2026 Bai Quartz sand acid leaching optimization

The occurrence characteristics of impurities and the precise technologies used for their removal are the main factors limiting the high-end applications of quartz sand. To simultaneously achieve ultrahigh purity and a high yield while incorporating a sustainable waste acid treatment strategy, quartz sand (SP1) from India was selected as the research material. A stepwise experimental scheme involving single-acid and mixed-acid treatments was adopted to optimize the purification conditions, incorporating a complete process of pretreatment, acid leaching, and post-treatment along with a defined waste liquid management method. The raw SP1 quartz samples and samples treated under the optimal acid-washing conditions were characterized through qualitative and quantitative analyses, including X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and inductively coupled plasma mass spectrometry. The optimal result for the single-acid system was obtained by treating quartz sand with 70 mL of hydrofluoric acid at 120 ◦C for 2 h, resulting in a purity of 99.9963%. For the mixed-acid system, the volume ratio of hydrofluoric acid, hydrochloric acid, and nitric acid was maintained at 1:6:2, and acid leaching was performed at a constant temperature of 120 ◦C for 5 h. Under these conditions, the aluminum and iron contents were reduced to 15.23 and 0.15 µg/g, respectively, while the purity and production yield of the acid-washed quartz sand reached 99.9964% and 82.11%.