Coal Age

APR 2017

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April 2017 www.coalage.com 39 rebuilds continued board transformers, which were deemed to be less costly and more reliable while altering the input supply from 8 kilovolts (kV ) to 25 kV. The revolving frame deck was extended to house these, while the machine's ballast was recalculated to take the weight of the transformers into ac- count. Cabot chose, however, to stay with the machine's original DC system rather than upgrading to AC, citing cost-effec- tiveness constraints. All of the dragline's gear cases were rebuilt, with thicker baseplates installed under the hoist and drag drums, with new hoist and drag pads. A completely new up- per superstructure provided an improved operator's cab, with electrical upgrades including LED lighting and a PLC-based operating system. Recommissioned into service in No- vember 2014, the dragline is stripping some 18 m (60 ft) of overburden to reveal a lignite seam that provides the raw mate- rials for Cabot's activated carbon plant. As Coal Age reported, the move and rebuild project came in under budget and ahead of schedule, involving more than 200,000 man-hours with no major safety issues, recordable incidents or lost-time injuries. Certified Rebuilds From Cat's Dealer Network In a presentation made at last year's Min- Expo in Las Vegas, Dave Faber, general manager for Caterpillar's aftermarket solutions division, provided some equiv- alent figures for the various options that the company provides for component repair or replacement. Again taking the cost of a completely new component as the yardstick, basic repair and adjustment before failure will extend a part's life at a cost of less than 25% of new, he said. A more comprehensive time and material overhaul will extend this further, costing 25%-50% of new, while a dealer rebuild or exchange—again before failure—will run to 55%-65% of the cost of a new part. Remanufacturing, before or after failure, is the most drastic procedure and carries the highest relative cost, perhaps reach- ing 80% of new, although still achieving worthwhile savings. Faber went on to highlight five key points that need to be considered when decisions are made about repairing or re- placing mining equipment: • Ownership – how long does the owner plan to keep the machine? • Utilization – how much or how often is the machine used? • Affordability – what are the cost expec- tations for repair? • Turnaround – how quickly does the ma- chine have to get back to work? and • Availability – where the cost of repair is offset by the cost of the machine not working. Faber then gave the example of differ- ent repair options and costs for the final drive for a Cat 793F haul truck. For basic repair and adjustment after 15,000 hours, with maximum reuse of Cat parts, at $2.97/hour the cost comes out at around 20% of new, he said. After 18,000 hours, slow-wearing parts begin to deteriorate, so exchange becomes necessary and the comparative cost rises to 43% of new at $5.30/hour. That assumes that nothing has actual- ly failed before replacement. If this occurs, then the potential for reusing parts is re- duced, exchange is essential, and the cost increases to 66% of new, at $7.29/hour. The final scenario is where full new com- ponentry is needed after failure, costing $11.07/hour over a 20,000 hour overhaul period. Faber outlined what is involved in a Cat Certified Rebuild, in which the com- plete rebuild process, undertaken only by Cat dealers, is endorsed by Cat. Using around 7,000 reman or reconditioned genuine Cat parts, the dealer rebuilds a machine to like-new condition, includ- ing any critical engineering updates. At the end of the process, the unit is new in both appearance and operation, and is expected to perform like a new machine, Faber added. To illustrate the way in which the re- build market has taken off, Faber noted that whereas in the mid-1980s, rebuild re- quests were very few and far between, by 2000 the interest was definitely beginning to grow. By 2005, Cat dealers were han- dling around 100 Cat Certified rebuilds a year, a figure that has since shot up to 300 in 2010 and around 900 in 2015. • Wet Drum Separators (LIMS & MIMS) • WHIMS • Magnetic Mill Liners • Trunnion Magnets • Suspended Magnets • Metal Detectors • Vibratory Feeders • Flotation Column Systems & Coarse Flotation Cells • Mini-Pilot Plants & Flotation Test Equipment • Gas Sparging Systems • Slurry Distributors • Test-Work & Services 814-835-6000 • Eriez.com 604-952-2300 • EriezFlotation.com Advanced Separation Technologies

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