Engineering & Mining Journal

MAR 2016

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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Controlling the Flow For larger leach-pad stacking systems, an inte- grated control system is essential to achieve smooth, uninterrupted material flow at high volume levels. As an example, FLSmidth engi- neered and delivered a heap-leach stacking system for CNMC Luanshya Copper Mines PLC, located in Luanshya, Zambia, designed to load more than 1,000 t/h of agglomerated copper ore onto the mine's pads. The order included an overland (OL) conveyor, a mobile overland tripper (MOT), 20 grasshopper conveyors, a mobile trans- fer and bridge conveyor, and an automated radial stacking conveyor. One FLSmidth team designed and detailed the leach pad stacking conveyors, and another team designed and detailed the OL conveyor and MOT. All conveyor structures were fabricat- ed in South Africa. The MOT, which straddles the OL con- veyor, was equipped with two driving sta- tions so it could be driven to the required stacking location along the OL conveyor. The MOT has intelligent anti-collision instrumentation to assist the operator in keeping it located on the overland center- line while being driven, thus preventing a potential collision that would damage the OL conveyor stringers. The bridge conveyor was configured with hydraulically driven tracks that could be manually or remotely driven via an oper- ator-controlled radio pendent. The bridge had a separate onboard generator used to power the bridge track drives while towing the radial stacker over long distances. The radial stacker included an elevated opera- tor control cabin featuring an HMI and manual operator controls. An auto-stacking solution was developed to provide the radial stacker with full opera- tional capabilities in automatic mode. To do this, a mathematical auto-stacking solution was formulated in-house on a conceptual level and refined through numerous design iterations. The final auto-stacking algo- rithms required specialized programmable logic controller coding and included pro- cesses for cone stacking at low tonnages, continuous stacking and manual stacking. Two HMI modules were supplied—one in the field at the head end of the OL con- veyor and the other in the operator control room on the radial stacker. FLSmidth pro- vided a wireless network for the transfer of all instrument signals from each mobile conveyor to both HMIs, which allows one operator to efficiently pinpoint a technical problem. The wireless network is used for indication only, while all controls were hardwired on each mobile conveyor. A group-start function can be controlled from the radial stacker's HMI operator interface. Maintenance mode can be selected from dedicated conveyor local control system panels so that each piece of equipment can be started individually. Stockpile height and slew speed are deter- mined by two radar ultrasonic level sensors located on the mobile slinger. The control algorithm of the radial stacker was pro- grammed to suit the design requirements in stockpiling height (trough to peak). Intelligent pull keys were used on the overland conveyor with feedback to the HMIs, where status could be monitored in defined zones. Thermistors were supplied on the 250-kW overland conveyor drive motor to monitor winding temperatures. All of the system's gearboxes are monitored for oil temperature, and fluid couplings were supplied with thermo switches. All process and control instruments were hardwired back to their respective mobile conveyors. Monitoring the Flow The use of automation in heap-leach oper- ations extends to leach-solution application practices, as well. Earlier this year, Netafim 40 E&MJ; • MARCH 2016 www.e-mj.com H E A P L E A C H Stroke and fl ywheel size doesn't matter. WE DISAGREE. TOUGHNESS REFINED. The 3055 Jaw Crusher offers up to 25% more capacity than competitive models. Class-leading, 1-1/2" stroke offers faster throughput for higher capacity. Dual wedge adjust eliminates manual shims and enhances operator safety. Loading/Unloading Construction Infrastructure Energy Aggregate Mining Recycle www.kpijci.com KPI-JCI and ASTEC MOBILE SCREENS Astec Industries Companies 700 WEST 21 STREET • YANKTON, SD 57078 USA • 800.542.9311 • FAX 605.665.8858 • kpijci.com

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