Standard method of test for grindability of coal by the ...
Optimum milling conditions are: 40% V/V coal about 46% W/V), 140 cc slurry/kg media, 60 seconds milling time, agitator shaft speed 290 rpm, and 1/4-inch diameter stainless steel media. Under these conditions the energy requirement is in the range of 6.5 to 7.0 kwh/ton of coal.