October 06, 2019

How to produce high purity fused quartz sand?

In this paper, the raw materials and production process of high purity fused quartz sand are described in detail, which can provide technical reference for high purity fused quartz sand production enterprises.

High Purity Fused Quartz Sand
 
High-purity fused quartz sand is made of high-quality natural quartz. It has high silica content and low impurity content. The main component of high-purity fused quartz sand is SiO2, whose content is more than 99.8%, which is an amorphous state of SiO2.
High purity fused quartz sand is a hard, wear-resistant and chemically stable silicate mineral with a particle size distribution of 0.01-1 mm. It has a colorless and translucent appearance, a density of 2.65, insoluble in acid and slightly soluble in potassium hydroxide solution.
The selected high quality natural quartz is melted in arc furnace, resistance furnace or high temperature sintering furnace. The melting temperature is 1800-1900 degree and melted for about 12 hours. After cooling, it becomes melted quartz. Because of its long-range disorder of atomic structure and cross-linking of its three-dimensional structure, the fused quartz has the characteristics of using temperature, low thermal expansion coefficient, no reaction with other substances at room temperature and wear resistance. It is characterized by high hardness, high temperature resistance, excellent light transmission, refraction and piezoelectric properties.

Fused Quartz Sand

The content of SiO2 in high purity fused silica sand should not be less than 99.99% in the first grade, 99.96% in the first grade, 99.95% in the second grade, 99.7% in the third grade and 99.6% in the fourth grade.
The impurities of high purity fused quartz sand are as follows:
Fe2O3 10PPM-25PPM max
Li2O 1-2PPM max
Al2O3 20-30PPM max
K2O 20-25PPM max
Na2O 10-20PPM max

Fused Quartz Sand

High purity fused quartz sand products should be mainly in the following fields:
1.As float glass, optical glass, conductive glass, anti-radiation and other special glass manufacturing.
2.Embryo and glaze for porcelain.
3. Production of high silicon bricks, ordinary silicon bricks and silicon carbide for kilns and furnaces.
4. As raw materials for producing silicon metal, ferrosilicon alloy and silicon aluminum alloy.
5. As artificial marble, cement, physical properties testing materials production, etc.
6. As an important raw material for high purity metal silicon, optical fibers for communications, aviation and aerospace fields.

Technology Process of High Purity Fused Quartz Sand
 
This technology process of this quartz sand is a method of mass production of high purity fused quartz sand. This method takes high quality natural quartz as raw material and is processed by washing, peeling, crushing, magnetic separation, pickling, re-washing, melting, re-crushing and grading of natural quartz.
The raw materials used in the production of this product are: high quality natural quartz, 10% dilute hydrochloric acid and water.
The production process of high purity fused quartz sand consists of the following steps:
1.The massive natural quartz is fed into the washing machine and washed with high pressure water to remove the attachment on the outer surface of natural quartz. Then the washed natural quartz is fed into the quartz skinner to remove the outer surface of natural quartz.
2. The natural quartz removed from the outer surface is fed into the crusher to crush the natural quartz sand with a diameter of 1-3 mm, and then the natural quartz sand with a diameter of 1-3 mm is fed into the magnetic separator. When quartz sand passes through the magnetic separator, quartz sand containing magnetism, metal and metal oxide is removed by strong magnetic field adsorption in the magnetic separator. After 0.2-0.3 hours of magnetic separation, the natural quartz sand after magnetic separation is sent into the acid tank.
3.A dilute hydrochloric acid solution with 10% concentration was added to the acid pond to immerse the solution completely in quartz sand. After stirring, the natural quartz sand soaked in the acid pond was soaked for 26-28 hours. Then the natural quartz sand in the acid pond was washed by high pressure water through the conveyor, or the hydrochloric acid on the surface of quartz sand particles was scrubbed by attrition scrubber and then washed by spiral sand washing machine, and then dried naturally and sent to a high temperature sintering furnace.
4. The high purity quartz melt was obtained by setting the temperature in the high temperature sintering furnace to 1825-1855 degree and the melting time is 13-14 hours. After the melting, the power supply to the sintering furnace was stopped. After cooling to room temperature, the solid pure fused quartz was obtained. The solid pure fused quartz was first mechanically impacted into small pieces and then sent to the crusher to break into pure fused quartz sand with a diameter of 0.1-1 mm. The fused quartz sand is classified by vibrating screen into 0.1-0.5 mm and 0.5-1 mm high purity fused quartz sand products.
The production method has the advantages of simple process, easy operation, less investment in equipment, low cost, pollution-free and mass production. The high purity fused quartz sand has the characteristics of low thermal expansion coefficient, no reaction with other substances at room temperature, good wear resistance, higher hardness, high temperature resistance, excellent light transmission, refraction and piezoelectric properties.

Suggestion: Fused quartz sand belongs to high-end quartz sand products, whose market demand exceeds supply. When producing fused quartz sand, you should study quartz raw material, which has great influence on producing high-purity fused quartz sand.

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