Mineral Processing Equipments: Screens

Screens are used to sort material according to size. The material fed into a screen is separated into a least two sizes:
Undersize material, which passes through the screen opening
Oversize material, which is retained on the screen surface
Although screening can be either wet or dry, dry screening is most often used in minerals processing operations.

Dust is generated in all dry screening processes. However, the amount of dust depends on the particle size contained in the ore, the moisture content, and the type of screening equipment used. Generally, a screen processing finer material produces more dust. Also, screens agitated harder and faster produce more dust than those vibrated more gently and slowly.

Types of Screens

The four most common types of screening equipment are-
Grizzlies
Shaking screens
Vibrating screens
Revolving screens

Article Sources:
http://www.osha.gov/SLTC/silicacrystalline/dust/chapter_2.html