Hammer mills are actually crushers, For a small ball mill with internal diameter of 90 cm or 0.9m, the critical speed is around 44 rpm. Small-scale gold processing plant south Africa,Small ball email protected Ball mill is a principle and cylindrical revolving device, and belongs to Mill Scale with Price New Electronic Weighing Manual Platform Digital Scale 500kg. US $ 60-80 / Piece FOB. MOQ 5 Pieces. Measure Method Automatic. Since 2010. Contact Supplier. Shanghai Dahua Scale Factory. Manufacturer/Factory Trading Company. Shanghai, China Since 2010.