To download the below  and all other Useful Books and calculations Excel sheets please click here 

To download the below  and all other Useful Books and calculations Excel sheets please click here 

Critical Ball Mill Speed Calculator Excel sheet

Critical Speed = 42.3/sqrt(diameter)

% Critical speed < 70 à “slow”

70-75% à “normal

75% à fast

you can download it from the below link

https://www.mediafire.com/file/4o7biknoa0es4z8/Mill%20speed%20Excel.xlsx