Patent ID: 9409810
Filing Date: 2016-08-09
CPC Classification: C03B,C03C

Claim Text:
1. A method for producing synthetic quartz glass granules by vitrifying a free-flowing SiO 2 granulate, the method comprising: granulating pyrogenically produced silicic acid so as to form the SiO drying the SiO cleaning the SiO vitrifying the cleaned SiO2 granulate in a treatment gas containing at least 30% by vol. of helium, hydrogen or a mixture of helium and hydrogen so as to form vitrified quartz glass granules, and subjecting the vitrified quartz glass granules to a post-treatment in an atmosphere containing helium or hydrogen in an amount less than 20%, and at a treatment temperature of 300° C. or more for a treatment period of at least 10 minutes, wherein the kiln is a rotary kiln rotating about a central axis, wherein the cleaning and the vitrifying of the SiO2 granulate and the post-treatment of the vitrified quartz-glass granules are carried out in a rotary tube of the rotary kiln rotating about the central axis, and wherein the rotary tube comprises an inner wall consisting of a ceramic material and the vitrifying takes place inside said inner wall.