Savings by feeding Flyash at mill outlet instead of mill inlet

Dear All

Can anybody explain me in an excel sheet what is the increase in production & the estimated savings in rs i will get if I put flyash at mill outlet instead of inlet.

The parameters are

Close ckt ball mill 

CF = 2.5

Product = 100 tph (PPC)

FA % = 25

FA Blaine = 3000 

Product Blaine = 4000

Mill KW = 2600

Please do reply in an excel sheet

Jolly