Once the mining ore has been crushed using an impact crusher or a jaw crusher there is always need to grind the material down to an even finer powder that can be used for processing. There are many grinding system variations that can be used to achieve the final grain size including ball mills, rod mills and hammer mills. All these types of mills have their own advantages, depending on the ore that is being fed for grinding.
The ball mills are large cylindrical devices that rotation about the horizontal axis. The drums contain that material that is being ground together with the grinding medium. In most cases, the grinding medium is ceramic balls, steel balls or flint pebbles. The mills operate through internal cascading motion that causes the grinding balls to reduce the size of material through impact and friction. The ore is usually fed at one end as the fine powder is discharged at the other end.
The rod mill is a grinding system very similar to ball mills, but use steel rods instead of balls as the grinding medium. When they are being operated the ore and the rods tumble within the mill and causes a lot of friction. There is no cascading and therefore the grinding process is much faster compared to the ball mill.
The hammer mills act by shredding material as opposed to grinding it. This grinding system is made using steel drums that have horizontal or vertical rotating shafts with hammers mounted on them. The hammers swing freely in the drum from the fixed point. When the shaft is rotating at high speed the hammers beat the material and shred them into finer particles. The particles are then passed through screens of varying sizes to get even finer sizes.
Your choice of grinding system should come from a reliable manufacturer. Always ensure that you check the reviews of a machine online before purchasing it.