Quartz sand purification is a difficult separation technique for removing fine or trace impurities in quartz sand to obtain refined quartz sand or high-purity quartz sand. The domestic and international quartz sand purification processes mainly include water washing, classification desliming, scrubbing, magnetic separation, flotation, acid leaching, microbial leaching, and etc.
The quartz sand beneficiation production process can be applied to quartz sand containing iron or mica.
Washing and classification desliming
The grade of SiO2 in quartz sand decreases with the finer grain size of quartz sand, but for the grade of impurity minerals condition is opposite. The phenomenon is especially obvious in quartz sand containing a large amount of clay minerals. Therefore, washing and classification desliming are very necessary the quartz sand ore before the selection is carried out.
Scrubbing is to remove the thin film iron and muddy impurity minerals on the surface of the quartz sand by mechanical force, grinding and peeling force between the sand grains. Further smash the unassembled mineral aggregates. And then purify the quartz sand by the classification operation. There are two main methods: rod scrubbing and mechanical scrubbing.
The separation of mica and quartz is difficult, and it can be obtained by using an anion collector under acidic conditions, or an anion-cationic collector under alkaline conditions. The two method could achieve an effective result. Generally, after scrubbing, desliming, magnetic separation and flotation, the purity of quartz sand can reach more than 99%, which could basically meet the requirement of industrial sand.
Dilute acid has a significant effect on the removal of iron and aluminum, while the removal of titanium and chromium need to be carried out by acid leaching with concentrated sulfuric acid and aqua regia. Usually, the mixed acid composed of the above acids is used for acid leaching of impurity minerals. The control of various factors of acid leaching should be based on the requirement of the final grade of quartz. The concentration, temperature and amount of acid should be reduced as much as possible to achieve quartz purification at a lower cost of the beneficiation equipment.