By 2024, the global market space of high-purity quartz sand for photovoltaics is expected to reach 91,500 tons, with a CAGR of 27.3% in 21-24. In the field of photovoltaics, high-purity quartz sand is mainly used to make quartz crucibles for pulling single crystal silicon rods.
1. Quartz glass—a key raw material in high-tech fields
Quartz glass is an increasingly widely used high-tech material. The composition of quartz glass is silicon dioxide (SiO2), which has excellent physical and chemical properties such as high light transmittance, good temperature resistance and low expansion coefficient, so it is widely used in high-tech fields such as semiconductors, photovoltaics, optics, optical fibers and military industries. . Quartz glass has become an indispensable material for modern science and technology and modern industry. Experts in the field of new materials refer to quartz glass as the “King of Glass”. In terms of the high index of manufacturing, the complexity of the process, or the technical difficulty of the application, quartz glass can be called the “crown” of glass materials.
1.1 Quartz glass materials and products have excellent physical and chemical properties and are widely used
Quartz glass has excellent mechanical, thermal, optical and chemical properties, and is widely used in semiconductors, optics, optical fibers, photovoltaics, electric light sources, aerospace and other fields. Quartz glass is an industrial technical glass composed of a single component of silicon dioxide. Since silicon dioxide is an atomic crystal and there are covalent bonds between Si-O, quartz glass has strong temperature resistance and stable chemical properties; the chemical bond energy between Si-O is large. And the structure is compact, which makes the quartz glass have good mechanical properties and strong pressure resistance; in addition, the quartz glass has a small density, and the microstructure of the quartz glass is a simple network composed of silica tetrahedral structural units. Ordered, long-range disorder, resulting in excellent optical properties and high dielectric strength. With its excellent physical and chemical properties, quartz glass is widely used in many high-tech fields including semiconductors, optical fibers, optics, photovoltaics, electric light sources, and aerospace.
1) Semiconductors (accounting for about 65%): Quartz products are important semiconductor consumables used in the whole process of semiconductor processing. The silica in the quartz glass has high purity and stable chemical properties, and does not react with any acid except hydrofluoric acid and phosphoric acid. The requirements of cleaning and other containers are widely used in the semiconductor production process. In addition, due to the low refractive index and strong temperature resistance of quartz glass, it can meet the requirements of the mask for high optical transmittance and low thermal expansion rate of the base material, and is an important material for high-precision glass masks.
2) Optical fiber (accounting for about 14%): Silica glass material is the main consumable material in the production of optical fiber preforms and optical fiber drawing. The refractive index of quartz glass is extremely low, the absorption coefficient is small and the light transmission band range is wide, and optical fiber, as a light transmission tool transmitted by the principle of total internal reflection, has extremely high requirements on the refractive index, so quartz glass is widely used in optical fiber manufacturing , the main products are preform, furnace tube, quartz tube and so on.
3) Optics (about 10%): The components composed of quartz glass are the key components in optical instruments. Transparent quartz glass has good optical properties and low refractive index, and can meet any light transmission band in the range of 185-3500mμ, so it can be used as both an ultraviolet-transmitting material for optical instruments and an infrared-transmitting material. The main products are spectrographs, Infrared cameras, prisms and lenses. At the same time, quartz glass has strong thermal stability, and the value is between 800 and 1000 ° C. Optical quartz glass is also widely used in high-altitude high-temperature photography, such as: high-temperature operation peeping windows, high-precision rangefinders and large astronomical telescopes.
4) Photovoltaic (accounting for about 7%): In the production and processing links in the photovoltaic field, quartz glass products are rigid consumables. Quartz crucible made of quartz glass is generally used as a container for molten polycrystalline silicon material due to its cleanliness, homogeneity and high temperature resistance. It is used for the subsequent process of pulling monocrystalline silicon rods/polycrystalline silicon ingots. With the strong development of the new energy industry, the scale of China’s photovoltaic industry continues to grow, and the market demand for natural quartz products, especially quartz crucible products, continues to expand.
5) Electric light source (accounting for about 4%): In the field of electric light source, quartz glass electric light source products are widely used in household, medical, transportation, entertainment and other industries. Xenon lamps for automotive lighting, ultraviolet germicidal lamps for sanitation, and metal halide lamps for entertainment all use quartz glass as lighting fixtures.
6) Military industry: In the aerospace field, quartz glass products are the core components of spacecraft and space shuttles. Quartz glass has low density, strong compressive ability and good optical performance, which meets the requirements of space window materials for filtering ultraviolet radiation and radiation resistance, and avoids the formation of “color centers” under the irradiation of high-energy rays. It is widely used in satellites and spacecraft. Quartz glass can effectively control the attitude of the spacecraft, and the high-strength radiation-resistant glass cover can provide effective protection for the solar cell energy system of the spacecraft. In composite materials for carrying radomes.
1.2 The concentration of the quartz industry chain is relatively high, and overseas enterprises dominate
The complete quartz glass product industry chain includes the whole process from high-purity quartz sand raw materials to downstream applications: high-purity quartz sand – quartz glass materials – quartz glass products – downstream applications. The quartz industry is a material and product industry with silica as the main raw material component. In the industrial chain, the upstream is the production and supply of high-purity quartz sand. At this stage, since the production of high-purity quartz sand is closely related to high-quality ore sources, the industry is mainly monopolized by overseas companies that rely on high-quality quartz mines. The manufacturer is Quartz. Midstream quartz glass materials are generally stored in the form of ingots, cylinders, rods, tubes, etc. At present, the main competitors in the industry include Momentive, Heraeus, Tosoh, Kunxi, and domestic Philippine, Quartz, etc. ; Downstream quartz products are a series of devices made of quartz glass, including quartz boats, bell jars, crucibles, etc., which have high requirements for production technicians and production equipment, and the technology of domestic quartz product processing enterprises and foreign-funded enterprises are still There is a gap. Foreign-funded enterprises such as Heraeus Shin-Etsu, Hangzhou Yamato, Shenyang Hanke, and Taigunuo occupy the main market share. The domestic quartz product processing enterprises mainly include CapitaLand, Feilihua Shichuang, Dongke Quartz and Qianghua Co., Ltd. The downstream customers of quartz products mainly include semiconductor equipment manufacturers and wafer manufacturers, photovoltaic quartz crucible manufacturers, photovoltaic silicon wafer manufacturers, and related manufacturers in the fields of optics, optical fibers, military industry and electric light sources, of which the semiconductor market is the main application market .
2. Upstream: High-purity quartz sand resources have strong properties, showing an oligopolistic competition pattern
2.1 High-purity quartz sand is the upstream raw material, and the purity of the product determines its application field
High-purity quartz sand is the key raw material for the preparation of quartz glass, and the product purity standard determines its application field. High-purity quartz sand refers to quartz sand with Si content greater than 99.9%, Fe2O3 content less than 0.0001%, and Al2O3 content less than 0.01%. According to the purity index, high-purity quartz sand can be divided into 3N (low-end), 4N (mid-end), 4N8 (high-end), 5N2 (ultra-pure), 6N (high-purity SiCl4), and the purity determines its application field. Semiconductor: 6N SiCl4 is used to make photomask substrates, 5N2 sand can be used to make silicon growth crucibles, 4N and 4N8 sands can be used to make silica materials for silicon wafer oxidation and diffusion; optical fiber: 6N SiCl4 is used to prepare mandrels, 4N8 And 4N sand can make seed rods and preform sintered furnace core tubes in the deposition process; photovoltaic: 4N8 sand can make silicon growth crucibles, 4N sand can make quartz materials for photovoltaic cell diffusion, etc.; light source: 4N8 and 4N sand can make special , Quartz materials for automobile lights and infrared light sources; military and aerospace: 6N SiCl4 can be used to make sensors with extremely high precision requirements, 4N sand can produce quartz fibers; optics: 6N SiCl4 glass can be used for lithography lenses, laser gyroscopes and other high-end products, 4N, 4N8 sand can be used to make products such as coating ingots.
2.2 Mineral purification is the mainstream preparation process, and mineral quality and lattice impurity removal are the keys
The preparation process of high-purity quartz sand can be divided into mineral purification and silicon tetrachloride synthesis according to natural and synthetic methods. Subject to raw material reserves and cost, mineral purification is currently the main preparation process. Natural high-purity quartz sand can be obtained through the traditional process of natural crystal crushing-magnetic separation-flotation-acid leaching-drying-roasting, or it can be obtained by granite pegmatite, vein quartzite, etc. Processes such as complexation and chlorination calcination remove inclusions and impurities in the crystal lattice and obtain it by deep purification. Synthetic silicon tetrachloride is prepared by increasing the boiling point of silicon tetrachloride impurities through photoreaction, and then preparing by rectifying and removing impurities. Due to the small reserves of natural crystals and the high price of raw materials, the preparation cost of synthetic silicon tetrachloride is high, and it is difficult to produce on a large scale. Therefore, the purification and processing of quartz minerals is the main preparation method of high-purity quartz sand at present.
The natural high-purity quartz sand is prepared by a combination of physical and chemical purification. The quality of the ore and the process of removing impurities from the lattice are the determinants of the product quality. The preparation process includes 12 steps including roughing – crushing – water quenching – crushing – magnetic separation – classification – roasting – water crushing – flotation – deionized water washing – drying – acid leaching. The purification process of quartz minerals is relatively complicated, and the quality of ore and the process of removing impurities from the crystal lattice are the decisive factors for the quality of the product.
Ore quality: The content of different mineral inclusions, fluid inclusions and lattice impurities in the ore determines the final quality of the purified and processed high-purity quartz sand. According to different mineralization and physicochemical properties, quartzite can be divided into granite pegmatite, vein quartzite, quartzite and quartz sandstone. Ideal raw material for high-end high-purity quartz sand. At present, it is believed that the evaluation of raw materials should take the chemical composition, embedded particle size, gangue minerals, inclusions and lattice impurities as key indicators for comprehensive evaluation. It is high-purity quartz raw material. According to the data of China Powder Network, at present, the global high-purity quartz raw material deposits are distributed in 7 countries including the United States, Norway, Australia, Russia, India, Canada, China, etc. There are 14 deposits except China, of which 7 are not yet mined. , the mine with the highest quality and the largest reserves is the Spruce Pine mine in the United States. Deeply binding high-quality ore resources is the key to the competition of enterprises in the industry.