Engineering & Mining Journal

AUG 2018

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SCREENINIG MACHINES AUGUST 2018 • E&MJ 39 www.e-mj.com columns in each plant and each plant also has three of the Derrick screens in it." After that, the miner adopted the ma- chines for their gold mines in Chile and Brazil. "They are basically seeing Derrick as a provider of a solution to some diffi- cult applications." Derrick Linear Motion machines are available in sizes ranging from 3-ft-by-8- ft to 5-by-14. Feed box options are avail- able for "all flow conditions," the compa- ny reported. "Abrasion-resistant urethane coatings and sealed-for-life Derrick vibra- tory motors assure long-life, low-mainte- nance operation," the company reported. "The machines' versatile design allows for the use of both traditional wire and Derrick anti-blinding, high open-area Polyweb urethane screen panels." Perkins describes the machine as the "workhorse for a lot of our gold applica- tions," which also include carbon-in-pulp or carbon-in-leach (CIP/CIL) plants. "So, at the typical CIP/CIL plant, most of these safety screens are screening at 600 mi- crons on average," he said. "Derrick is able to offer to our customers to screen at 300, 350 microns." The machines, he said, pay for them- selves in two or three months. "What they are able to do is recover more gold than they were with other technologies," he said. "And it is because these machines are more effective at screening out these carbon particles, whether it is ultra-fine at 75 microns at an ADR plant or it is 300 microns at a CIP plant." That, while taking up less floor space, Perkins said. He gives the example of another major gold miner in Nevada that switched to Linear Motion machines af- ter competitor machines failed to meet expectations. "(The miner) just installed a new resin-in-pulp system and needed screens to screen the resin beads at 300 microns," he said. "And when they ini- tially built the plant, they built it with ma- chines with screens that were 10 ft wide and 20 ft long, and unfortunately these machines weren't able to meet the ex- pectations, and in some cases they even destroyed themselves mechanically." Derrick installed one of its Hyperpool Linear Motion machines equipped with patented screens and panel technology. "We replaced that 10-by-20 with essen- tially a machine that has a footprint of 4-by-8," Perkins said. A Derrick machine outperforming a competitor machine more than double its size is not unex- pected, he said. "We are able to do some very interesting things for a lot of our cli- ents because we are thinking about how we can do things smarter instead of just throwing brute force at challenges." Rubber Gains Ground Rubber is in, and Metso's 1-ft-by-1-ft Trellex 305PS proves it, according to Claes Larsson, director, screening media, consumables, Metso Mining. The line of screening media, released in 2016, beats the competition in wear-resistance, and has, in turn, seen an uptick in demand. "We have gained traction due to increased wear-life," Larsson said. "The trend in my opinion in the mining industry, not only in the U.S., is rubber gains ground over ure- thane from a performance perspective." Company literature labels the rubber compounds available for the 305PS as "unique" and "the result of decades of dedicated research" that led to the devel- opment of "highly flexible materials that are unbeatable in fighting blinding and pegging." Larsson said that translates to in- creased availability and uptime. "We have actually done our homework," he said. "We have come up with solutions to differentiate ourselves and we have done some good trials, some good installations where we feel our product is performing better than what we are replacing and that has led to a growing confidence." The trials consisted of replacing "poly- urethane decks with rubber decks that we have developed in the same format," Larsson said. "We have proven that we can reach the cycle time or the goal the customer has for how long they can oper- ate the equipment before the need to take it out for maintenance." The rubber compounds are the deliv- erables from internal research and devel- opment spanning more than "40 or 50 years in the mining consumables indus- try," Larsson said. "We have a range of different rubber compounds to meet dif- ferent applications." The range includes compounds for coarser duties, compounds that withstand high pressure, and softer compounds for applications otherwise prone to blinding and paving, he said. "We specify our own recipe," Larsson said. "While most others buy from rubber batchers in certain compounds, we have developed our own unique recipe." Beyond the rubber compounding, the series features a "hammerless design" and injection molding, the company reported. "The unique item about this system is the hammerless design in which you screw the holding device with the holding wrench to hold the panel down, which means you don't have to use a hammer," Tom Dougherty, mining sales, Minnesota, North and South Dakota, Metso, said. "There are no pry bars to pry it out or hammers to pound it in." Company literature reports the system is centered on "specially developed pins" that "can be screwed into place as well as removed using an impact driver." The system saves time normally spent on removing traditional pins and sleeves, Larsson said. "Basically, you have a polyurethane pin with a thread and can knock it in, and then The 305PS screens are made of Metso's patented rubber compounds, which range in hardness, allowing the customer to select based on the abrasiveness of the feed material. (Photo: Metso)

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