China Powder Network News Quartz is one of the most common minerals in nature. It is the scientific name of a group of minerals composed of silicon dioxide (SiO2). It is widely used in traditional industries such as glass, construction, and gemstone decoration. Since the 1960s, emerging technologies such as computers, new materials, and new energy have put forward higher requirements for the purity of quartz products, and the concept of high-purity quartz was born.
Image credit: Pexels
High-purity quartz is an irreplaceable basic material in the development process of national strategic industries and pillar industries. It is indispensable and irreplaceable for high-tech industries such as semiconductor chips, solar photovoltaics, optical fiber communications, aerospace, precision optics and special glass. Important functional materials are mineral resources that are truly "stuck in the neck". In nature, although quartz is widely distributed, high-purity quartz with high purity is very rare.
1 What is high purity quartz?
High-purity quartz is naturally formed (such as crystal) or purified and processed from relatively pure quartz raw materials. Due to the different quality requirements of quartz in different industries, there is no uniform quality standard for high-purity quartz in the world today.
According to the quality requirements of quartz glass used in the semiconductor and photovoltaic industries, some scholars in Norway and the United States believe that the total impurity content of quartz should be less than 50 parts per million, that is to say, the purity of SiO2 must reach more than 99.995% to be called high purity quartz. Some scholars in my country believe that quartz with a purity of 99.9% or more than 99.99% SiO2 is high-purity quartz.
Image Credit: Pacific Quartz
Generally speaking, the higher the purity of quartz, the lower the impurity element content, and the better the quality. This is because high-purity quartz has better properties such as high temperature resistance, corrosion resistance, low thermal expansion, high insulation and light transmittance, which can meet the quality requirements of high-tech industries such as semiconductor chips, solar photovoltaics, and precision optics.
2 The strategic significance of high-purity quartz
As early as 2011, the General Office of the State Council issued the Strategic Action Outline for Mineral Prospecting Breakthroughs (2011-2020), which clearly identified high-purity quartz as minerals required by strategic emerging industries. High-purity quartz and its raw materials are also mentioned many times in the 2017-2019 edition of the "Key New Materials First Batch Application Demonstration Guidance Catalog". Relevant documents such as "Building Materials Industry Development Plan (2016-2020)", "Guidelines for the Development of Key Common Technologies in the Industry (2017)", "Industrial Structure Adjustment Guidance Catalogue (2019)" and "Industry Catalogue for Encouraging Foreign Investment (2019)" are also vigorously Support the development of high-purity quartz. In 2020, the "Guiding Opinions on Expanding Investment in Strategic Emerging Industries to Cultivate and Strengthen New Growth Point Growth Pole" jointly issued by the four ministries and commissions also clearly requires focusing on key industrial fields and accelerating the development of key materials, key chips, high-end components and other core technologies. Attack. High-purity quartz and its raw materials are closely related to these fields. At present, some core technologies related to high-purity quartz have not yet made breakthroughs. It is necessary to raise the core technologies related to high-purity quartz to the perspective of national strategy to tackle key problems.
Image credit: Pexels
In addition, the supply risk of high-purity quartz and its raw materials in China is relatively high. On the one hand, its resources are mainly concentrated in foreign production, and the proportion of domestic production is relatively low. With the continuous advancement of Made in China 2025, the contradiction between supply and demand of high-purity quartz and its raw materials will also become more prominent; on the other hand, due to the political situation. Its trade channel has great insecurity, and the supply of high-purity quartz and its raw materials will face huge risks in the future. From the perspective of economic value, this type of resources plays an important role in the development of my country's strategic emerging industries. Although the proportion is not high, if the supply of such resources is restricted, it will directly affect the efficient and orderly development of strategic emerging industries.
3 Preparation of high-purity quartz
There are three main types of preparation methods for high-purity quartz, namely natural crystal grinding, deep purification of quartz minerals, and chemical processing and synthesis.
3.1 Natural crystal grinding
High-purity quartz was originally obtained by deep purification from primary and secondary natural crystals. The process of preparing high-purity quartz sand from natural crystals is relatively simple. The raw crystal ore is crushed, magnetic separation, flotation, acid leaching, drying, and roasting to obtain finished quartz. sand.
However, at present, my country's crystal resources are gradually scarce, and the cost is getting higher and higher; and the production process has high impurity content, high energy consumption, and poor product quality stability. At present, the primary and secondary crystals of purified high-purity quartz in my country mainly come from East China Sea, Jiangsu, and the unit price is about 30.0~40.0 yuan/kg, and the large-scale primary and secondary crystal mining in this area is basically depleted.
3.2 Deep purification of quartz minerals
Due to the advantages of low price of natural quartz minerals, relatively abundant resources, and low pollution in the preparation process, currently high-purity quartz sand is mainly purified from quartz minerals.
The deep purification of quartz minerals is mainly to remove a small or trace amount of impurities and obtain high-purity quartz. According to the current level of technology, people can purify high-purity quartz from mineral resources such as vein quartz, quartzite, powder quartz and pegmatite, and even from the tailings of some metal mines. Among many quartz mineral deposits, granite pegmatite is the most ideal mineral for purifying high-purity quartz.
However, the global distribution of raw materials that can be processed into high-purity quartz is less distributed and uneven.
3.3 High-purity quartz chemical processing method
In recent years, the research on the preparation of high-purity quartz by chemical synthesis has gradually attracted attention at home and abroad. At present, the chemical processing methods of high-purity quartz mainly include gas-phase synthesis method, chemical precipitation method, sol-gel method, and silicon tetrachloride liquid-phase hydrolysis method.
At present, the world's major producers of high-purity synthetic quartz materials include Corning Corporation of the United States, Heraeus of Germany, Tosoh Corporation of Japan, Shin-Etsu Quartz Corporation of Japan, and Philippine in China.
4 Current situation of high-purity quartz in my country
Due to the particularity of raw materials and technical confidentiality, the production and export of high-purity quartz and its raw materials are highly concentrated in a few countries and enterprises in the world. Among them, high-end processing and purification technologies and products are mainly mastered by developed countries such as the United States. The high-end high-purity quartz mainly relies on imports.
In 2019, the global import volume of high-purity quartz was 205,400 t, of which China imported 144,500 t, making it the world's largest importer of high-purity quartz, accounting for 70.35% of total global imports. In China's high-purity synthetic quartz market, Corning's high-purity synthetic quartz products accounted for the highest proportion, reaching 33.4%; Germany's Heraeus accounted for 21.0% of China's high-purity synthetic quartz market; Japan's Tosoh Corporation's high-purity synthetic quartz products accounted for 33.4%. The products account for 16.9% of the domestic market; the high-purity synthetic quartz of the domestic company Feilihua currently accounts for about 9.8% of the domestic market.
The quality of high-purity quartz products is controlled by the quality of high-purity quartz raw material resources. At present, there is not much exploration and evaluation of high-purity quartz raw materials in my country. So far, no large-scale and stable high-purity quartz raw material deposits have been found, and it is impossible to provide high-purity quartz raw materials with stable quality for production enterprises. The production capacity of high-purity quartz in my country cannot meet the needs of the market, and the contradiction between supply and demand will gradually become prominent.
5 High-purity quartz applications
Industries and fields such as semiconductors, optical communications, photovoltaics, optics, and electric light sources are important areas that support the development of strategic emerging industries. They are important guarantees for building major projects, improving people's livelihood, and consolidating national defense and military industries. They occupy an important position in the construction of the national economy. , High-purity quartz is widely used in these industries and fields, and is a rare and common high-value-added mineral resource required by these fields.
Main application fields of high-purity quartz products
Note: ① means SiO2 content of 99.995%; ② means SiO2 content of 99.998%.
Reference source:
[1] Wang Ziguo. Thoughts on the strategic layout of my country's high-purity quartz industry. China Mining. 2021.
[2] Wang Jiuyi. High-purity quartz—the "giant panda" in silica. Earth. 2022.
[3] Limu Information Consulting. "Market Development Overview of China's High Purity Synthetic Quartz Industry in 2022"
[4] Hao Wenjun, et al. Status, production, consumption and trade pattern of global high-purity quartz resources. China Nonmetallic Mining Industry Guide. 2020.
[5] Li Guanghui, et al. Analysis and suggestion of high-purity quartz raw material as a strategic mineral. China Nonmetallic Mineral Industry Guide. 2020.
[6] Wang Ziguo, et al. Analysis of the causes of quartz price fluctuations in my country. China Coal Geology. 2021.
[7] Yan Lingya, et al. Current situation and supply and demand situation of high-purity quartz resources development and utilization in China. Land and Resources Information. 2020.
[8] Li Aimin, et al. Preparation technology and application of high-purity quartz. Nonferrous equipment. 2021.
(Edited by China Powder Network/Xingyao)
Note: The pictures are not for commercial use, please inform and delete if there is any infringement!