company news about high-purity quartz sand industry's structure, purity standard, technological obstacles and application scope (3)

2. Different applications have different purity requirements.

For the different physical and chemical properties, each purity standard product has different application fields and large price differences.

High-purity quartz sand has excellent physical and chemical properties and has a wide range of applications. High-purity quartz sand usually refers to quartz powder with w(SiO2)>99.9%, which is generally produced from high-grade natural quartz minerals through purification technology. The unique crystal structure and lattice change rules of high-purity quartz sand make it resistant to high temperatures, small thermal expansion coefficient, highly insulating, and corrosion-resistant.

In China, low and mid-end high-purity quartz sand has been domestically produced, while high-end products are mainly imported from overseas. Domestic academic circles currently define high-purity quartz sand as quartz products with SiO2 content >99.9%, Fe2O3 content <10ppm, and Al2O3 content <25ppm. According to product standards, they can be divided into low-end (3N), mid-end (4N) and high-end (4N8) products. Low-end and mid-end products have been domestically produced, while high-end products are mainly imported from overseas.

High purity quartz sand has high purity and impurity content is less than 20ppm.

High-end products in high-purity quartz sand are based on the IOTA-STD of Unimin (North America) Company. The content of twelve elemental impurities is less than 20 ppm, among which the alkali metals (K, Na, Li) are each less than 1 ppm. product. The high-purity quartz sand series products produced by Unimin occupy most of the world market, and the purity of its quartz products is known as the "world standard purity of high-purity quartz sand".

The standards for high-purity quartz sand for single crystal crucibles are much more stricter than those for photovoltaic glass quartz sand.

The purity of quartz sand used in photovoltaic crucibles must reach 99.998%, and the purity of quartz products used in photovoltaic production processes (such as cleaning processes) must be above 99.99%, both of which are higher than the 98.55% purity requirement of photovoltaic glass quartz sand, and the impurity content requirements are also far behind. Higher than photovoltaic glass.

In order to ensure the melting effect of the crucible, the content of each metal impurity is strictly controlled in the crucible raw material. If the purity of the high-purity quartz sand is insufficient: 1) the melting process will cause the crucible itself to deform, resulting in a reduction in the service life of the crucible; 2) it will affect the purity of the drawn single crystal silicon, resulting in a reduction in the yield rate of the silicon rod.