Roller screens are suitable for classifying coarse, moist, sticky or clayey raw materials. They are used for primary screening and crusher relief as well as for classifying/control screening after the crushing process.
The Feed Materials
Hard coal and lignite from coal plants, limestone, gypsum and other similar minerals.
The Mode of Operation
Roller screens are screening machines that have screening surface consisting of separate screen rolls which are driven in the same sense of rotation. They are equipped with curved triangular discs or as per requirement. For separating special kinds of grain sizes the discs are arranged in a way that they are set either opposite to each other or with interstices. Thus, it is possible to form square or rectangular screen openings. The fine sized grains can now pass these screening openings.
The parts of the feeding material that have not been screened are transported by the roller screen rolls to the roller screen discharge and then fed into the crusher.
Due to this process and the particular arrangement of the roller screen rolls, the feeding material is subject to a harmonic, gentle, rolling motion. Loamy particles, which stick to the coarse material, are separated and screened together with the final product. In case of very moist, sticky or clayey raw materials the roller screen rolls are fitted with scrapers, which clean the bottom of the rolls. They are individually adjustable. Another possibility is using surrounding scrapers driven via geared motors including chains. The type of scraper depends on the plant requirement.
Roller screens are arranged either horizontal or inclined. With the horizontal design, the drive of each roll is by a bevel gear pair with common longitudinal shafts. Depending on the feeding material, one or two drives are provided. The drive for the longitudinal shafts is by front electro motors including fluid starter coupling, transmission gear and flexible coupling. Alternatively, the roller screen rolls can either be driven by tooth chains running in an oil bath or individually. In case of roller screens in inclined arrangement, the drive is by tooth chains running in an oil bath.
- Roller screens with horizontal arrangement
- Roller screens with inclined arrangement
- Firmly installedadjustable scrapers
- Heated scrapers (stem-heated)
- Surrounding scrapers being linked via band chain
- High specific capacity at low power requirements
- Low spare parts requirement
- Smooth and quiet running
- Adequate primary screening machines for crushers (i.e. Hammer Mill,Roll Crusher etc)