Characterization and Industrial Suitability Assessment of Erusu Clay for Refractory and Foundry Applications

This study presents a comprehensive physicochemical and mineralogical characterization of Erusu clay from Ondo State, Nigeria, with the aim of evaluating its suitability for industrial applications. Analytical techniques employed include X-ray Fluorescence (XRF), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermal Gravimetric and Differential Thermal Analysis (TGA/DTA), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS), and standard plasticity and mechanical tests. The XRF results revealed that silica (SiO₂) and alumina (Al₂O₃) are the predominant oxides, with mean values of 54.8% and 24.5%, respectively, yielding a SiO₂/Al₂O₃ ratio of 1.89, typical of kaolinitic clays. XRD and FTIR analyses confirmed kaolinite (62.3%) as the dominant mineral phase, with quartz, illite, and hematite as accessory minerals. Thermal analysis indicated a total weight loss of 8.2%, with dehydroxylation occurring at approximately 525°C, suggesting good thermal stability. The clay exhibited medium plasticity (PI = 19.6%), low swelling (8.3%), and satisfactory mechanical properties, including green and dry compressive strengths of 118 kN/m² and 410 kN/m², respectively. Its refractoriness, ranging between 1670–1700°C (Cone 32–33), classifies it as a high-refractory clay. The integrated results indicate that Erusu clay possesses favourable structural, thermal, and mechanical characteristics suitable for refractory linings, foundry moulds, and ceramic applications. This study contributes to the valorization of indigenous raw materials for sustainable industrial development in Nigeria.