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SKIP-WAY TRAM 38 E&MJ; • APRIL 2016 www.e-mj.com overburden onto mine trucks via a spe- cial bin station with apron conveyor dis- charge. This conveying system requires stable ground with no potential risk of earthquakes and landslides. If there is al - ready a semimobile crusher station at the pit bottom or on an intermediate level, a third steep-angle conveying option could be advantageous. In cooperation with Continental and Siemens, thyssenkrupp is currently devel- oping a continuous steep-angle conveyor, based on pipe conveyor technology, that can transport pre-crushed ore or minerals from depths of 200 to 700 m up a 30°- 45° slope at rates of up to 5,000 mt/h. The S–shaped track is located in the slope by means of a steel structure. The pipe belt conveyor has an inside diameter of 900 mm. The center of the belt has a chevron pattern that prevents bulk ma- terial and individual lumps up to roughly 350 mm edge length from sliding back even at a steep conveying angle. After material transfer at the pit rim, onward transportation is by means of convention- al overland conveyors with troughed belts. Details of the design of this conveyor sys- tem are provided in a publication. 2 Returning to the Skip Way System, the advantages of the system for handling rates up to 2,000 t/h and maximum truck payloads of 60 mt can be summarized as follows: • Reduction of haulage costs in small- er but deep open-pit mines. • Reduced operating and manpower costs; capital and operating costs over mine life (capex, opex); and the expense of building and maintaining roads in and out of the mine. • Single-lane roads—instead of two- lane roads to allow two-way traffc— are suffcient and permit steeper slopes and therefore either higher recovery of valuable minerals or less removal of overburden. • The system can be used in weath- er conditions that could cause truck haulage to be suspended. • Use of the system provides a signif- icant reduction in noise, dust and CO 2 compared with truck haulage. • The system lends itself to partial or full automation. • In contrast to the alternative sys- tems presented in Figure 11, the Skip Way System can be employed in earthquake-prone regions or mines with unstable slopes, as the rope support masts are located off the mine slope and are anchored fexibly in ground foundations us- ing pins. From the mine bottom to the unloading station at the top, no additional support structures for the track and travel ropes are required. • Existing pit slopes do not generally need to be adjusted for installation of the system, nor is it necessary to relocate existing access roads. • The system allows the reloading of trucks in the case of waste (truck– to–truck operation) or the parallel charging of a crusher and processing station in the case of valuable miner- als (truck–to–crusher operation). • As mining progresses, the bottom station can be relocated to greater depths as the necessary additional rope lengths are stored at the an- chorage points. • The entire system, including loading, unloading and drive stations, can be relocated as soon as new anchorage points have been installed. • If the system is used to feed a crush- er station at the mine rim, mine trucks from other mines or higher mining areas in the same mine can also use the crusher's bin feed sys- tem (Figure 9). This provides further redundancy during inspection and maintenance of the skip system. Many mine operators using truck haul- age will face increasing production costs as their mines get deeper. The thyssen- krupp Skip Way System is a cost-effective and eco-friendly steep-angle conveying technology that can be integrated easily into existing steep open-pit mines. This steep-angle conveying system offers an ingenious, cost-effective alternative to truck haulage. Obviously such a steep-an- gle conveying system will need to be adapted to the conditions of an existing mine and the technical/fnancial aspects (capex/opex) will need to be clarifed in advance, jointly with the mine operator. Dr. Franz M. Wolpers is head of thyssen- krupp Industrial Solutions AG Materials Handling Division and head of R&D; Min- ing World. He can be contacted at +49 6894 599 434 or at franz.wolpers@thys- senkrupp.com. References: 1. Wolpers, F., Skip-Conveying in Open- cast Mines - TKF's Technology Ap- proach to Optimize the Cost and En- ergy Effciency in Hard Rock Mines, BulkSolids Europe Conference, 2012. 2. Minkin, A., Börsting, P., Becker, N., A new technology for steep incline high capacity open-pit conveying The Chevron MegaPipe - Conveyor by ContiTech, thyssenkrupp and Sie- mens, BulkSolids Europe 2016. Figure 11—Comparison of the three conveyor systems described in the article. Reduction of heavy haul traffc in open-pit mines through use of steep-angle conveying systems.