Separation and purification of high-purity quartz from high-silicon iron ore tailing: An innovative strategy for comprehensive utilization of tailings resources

High-silicon iron ore tailing is typically regarded as abundant mining waste of little use; it occupies a vast area of land and is harmful to human health and the ecological environment. Nevertheless, high-silicon iron ore tailing contains abundant quartz resource. In this study, a superconducting high gradient magnetic separation (S-HGMS) coupling fluorine-free mixed acid leaching technology was used to prepare high-purity quartz from high-silicon iron ore tailing. The S-HGMS technology was applied to separate and extract quartz from high-silicon iron ore tailing. Subsequently, the obtained quartz concentrate was subjected to an acid mixture leaching procedure to extract its impurities and obtain high-purity quartz. The optimal conditions determined for the magnetic separation process were a solid concentration of 4% and slurry flow velocity of 0.12 m/s. Under these conditions, the SiO2 grade of the quartz concentrate reached 98.56 ± 0.13%, and the SiO2 recovery was 60.59 ± 0.13%. The optimal conditions of the leaching process were a solid–liquid ratio of 1:4, leaching temperature of 80 °C, reaction time of 10 h, and acid mixture of HNO3, HCl, and H2SO4 (molarity ratio of 1:4:1). Under these conditions, the SiO2 purity reached a maximum value of 99.92 ± 0.01% in the high-purity quartz. Furthermore, we proposed a process for evaluating the recovery potential of Fe from iron-rich substances and recycling the leaching solution. The applied technology achieved a comprehensive utilization of high-silicon iron ore tailing and no waste discharge, meanwhile provides a theoretical basis and data support for its industrialization.