Coal Age

MAR 2013

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VDMA environmental regulations while providing maximum safety for employees, machines and material. Siemens' Drive Technologies division supplies all-around solutions that meet customers' individual requirements. The company states that with its Simine product family, it links up automation, drive and power-supply systems to provide one all-around solution. According to Siemens, its gearless drives for mills, hoists, conveyors, excavators and pumps are setting a new standard for productivity in the mining industry. Benefits claimed for these drives include the highest availability on the market, the highest efficiency and intelligent use of energy in weak grids, and a proven design that can help keep an operation ahead of its competition, with systems that provide answers to the challenging demands of the mining industry. The company explains that the gearless mill-drive concept avoids any contact and wear between the rotating mill and the motor stator, with the same concept being used for gearless drives for hoists and conveyors. This allows production to carry on continuously without any need for maintenance on couplings, gears and pinions. The high availability of the gearless drive is based on mature technology, the company says, which it continually updates with new proven features. As an example, the cyclo-converters used in the design are just one of the reasons for this, since they are highly efficient, reliable variable-speed drives. In March 2012, Siemens reported that it had completed modernizing a gearless grinding-mill drive at Newcrest Mining's Cadia Valley operations in New South Wales, Australia. It fitted the 40 ftdiameter, 20 MW SAG mill with a Sinamics SL150 cyclo-converter for closed-loop control as well as with a Sinamics DCM control module for the excitation circuit—the first time that both types of converter had been used in a gearless drive, the company says. Late last year, Siemens Drive Technologies division commissioned a gearless belt-conveyor system from ThyssenKrupp at Xstrata Copper's Antapaccay mine in Peru. The first large-scale reference for this technology outside Germany, the gearless drives will help to boost the efficiency and reliability of the conveyor system, as well as reducing maintenance requirements. Siemens' scope of supply also included the entire switchgear and gearless drive systems for a 40 ft SAG mill and two 26 ft ball mills, with the gearless drive system using the latest version of the SL150 cyclo-converter. The success of the Antapaccay system led to Siemens' gearless drive for Los Pelambres' ball mill. VDMA 46 Siemens receiving a follow-on order from ThyssenKrupp Robins to supply a gearless drive system for an overland conveyor system at Xstrata's Las Bambas copper mine. Fluid Couplings for Conveyor Drives A group division within Voith GmbH, Voith Turbo specializes in hydrodynamic drives, coupling and braking systems for road, rail and industrial applications, and in ship-propulsion systems. Voith explains that the hydrodynamic principle of a fluid coupling makes it easy to accelerate driven machines gently. At the same time, fluid couplings limit torque, provide load sharing and dampen torsional vibrations. The coupling protects the drive system from damage, even under extreme operating conditions, so reducing downtime and helping to ensure continuous production. The company's product portfolio for mining and raw-materials handling includes constant-fill and fill-controlled fluid couplings, as well as customer-specific drive solutions that are reliable and specifically tailored to the requirements of each application—from individual couplings to complete drivelines that can transmit power in the range of 300 W to 6 MW, it says. Developed especially for the drives on open-pit mining belt conveyors, its latest fluid coupling technology—the TurboBelt 780 TPXL—transmits twice the power previous couplings of a similar size could achieve. This, according to Voith, is because of its innovative XL blade wheel profile. The fill-controlled coupling is designed for 6- and 8-pole induction motors operating at speeds of 900-1,200 rpm. The start-up procedure, with a precisely-controlled introduction of torque, protects not only the belt but also the entire driveline. Start-up times of up to several minutes can be individually set in the control system, and even overloaded belt conveyors can be started reliably, the company says. In May 2012, the first installation to use this technology was commissioned at one of the biggest sea terminals in northern Brazil. To handle increasing tonnages of iron ore, the mining company decided to install three TurboBelt 780 TPXL couplings in the drives of a 1,451 m (4,760 ft.)-long main conveyor that carries around 10,000 mt/h. Reliability is, of course, a high priority for the customer, and Voith reports that the TurboBelt 780 TPXL coupling has given a system availability of up to 99.8 % when combined with reliable mechanics. The company also points out that maintenance can be cut to a minimum since hydrodynamic power transmission is completely wear-free. Compared with traditional couplings, the TurboBelt 780 TPXL requires only half as much installation space and is also significantly lighter, so installation and alignment was quick and straightforward. As well as fluid couplings, Voith supplies drive packages that help operate belt conveyors in the most efficient way, including the drive hardware, PLC controller and supervision of installation, together with commissioning. A cutaway of Voith's 780 TPXL coupling. VDMA MINING SUPPLEMENT • 2013

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