The production process of high purity quartz powder

With the development of electronic industry, optical communication, laser, optics and other fields, the demand for high-purity quartz powder is increasing.

Because vein quartz mineralization is associated with many impurity minerals, and the types vary with the ore-forming environment, the main impurity minerals generally include feldspar, mica, clay, hematite, etc.

At present, quartz fine powder is prepared using quartz veins as a 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 the 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 to prepare high-purity quartz powder from ordinary quartz veins. The specific steps of the method are as follows.

1) Calcination

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

2) Quenching flotation

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

3) Pickling

Transfer the quartz powder at the bottom of the flotation liquid to the mixed acid solution and soak 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 2-6:1.

4) Complexation

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

5) Washing and drying

The quartz powder immersed in the complex solution is taken out, washed with deionized water, and dried to obtain a high-purity quartz powder product. The SiO2 content in the product is greater than 99.99%.

Through the treatment of quartz powder, high-purity quartz powder of electronic grade and microelectronic grade can be produced. The preparation process adopts high-temperature calcination with adding NaCl solid, quenching, 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 microelectronics and optical communication industries.