Laboratory, and Department of Materials Science and Engineering, College of Engineering, University of California, Berkeley, California 94720 |
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| Abstract: | Four samples of kaolinite were investigated to determine the exothermic reaction enthalpy by differential thermal calorimetry. The measured 9 kcal/mol for the 980°C exothermic reaction enthalpy corresponds to the calculated heat of crystallization of silica at this temperature. Literature evidence discounts the crystallization of the other participating phases, mullite and silicon spinel. An NaOH extraction technique was used to remove the amorphous silica from a kaolinite fired at 850°C; this extraction removed the 980°C exotherm. It is tentatively suggested, therefore, that most of the heat release at 980°C on firing kaolinite accompanies the reaction SiO2(amorphous) → SiO2(β-quartz). |
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