Capital Equipment News November 2017

MORE THAN A MEANS OF SEPARATING AND SIZING MATERIALS

Once a secondary design consideration, screening technology, now deemed the mainstay of any mill circuit, has over the years become a crucial area of attention for both mines and quarries as they seek to ensure that their mineral processing operations run cost-effectively, writes Munesu Shoko .

screen for the job at hand. Weir Minerals offers single- and double- deck configurations for linear motion screens; circular/elliptical motion screens; and grizzly feeders. “Our linear motion screens, comprising multi-slope (banana), horizontal deck and inclined dewatering screens, are engineered to order to fit various screening duties including primary, secondary, tertiary, trash, drain and rinse, de-sliming, dewatering and protection screens,” says Kleyn. “Our circular/elliptical motion screens include single-, double- and triple-deck horizontal and declined screens, suited for all applications in the aggregate market. We also offer grizzly feeders for primary screening and scalping duties,” adds Kleyn. MBE Minerals SA is able to supply a comprehensive range of vibrating screens to suit most applications. These include RS/RFS type heavy duty resonance drive scalpers; circular motion declined screens for wet or dry coarse separations; linear motion horizontal screens for fines separation, such as classifications and grading under wet or dry conditions; as well as wet applications such as feed preparation (desliming and dedusting); media recovery (drain and rinse); dewatering and trash removal. “We also have multi-slope (banana) screens for specialised applications. We also offer an option of drives types, from vibrator motors on smaller equipment, to MBE Minerals’ proprietary side plate mounted drive on larger equipment,” says Standers. End-to-end solutions Bearing in mind the diversity of screening

According to Standers, correct selection of screening equipment in terms of the required area is very important in order to provide sufficient screening area for the required process, and factors such as increased future feed requirements, as well as changing feed conditions, should be carefully studied. “The conditions under which the screen operates, such as operating speed, machine acceleration and vertical acceleration, are essential considerations,” he says, adding that the cost of the equipment, not only in terms of capital cost, but the cost of operating and maintaining it during the expected lifecycle of the plant, should also be a primary consideration. Kleyn reiterates that selecting appro- priate screening technology to use in an application is absolutely critical to en- sure the screen operates reliably and ef- ficiently. “Some of the factors to consider include material type, bulk-density, feed gradation, material top lump size, required cut size, clay content and feed-moisture,” says Kleyn, adding that, based on these variables, OEMs need to consider design decisions, including required stroke, mate- rial travel rate, bed depth, deck load, wear protection, angle of inclination, spray water addition and other parameters. Application matters There are several typical screening appli- cations, including classification, dewater- ing, heavy media recovery, scalping, trash removal and grading. Each screening appli- cation is suited to a certain type of screen, and it is important to choose the right

and removing unwanted trash material from feedstock. Graham Standers, sales manager – vi- brating equipment at MBE Minerals SA, says milling circuits are designed to op- erate under specific conditions , not least is the size range of material being fed to the screen. “Efficient screening ensures an accurate size range of material feed to the milling circuit,” he says. Dave Sibley of ELB Screening Technology Solutions, says far from merely acting as a means of separating and sizing materials, the effective use of screening technologies can contribute to the overall efficiency of a plant and can significantly improve return on investment in terms of processing costs. Key considerations There are several criteria to consider when evaluating screening technology, from separation efficiency and equipment durability, to overall maintenance costs and aftermarket support.

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