Multi-deck vibration screeners are used for removing foreign materials from a process stream. There are three main reasons for their application.
- Foreign materials do not form part of the end product and therefore must be removed.
- Foreign materials may damage production machinery and should be removed so that the machinery has a longer working life with less cost related to maintenance and spare parts.
- Foreign materials would reduce the final quality of the product, which reduces the products monetary value.
Three Deck Screener Example
Multi-deck screeners consist of several decks. Each deck –or screen- consists of a flat piece of metal with holes of varying sizes. The size of the holes determines which materials are separated and which remain in the process stream.
- The upper deck has large holes that remove large foreign materials from the product stream, but allow everything else to pass through. Large foreign materials are usually items such as sticks and ropes etc.
- The middle deck is often referred to as the ‘clean deck’ or ‘intermediate deck’. This deck contains holes smaller than the upper deck, but larger than the lower deck. The intermediate deck retains the material that will eventually become the product, but sand and smaller particles fall through the holes to the deck below.
- The lower deck contains sand and other fines that have passed through the two decks above.
Design and Features
It should be noted that the discharges from the three screens go to three separate processes. The upper deck screened materials such as twigs and rope etc. are sent for milling and sold, or, sent straight for waste disposal. The intermediate deck discharges the product to the next stage in the production process. The lower deck normally discharges straight to a waste disposal area.
Unfortunately, some foreign materials such as stones, can be the same size as the product itself and this makes the use of a screener somewhat redundant. In order to get around this problem, a machine known as a ‘destoner’ is used. Destoners separate materials based upon density, whilst screeners separate materials based upon size and shape. It’s common to have both a screener and a destoner installed, in series, within the process, as this gives a good level of foreign material separation.
3D Model Details
This 3D model shows all major components associated with a typical vibration screener, these include:
- Electric Motor
- Suction and Discharge Ports