Selecting the right screening equipment

Screening equipment can fit into different points of a material handling operation, depending on the aggregate processing application at hand.

Screens size and separate material after crushing, but they may be integrated just after the primary crusher – as in most crushed stone plants. Screening also occurs just before stockpiling or material transport.

The bottom line is, you need screens. But choosing the right ones – especially if you’re new to the industry – can be complicated. To ease your pain, here are some key points to consider as you prepare to purchase or lease new, high-tech screen machinery.

An art and a science

Separating and sizing material is a bit artful yet very much a scientific process. According to Pit & Quarry University’s lesson on screening, “the art of screening lies in the meticulous fine-tuning, tweaking and synchronizing of screen setups within a near-limitless number of applications. Its science is stratification.”

Stratification is a big word for the separation of large and small particles. Screening machines achieve this through vibration or agitation of material, although that vibrating movement may be mechanically different depending on an operator’s particular needs. No matter what, stratification is the reason screening works.

Machines to consider

There are a couple of screening equipment types: incline and horizontal configurations. Producers should have a good understanding of their operating parameters and overall production goals to make the call on which screen works best.

In addition, there are several options related to how screens run that need to be considered. Producers need to evaluate their requirements for feed tonnage, screening area, and efficiency to guide their choice.

Make the wrong equipment selection in screening, and a producer may be introducing the biggest bottleneck to the entire flow of the production process.

Incline versus horizontal

Incline screens harness the power of gravity to reduce power consumption. As a result, the incline configuration has better capacity abilities when operating at similar speeds versus horizontal screens.

Of course, if producers are limited by vertical clearance challenges at a quarry or mine site that would prevent the incline from being constructed at the proper angle – often about 20 degrees on the top deck – they will have to choose a horizontal screen.

Consider, too, that horizontal screens are commonly used in portable plants – or if producers are feeding from a dredge in a water-intensive operation.

Motion differences

There are three main ways screens move to achieve the necessary stratification.

Horizontal screens typically vibrate with either linear motion or an elliptical motion. Both movement patterns are effective, but the linear motion produces high G-forces that can dislodge material and convey it forward across the screen.

Inclined screen machines can also vibrate in linear or elliptical patterns, as well as in a circular motion, which is often preferable in continuous-feed setups where screening of large material must be accomplished.

Other considerations

In addition to considering an incline or horizontal screen and how they should vibrate to provide the desired output, setting up a screening operation requires producers to consider a couple of other points:

Dust suppression. Screening is one of the bigger drivers of dust in operations. A producer’s screening equipment should incorporate dust covers that physically block dust from escaping machinery – a dry suppression tactic.

Producers may also want to consider wet dust suppression techniques, depending on the material they’re working with – especially if they’re subject to the Occupational Safety & Health Administration’s new silica standard.

Feeders. Per Pit & Quarry University: “Depending on the process stage, the material to be screened is fed to the screen from an intermittent-feed-loading device like a wheel loader or from a continuous-feed device like a hopper or a conveyor.” In other words, producers must understand whether their operation’s production goals require the use of continuous or intermittent feeding tactics.

Information for this article courtesy of Kemper Equipment.