Engineering & Mining Journal

OCT 2018

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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HOISTING SYSTEMS OCTOBER 2018 • E&MJ 63 that was "the first permanent-service hoist, … able to lift a 10-metric ton (mt) payload from a depth of 5,250 ft at a maximum speed of 3,000 ft per minute (ft/min.)." It was a glimpse of the future. Hoist- ing that tonnage, at that depth, at that rate, makes the BMR an increasingly attractive solution to head offices brain- storming on expansion projects today, according to Todd Kennedy, business development and general sales manag- er, FLSmidth. "Although there is a large number of BMRs installed in Africa and put into service, other parts of the mining world are starting to realize not only the merits for BMR, but also the need for BMR," Kennedy said. The uptick in interest and demand, he said, is due to "depth of wind and required payloads ruling out friction hoists or Koepes, and they are ruling out single-rope hoists." The BMR could help a miner "avoid a winze or a subver- tical machine," he said. Greater depths and payloads were among the capabilities that sold Anglo- Gold Vaal River Operations, Glencore and others on FLSmidth-made BMR hoists in the recent past. That and the fact the supplier has manufactured the lion's share of the BMRs currently in op- eration worldwide. Most recently, FLSmidth fulfilled an engineering, manufacturing and supply contract for four BMRs for the Mopani Deeps Project in Zambia. The hoists were cold commissioned in ear- ly 2017 and since have been on care and maintenance. The hoists could help render the Deeps, as the 30-year-old Mindola and Mufulira copper mines are known, "feasible again," said Francois Koekemoer, mechanical design engi- neer, FLSmidth. A glance over the numbers reveals why. The two rock hoists, one for each mine, each feature a 27.5-mt payload and a length of wind of 2,010 m. Con- veyance speed is 3,600 ft/min. (or 18 m per second [m/s]), for a projected 20.27 skips per hour. The two personnel hoists, one for each mine, each feature an 11-mt (135-person) payload and a length of wind of 1,940 m. Conveyance speed is 2,940 ft/min. (or 15 m/s), for a total of 5.5 trips per hour. For all four, drum diameter is 5.7 m, the rope compartment width is 1.8 m, and the rope diameter is 51 mm. The hoists are designed to be used 18 hours per day, 25 days per month. They were selected because, of the types considered, the BMR best re- solved the depth-of-wind and fleeting angle challenges. With the existing shafts at between 1,700 m and 1,800 m deep and approximately 6.1 m in dia- meter, other hoist types theoretically could have been designed to suffice, but would have come with potentially prohibitive tradeoffs and concerns. The double-drum hoist presented "handling problems of ropes in excess of 70 mm in diameter," the minimum legal size for that type of hoist at that depth of wind, FLSmidth reported in a white paper. A multilevel Koepe (friction hoist) solution would mean longer and more complex rope changeouts, shorter rope life, more expensive headgear, and, importantly, at that depth of wind was without precedent in southern Africa. "One of the advantages of Koepe is it is multi-rope, and therefore very heavy payloads," Kennedy said. "But rope-life limits the depth of wind, so it gets ruled out below 1,500 m or thereabouts." The BMR solution introduced com- pensating sheave requirements, higher capital costs, and higher peak power requirements. In the end, it was the main challenge of depth of wind that forced the selec- tion of machine into the BMR category. FLSmidth offers four types of BMR: a geared, an inline configuration, a Hooke's joint, or an electrically coupled A sketch of an FLSmidth BMR hoist installed at the Mopani Deeps Project in Zambia. (Image: FLSmidth)

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