subject: Ball Mills [print this page] Ball mills are used primary for single stage fine grinding, regrinding, and as the second stage in two stage grinding circuits.
Grinding of materials in a tumbling mill with the presence of metallic balls or other media dates back to the late 1800's. Since that time, Metso
and its predecessor companies, MPSI, Sala, Marcy, Hardinge, Kennedy Van Saun (KVS), Denver Equipment, Allis Chalmers, Boliden
Allis, and Dominion Engineering, have designed and manufactured more than 8,000 grinding mills.
Metso overflow ball mill sizes range from 5 ft. x 8 ft. with 75 HP to 26 ft. x 41 ft. with 20,000 HP.
Normal feed size to a Metso ball mill is 80% passing 1/4" (6mm or finer) for hard ores and 80% passing 1" (25mm or finer) for soft ores.
Ball mills operate either in open or closed circuit. Open circuit operation is best utilized when:
* Another stage of grinding follows the mill
* Reduction ratio is small
* Feed material is already fine and one pass through the mill produces the desired results
* Product size control is not critical and oversize material can be tolerated in the product
Where size control of the final product is important, closed circuit grinding is the most efficient method ofoperation. The production of a higher quality product
at a lower cost justifies the additional capital investment. Common wet grinding flowsheets include:
* Open circuit
* Closed circuit with hydro cyclones
* Closed circuit with vibrating screens
* Two stage variations of the above utilizing two mills in series
Let our engineers review your specifications and recommend the optimum circuit for your application
Application
A ball mill grinds ores and other materials to a typical product size of 35 mesh or finer.
