Engineering & Mining Journal

JUN 2012

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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OPERATING STRATEGIES haul profiles and haul road mainte- nance, you can see increased truck speeds (if you are not already at maxi- mum for the corresponding road grade). To monitor and improve load distri- bution: Because RAC is constantly measuring the strut pressures for cor- rect load distributions, you can deter- mine when the truck is not at 33%:66% front/rear and 50%:50% right/left load- ing. You can then identify the shovel operators that need further training. To monitor and improve payload optimization: Within VIMS, there is a function called TPMS (Truck Payload Monitoring System). When the struts are properly calibrated (I would advise adding that as a maintenance item at the 500-hour preventative maintenance interval), TPMS will accurately provide payload weights. This data is stored and shown locally and/or streamed wireless- ly to the office. VIMS and TPMS data require proprietary Caterpillar software to decode, review and analyze. Using this data, you can then create charts to see what the payload percent curve/histogram looks like. With that, you can spot-train shovel operators. When trucks are loaded properly, you should maximize GVW minus EVW of your equipment (see spec sheets for GVW and EVW). Depending on whether a mine is over-trucked or under-trucked and many other parameters such as cycle time, commodity materials grade, etc., it may or may not be worthwhile for the shovel to load a partial bucket to bring the truck up to maximum payload. This is why shovel/truck pairing is so important when purchasing equipment during the capex phase. Do the calculations to see what it shows on paper. To monitor and improve truck box design: To review your truck box, first make sure it is loaded correctly: to avoid spillage, there should be slight extra room on the left, right and rear of the truck box. I have typically recom- mended a 1/1/1-ft margin space in training materials for shovel operators when they load a truck. This could change from site to site depending on uphill loaded road grade. If you are loading the truck properly and your scales are calibrated, but you are still not able to maximize payload (GVW minus EVW), then consider a new truck box design (lighter material/short- er life but higher payload). Do the cost analysis to see if the shorter component life is worth the higher payload (at cur- rent commodity prices, the payback is generally available). If trucks are constantly spilling but the truck scales say they are not over- loaded, then consider installing "hun- gry boards" on the side to increase the carrying volume of the box—or redesign the box to increase volume while maintaining the same box metal/liner weight. As with all technologies, success is based on the users. Unless operators and/or downstream users of this infor- mation are educated and unless there is a process to create/fix the source of the alarms, the technology will not yield cost savings or other benefits for the operation. Vivien Hui is a mining engineer with operations experience in gold and copper mining, and author of an in- dependent mining-technology blog at vivienhui.com. 146 E&MJ; • JUNE 2012 www.e-mj.com

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