Engineering & Mining Journal

JUN 2019

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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MATERIAL HANDLING JUNE 2019 • E&MJ 61 www.e-mj.com stockpiles, then retrieved by a buck- et-wheel reclaimer. The product stockyard will have two slewing and luffing stackers of 5,700-t/h capacity, one for fines and one for lump products, as well as a sin- gle slewing and luffing boom-type buck- et-wheel reclaimer with an average stock- pile reclaim capacity of 4,690 m 3 /h. The reclaimer will collect either lump or fines for transfer to a load-out system capable of filling a 240-car train in 200 minutes. As part of a billion-dollar capex pro- gram aimed at sustaining existing oper- ations at its Western Australia iron ore operations, Rio Tinto Iron Ore also is spending about $50 million to replace two ageing stockpile stacker machines at its Paraburdoo mine with new units from Tenova T . According to Rio Tinto, the old machines were part of the mine's original infrastructure, stacking the first load of iron ore from Paraburdoo in 1972. In 46 years of operation, they stacked more than 800 million tons of ore, re- portedly requiring only minimal structural changes throughout that time. TAKRAF said its office in Perth will manage the entire project, with support provided from the company's offices in Brisbane and global competence centers. The design of the new stackers is under way and the start of fabrication is scheduled to begin later this year with installation and commissioning completed by early 2020. In April, Bosch Rexroth announced it had been selected to supply the drive system for what is thought to be the world's largest rail-mounted bucket wheel reclaimer. Featuring an ore-mov- ing capacity of 20,000 t/h, the reclaimer will be installed at the new BHP South Flank iron ore mine in the Pilbara region of Western Australia. Bosch Rexroth will deliver the buck- et-wheel drive system to thyssenkrupp Industrial solutions, which will design, supply, construct and commission the complete machine. The drive system will be based on Bosch Rexroth's Hägglunds hydraulic direct drive technology, which it said offers a flexible-drive layout that is well-suited to bucket-wheel reclaimers. The system will utilize the largest hydraulic mo- tor ever built, the Hägglunds CBM 8000. In addition to the bucket-wheel drive system, Bosch Rexroth will supply Häg- glunds drive systems for the slew func- tion on both the bucket-wheel reclaimer and two stacker machines at the same mine site. Each slew drive will comprise four Hägglunds CB motors with torque arms and brakes. According to Hägglunds, its hydrau- lic direct-drive systems provide the high torque needed for bucket-wheel reclaim- ers, yet remain lightweight and highly flexible. The hydraulic motor is mounted on the boom to drive the wheel shaft, while the drive unit with electric motors and pumps can be situated in a more central position on the machine. In many cases, this lets equipment manufactur- ers reduce steel bulk and counterweight, which results in a leaner, more agile and more fuel-efficient machine. Metso used Hägglunds CBM hydrau- lic motors in the feed system for a new crushing plant at Boliden's Aitik mine in Sweden, a facility that will be instrumen- tal in reaching the company's long-term goal to raise that mine's production from 36 million to 45 million tons of crushed ore by 2020. One of the reasons why Boliden decid- ed to invest in apron feeders powered by di- rect hydraulic drive was frequent problems with gearboxes. Another was curiosity. Jörgen Larsson, project manager at Boliden, explained the original crushing plant had feeders that "…were unreli- able in every way. We had many gearbox breakdowns over the years and wanted to improve availability. This will be a test of hydraulic technology. I have seen Häg- glunds drives in various reference instal- lations around the world, and during my investigations I did not hear of any nega- tive experiences," said Larsson. The new feed system, incorporating horizontal apron feeders to the crushers, is a proven design with many installations in use around the world. Metso adapted the system to suit the particular needs of the Aitik mine. In addition to improved availability, Boliden set other high perfor- mance demands for the equipment and Metso accordingly developed a design based on two CBM 2000-1400 motors sharing the load on each feed unit, with a capacity of 8,000 t/h, variable speeds from 0 rpm to 7.46 rpm and a starting torque of around 1,000,000 Nm. "We wanted to have some power in reserve, so that's good. It gives us a max- imum capacity of 9,000 tons per hour. It also gives us redundancy for all the main components, so we can drive with one motor if needed," said Larsson. On the Pad Successful heap-leach operations need consistent, controllable placement of ore on the leach pad and, in the case of dy- namic (on/off pad) leach operations, the ability to remove spent ore efficiently and relatively quickly. Recent developments at two German firms, FAM and thyssenkrupp Industrial Solutions, highlight equipment capabilities that cater to these needs. Chilean copper producer Codelco bought a new SR800P9 bucket wheel ex- cavator from FAM Group for its Radomiro Tomic mine. The 995-mt machine is as- signed to a dynamic leach-pad operation and has a handling capacity of 14,500 mt/h, a cutting diameter of 19 m and bucket-wheel drive rated at 1,000 kW. Ac- cording to FAM, it provides cutting-edge electrical and control technology, includ- ing automatic operation, video monitor- ing, multiple radar systems for collision and stockpile recognition and positioning, precise GPS positioning, and comprehen- sive monitoring to ensure availability. thyssenkrupp introduced the lizard system for stacking ore and tailings earli- er this year, explaining that it merges two established material handling technolo- gies — the conveyor bridge and the crawl- er-mounted tripper car — into a new con- cept that features a tripper car decoupled from the conveyor bridge, allowing it to be controlled independently of the bridge. According to the company, a stand- alone tripper car has several advantages. Because there is no stress from a travel- ing tripper car on top of the bridge, the bridge's structural components can be less bulky and truss assemblies can be of a simpler design, which results in a lighter, lower bridge configuration with smaller bridge crawler drives and re- duced ground pressure. The bridge span's flexible joints ar- en't stressed by the additional intermit- tent load of the tripper car when it is traveling over the connected bridge seg- ments, alleviating fatigue issues caused by cyclic loading. With lighter loading on the bridge, re- duced bridge construction costs balance out the cost of the additional chassis and structure of the tripper car. This design cuts capex requirements, says thyssenkrupp, and allows greater dump height and longer outreach. The same light design can be applied for the reclaiming bridge.

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