ALPINE - Model S.O - Super Orion Ball Mill
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 centimetres to suit the application - smaller balls for fine milling results and larger ones for coarser milling tasks.
The drive sets the milling drum into slow rotation and the bed of milling media is thus activated, i.e. the balls are lifted and then impact back against the bed. Ball mills are usually operated at 75% of the critical speed. The critical speed is the speed where, mathematically calculated, the grinding media would centrifuge out. Mills of 2 m in diameter therefore rotate in operation at about 23 revolutions per minute, which corresponds to a peripheral speed of 2.4 m/s.
A mill of this size equipped with steel grinding media converts approx. 50 kW per m³ of feedstock. 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 is charged to a downstream classifier. The coarse material is returned to the mill together with the feed product.
The classic standard design which has proved itself in operation throughout the world for decades. Both the design and efficiency are continually improved to pay tribute to new technology and market requirements.
- Cast side plates bolted to a rolled-steel drum with integrated manhole.
- Drive via ring-and-pinion gear with automatically controlled tooth lubrication, back gearing with couplings and high-performance gear unit.
- Bearing unit: journal bearing designed as a friction bearing with permanent oil-recirculation lubrication and
- temperature control.
- Option: self-aligning roller bearings.
- Product discharge via adjustable slots located around the periphery of the drum. Two-part discharge housing
- with top venting connection and inspection cover.
- Ball mill for the dry comminution of hard materials, especially for the ultrafine range < 10 µm in circuit with an ALPINE ultrafine classifier.
- Grinding drum supported in water-cooled, oil-lubricated journal bearings.
- Grinding drum lined with tungsten carbide wear plates or with silex or ceramic elements when the requirement is grinding without iron contamination.
- Grinding elements dictated by the type of lining.