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SKIP-WAY TRAM 32 E&MJ; • APRIL 2016 www.e-mj.com thyssenkrupp's Skip Way System Offers an Alternative It's an energy-balanced, steep-angle conveying concept designed to reduce operating costs and optimize energy effciency for smaller, deeper open-pit mines By Dr. Franz Wolpers Mines and quarries are often character- ized by steep terraced slopes formed over many decades by blasting and material removal. Depending on the stability of the ground, a slope angle is chosen that will prevent slippage, particularly in loose rock and in regions at risk of earthquakes. The terraced slopes with inclines from 25° up to 75° are intersected by roads that carry heavy truck traffc and also secure access to the mine. The serpen- tine roads generally have two lanes or feature lay-bys to allow two-way traffc. Maintaining these roads is complicated and costly. Larger open-pit mines use trucks with deadweights from 106 to 260 metric tons (mt) and payloads of 136 to 400 mt and more. Smaller mines use all-terrain trucks— usually with payloads of 40 to 100 mt— to transport uncrushed material from the bottom of the mine or distant mining ar- eas. They travel on unpaved, often muddy inclined haul roads to a tipping area or a crushing and processing station near the pit rim. The distances the trucks have to travel are usually long; based on an aver- age speed of 15-20 km/h, a truck cycle can take almost an hour. thyssenkrupp has developed a new steep-angle conveying system that makes it possible to transport hard rock, ore or overburden from a mine more effciently by the shortest direct route while at the same time signifcantly improving the CO 2 footprint of the mine. The system and pro- cess, for which patents have been fled, are based on well-known and proven ca- ble crane technology from thyssenkrupp. With the Skip Way conveying system, trucks travel only relatively short distanc- es without major gradients between the loading station and unloading points. For a given handling capacity, the number of trucks in a mine can be reduced, with an associated reduction in capital, operating and manpower costs. Even with diesel fuel costs relatively low at present, it has to be assumed in light of rising energy requirements and increasing fuel scarcity that world mar- ket prices will rise again soon. In addi- tion, standards for environmental protec- tion and resource conservation are being raised worldwide. Both aspects will also impact on the sustainability and proft- ability of existing open-pit mines. The "tk Skip Way System" is based on cable-crane system technology, which is used in the construction of large dams. At two truck unloading stations at the bot- tom of the mine (Figures 1 and 2), skips running in opposite directions are load- ed with uncrushed material from dump trucks. The skips are ftted with wear plates and slide rails and are suspend- ed in a vibration-damping support frame and carriage assemblies from two parallel track ropes in each direction (Figure 3). Figure 1—Tandem Skip Way System with 'truck-to–truck' and 'truck–to–crusher' options. Figure 2—Truck unloading/skip loading station at pit bottom.