Concepts of Gearless Ball-Mill Drives

In the past the conventional method of driving large ball mills included some form of speed reducing gear between the higher speed driving motor and the lower speed ball mill. Process developments in the mining and cement industries have increasingly tended toward the use of ever larger ball mills for grinding their products. As the horsepower drive ratings required have increased to several thousand horsepower, and as advances in technologies in terms of the use and application of adjustable frequency power conversion equipment have occurred, the basis for driving the ball mill directly by the driving motor with no intervening gear has been created. Several such units will shortly be in service in Europe. The use and application of such drives are described.