Synthesis of mullite ceramics from powdered mine tailings reinforced with Al2O3

Abstract

Mullite is an aluminosilicate compound that can be fabricated from various sources of raw materials. Mullite (α) was synthesized from six different mine tailings reinforced with alumina. The tailings were finely ground into powder to determine their chemical components using X-ray fluorescence (XRF) and X-ray diffraction (XRD) spectroscopic technologies. Silica was discovered in all the tailings in significant quantities followed by alumina (high purity α-alumina). 50 g of the first sample which composed 68.8 w(M)/10⁻² of SiO₂ and 13.2 w(M)/10⁻² of Al₂O₃ was measured, reinforced with 81.1 g of Al₂O₃ and subjected to a high-energy ball mill for 30 min to enhance the reaction between SiO₂ and Al₂O₃. The process was repeated for all six powdered tailings. Each mixture was sintered at 1100°C and 1200°C in a muffle furnace for 4 hours at a heating rate of 10°C/min. The sintered materials were characterized using SEM, EDS, XRD, and FTIR techniques. Results and analysis show a significant amount of prismatic α-mullite formed in all six sintered samples. The formation of mullite crystals was observed to increase with an increase in temperature from 1100°C to 1200°C. The phenomenal fabrication of mullite from mine tailings is significant in ceramic technology.