use of pet coke
But existing coal mill was capable of giving 5% max on 90 micron (design was 15% on 90 micron for Indian coal which is softer). Pet coke is very hard to grind (Hard grove Index 35-45) against 60-65 HGI (Hardgrove Index) in normal coal. Therefore without any modification, it was not possible to get targeted value of fineness in pet coke.