An established concept with new technology: ball mills have been the mills of choice for decades for processing high-grade mineral powders. Regardless of whether the material displays Mohs hardness values of over 4 or is soft such as limestone or talc, Super Orion ball mills ensure low-wear and cost-effective processing. Over the years, we have continuously refined what started out as a simple ball mill for the industrial minerals sector to a high-tech machine for the mineral powder industry. The well proven grinding principle and the unmatched robustness of the machine are two features which have not changed, and today, there are three different standard designs available. Each of the three designs can be steel-plated or, if iron contamination is an issue, lined with silex or aluminium oxide.
Fig.1 Ball motion
Fig.2 Schematic of Super Orion ball mill S.O.
Ball mills are giant drums that are filled to between 30 and 40% of their volume with freely moving grinding media – in this case balls. The diameter of the balls is between one and several centimeters to suit the application – smaller pearls for fine grinding results and larger ones for coarser grinding tasks. The drive sets the grinding drum into slow rotation, whereby the bed of grinding media is activated. Ball mills are usually operated at 75% of the critical speed. If the speed is slower, the balls roll in a cascading motion, whereas at higher speeds, the balls are lifted and impact back against the bed (free-fall motion).
The feed product is fed continuously through the trunnion and is discharged through slots on the opposite side. The discharge rate can be adjusted as a function of the number of open slots. The ground product is transported – often pneumatically – and charged to a downstream classifier. The coarse material is returned to the mill together with the feed product.
Fig.3 Super Orion ball mill S.O.
The classic standard design, which has proved itself in operation throughout the world for decades. Both the design and efficiency have been continually improved to pay tribute to new technology and market requirements.
Fig.4 Super Orion ball mill S.O.-CL
High-tech mill for manufacturing ultrafine fillers and ceramic raw materials. Design as for S.O.-CL above, albeit with additional features:
Our modern PLEXCONTROL control unit with integrated load cell technology converts the robust ball mill with its time-proven grinding system into an extremely versatile high-tech system.
Fig.5 Compact system with S.O. and multi-wheel classifier ATP for the manufacture of fine fillers
Fig.6 Mill drive
Ball mills are usually operated at 75% of the critical speed, i.e. in the fringe area between cascading and free-fall. With a specially designed frequency converter, it is even possible to operate a heavy ball mill at variable speed. And if the S.O.-SF is to be used for grinding ultrafine products or if it is planned to change the product frequently, operation with a frequency converter is particularly advantageous.
Fig.7 Load cell
High quality application demands exact measurement of the amount of product in the mill. Because of this, an optional accessory offered for our ball mills is the load cell system which permits high-precision control of the product level. The complete ball mill is bedded on a steel or concrete frame designed to rest on a defined number of load cells. The load cells are integrated into a control unit and determine the total weight of mill, grinding media and product. The addition of virgin feed can be controlled with such precision that the mill always operates at optimum load. This means reliable prevention of no-load operation or overfilling, and mill operation is exceedingly cost-effective.
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