Coal Age

APR 2017

Coal Age Magazine - For more than 100 years, Coal Age has been the magazine that readers can trust for guidance and insight on this important industry.

Issue link:

Contents of this Issue


Page 40 of 51

April 2017 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 • 604-952-2300 • Advanced Separation Technologies

Articles in this issue

Links on this page

Archives of this issue

view archives of Coal Age - APR 2017