With the progress of industry, the demand for high-purity quartz sand is increasing day by day. It is an important way to obtain high-purity quartz sand through the quartz sand beneficiation and purification process. This paper takes a quartz sand purification project undertaken by Xinhai as an example to explain the processing flow of high-purity quartz sand.
The quartz sand is white compact massive, and its main component is quartz, with the content of more than 96%, followed by a small amount of hematite, limonite, ilmenite, garnet, trace montmorillonite, hydrobiotite, etc. Through the analysis of beneficiation experiment, the process flow of raw ore - coarse crushing - manual separation - fine crushing - classification - magnetic separation - flotation - acid leaching - washing - dehydration - drying was finally designed for the quartz sand concentrator.
1. Quartz sand crushing process
This stage mainly includes crushing manual selection and fine crushing. Jaw crusher is used in the coarse crushing stage, and the crushed products are sent to the next stage by belt conveyor. Manual selection operation is set up in the process. Qualified quartz sand ores are selected in advance by mineral color. The minerals selected manually will enter the twin roll crusher for fine crushing, and the qualified products after fine crushing will enter the vibrating screen for screening, The material on the screen returns to the roller crusher for crushing again, while the material under the screen enters the grinding and grading link.
2. Magnetic separation process of quartz sand
The dry magnetic separator is used for primary separation, mainly to remove garnet, hematite, limonite, ilmenite and their associated particles. The equipment adopts dry roller magnetic separator with magnetic field strength of 5000 ～ 11000Oe. After magnetic separation, the grade of+40 mesh SiO2 can reach 99.05%, and the content of Fe2O3 is 0.071%; 40 ～ 80 mesh SiO2 position is 99.09%, Fe2O3 content is 0.070%; 80~140 mesh SiO2 grade 99.14%, Fe2O3 content 0.067%; The grade of 140~200 mesh SiO2 is 99.10%, and the content of Fe2O3 is 0.069%.
3. Quartz sand flotation process
The flotation process is mainly to remove mica and Fe2O3 from quartz. XFb single cell flotation machine is used, H2SO4 is used as the adjusting agent, pH=2.5~3, sodium petroleum sulfonate is used as the collector, and terpineol oil is used as the foaming agent to obtain quartz by flotation. After flotation, the mica can be removed by about 70%, and the Fe2O3 content can be reduced to below 0.013%.
4. Acid leaching process of quartz sand
The main purpose is to remove the harmful components (all connected on the surface in the form of spots or inclusions) in the quartz particles after flotation. HCl, HNO3, H2SO4 and HF4 acids can be used, among which H2SO4, aqua regia and HF have better effects on removing Ti.
5. Quartz sand washing process
After acid leaching, the surface of quartz sand is adhered with soluble impurity residue, which needs to be removed by washing. The washing process is a process of diffusing the impurity compounds and residue on the quartz surface to the liquid phase. For washing after acid leaching I, tap water is used (washing for 3 times); For the washing after acid leaching II, tap water shall also be used for washing first, and deionized water shall be used for washing 3 times when the washing solution is close to neutral.
6. Quartz sand dehydration process
The washed quartz sand solution is sent to the thickener for concentration and dehydration, and the dehydrated product is pumped to the filter press for secondary dehydration. The final filter cake water content is less than 20%, which can be sent to the tailings pond for stockpiling.
7. Quartz sand drying process
The final high-purity quartz sand is obtained by drying at 120 ℃ for 15-20 min.
