Engineering & Mining Journal

APR 2013

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VDMA Materials-handling Technology: Moving More as Mines Get Bigger Mining and quarrying companies around the world are facing new challenges, especially in relation to the tonnages of material that they need to move as ore grades continue on their long-term downward trend. And it is not just a question of handling ore—increasing tonnages being run through the mill mean greater volumes of waste rock to handle as well. German companies have long been at the forefront of materials-handling technology, not just for mines, but for overland conveying, stockpiling and reclaiming, shiploading and unloading. The boom in seaborne commodity trade—especially for coal and iron ore—has led to increased demands for port facilities that can handle the volumes involved, while the opening up of new mining areas, such as the coalfields in Mozambique or the iron ore deposits in West Africa, has required the installation of complete new materials-handling infrastructures. An Alternative for In-pit Haulage? With its headquarters in Essen, ThyssenKrupp Fördertechnik GmbH (TKF) is one of the world's leading suppliers of high-capacity equipment for open-pit mining, crushing, mineral processing, bulk-materials handling and stockyards. For example, its in-pit crushers—both stationary and semi-mobile—are to be found in open pits worldwide, the company having installed some of the largest, highest-capacity units operating today. For this edition of Best of Germany, however, TKF has chosen to focus specifically on a radical new concept which, it claims, could cut open-pit haulage costs substantially as well as reducing mines' carbon dioxide emissions through lower energy usage. As described to Best of Germany by the company's Dr. Franz Wolpers, the system—which the company is patenting—envisages skip haulage replacing conventional haul trucks to move ore and waste from open pits as these get progressively deeper and, hence, require larger truck fleets and longer haul cycles. ThyssenKrupp Fördertechnik's skip concept for open-pits. VDMA 26 Dr. Wolpers, executive vice president for its materials-handling business unit and head of TKF's central R&D; division, explained the concept behind the system. "A typical open-pit mine has steep walls and winding haul roads," he said. "Take, for instance, Freeport's Grasberg mine in Indonesia, which handles around 220,000 mt/d of copper-gold ore using trucks and shovels. The trucks move up and out of the mine in a train-like formation on ramped roads, travelling at average speeds of 15-20 km/h. "The mine uses a fleet of up to 220 trucks, each carrying between 240 and 400 tons. But, to carry 240 tons of payload, around 160 tons of deadweight has to be moved as well—both up out of the pit and back down again once the truck is empty. Newgeneration trucks may carry 400 tons, but weigh up to 260 tons each, with diesel engines of around 3,000 kW." TKF's concept revolves around trucks dumping rock into pitbottom hoppers that then feed balanced, rail-mounted skips, each with a 136 mt capacity, that lift material the full height of the pit wall. Using balanced skips, Dr. Wolpers said, removes the deadweight load during haulage at a stroke. Loaded skips would discharge into a primary crusher at the pit top. For a 200-m vertical rise at a pit slope angle of 45°-55°, TKF estimates that each skip would have a 3-minute cycle time, with the whole system capable of handling around 2,000 mt/h. Two 1,300 kW drives would be needed in this instance, compared with a fleet of seven, 136 mt-capacity trucks that would be needed to move a similar tonnage of rock conventionally. Major advantages would include a cut of up to 50% in rocktransport costs, significant energy savings, lower CO2 emissions, higher system availabilities in bad weather, lower truck and haulroad maintenance costs, fewer operators, and reduced capex costs since truck fleets would be smaller, Dr. Wolpers suggested. High-strength Belting for Heavy-duty Conveyors With a number of installations that have established world records in terms of belt strengths over long distances, Hamburg-based Phoenix Conveyor Belt Systems GmbH reports that its achievements include the records for the strongest textile and steel cord belts, the steepest overland belt and the world's heaviest belt. As an example, the company delivered 16,000 m of belting for what is believed to be the world's longest pipe conveyor, supplied to a cement company in Peru. Phoenix's exhibit at MINExpo 2012 focused on the company's new Phoenocord® ST 10,000 steel-cord belt, used primarily for downhill or extremely long conveyors. This, the company says, is the latest stage in the development of high-strength belts. It states that five fully laden Airbus A380 jets could be hung on a 2 m-wide belt of this type, and it would not tear, such is its loadcarrying capability. One question, of course, is whether durable splices can be made in this type of belt, and on this the company is reassuring. It reports that since the 1970s, thousands of splices have been made successfully on its steel-cord belts, and that samples taken from belts in use have shown the splice zones to be as strong as the main belt structure under dynamic testing. VDMA MINING SUPPLEMENT • 2013

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