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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P R O C E S S I N G S O LU T I O N S Maximize Heap Leach Site Mobility Customized mobile conveyor systems optimize material transfer for greater stacking volume and efficiency in heap leach mining applications The correct combination of conveyors, stackers and base units in an integrated system can significantly improve heap-leach material stacking efficiency, leading to better overall performance, according to mining and aggregate equipment builder Superior Industries. Heap leach mining operations continually seek greater capacity, continuous material flow and reduced downtime. In any precious metal application these challenges are ongoing top-of-the-mind initiatives, particularly due to the complexity of stacking plans. Material handling equipment must be highly mobile and extremely flexible. And, for optimum performance, more and more operations are utilizing integrated conveyor systems, which can be customengineered for the specific pad design. The speedy payback from the latter is measured in more tons per move, larger leach pad footprints and increased profitability. "Because every heap leaching operation maintains a specific process with unique characteristics, mines are far more likely to improve efficiency with a customized and comprehensive material handling system," said Bob Domnick, vice president of engineering for Superior Industries, a manufacturer of aggregate- and mine-duty conveyors, components and integrated systems customized for heap leach operations that include valley fill pads, billiard table pads, and advance or retreat stacking. Domnick said an integrated heap leach system comprises a core group of mineduty conveyors, with the customization of the system being applied with various belt lengths and widths, belt speeds, and load areas, as well as choices in hoppers, mobile tracks, control systems, electrical components, and the total number of jump or grasshopper conveyors. "This strategically selected system of machines and machine attributes ensures smooth material transfer and far greater efficiency over that of older, conventional methods," he added. 80 E&MJ; • JULY 2013 Dominick said many current heap leach mining operations work in a manual radial stacking mode. Operators will move the radial stacker with a loader to a given location, leaving it to stack there while they perform other maintenance duties. Later the operators return to either fill in holes or move the stacker to the next location. "This typically results in saw-tooth pile tops, which are not ideal for irrigation," he said. Getting Even Alternatively, automated heap leach conveying systems are programmed to stack per desired lift specifications. At the core of Superior's system is the mine-duty TeleStacker conveyor, which is engineered with an internal stinger conveyor that maintains constant motion along a cell, distributing material evenly to achieve a flat top to each heaped pile, while also piling more material per move. "Its stinger conveyor, longer than those supplied with conventional radial telescop- ing units, allows for greater flexibility in complex valley fill applications," said Domnick. The TeleStacker conveyor is equipped with the FD Series axle assembly, a technology that allows a quick transition from radial to linear mode, enabling movement along the leach pad cell centerline. Also, the unit features the patented FB undercarriage support system, which is constructed of durable steel and a tubular braced structure that prevents any twisting and shifting. "This level of stability is required for the uneven ground and the constant movement typically seen in the heap leach environment," he said. Regarding additional mobility options, Dominick said operations may utilize radial travel tracks and/or a track-mounted mobile pivot base in conjunction with the telescoping conveyor. "Radial travel tracks are a cost-effective method to gaining optimum flotation and traction. When combined with the mobile pivot base, operations can achieve free-ranging onsite and transfer An integrated heap leach system comprises a core group of conveyors, with customization applied by choosing belt lengths and widths, belt speeds and load areas; similar choices in hoppers, mobile tracks, control systems, electrical components; and the total number of jump or grasshopper conveyors. www.e-mj.com