Coal pulverisation with vertical roller mills
· Quartz (SiO2), found in ash, is the most abrasive component of coal and has a hardness of Vickers. Quartz, being dense, will tend to concentrate itself on the table/bowl. The buildup of quartz on the bowl will increase the wear due to compression and the quartz that becomes entrained in the air stream will aggressively attack by abrasion the exposed grinding .