The Attritor mills can be operated in a batch or continuous mode, utilizing either dry grinding or wet grinding. When used in continuous grinding, the material is fed into the vessel at the top. It then falls through the agitating media bed where it is processed to a desired particle size, and is discharged through metering bar grids at the bottom of the tank. In the batch mode, material is charged into the mill at the top, ground for a pre-determined time, then discharged through grids at the bottom. The system an easily be sealed for grinding under inert gasses such as nitrogen or argon.