Honglei New Material

Quartz sand is a non-metallic mineral, the main component is silica, the color is milky white or colorless translucent, the aggregate is often granular, dense block, crystal cluster or cryptocrystalline stalactite.

High purity quartz sand is widely used in high-tech industry.In the semiconductor industry, wafers with excellent high temperature thermal performance can be made from fused quartz, which can be used to manufacture high-tech heat pipes with good high temperature thermal stability.In the communications industry, quartz glass produced from quartz sand is the basic material for optical fibers and other photoelectric devices.

In addition, it can also be used to produce silicone resin, solar cell substrate, in abrasives, fillers, coatings and silicone rubber and other industries in greater demand.With the improvement of the purity of quartz sand, its value is also increasing, especially in the high-tech field, the purity of quartz sand is extremely high.

However, with the gradual depletion of natural crystal resources, the extraction of high-purity quartz from ordinary quartz sand has become an inevitable trend.

Improve the selection of pure technology, more extensive use of ordinary quartz sand is the key to solve the problem.In recent years, the research of quartz sand purification mainly focuses on physical, chemical and biological purification.Among them, physical methods are widely used.

The physical method is mainly to remove impurities in quartz sand by washing - fractional desliming, scrubbing, magnetic separation and flotation, and can also be combined with several processes to further remove impurities.

Physical purification of quartz sand

Wash - stage desliming and scrubbing

In the mineral processing process of quartz sand, the fine particle size of less than 0.1mm is usually called slime.For quartz sand with a large amount of clay and slime, the grade of silicon dioxide gradually decreases as the particle size becomes finer, while impurities such as iron and aluminum increase instead.

The water washing and fractional desliming method can effectively improve its grade.For the film iron and adhesive impurities on the surface of quartz sand, the effect of washable and fractional desliming is poor, which requires the grinding and stripping force between the mechanical force and the sand to remove the film iron and adhesive impurities on the surface of quartz sand, and better impurity removal effect can be achieved after the fractional desliming.

Summarizing the previous experience, the effect of rod friction washing is ideal, the general scrubbing concentration is 50% ~ 60%, the scrubbing time should be determined according to the nature of the ore, in order to initially meet the product quality requirements, the time should not be too long, in order to avoid too much energy consumption and excessive wear on the equipment.

Gravity separation, magnetic separation and flotation

Gravity separation is a mineral separation method that makes use of the difference in relative density, particle size and shape between mineral particles and the difference in speed and direction of movement in water, air or heavy liquid.For quartz sand ore, spiral separator, chute, shaking table and other gravity separation equipment are often used.

For some iron impurities occurring in iron ore particles or in mineral particles such as biotite, garnet and hornblende, as well as aluminum occurring in feldspar, the effective removal method is flotation.

At present, the flotation mainly uses acidic conditions, according to the different agents used can be divided into fluorine flotation and fluorine free flotation, there are some flotation under alkaline conditions, but from the point of view of industrial production, fluorine flotation is still the main flotation method, its advantage is the purification effect is better, mature technology, but the corrosion of equipment is larger, environmental pollution is more serious.

Quartz sand deep processing technology

Superfine grinding

With the rapid development in the field of high-tech, high-purity quartz powder as a filler material has shown broad application prospects, it has excellent dielectric properties, high thermal conductivity, low thermal expansion coefficient, high temperature resistance, corrosion resistance, controllable particle size distribution, good suspension performance and many other advantages, in the catalyst, advanced abrasive, fine chemical industry and other fields widely used.In the processing process, high purity quartz sand is usually used as raw material, and qualified ultrafine quartz powder is produced by melting calcination, ultrafine grinding and grading.

spheroidization

The spherification of ultrafine quartz powder can make its surface fluidity good, and the resin is stirred into a more uniform film, and the performance of the electronic components produced thus is better;Second, the spheroidized plastic sealant has low stress concentration, high strength, and high yield of the integrated circuit chip encapsulated by the spherical powder.Third, the friction coefficient of spherical powder is small, the friction generated on the mold is small, and the service life of the mold can be improved.

Preparation of spherical quartz powder technology is difficult, foreign countries usually use high temperature melt injection method, control in the liquid phase of ethyl orthosilicate, silicon tetrachloride hydrolysis and so on.

Surface modification

The natural quartz powder has poor affinity with polymer materials, and is often dispersed unevenly when used as a filler, or even clumped, which has a great impact on the quality of the product, so it is necessary to modify the surface of the quartz powder to make it reactive.Surface modification methods are mainly divided into encapsulation modification, deposition modification, microcapsule modification, surface chemical modification, mechanical chemical modification and high-energy treatment modification, of which surface chemical modification is used more, the modifier is a wide variety, mainly silane coupling agent, titanate lipid coupling agent, organic chromium coupling agent, zirconium aluminate coupling agent and so on.