Engineering & Mining Journal

JUN 2014

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

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depths. In addition, poor screening effi- ciency can lead to higher recirculating loads. This in turn can have the effect of increasing the cost per ton in downstream equipment, such as higher wear rates of crusher manganese and the over-genera- tion of fines in the product. "As far as spillage is concerned, poor housekeeping and inappropriate mainte- nance are health and safety risks. They also push up the cost per ton, but can be corrected with proper plant management. The old saying of 'penny wise, pound fool- ish' springs to mind, with the main empha- sis being placed on initial cost rather than the cost per ton. Disregarding the overall importance of any screen media used in a process also has a negative impact on achieving the lowest cost per ton." Cutting Screening Costs Here, the respondents gave their views on the measures that operators can take to reduce screening costs within the overall cost of mineral processing. Sandvik: Make a close study of the process, ensuring to really get what is being aimed for. It might be better overall economy to produce a smaller tonnage of higher-quality material than a higher total tonnage at lower quality. It is most impor- tant to fully know and understand the process. Study the screens very closely; in general, there is a lot of focus on crushers, but screens are allowed to run with very little attention—unless problems occur. Having large amounts of unscreened final product will only cause high circulating loads in the process, so causing un- necessary wear on all the other equipment involved. Naday: Screens do not get the respect given to more costly equipment, even though screening is a critical part of the process that can cause exorbitant costs in other equipment. A screening expert can determine and recommend the optimal parameters for an operator's specific con- ditions. Questions to ask include: Is the screen running at the correct speed? Is the media performing its metallurgical duty? Is the media maintenance fine-tuned to the plant maintenance cycle? Are fines ade- quately removed from the circuit? McElvenney: As a belt linear screen receives and cleans a considerable slurry flow, it is imperative that it is regularly maintained to ensure free roller movement, which in turn reduces stresses applied to the screening cloths. Flood detection sen- sors also reduce flood events. Sibley: As noted above, the cost per ton can be improved with appropriate manage- ment. To assist this process, plant surveys JUNE 2014 • E&MJ; 75 www.e-mj.com S C R E E N S Polydeck says its modular panels are easy to place and remove, but they—like all modular products—must be installed correctly for maximum effectiveness. EMJ_pg72-77_EMJ_pg72-77 6/3/14 3:06 PM Page 75

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