Types of aggregate Vibrating Screens

What is a Vibrating Screen?

Vibrating screener is machine used to separate aggregates by particle size by means of an exciting force applied to the machine. The vibration lifts the material, causing it to stratify, allowing the smaller material to move from the top of the depth of material to the bottom of the material, thus exposing them to the screening surface. 

Types of aggregate Vibrating Screens

There are two main types of aggregate vibrating screens for dry screening applications:

• Horizontal Screens

• Inclined Screens

The primary difference between Horizontal Screens and Inclined Screens is the Inclined Screen uses gravity to help with the flow and conveyance of the feed material.

However, both screens offer advantages for various applications. 

INCLINED SCREENS

Inclined Screens are the most popular for aggregate applications. They are installed on an incline (anywhere from 5-45 degrees depending on the type of screen and the required cut) and employ the use of gravity to propel material down the screen. Since gravity helps to move the material, this type of screen requires low energy and low stroke. 

HORIZONTAL SCREENS

Horizontal Screens are run flat at zero degrees but can be inclined or declined as much as 10 degrees in either direction. Because they don’t rely on gravity to move the material forward, Horizontal Screens require higher energy and a larger stroke. 

These types of screens are ideal for low-profile applications where height requirements are limited, which makes them a great choice for portable plants. In stationary plants, they are often used as tertiary or finishing screens. Finer screening applications can greatly benefit from this type of screen.

Known for their efficiency and reliability, Horizontal Screens offer more accurate particle sizing. The high G-forces required to move the material ensure screen plugging is virtually eliminated, allowing for more continuous open area. The flat orientation of the Horizontal Screen allows material to be retained on the screen longer for higher efficiency. It also makes them a great choice for wet screening applications.

How to select the right aggregate screen

Because screening plays such an important role in producing the required specifications of a final product, it is imperative that the right vibrating screen is selected for the job.

Vibrating Screen selection is based on the following factors:

• The maximum tons per hour

• A gradation of the feed material

• The type and weight of material

• The desired size of separation

• Any surface moisture on the material

• Any special operation requirements, including physical characteristics of the feed or product requirements

Sizing Vibratory Screens

Vibratory Screens come in a variety of sizes. They can range from 4’ to 12’ wide and 6’ to 32’ long. The width of the screen determines the carrying capacity of the screen deck, while the length of the screen determines the overall efficiency of the screen. Typically, the length of the screen is 2.5 to 3 times the size of the width. 

Every Mining Equipment manufacturer​ has its own screen sizing formula. Screens are tailored to an operation based on the following factors:

• Basic capacity – how much material is going to pass through a certain opening

• Incline – how much of an incline, if any

• Deck – not all of the length of the lower decks may be utilized, as material has already traveled down some length of the upper decks before reaching the lower ones

• Oversize – how much material should go over the deck

• Half size – how much material is half the size of the media opening With a high percentage of half size, the probability of the material passing through the screen openings will be higher, and the screen will be that much more efficient.

• Slot – how large the openings in the screen are

• Condition – applies to both the feed material and the atmosphere around the plant. Is the material wet and sticky? Does it have a high percentage of clay? What is the temperature outside? Is it a wet or dry climate?

• Shape – Round or cubical particles have a higher chance of passing through the screen openings than a flat, elongated particle that has to find just the right position to fall through

• Weight – the density of the material

• Open area – the more open area on the screen, the better the chance particles will find an opportunity to pass through