Issue link: http://read.dmtmag.com/i/75471
OPERAT 1 Dust at the processing plant W Expert Advice on Emissions hether they're from fugi- tive dust or internal com- bustion engines, plant emissions are under an increasingly watchful eye by regulators and aggregate producers alike. According to Derek Roberts, vice president of Alabama operations for Rogers Group Inc., as an example, the Lacey's Spring Quarry's entire facility is covered by a state-issued air permit for process and fugitive emissions from the Alabama Department of En- vironmental Management (ADEM). Once the permit is issued, the ADEM monitors the plant annually. Kirk Fuller, plant manager for Lehigh Hanson Bridgeport Quarry in Bridgeport, Texas, explains that the Texas Commission on Environmental Quality's measure for fugitive dust is a rated opacity, which the plant takes care to stay well below. "From haul trucks going from the face to the primary crusher to the crushing/ screening process to the stockpiling processes, we constantly monitor to make sure dust suppression methods are working properly," he notes. Th e greatest sources of fugitive dust at the processing plant are screens and crushers, Roberts says. "If you were to review AP-42 emissions factors, screens typically have the highest potential to emit. But when you take full advantage of existing technologies related to emission controls, the emissions from these sources are eliminated for the most part," he says. "Th is plant is subject to the New Source Performance Standards (NSPS), which allow AGGREGATES MANAGER for 10 percent at conveyor transfer points and screens and 15 percent at crushers. When opacity testing was completed at this facility, the results were remarkable, as most points were reported with no emissions." And mobile equipment, including customer trucks, potentially creates as much or more fugitive dust when compared to the processing plant. "Bridgeport has a paved concrete road from the entrance all the way to the loadout portion of the plant. Because we fractionate and load from blending bins, most customer trucks don't leave the pavement, which helps greatly with fugitive emissions," Fuller adds. Greenhouse gas tracking and regula- tion also brings fuel emissions from engines into the overall plant emissions picture. According to Brian Yureskes, product manager, excavators, for Kom- atsu, engine emissions tie in with fuel effi ciency in that the more effi ciently an engine burns its fuel, the fewer emissions it will release. Komatsu is one of the early heavy equipment manufacturers to off er products in the North American market that use hybrid engine technology to improve fuel effi ciency. Other manufacturers are making inroads, as well. Yureskes says the Komatsu hybrid excavator is able to store the energy created during the braking portion of the machine's swing cycle, and then use that energy later to assist the engine. "Th e engine is still an engine," he says. "What we've done is utilize the energy the machine naturally creates to assist the engine during various parts of the work cycle. " Fugitive dust — visible emissions from the processing plant, com- ing off of vehicle tires or the ground itself — is regulated in most states. The biggest culprits at the processing plant, typically, are screens. Dust-suppression methods can include fi lters, bags, hoses, and sprays. For the latter, more water doesn't necessarily mean less dust. An atomizing spray is more effi cient, offering more coverage with less water. 4 Proper maintenance is a must By conducting regular inspections and meeting all OEM recom- mendations for proactive maintenance, producers can ensure their engines will run at peak performance, while minimizing the effects of soot and low viscosity. Annual exhaust gas testing provides critical information about engine emissions so that corrective actions can be taken, if necessary, to adjust the air- to-fuel ratio or replace sensors and injectors.