Preparation method of high-purity silicon dioxide

Abstract

The invention discloses a method for preparing high-purity silicon dioxide. The method comprises the steps as follows: getting kieselguhr as a raw material to react with an ammonium fluoride aqueous solution at certain temperature; precipitating, filtering and centrifuging to obtain an ammonium fluosilicate solution; evaporating and crystallizing to obtain high-purity ammonium fluosilicate solid; thermally decomposing the ammonium fluosilicate solid to obtain high-purity silicon tetrafluoride; carrying out reaction between the silicon tetrafluoride gas and the high-purity ammonia water to obtain silicon dioxide precipitate; then separating the solid and liquid, washing, and drying in vacuum to obtain the high-purity silicon dioxide powder. The preparation method disclosed by the invention is low in cost of raw material and simple in operation technology, has no pollutant produced in the production process, and the prepared silicon dioxide powder has purity more than 6N.

Description

technical field [0001] The invention relates to the field of preparation of inorganic chemical raw materials, in particular to a preparation method of high-purity silicon dioxide. Background technique [0002] High-purity silicon dioxide (above 5N) (N represents 9 digits after the decimal point, such as: 5N represents a purity of 99.99999%) is an indispensable and important basic material for polysilicon, optoelectronic industry and other industries, and it is also a high-tech that is increasingly widely used Material. [0003] The traditional methods of producing high-purity silica mainly include: silica refining method, gas phase synthesis method (dry method) and precipitation method (wet method). The silica refining method uses natural high-purity quartz and silica to obtain high-purity silica. This method is subject to the limitation of raw materials, not only limited in quantity, but also difficult to meet the requirements of the high-tech material field in terms of q...

AI Technical Summary

Problems solved by technology

This method is subject to the limitation of raw materials, not only the quantity is limited, but also the quality is difficult to meet the requirements of the field of high-tech materials

The gas phase method uses silicon halides or silanols as raw materials, which is expensive, flammable, and highly corrosive. It has high requirements for production equipment, large investment, and high production costs. It is not suitable for large-scale production.

Precipitation method usually uses sodium silicate or ammonium fluorosilicate as raw material, the price is relatively low, and the operation is relatively safe, but the purification is difficult, the product quality is easily affected by the purity of raw materials, and pollutants are discharged during the production process