Vertical Roller Mills belongs to the category of grinders that are used in grinding materials converting them into supreme fine powder. The machine is extremely useful in various industrial process including cement processing industry, ceramics, pyrotechnics, paints and mineral dressing process. This instrument is suitable alternative for a ball mill in saving considerable energy. There are various forms of vertical roller mills but the basic mechanism of all remains the same. The machine is designed with roller and roller along disk track in circular movement executed by the external roller in vertical pressure exerted on disc due to the combined action of the shear and compression then to crush.
The vertical roller is made up of two grinding roller pairs, with two narrow rollers placed on same axis. The two rollers are capable of rotating at varying speed. There is also tire shaped rollers, slot for circular disc and work pressure prevails in the tank. The material that needs to be grinded fall from mill near the centrally placed entrance and later on exit because of the action of the centrifugal force applied on the edge of the disc by roller in order to move. The crushing and grinding of the material done at increased speed with the help of a separator which enables the re-grinding process. There is a dust collecting option attached to collect the product. The instrument used in the cement processing industry is available in various forms including cone type, cylinder type and ball type. The surface of the roller may be convex, curved or flat.
The major advantages of this vertical roller mills when compared to the ball mill is that it can grind more capacity (nearly 20 to 25 percent) than the ball mill. It possess low wearing rate, and can also get erected on its side in order to get rid of logical issues. The footprints of vertical roller mills are very smaller when compared to that of ball mills. However, the roller mills got is own limitations. The overall cost of this instrument is slightly higher. It requires higher maintenance too. The system is slightly complex in its operation when compared to ball mill.