Engineering & Mining Journal

OCT 2018

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HOISTING SYSTEMS OCTOBER 2018 • E&MJ 65 www.e-mj.com service," said Jim Brownlee, sales and product manager, shaft equipment, NMT. NMT's compensating sheaves, a rel- atively recent addition to the company's equipment portfolio, are designed to an- swer BMR-type application design chal- lenges related to safety, performance and maintenance costs, the compa- ny reported. "It is normal for the wire ropes to stretch over time and they may stretch at very different rates," Brown- lee said. "Our sheaves compensate for this hydraulically by maintaining a com- mon pressure between the two support- ing cylinders. The system includes fea- tures that adjust the sheave levels and also interlock with the hoist controls." At Onaping Depth, NMT will face challenges now proving common to deep mine expansion projects. Adher- ing to a strict order of operations will be key. The new subvertical shaft, or winze, will be accessed via the existing shaft starting at roughly the 1,200-m level. The winze will be raisebored down 700 m and extended to roughly the 2,700-m level with conventional shaft sinking. "This means all of our equipment must be modular for disassembly and transport to the winze," Brownlee said. Additionally, the mine is widely re- ported to feature relatively small open- ings. "The necessary openings are reduced due to a lower ventilation de- mand for electric mobile equipment," Brownlee said. That means less space for both NMT's equipment and the transportation of it, he said. "This creates an additional level of complexity as the pieces must all be reassembled underground and some of this equipment is very large," Brownlee said. To accommodate the NMT team, Glencore will "excavate a shop for as- sembly and maintenance," he said. The adoption of a BMR solution at Onaping points to a future wherein, among other things, greater safety is prioritized, Brownlee said. "In Canada, we must provide a safe- ty mechanism that will stop a free-fall- ing conveyance with an acceleration between 0.9 and 2 gravities," he said. To date, the requisite solutions are only available for wood guides, Brownlee said. Wood guides "are expensive and require continual maintenance" and regular re- placement, he said. "By using the BMR arrangement with two ropes, if there is a failure of a rope or attachments, the sec- ond rope satisfies our Ministry of Labour, and we are allowed to use steel guides, which require minimal maintenance and typically last the life of the mine," Brownlee said. "Which amounts to a great savings for the mine long term." Possible savings and increased safe- ty are part of the reason why Kirkland Lake Gold recently tapped NMT to sup- ply sinking sheaves, service sheaves and production sheaves for the mine's planned Macassa Shaft No. 4. The miner reported the four-compart- ment shaft will be 21.5 ft in diameter and concrete lined. It will initially sink to a depth of roughly 5,500 ft, and from there will be extended to reach 7,000 ft. Projected hoisting capacity is reported to be in the 4,000-mt/day (mt/d) range. The service sheaves NMT will supply for Macassa Shaft No. 4 "are a com- pensating-type sheave very similar to that supplied for the Glencore ODP mine," Brownlee said. The production sheaves are "larger than typical" for mines in the Abitibi gold belt. "They are just under 18 ft in diameter." Anything more than 16 ft is considered large, he said. "We can produce sheaves up to 26 ft in diameter." Helping bring BMR-solutions to North America and partaking in the de- velopment of precedent-setting mines is par for the course for NMT, Brownlee said. "These projects are demonstra- tions of Canadian leadership in this in- A FLSmidth Hooke's joint BMR hoist solves fleeting angle challenges at the Deeps. (Image: FLSmidth) NMT's gold head sheave, above, can be designed split for ease of transportation and installation. (Photo: NMT)

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