Modern Quarrying Q2 2019

Screening efficiency is the degree of accuracy at which undersize material is passed through an opening.

SCREENING – PART 1

ACHIEVING SCREENING EFFICIENCY

I n the aggregates world, where selling prices are often fixed and very competitive, efficient screening is the cheapest method of dropping the overall cost per tonne on a plant. This is according to Fernando Abelho, head of sales for Africa at Pilot Crushtec International, who adds that, sadly, it is also generally the most neglected facet by plant operators. “Many operators will spend time and money in the acquisition of best crushing equipment, then look for cheap options for their screens – be it the screen itself or the screening media. A simple example is picturing a 100 tph plant, where the correct screen or screening media could make a simple 2% differ- ence,” says Abelho. “In a 5-day, 7-hour operation, that’s an additional 70 t (3,5 tipper trucks) of production per week. That’s an additional +/-14 extra loads a month for the same overheads and fixed costs! This would apply to the type and quality of media, with cheaper meshes requiring more change outs, meaning more downtime and loss of production,” adds Abelho. Speaking about the significance of efficient screening, Waylon Kukard, sales manager at Wirtgen South Africa, the supplier of the Kleemann range locally, says screening is critical to the overall aggregates The last important production step in aggregates production is screening (classifying), which has to ensure high quality screening curves of end- products in accordance with standards. It is imperative that the process is executed in the most efficient manner. What is screening efficiency and what are some of the crucial factors that affect it? By Munesu Shoko.

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MODERN QUARRYING QUARTER 2 - 2019