Grizzly-type screens for lumpy material are used as primary screens and feeding devices upstream of crushers and mills as well as for coarse screening operations.
Depending on the application, they are equipped with a conveyor floor and an anti-vibration frame and can be provided as single-deck and double-deck screens. Size 0.5 – 4 double unbalance gearboxes are used as drive units. Depending on the application, different designs of bar screens and perforated plates made of different materials are used as screen coverings.
One of the most diverse tasks of mechanical processing of bulk materials is the sizing by means of screens. The standardized system of assemblies allows screen widths of up to 3,200 mm and screen lengths of up to 9,000 mm to be adopted in single-deck and multiple-deck screens for dry and wet sizing operations.
A special screen called the “banana screen” is used for a low-bed of large feed quantities. Depending on the specified application, different designs of tensioned and flat screen coverings made of different materials offer an optimal solution for screening granular bulk materials.
Dewatering, depulping and deslurrying screen
Linear vibrating screens for wet processing of bulk materials, pulps and slurries are used for the following purposes:
1. Dewatering of wet or wet processed materials allowing them to be transported by belt conveyors or to be loaded.
2. Depulping to recover the heavy medium and/or to feed dilute medium to the magnetic separating system, the separation limit being approx. 0.5 mm.
3. Deslurrying suspensions with separation limits of approx. 0.1 – 1mm.
Double Unbalance Drive Units
Linear vibrations are produced by the double unbalance drive units with adjustable unbalance discs. Five types of gearboxes are available. Their number and size depend on the task and the vibrating weight of the screen.
The gear units are driven through a non-vibrating V-belt intermediate gear with cardan shaft or through a cardan shaft which is directly coupled to the motor. If directly driven, the speed of the motor can optionally be changed by a frequency converter. The use of an electric braking device allows resonance speeds to be quickly run through during shutdown.