company news about high-purity quartz sand industry's structure, purity standard, technological obstacles and application scope (4)

3. “Raw ore” resource peculiarity + “purification” processing technique build the industry barriers

The source of minerals that can be used for high-purity quartz sand production are limited.

High-purity quartz placer sources are mainly granite quartz and vein quartz. Natural crystal features in high purity and few inclosures. It was once the raw material for making high-purity quartz, but now it is mainly used as the raw material for crystal craft. Natural crystal reserves are small and unevenly distributed, and there are relatively few high-grade crystals in China. At present, granite quartz and vein quartz are the main raw materials for the production of high-purity quartz sand. Granite quartz deposits are with large-scale and have high quartz purity, but the quartz content is low. Pegmatite contains about 40% feldspar, 25% quartz, 20% Microcline feldspar (generally perthite) and 15% muscovite; vein quartz deposits are widely distributed, but relatively small in scale.

Global high-purity quartz raw material deposits are found in 9 countries including the United States, Norway, Australia, Russia, Mauritania, China, Canada, India, and Brazil.

The Spruce Pine Mine in the United States has a unique white granite type high-purity quartz raw material ore, which once provided 90% of the world's high-purity quartz sand. Unimin also monopolizes the production and sales of IOTA super-pure quartz. Other countries Similar deposits are difficult to find. However, in recent years, various countries have increased their exploration and mining efforts, and have discovered more than 10 mineral deposits that can be used as high-purity quartz raw materials to produce low to mid-end high-purity quartz sand, gradually breaking the monopoly structure of Spruce Pine Mine in the high-purity quartz sand industry.

The quality of raw ore is related to purity, inclusion characteristics, and element existence forms.

The requirements for raw ore are high: the quality and the content of impurity elements are not simply related to each other, but are related to the characteristics of the inclusions in the raw materials, the occurrence state and form of the elements.

Quartz Co., Ltd. has sufficient raw ore reserves, which can meet the production of approximately 47,000 tons of high-purity quartz sand. Judging from the quartz stone purchase price of Quartz Co., Ltd. in 2016-19H1, the unit price has increased year by year. At the end of 2021, the book balance of quartz shares' raw materials was 236.21 million yuan. Based on the quartz stone purchase unit price trend of quartz shares in recent years, assuming a unit price of 2,500 yuan/ton, the quartz stone inventory of quartz shares in 21 years will be approximately 94,000 tons. Based on the estimation that every 2 tons of raw ore can produce 1 ton of high-purity quartz sand, we estimate that Quartz's quartz inventory by the end of 21 will be able to meet the production of nearly 47,000 tons of high-purity quartz sand.

The main process flow of the high-purity quartz sand purification method is: the raw ore silica is washed away by the ore washing machine, and after rough crushing by the crusher, the qualified quartz material is put into the roasting furnace and roasted at 850℃~980℃ for 6 hours. After roasting, the quartz material is dragged into clean water for water quenching, and then manually selected to remove impurities and then sent to the crusher for crushing and screening. The quartz sand that passes through the screen is then sent to the magnetic separator. After magnetic separation, the quartz sand It is put into an acid tank equipped with HCl and HF mixed acid and soaked for a week, and then undergoes flotation, dehydration, baking, cooling, and packaging to obtain high-purity quartz sand.

Chemical synthesis method: including gas phase synthesis method, liquid phase synthesis method, fluorosilicic acid method, etc.

Chemical synthesis technical routes include gas phase synthesis, liquid phase synthesis, fluorosilicic acid method, etc. Synthetic quartz has higher purity (6N) and better optical properties, and is gradually becoming an alternative material in the production of semiconductor products below 7 nanometers.

Gas phase method: SiCl4 is used as raw material, and is hydrolyzed at high temperature (1200-1600°C) by hydrogen-oxygen flow to obtain smoke-like SiO2. After cooling, separation, deacidification and other processes, the finished SiO2 particles are obtained. Synthetic SiO2 powder is prepared through a temperature-controlled, two-step gas phase hydrolysis method. However, the technical process is complex, the efficiency is low, and the technology is not yet mature. It is currently only suitable for laboratory development, and large-scale industrial production is difficult.

Purification and testing: foreign countries take the lead, domestic companies catch up

Overseas giants have more complete R&D and testing systems and have leading advantages in stable batch supply of products.

Testing technology: Reagent purity, processing materials, and production environment have an impact on product quality. Online testing of each link can effectively control product quality. For IOTA-standard high-purity quartz, chemical analysis and X-ray fluorescence spectrometry (XRF) testing are difficult to meet the quality testing requirements. At present, ICP-OES has become an effective method for detecting trace chemical components of high-purity materials.