Coal Age

MAR 2017

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March 2017 33 roofbolting continued cable bolt to North America. "The 62-ton Sumo cable bolt was develped by Peter Craig, Engineering Manager, with our af- filiate in Australia," Stankus said. "It works well for extreme conditions and it should be popular in the West and some of the deeper coal mines in Alabama and Vir- ginia. We used it at Signal Peak, and other western mine operators have shown an interest in it." While the early months of 2016 were difficult, Stankus said Jennmar used that opportunity to advance programs in other areas. "That decision has paid dividends because now we are very busy again," Stankus said. "Everybody was struggling, and some activity started in spring 2016, and then almost the day after the election, business improved dramatically." Developing the Pumpable Resin System "Over the years, many engineers have attempted to develop a pumpable res- in system, but none of them succeeded until now," Stankus said. "We came up with some new ideas and we have sever- al machines in operation. To get to that automated system, where the roof bolter does not have to leave his station to insert a cartridge, especially in the high places out West, that has been a big push for Jen- nmar. These self-drilling pumpable hol- low-bar bolts, which are designated Mul- tiple Point Anchor (MPA), have multiple point-anchor locations that yield under load, will work great for deep mines with high stress." This injectable resin aspect of the sys- tem is really slick, Stankus explained. "The units can mount right on the bolting ma- chines or be a stand-alone, skid-mounted unit," Stankus said. "It's all computer con- trolled with a monitor in the cabin and the operator does not have to leave his station." To develop this system, a major tech- nological hurdle had to be cleared. "The problem that everyone encountered was getting the resin and the catalyst into the hole without mixing them," Stankus said. "We perfected a system that places both in the hole without mixing and we devel- oped a special pump that works well. We took this on working with a few mining companies and now we have interest from bolter manufacturers." Different professionals have tried to develop this system since miners started using resin and Jennmar finally solved the riddle. They developed a special manifold that allows the pump to push resin through a two-line system into the hole using an injection nozzle. Resin is relatively abra- sive. Jennmar's J-Lok subsidiary developed a new resin that pumps easier and is less abrasive. Then they developed a set of spe- cial cylinders as part of the pumping sys- tem that would withstand the abrasion. Engineering Slopes Jennmar has been heavily involved with the design of slopes for years. Many slope projects were placed on hold during the Obama administration and now there are four major slopes being constructed for new mines, one in Pennsylvania, one in West Virginia, one in western Kentucky and another in Nebraska. The Nebraska project is a 3,500-ft double-entry slope supporting an aggregates operation. For slope work, Jennmar developed the patented Stress Geologic and Support (SGS) system about eight years ago. An SGS analysis assists with slope support design. "We have designed more than 50 slopes using this system," Stankus said. "No one installs a slope without drill- ing a few holes. With some geologic data and knowing some of the rock mechanics properties associated with the geology, the SGS system develops a model where the entire profile of the slope can be plot- ted. The system identifies the strong and weak zones and then we design primary and supplemental bolting support sys- tems and then follow up with the long- term steel structure supports, which could be square sets, long-radius arches or semicircular arches. Once the lagging is in place, the mine backfills it with cemen- titious material." Slope projects are a sign of new de- velopment activity and Stankus said there are several more slope projects on the drawing boards. "Money has loosened up a little for these capital projects and it has helped the coal-mining business," Stankus said. He believes it is just going to get better in 2017 and 2018. Editors note: patents applied for both J-Lok P and MPA systems. Resin can be injected throught these self-drilling, hollow-bar bolts. Jennmar is bringing the 62-ton Sumo cable bolt (above) to the North American markets.

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