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It is difficult to purify quartz sand, mainly because some of it contains iron elements, such as goethite, hematite, limonite, ilmenite, pyrrhotite, tourmaline, amphibole, biotite, etc. These impurities greatly reduce the use value of quartz sand, so the separation of stone iron ore and quartz sand is very important. The following introduces 6 methods and equipment for quartz sand iron removal.
Gravity separation can generally be used effectively for the entire particle size range of quartz sand. When the iron in quartz sand is mainly heavy minerals (relative density > 2.9), gravity separation should be considered first. However, the gravity separation of mixed particles, flake particles, light mineral particles and medium density minerals is difficult.
Quartz is the main mineral in quartz sand and is a diamagnetic substance that cannot be magnetized in a magnetic field. Iron-containing impurity minerals in quartz sand, such as hematite, limonite, magnetite, goethite, etc., are mostly magnetic.
The magnetic separation method can remove weakly magnetic impurity minerals such as hematite, limonite, and biotite to the maximum extent, including conjoined particles. The more times of magnetic separation, the finer the quartz sand particle size, and the better the iron removal effect.
Quartz sand flotation method mainly removes mica, feldspar, garnet, amphibole and other iron-containing mineral impurities. The three-stage flotation process is used to remove iron-containing mud, mica and feldspar minerals from quartz sand respectively.
Flotation method can achieve better results than other methods by removing iron from minerals through flotation. It can not only remove iron minerals, but also particles and clay minerals with iron films.
If the finished quartz sand is reddish and the iron and titanium content does not meet product quality requirements, acid leaching can be used. The quartz sand is washed with water to remove powder and impurities, then acid-leached, and then dried.
Quartz sand acid leaching method has good iron removal effect, but the cost is high, the technical requirements are strict, and it is harmful to the environment.
Stirring and scrubbing are accomplished by friction between particles caused by vigorous stirring of the blades. However, since iron oxide films are thin and strong, this method is unlikely to remove them. If necessary, chemical reagents can be added.
Ultrasonic iron removal mainly removes the secondary iron film on the surface of particles. After 10 minutes of ultrasonic treatment, the iron removal rate can generally reach 46% to 70%. In order to improve the effect of ultrasonic cleaning, a small amount of reagents (such as sodium carbonate) and surfactants (such as water glass) can be added.
The current cost of ultrasonic iron removal for quartz sand is relatively high, and it is still difficult to apply in large-scale mineral processing plants. However, for high purity requirements, low output is possible.
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