Engineering & Mining Journal

JUN 2013

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UNDERGROUND HAULAGE Again, the locos are equipped for electro-dynamic braking and carry an ATP system, although the Grasberg units have been designed with an operator's cab at each end whereas the LKAB machines are single-ended in this respect, reflecting the one-direction system of operation at Kiruna. The Rubber-tired Alternative Since the time that heavy locomotives became available, long-distance underground haulage has largely remained the domain of rail-bound systems, and for good reason. Although expensive to install, rail networks are relative cheap to maintain, whereas haul roads need constant cleaning to remove spillage as well as regular repairs to the wearing surface. Nonetheless, a few operations— such as LKAB's Malmberget mine—recognized the potential for using highcapacity haul trucks underground to give additional flexibility in terms of routing from drawpoint to dump. The use of the 120-mt-capacity Sisu SRH450 Mammut paved the way, although only six were ever built, while Sandvik took a Sisu concept for a sidetipping hauler and developed it into its current top-of-the-range model, the five-axle 80-mt-capacity TH680. However, there is only a limited number of mines for which machines of this size would be suitable, and Sandvik's most recent hauler introductions have been the 51-mt-capacity TH551, designed for 5 × 5-m declines, and the 63-mt-capacity TH663, designed for 6 × 6-m declines. Both machines, which were announced at last year's MINExpo show in Las Vegas, are scheduled for official launch in September. Meanwhile, a TH551 has been undergoing mine-site trials at Wolfram Bergbau und Hütten's Mittersill underground tungsten mine in Austria, and the first TH663 is scheduled to begin moving rock at Barrick Gold's Darlot mine in Western Australia this month. According to Sandvik, the new trucks have the highest haulage capacity in their class and "envelope size." Other key features include higher ramp speeds for increased productivity, the use of more than 60 safety features that are designed to protect the operawww.e-mj.com tor, maintenance crews and the trucks themselves, and careful matching to Sandvik's underground loaders to ensure precise three-pass loading for optimum loading speed and efficiency. The TH663 has been matched to the company's LH621 underground loader, which carries a 10.5-14 yd3 (8-10.7 m3) bucket, while the TH551 is matched to the 8.5-11 yd3 (6.58.6 m3) LH517. In addition, the TH551 has an option of a Tier 4i low-emission engine that eliminates the need for a diesel particulate filter, while both machines have the option of an on-board jacking system for faster and safer tire changes that will help minimize production holdups. The TH551 has a 51-mt payload with a standard body capacity of 28 m3 (36-yd3) and can haul at speeds of up to 37.5 km/h. The 63-mt-payload TH663 has a 36-m3 (47-yd3) body, and a top speed of 42.5 km/h provided by a Cummins QSK19 engine rated at 567 kW (760 hp). The standard engine on the TH551 is a 515 kW (690 hp) Volvo TAD1642VE-B, while the optional lower-emission Tier 4i power unit is a Volvo TAD1662VE, also rated a 515 kW. According to Sandvik's product manager for trucks, Mark Ryan, the Tier 4icompliant engine will significantly reduce underground ventilation costs and help improve underground working conditions, as well as combining good torque characteristics with low fuel consumption. Felix Gaul of Wolfram Bergbau und Hütten added, "All our heavy machines have to be equipped with diesel particulate filters for underground operations. With the Tier 4i engine, this is not necessary, resulting in savings of about €100,000 ($130,000) over the lifetime of the machine." Atlas Copco Goes Greener At the end of April, Atlas Copco launched its new Green Line of electric-powered LHDs and haulers, aimed at reducing mines' fuel costs and environmental footprint. "With these new products, we are ready to be part of the global solution for reduced environmental impact," said David Shellhammer, president of the company's underground rock excavation division. "We are especially proud to be the only supplier of underground electric trucks, and I believe this development marks the beginning of a change in the mining industry." Sandvik's new TH551 underground mine truck has a 51-mt payload and can be fitted with a low-emission Tier 4i-compliant engine. (Photo courtesy of Sandvik) JUNE 2013 • E&MJ 57

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