Patent RU 2822489
A method for chemical purification of natural quartz raw materials, an apparatus for implementing the method and grain obtained according to the method
Summary:
The invention relates to the chemical purification of natural quartz raw materials by acid leaching and can be used as part of the technology for producing high-purity quartz concentrates for the lighting and optical industries, including photovoltaics. The method includes the treatment of quartz grains with a solution of hydrofluoric acid for a time sufficient to achieve a given criteria of purity of quartz raw materials, followed by washing the purified grains with deionized water, carried out in a sealed rotating reactor with a horizontally oriented central axis with continuous removal of hydrofluoric acid vapors formed when the temperature in the reactor rises above room temperature. Vapor removal is carried out through a gas outlet pipe located in the cavity of the reactor rotation shaft coaxially with its axis, while the reactor is rotated for a time sufficient to achieve a given criteria of purity of quartz raw materials, then stopped, waste hydrofluoric acid is removed, after that deionized water is supplied to the reactor and its rotation is started for a time sufficient to wash the grains quartz from residues of hydrofluoric acid solution and dissolution products. Quartz grain purified by this method contains as contaminating elements in ppm: less than 5 aluminum, less than 0.3 calcium, less than 0.3 iron, less than 0.5 sodium, less than 03, potassium, less than 0.4 lithium, less than 0.02 copper, less than 0.02 chromium, less than 0.02 nickel, less than 0.02 manganese, less than 0.1 boron. The invention is aimed at improving the cleaning efficiency and achieving purity indicators of the finished product that meet the requirements of the modern semiconductor industry, achieved in a simpler device.
