Modern Quarrying Q2 2019

Screening efficiency is the classification of different products according to a grading curve of the specific application.

In the aggregates world, where selling prices are often fixed and very competitive, efficient screening is likely the cheapest method to reduce the overall cost per tonne of a processing plant

Scan QR code to watch the Kleemann MS 703 EVO triple-deck screen in action.

production process. “Without proper screening efficiency, your final products can be contam- inated and out of the grading curve. This also impacts your production rates as undersize material will go back to the crusher if you are operating in a closed circuit,” says Kukard. The same view is shared by Rasheel Sukdhoe, product manager of the McCloskey Crushing, Screening, Stacking and Washing range at HPE Africa, who says that the screen- ing process is the most important part of the the aggregate production process. “Screens are a way to control quality and gradation of aggregate product. Prior to screening, the product might not have as much of a value, however after screening the value of the prod- uct will increase,” he says. Abelho adds that inefficient screening may result in the final product being out of specifi- cation. “This can have huge financial implica- tions, not only in production costs related to the need to rescreen or re-crush the material, but can also result in penalties and potential loss of sales,” says Abelho. Defining screening efficiency When talking about screening efficiency, it is important to understand what it is in the first place and how it’s measured. In technical terms, screening efficiency is described as

Screens are a way to control quality and gradation of aggregate product

When it comes to screening efficiency, there are often factors that are crucial to a specific site but not necessarily a factor on another site, so site information is critical to make a proper assessment

The operating conditions, product shape, abrasiveness and final specifications are all significant when selecting the type of media to use

As a general rule, no screen is 100% efficient – a screen operating at 95% efficiency is often considered ‘perfect’

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QUARTER 2 - 2019 MODERN QUARRYING