Preparation of High Purity Quartz Sand by Mixed Acid Leaching from Quartz Associated with Kaolin and Its Leaching Kinetics Analysis

Abstract

The process mineralogy of kaolin associated quartz flotation concentrate was studied. The experimental results show that the content of SiO₂ in the flotation concentrate is 99.66%, and the main impurity elements in the concentrate are Al, Fe, K, and Na. The gangue minerals in the flotation concentrate are mainly mica and feldspar symbiosis with quartz in the form of connexion or mineral inclusion. By taking the flotation concentrate as the raw material, the experimental research on HF concentration, HCl concentration, HNO₃ concentration, acid leaching temperature, acid leaching time, and the leaching liquid solid ratio of hot pressing acid leaching conditions was carried out. Finally, the factors affecting the quality of purified products were analyzed. Through the acid leaching experiment, it can be seen that hydrofluoric acid has a greater effect on Al and Fe elements, hydrochloric acid has a greater effect on Fe elements, and nitric acid concentration has a smaller effect on impurity elements (which can also be confirmed from the thermodynamic analysis); the acid leaching temperature, the acid leaching time, and the leaching liquid solid mass ratio are proportional to the acid leaching effect. The Al content decreases from 1 304.73 to 214.10 µg/g, and the aluminum removal rate is 86.12%. The Fe content decreases from 39.35 to 3.72 µg/g, and the iron removal rate is 90.55%. Thermodynamic and kinetic studies show that at 220 °C, the chemical reaction between quartz and gangue minerals and the leaching agent can be spontaneous in the direction of positive reaction, and gangue minerals and the leaching agent had priority reaction. The mixed acid leaching process accords with the diffusion control model, E_a is 15.16 kJ/mol, which can provide a theoretical guidance for the purification of quartz.

Keywords

kaolin associated quartz / hot pressing acid leaching / high purity quartz sand

RIGHTS & PERMISSIONS

Wuhan University of Technology and Springer-Verlag GmbH Germany, Part of Springer Nature