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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MINE POWER Banks: The Cat off-grid technology solution allows our customers to operate rope shovels on diesel gensets at less than half the cost of a traditional off-grid rope shovel application due to reduced capital costs and fuel consumption. The fuel savings also contribute to a reduced carbon footprint. New Motivation Looking at rope-shovel power supply from another angle, MTU Onsite Energy recently developed a mobile generating solution to help a major North American coal producer move its shovels more efficiently. Teck Coal, a Canadian producer of coking coal, runs a number of large, AC and DC-driven electric rope shovels at its operations in British Columbia and Alberta. At the company's Elk Valley operations in southeastern B.C., the shovels normally get power from the utility grid. However, when the shovels move from pit to pit their power source is the mining 'motivator', which is essentially a generator set on wheels. At Elk Valley, the existing 30-year-old motivator was underpowered and frequently in need of maintenance. Downtime costs were significant. To solve the problem, a local power products supplier designed an innovative replacement specific to the mine's needs that relies on a state-of-the-art generator set from MTU Onsite Energy. "The old motivator was sufficient for some of our older shovels, but it was severely underpowered for a lot of our new shovels," said Mehul Joshi, P.E., electrical engineer for Teck Coal. "It ran at 1,400 kW, and whenever we tried to move a shovel, the breaker would trip, sometimes as many as four or five times during a move." Joshi and his engineering team worked with Cullen Diesel Power Ltd., Vancouver, the local MTU Onsite Energy distributor, to design a new motivator meeting Teck's needs. The power source in the new motivator is an MTU Onsite Energy generator set that includes an MTU 20V 4000 G83L engine, which meets EPA Tier 2 emission standards in accordance with Teck's specifications. The genset's output is rated at 7,200 v and 2,575 kW at an elevation of 1,300 m. With a full tank, the genset can run for more than 7 hours at 100% load and for 20 hours or longer under partial load, said Ethan Baily, a Cullen Diesel generator sales representative who worked on the new motivator design. Designed for off- or on-road travel, Teck Coal's new shovel motivator contains an MTU Onsite Energy generator set powered by an MTU 20V 4000 G83L Tier 2-compliant diesel. 62 E&MJ; • MARCH 2013 When needed at another site, the new motivator can be transported on public highways. "We can remove the mufflers and fold down the roof ladder, and [then] we're at the upper height limit for traveling on British Columbia highways," according to Baily. The enclosure, designed by Alum-Tek Industries, a British Columbia firm that designs and fabricates generator set enclosures, contains all of the motivator's power-generation and control equipment. A separate control room inside the new unit houses all the electronic components, which are protected by dust-tight enclosures. Keeping the electronics much cleaner than in the old motivator significantly reduces component maintenance and replacement. Because the electronics are in a room separate from the engine, crews working the controls have more space, better air quality and less noise. The new motivator is about 130% more powerful than the old one—and more than capable of meeting the 1,434kW peak power needs of Teck's newest shovels. The rope shovels' AC and DC drive systems can induce large amounts of harmonic distortion, so Cullen Diesel and MTU Onsite Energy designed a custom alternator that can handle the drive motors' high levels of harmonic distortion and still maintain required output. This slightly oversized device has a rated capacity of 3,000 kW at 105°C temperature rise. User-friendly features on the new unit include simpler procedures for starting and operating the engine, and automatic equipment-monitoring systems that indicate problems and eliminate the need for personnel to check gauges and equipment operation. Indicator lights on the control panel, as well as on the outside of the enclosure, ensure that operators can spot problems even when no one is in the control room. A reserve oil tank automatically levels engine oil, while oil and coolant lines extend to the outside of the unit, allowing faster fluid changes. With occupant safety being a design priority, the new motivator has three exits instead of just one. Two of these are in the engine room and one, a trap-door exit, is in the control room. The new unit also has more sophisticated safety equipment than its predecessor. This includes up-to-date fire-suppression systems, spark-detection devices, and arc-flash relay protection. www.e-mj.com