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P R O C E S S I N G S O LU T I O N S Siemens Gearless Drives for Las Bambas Overland Conveyors Siemens Drive Technologies Division, in response to an order from ThyssenKrupp Robins, Greenwood Village, Colorado, USA, will supply gearless drive systems for overland conveyors at the Las Bambas copper mine in Peru. Las Bambas, scheduled to begin operation in 2015 with an estimated annual output of 400,000 mt/y of copper at full production, will be the second mine owned by Xstrata Copper in Peru to use gearless drives from Siemens on its overland conveyors—the first being Antapaccay, which began commercial operations in November 2012. The two overland conveyors at Las Bambas will be designed and supplied by ThyssenKrupp. Each of the conveyors is approximately 2.5 km long and both will transport ore from the mine to the processing plant. The belts will be 1,830 mm wide, travel at 6.5 m/s, and are designed to move approximately 9,400 mt of material per hour. The Siemens drive systems for each of the two overland conveyors comprise two low-speed synchronous motors, each with a total power of 4,400 kW, and associated Sinamics SL150 cycloconverters. According to Siemens, the gearless drive solution has several advantages over the combination of high-speed motor and gearbox drives usually used on conveyor systems, including: • Motor size is not dictated by the size of gearbox available, thus eliminating the necessity to install multi-motor drives; • Power required to drive the belt can be provided by just one drive per belt pulley, allowing the size of the electrical room to be reduced, thus saving space and weight. • The elimination of a whole series of mechanical and electrical components increases the reliability and efficiency of the overall system by 3%–4%. • Using gearless drives instead of standard motor reducer packages will eliminate approximately 40 bearings and eight couplings per conveyor. • The maintenance requirements of the drive system are also substantially lower. • Lubrication and gearbox cooling systems—and their maintenance—are also unneeded for this solution. Xstrata Copper's new Las Bambas mine in Peru will use the same Siemens gearless drive systems on its overland conveyors that were installed on a similar setup at the company's Antapaccay mine, shown here. www.e-mj.com FEBRUARY 2013 • E&MJ; 89