Quartz is one of the most common minerals in nature, a mineral group made up of silicon dioxide (SiO2). It is widely used in traditional industries such as glassmaking, construction, and gemstone decoration. High-purity quartz is naturally formed (such as crystals) or processed from purer, higher-quality quartz raw materials.. Due to the varying quality requirements across different industries, there is no global standard for high-purity quartzs quality today.
Some scholars in Norway and the U.S., based on the quality requirements for quartzes glass used in the semiconductor and photovoltaic industries, argue that the total impurity content of quartz should be less than 50 parts per million (ppm), meaning the SiO2 purity should reach 99.995% or higher to be considered high-purity quartzes.
Generally speaking, the higher the purity of quartz, the lower the impurity content, and the better the quality. This is because high-purity quartz has superior characteristics such as high-temperature resistance, corrosion resistance, low thermal expansion, high insulation, and excellent light transmittance, which are essential to meet the quality requirements of high-tech industries like semiconductor chips, solar photovoltaics, and precision optics.
Preparation of high-purity quartz
There are three main methods for preparing high-purity quartzes, namely natural crystal grinding, deep purification of quartz minerals and chemical processing synthesis.
Natural crystal powder grinding
High-purity quartz is initially derived from primary and secondary natural crystals through deep purification. The process of preparing high-purity quartzes sand from natural crystals is relatively simple. The raw crystal ore undergoes crushing, magnetic separation, flotation, acid leaching, drying, and roasting to produce finished quartz sand.
Deep purification of quartz minerals
Due to the advantages of low price, relatively abundant resources and low pollution in the preparation process of natural quartz minerals, high-purity quartz sand is currently mainly purified from quartz minerals.
The deep purification of quartz minerals is mainly to remove a small amount or trace impurities to obtain high-purity quartz. Common mineral processing processes such as scrubbing, gravity separation, magnetic separation, flotation, acid leaching, and high-temperature chlorination are commonly used. According to the current technical level, people can purify high-purity quartzes from mineral resources such as vein quartz, quartzite, powder quartz and pegmatite, and even from the tailings of some metal mines. Among the many quartzes mineral deposits, granite pegmatite is the most ideal mineral for purifying high-purity quartzes.
However, the global raw material resources that can be processed into high-purity quartzes are less distributed and uneven.
Chemical processing method of high purity quartz
In recent years, the chemical synthesis methods for producing high-purity quartzes have gained increasing attention both domestically and internationally. Currently, the main chemical processing methods for high-purity quartz include vapor-phase synthesis, chemical precipitation, sol-gel methods, and silicon tetrachloride liquid-phase hydrolysis.
High purity quartz application
Industries and fields such as semiconductors, optical communication, photovoltaics, optics, and optoelectronics are crucial for supporting the development of strategic emerging industries. They are also vital to the construction of major projects and the improvement of people’s livelihoods.
| High purity quartz products | Main application areas | Main applications | High Purity Quartz Grade |
| Quartz crucible | Semiconductor, Photovoltaic | Container used to produce silicon products in the semiconductor and photovoltaic industries. | 》4N5① , Quartz Crucible inner coating> 4N8② |
| Quartz tube | Aerospace, semiconductor, new electric light source, optical communication | Quartz fiber, quartz wool, quartz cloth, etc. produced by quartz tube are used to make fairings, radar covers, heat shields, wave-transmitting materials, and high-temperature resistant materials in the fields of aerospace and aviation. In the new electric light source industry, it is used to produce lighting bulb materials. In the optical communication industry, it is used to produce optical fiber holding rods. In the semiconductor industry, it is used to produce quartz diffusion furnace tubes. | 》4N5① |
| Quartz Rod | Semiconductors, photovoltaics, new electric light sources | In the photovoltaic industry, it is mainly used for the production of single/multi-grade silicon distillation towers, volatilizers, feed pipes and other instruments. In the new electric light source industry, it is used for single-ended halogen lamp bridge rods. In the semiconductor industry, it is used for semiconductor quartz boat bases and other auxiliary materials. | 》4N5① |
| Quartz Boat, Quartz Ingot | Semiconductor, Photovoltaic | In the semiconductor industry, it is used for quartz bells, flanges, quartz flower baskets and other auxiliary materials, mainly used in the silicon wafer diffusion process. In the photovoltaic industry, it is mainly used as consumables for silicon wafer production, etc. | 》4N5① |
Note: ① indicates SiO2 content of 99.995%; ② indicates SiO2 content of 99.998%.
conclusion
In conclusion, high-purity quartz is a critical material with exceptional properties such as high-temperature resistance, low thermal expansion, and excellent light transmittance. Its purity plays a significant role in meeting the stringent requirements of advanced industries like semiconductors, photovoltaics, and optics. As demand for high-tech applications grows, high-purity quartzes will continue to be an essential resource driving technological innovation and industrial development.
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