Patent ID: 8209999

Claim:
A process for preparing a silica glass granule, the process comprising: a) mechanically compacting pyrogenic silicon dioxide powder having a tamped density of 15 to 190g/l, to obtain slugs; b) crushing the slugs, to obtain slug fragments having a tamped density of 300 to 600g/l; c) removing the slug fragments having a diameter of <100 μm and >800 μm, to obtain classified fragments; d) heating the classified fragments at a temperature in a range from 600 to 1100° C. in an atmosphere comprising a compound which removes hydroxyl groups, to obtain treated fragments; and e) sintering the treated fragments at a temperature in range from 1200° C. to 1400° C., to obtain silica glass granules having: a median area in a range from 100 to 5000 μm 2 ; a median ECD in a range from 5 to 100 μm, a median circumference in a range from 20 to 400 μm; a median maximum diameter in a range from 10 to 140 μm. a median minimum diameter in a range from 5 to 80 μm, a specific BET surface area of <1 m 2 /g; and a total impurity content of <50 ppm.