Coal Age

MAR 2019

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March 2019 www.coalage.com 21 coal preparation continued what would the mining costs be, and the mining equipment needed." The mine could be crucial to the finalization of a rail system in the re- gion that would move the coking coal produced there to China, Trygstad said. "I think the rail grade is actually done and just needs completion rail and ballast," he said. Operations at ETT and a neighboring large project by the Mongolian Mining Corp. could "signal now there is enough critical mass to complete the railroad," Tryg- stad said. "They now have to truck 100-something kilometers. That is a challenge in itself." The other major project with a 2019 deadline that Stantec reported to Coal Age is a feasibility study for a new mine in British Columbia, Canada. "From a coal separation standpoint, I've been involved with developing a comprehensive bulk wash and testing program, which should lead now into a design of a greenfield operation," Trygstad said. "It would be a new mine, new coal preparation plant, and all the attendant stuff that goes with that." Trygstad described the met coal seam targeted as low yield with high middlings content that would man- date "somewhat traditional washing, heavy media cyclones, a reflux classi- fier and froth flotation." Also likely required are two stages of heavy-media cyclones. "The first stage will probably be a very high cut, at 180 gravity, to get rid of the rock, get it out of the way and be done with it," Trygstad said. "The second stage of the heavy-media cyclones will like- ly take a middlings stream and crush it to liberate any additional coal. Now that it is finer, rewash it to enhance the recovery." With the challenges posed by lat- itude and climate, "dry coal is a big deal," Trygstad said. A relatively novel solution is being considered, he said. "Traditionally, most of your ma- jor wash plants in British Columbia have thermal dryers," Trygstad said. "I think it would be very difficult to put in a new installation with a new ther- mal dryer either for just the amount of energy it uses or the carbon footprint from burning coal or natural gas." Thermal driers can leverage as big as 4,000-horsepower draft fans. "They just evaporate water," Trygs- tad said. "You evaporate a lot of wa- ter, and now you have more makeup water that you have to pull out of the ground for your operations." The alternative currently being considered is steam-assisted hyper- baric filtration, he said. "You take your traditional vacuum disc filter and you put it into a hyperbaric chamber," Trygstad said. "Basically, you put it inside of an enclosure and with some air compressors, you pump it up to several atmospheres." The vacuum and the air pressure move the water through the filter. The resulting fine is "-60 mesh, or mi- nus-250 micron-type material," Tryg- stad said. "If you inject steam into that pro- cess, it changes the surface tension of the water," he said. The steam is gen- erated by a boiler. "Some of the test results we've seen, it is a really dra- matic drop in surface moisture on the fines," he said. For example, the surface moisture can be reduced from 25% to 18% us- ing a disc filter in a hyperbaric cham- ber, he said. "That is pretty signifi- cant," Trygstad said. "You add steam to it and you'll drop that from 18% now to under 10%." The water is captured and re-cir- culated. "You are no longer sticking it up a smokestack or exhaust stack of a thermal dryer," Trygstad said. With the typical thermal dryer requiring a separate building, "the capital savings is pretty significant because you don't have conveyors," Trygstad said. "You can pretty much park one of these hyperbaric filter units right inside of a plant, getting it all in one structure," he said. "You take your concentrate off raw flota- tion and pump it right to your disc filter as opposed to having to drop it on a conveyor or drop it onto a screen bowl centrifuge so that you convey it and the conveyor goes outside to an- other structure." With a smaller footprint and limit- ed infrastructure requirements, com- paratively, it amounts to "a pretty sig- nificant reduction in capital," he said. Trygstad said more than 100 such systems have been deployed world- wide. "It is not new technology," he said. "In North American coal prepa- ration, it hasn't been very well re- ceived yet." Yet is the keyword. It has been well received in the base metals space. "There is hyper- baric filtration in North America, but it is in iron ore concentrators and places like that," Trygstad said. "It just hasn't happened in coal yet." Building steam into the system is a relatively new development, he said. "It is pretty remarkable," Trygstad said. "It is time to start taking it seriously." Phillips reported Raw Resources has three major plant projects under way in the Appalachia. "We've got two plant additions we are looking at," he said. "We've also got some efficiency improvements, and then one new po- tential plant that is more of a budget bid right now." The plant expansions are for met coal operations, he said. "One is just looking at a 200-ton-per-hour (t/h) increase in tonnage through the plant by adding a cyclone circuit," Phillips said. "One is looking at increasing spi- rals and flotation, that type of growth. You would be looking at the $3 mil- lion range for the additions." The possible new plant project is located in the same basin. "The new plant would be $20 million," he said, "and a relatively small plant at 500 t/h or less." Circuit upgrade work centers on installation of "large screens, large heavy-media cyclones, nothing totally new that people haven't used before," Phillips said. "It is staying in that realm

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