.

Hi, 

There are several factors of reduced Mill output for Petcoke grinding.

1.What is the Mill size please confirm and what are the residue levels on 90 and 212 micron. 

2.Any change in the Hard grrove index of the petcoke, normally HGI plays a vital role in the Mill       capacity, lower the HGI, i.e. high grindability (35-40), lower will be the mill capacity. 

3. Feed size of petcoke being used also affects the mill capacity

3.What is the Grinding Pressure in operation against Design Pressure of the mill. 

At what speed the Mill fan is operating, i.e. Normally for Petcoke Grinding, low volume of gases are required owing to higher fineness grinding.

we have to study the mill in complete with some process measurements activities to find the actual reason of reduced capacity. also what is the span on the reduced mill output.

Trust this will help you to analyse the reason of reduced mill capacity.

Regards,

SP