HOISTING SYSTEMS Today’s Hoists Reveal Tomorrow’s Priorities Recent projects leverage solutions that ensure future safety, productivity and depth of wind By Jesse Morton, Technical Writer An overhead crane moves equipment and parts during installation of possibly the largest production friction hoist in the world, at Oyu Tolgoi. (Photo: The Redpath Group) Like a beacon fl ash parting the midnight early 1960s. The BMR features two ble the rope. Compared to double drum horizon and warning of the shallows, the independent, two-compartment drums hoists, “smaller ropes could be used,” future announces its arrival beforehand. and two ropes per drum, each of which and the drums were of a smaller diame- In mining, in the hoist space, such attaches to a skip via its own head ter. was as much the case in the Witwa- sheave. Coverage from back then re- The smaller ropes, drum and, in tersrand Goldfi elds of the 1950s as it is ported “continuous equalization of rope turn, motor, allowed for easier instal- in the Sudbury Basin and the Gobi Des- tension is effected either by a simulta- lation underground. With the skip load ert today. The projects and innovations of neous coiling or uncoiling of the ropes “distributed equally on two ropes, … then and there, and here and now, shed on a compensating drum attached to payloads can be increased, and deeper light on the challenges and opportunities the conveyance or by movable headgear hoisting is possible.” to come. Summaries of some major head- sheaves supported on interconnected By 1961, BMR hoists were deployed line-grabbing hoist and hoist infrastruc- hydraulic cylinders, which permit the to South African mines operated by ture engineering projects illustrate. sheaves to move in vertical guides.”1 Anglo American Corp., Zandpan Gold Compared to a single-rope drum Mining and Buffelsfontein. Anglo Amer- Deep Made Possible hoist, the BMR featured at least dou- ican installed one at President Brand Start with when Blair multi-rope (BMR) hoists were fi rst deployed to deep South 1 “Blair Hoist Reaches Lower, Lifts More With Smaller Ropes.” (1961, November). The Engineering and Mining African mines in the late 1950s and Journal, 162 (11), 112. 62 E&MJ • OCTOBER 2018 www.e-mj.com EMJ_pg62-69.indd 62 10/9/18 2:26 PM HOISTING SYSTEMS that was “the fi rst permanent-service 2,940 ft/min. (or 15 m/s), for a total of A multi-level Koepe (friction hoist) hoist, … able to lift a 10-metric ton 5.5 trips per hour. solution would mean longer and more (mt) payload from a depth of 5,250 ft For all four, drum diameter is 5.7 m, complex rope change-outs, shorter rope at a maximum speed of 3,000 ft per the rope compartment width is 1.8 m, life, more expensive headgear, and, minute (ft/min.).” and the rope diameter is 51 mm. importantly, at that depth of wind was It was a glimpse of the future. Hoist- The hoists are designed to be used without precedent in Southern Africa. ing that tonnage, at that depth, at that 18 hours per day, 25 days per month. “One of the advantages of Koepe is rate, makes the BMR an increasingly They were selected because, of the it is multi-rope, and therefore very attractive solution to head offi ces brain- types considered, the BMR best re- heavy payloads,” Kennedy said. “But storming on expansion projects today, solved the depth-of-wind and fl eeting rope-life limits the depth of wind, so according to Todd Kennedy, business angle challenges. With the existing it gets ruled out below 1,500 m or development and general sales manag- shafts at between 1,700 and 1,800 m thereabouts.” er, FLSmidth. deep and approximately 6.1 m in dia- The BMR solution introduced com- “Although there is a large number meter, other hoist types theoretically pensating sheave requirements, higher of BMRs installed in Africa and put could have been designed to suffi ce but capital costs, and higher peak power into service, other parts of the mining would have come with potentially pro- requirements. world are starting to realize not only the hibitive tradeoffs and concerns. In the end, it was the main challenge merits for BMR, but also the need for The double drum hoist presented of depth of wind that forced the selec- BMR,” Kennedy said. “handling problems of ropes in excess of tion of machine into the BMR category. The uptick in interest and demand, 70 mm in diameter,” the minimum legal FLSmidth offers four types of BMR: he said, is due to “depth of wind and size for that type of hoist at that depth of a geared, an inline confi guration, a required payloads ruling out friction wind, FLSmidth reported in a white paper. Hooke’s joint, or an electrically coupled 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 fulfi lled 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,” Francois Koekemoer, mechanical design engineer, FLSmidth, said. 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 A sketch of an FLSmidth BMR hoist installed at the Mopani Deeps Project in Zambia. (Image: FLSmidth) www.e-mj.com OCTOBER 2018 • E&MJ 63 EMJ_pg62-69.indd 63 10/9/18 2:26 PM HOISTING SYSTEMS BMR, like the one selected by Anglo- is a function of the angle between both ited to use of a single overhead crane. Gold for Moab Khotsong. shafts; a method to mitigate this attri- “Since the pieces of the drum, the For the Deeps, each was considered. bute is to make use of a double joint.” drum shaft, the motor rotor, the motor The geared confi guration was ruled out The design allowed the drums to stator are all considered the heavy-lift due to the large drum and expensive be positioned asymmetrically, which components, the timing had to be well- components. The in-line confi guration saved space. planned,” Koekemoer said. was eliminated due to drum width. The Installation of the hoists required Which it was, with the result that the electrically coupled BMR had a higher overcoming signifi cant logistical chal- hoists were installed on time, within the capital cost, heavier components, and lenges, Koekemoer said. “All service budget, and with the miner “all happy,” would use more energy. “Due to the assemblies are trial-assembled in the amounting to “quite an achievement,” head gear layout, the head frame lay- manufacturing shop in the Vienna-Jo- Koekemoer said. out and the hoist house arrangement, hannesburg area of South Africa but Annual production at Mindola and a Hooke’s joint-type BMR was required then taken apart and shipped piece by Mufulira will eventually target 3 million to solve the fl eeting angle challenges,” piece, and then assembled on site as mt per year, a goal the hoists enable the Koekemoer said. the machine progresses,” he said. miner to attain, Kennedy said. “These The typical Hooke’s joint solution is Road conditions were less than ide- are impressive machines in terms of comprised of three parts, two yokes and al. “The drum shafts for these machines speed and connected power and that a center block, or spider, FLSmidth re- weighed in excess of 61 mt,” Koekemo- sort of thing,” he said. ported. “The Hooke’s joint used as a sin- er said. “Transporting those by road They are also harbingers of the fu- gle joint will transmit nonuniform mo- was quite a challenge” and not entirely ture of deep underground mining, Ken- tion between input and output shaft,” without incident. nedy said. “There is a marked increase the company reported. “The variation During the staged assembly that in feasibility studies going on for BMR in angular velocity at the output shaft followed, the FLSmidth team was lim- applications,” he said. “Five or ten years ago, you’d seldom see a request for a BMR; these days they occur sever- al times per year.” Ultimately, that work at some point fl ows back to where BMR hoisting be- gan. “It is a solution that has been de- veloped by FLS over many years, and South Africa was the fi rst country to go to those levels and to have such a num- ber of machines installed,” Koekemoer said. “The solution is there,” he said. “The problems of deep shaft mining just need to start in those other areas.” Enabling Safety and Savings Another brownfi eld project reportedly launched by a miner seeking to count- er the effects of dwindling reserves is the Onaping Depth nickel-copper pro- ject in the Sudbury Basin.