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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94 E&MJ • JUNE 2019 OPERATING STRATEGIES One of Asarco's 4100 XPC elec- tric-rope shovels needed major service. The central bearing on which the rope shovel rotates needed repair and the pro- cedure known as "splitting the shovel" would be necessary, during which the entire upper works of the shovel would be lifted to permit inspection and repair. The shovel weighs 1,500 tons, and the procedure requires lifting with signifi cant force and control. This process can be lengthy — in this case the upper works was suspended for more than a month — and issues may arise with setting up large cylinders and keeping them accurately aligned while lifting. Typically, the solutions for this kind of lift are either using custom long-stroke cylinders or doing a staged lift, which gets the job solved but not completely. Elko was looking for a better solution to offer their mining customers for this particular application as well as heavy- lifting jobs. Elko Wire ultimately selected Ener- pac's JS-500 Jack-up System, the fi rst time a shovel would be undecked using this multipoint lifting system. A typical system setup includes four jack-up units positioned under each corner of a load. A four-unit setup has a lifting capacity of 2,000 metric tons (500 tons per unit). The lifting frame of a jack-up unit contains four hydraulic cylinders in each corner, which lift and stack steel boxes known as barrels. A load is lifted in incre- ments as barrels are slid into the system, lifted, and stacked forming lifting towers. Jacking is controlled by a Smart Cylinder Control (SCC) computer-control system. Each unit's lifting or lowering operations occur simultaneously with others con- nected, and the SCC's synchronous tech- nology keeps the load under control and within the level tolerance programmed. Load readouts for each JS unit are shown on the operator screen and are used to calculate where the center of gravity is with- in the stability tri- angle for the lift. The hydraulics power units are embedded within each unit's lifting frame. The width of the system makes it stable and allows side loads that are superior to basic cylinder setups. A d d i t i o n a l l y , when the load is landed onto the tower, the load is held mechanical- ly instead of hydraulically, thereby increas- ing the safety of the operation. "The Enerpac JS-500 Jack-up System is truly an innovative solution to use for undecking," said Neely Hammond, man- ager at Elko Wire Rope. "The automation is smooth, safe, and you have the ability to add barrels to the system to go as high as you need. Other products have set lim- its and with this we can go up 40-50 feet high. We are excited to continue lifting with different heights and weights on fu- ture projects." Tackling Tooth Replacement At the other end of the maintenance spec- trum are one- or two-man jobs that recur frequently and need to be performed safely and quickly, with minimal fuss. As an example, Auger Technologies recently highlighted its Tooth Extractor, an inno- vative device made to quickly and safely remove conical auger bits. Powered either manually or with an impact wrench, the company said the Tooth Extractor removes worn bits in a fraction of the time normal- ly required and even larger-sized bits can be effi ciently replaced in minutes. To remove an auger bit, a worker fi ts the split-ring extractor collet over the bit, then slides the driver arm over the collet, locking it in place. Driving an extractor screw, in turn, backs out the tooth. Once out, motion is reversed on the extractor screw to remove the tooth from the collet. According to the company, the tool also can be paired with a driver for easy re-in- sertion of auger bits. Auger Technologies says its Tooth Extractor is ideal for removing all standard conical teeth and auger bits, and also is available in sizes suitable for handling larger bits. It also can be paired with a driver assembly for easy insertion of replacement bits. Elko Wire Rope, an industrial rigging company serving mining customers in the western U.S., successfully uses Enerpac's JS-500 hydraulic jackup system to 'split' this P&H 4100 XPC shovel for central bearing inspection and service.

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