Innovative technology for preparation of high-purity silica from vein quartz ore through S-HGMS coupling acid leaching process

Abstract

In the present work, an S-HGMS coupling acid leaching technology was established to prepare high-purity silica using vein quartz ore. Firstly, the magnetic properties of different phases in vein quartz were investigated through density functional theory (DFT) calculations and arranged the phases in terms of magnetic susceptibility: FeP2 > Al2SiO5 > SiO2 > Ca(Al2Si2)O8 > AlPO4. Those differences in magnetic susceptibility resulted from the spin state of electrons in the ions. After treatment using the S-HGMS process, weakly magnetic particles are effectively separated from silica particles, and the obtained silica concentrate contained SiO2 of 99.690% purity. Subsequently, lattice impurity ions were removed through a fluorine-free and low-fluoric acid leaching process. Under optimal conditions, the SiO2 purity in high-purity silica reached 99.954% and 99.990% in the two processes. The lattice parameters and volume of ɑ-quartz in high-purity silica obtained with low-fluoric acid leaching were less than those obtained with fluorine-free acid leaching. This difference can be attributed to the reaction between HF molecules and lattice impurity ions, resulting in the generation of coordination compounds. Meanwhile, HF dissolved SiO2 and opened the lattice impurity ions channel, promoting lattice impurity ions depth removal. This study established a complete set of critical technologies for preparing high-purity silica from vein quartz through the S-HGMS coupling acid leaching process, providing theoretical and scientific bases for industrial applications.