High purity quartz sand extraction steps

High-purity quartz powder has excellent optical, thermal, chemical stability and radiation resistance properties, so it is widely used in the electronic industry, optical communications, military and other fields. With the development of electronic industry, optical communication, laser, optics and other fields, the demand for high-purity quartz powder is increasing. Smelted crystal and high-quality natural crystal have always been the main raw materials for high-purity quartz materials, and the supply of these raw materials is becoming increasingly scarce.

Since there are many impurity minerals associated with vein quartz mineralization, and their types vary with the mineralization environment, the main impurity minerals generally include feldspar, mica, clay, hematite, etc. Currently, quartz micropowder is prepared using quartz veins as raw material. The technological process includes raw materials, coarse crushing, fine crushing, pickling, water washing, drying, grading and finished products. The SiO2 content in the quartz powder obtained by this process is 99.0-99.6%, while the SiO2 content in the refined high-purity quartz should reach 99.99%, and the total content of impurity elements is less than 100pm.

Xinhai provides you with a solution for preparing high-purity quartz powder using ordinary quartz veins as raw materials. The specific steps of this method are as follows.

1) Calcination

Use quartz veins as raw materials, crush them to 200~400 mesh, add an appropriate amount of NaCl solid and mix evenly. The amount of NaCl solid added is 2~4% of the quartz vein mass, and calcined at 800~850°C for 2~4 hours.

2) Quenching and flotation

Pour the calcined material into the flotation liquid while it is hot and quench it. The flotation liquid used is a mixture of 0.2-0.5g/kg dodecylamine and 0.2-0.5g/kg sodium dodecylbenzene sulfonate. Use dilute sulfuric acid to adjust the pl value to 2~3. The mass ratio of flotation liquid to quartz powder is 3 to 10:1. The flotation time of quartz powder in the flotation liquid is 3 to 10 minutes, and the temperature is maintained at 10 to 70°C.

3) Acid leaching

Transfer the quartz powder at the bottom of the above-mentioned flotation liquid to the mixed acid solution and soak it at 10-60°C for 6-12 hours. The mixed acid used is a mixed solution of 10-20% hydrochloric acid and 1-5% hydrofluoric acid. The mass ratio of mixed acid to quartz powder is 2 to 6:1.

4) Complexation

Transfer the above-mentioned acid-leached quartz powder into the complexing liquid and soak it at 10-60°C for 3-8 hours. The complexing liquid used is a mixture of 0.2-1% citric acid and 0.2-1% lauric acid. The mass ratio of complexing liquid to quartz powder is 1 to 5.

5) Wash and dry

Take out the quartz powder soaked in the above complex solution, wash it with deionized water, and dry it to obtain a high-purity quartz powder product. The SiO2 content in the product is greater than 99.99%, and the total impurity content is less than 100ppm.

Through the processing of quartz powder, high-purity quartz powder of electronic grade and microelectronic grade can be produced. The preparation process uses NaCl solid high-temperature calcination, rapid cooling, flotation, acid leaching, and complexation to remove impurities, so that the SiO2 content reaches 99.99% and the total impurity content is less than 100ppm. The product performance is excellent and can be used in the microelectronics and optical communication industries.