High-purity quartz sand from mineral purification: a review on process, mechanism, and environmental strategies

Abstract

High-purity quartz (HPQ) is a critical mineral resource valued for its stable physicochemical properties and broad applications in semiconductors, photovoltaics, quartz glass, and optical devices. Meeting strict impurity standards requires advanced purification technologies. However, the purification process faces challenges such as high energy consumption during calcination and environmental pollution caused by chemical-leaching waste. Despite these challenges, the high added value and increasing use of HPQ in advanced technologies underscore its importance. This review categorises purification technologies into physical and chemical methods, analysing their mechanisms and effectiveness in removing gangue minerals, fluid inclusions, and lattice impurities. Physical methods efficiently separate independent gangue minerals but are less effective for trace lattice impurities because of limitations in macroscopic physical properties. Therefore, chemical methods are essential for deep purification, with calcination enhancing leaching efficiency. Phase transformations during calcination promote the migration and surface enrichment of lattice impurities, enabling effective removal through chlorination roasting or acid leaching. Recent advances focus on environmentally sustainable processes such as superconducting high-gradient magnetic separation, bioleaching, and hybrid methods combining microwave or ultrasonic treatments with fluoride-free acid leaching. By integrating cutting-edge combined purification technologies, this review outlines key future directions for HPQ purification and offers insights for optimising green processing techniques.