MINERALOGICAL CHARACTERIZATION OF ISUA CLAY FOR HIGH TEMPERATURE APPLICATIONS

Abstract

This study investigates the mineralogical, chemical, and thermal properties of Isua clay to determine its suitability for high-temperature applications, including ceramics and refractory materials. X-ray diffraction (XRD) analysis identified kaolinite (Al₂ Si₂ O₅ (OH)₄) as the primary mineral phase, with secondary constituents such as quartz (SiO₂), feldspar (KAlSi₃O₈), hematite (Fe₂O₃), and anatase (TiO₂). X-ray fluorescence (XRF) analysis confirmed a high SiO₂ (51.3%) and Al₂O₃ (24.7%) content, which contributes to thermal stability and mechanical strength. The thermogravimetric (TGA) and differential thermal analysis (DTA) revealed that kaolinite undergoes dehydroxylation at ~550°C, followed by mullite formation at ~980°C, indicating moderate-to-high refractory potential. The pyrometric cone equivalent (PCE) test showed a softening temperature of 1540°C, classifying the clay as a moderate refractory material. With a bulk density of 2.3 g/cm³ and a linear shrinkage of 8.5% at 1300°C, Isua clay exhibits good dimensional stability and thermal resistance. These properties make it suitable for firebricks, refractory linings, foundry molds, and structural ceramics. However, its Fe₂O₃ content (6.1%) may require further processing for applications demanding high whiteness. The findings suggest that Isua clay is a promising raw material for industrial high-temperature applications, with potential improvements achievable through blending with high-alumina clays.