Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/908212
12 AGGREGATES MANAGER / December 2017 Set up screen deck properly W hen trying to maximize the effi ciency and throughput of your operation's screen me- dia system, it begins with a "holistic view of crushing and screening," says Craig Burke, P.E., director of engineering for Polydeck Screen Corp. and a former plant manager for a large aggregates producer. "Everything you tweak in a processing system affects all the other parts," Burke says. "To make screening more effi cient, you have to understand what is going on in front and behind the screen." The processes that feed the screen and the processes the screen itself feeds all interact to play a role in desired throughput, Burke points out. "In some cases, increasing throughput at one point can overload another point," he explains. "Once you establish a holistic view, you can antici- pate problems that may arise and plan for them." For example, if a producer is trying to maximize through- put on a particular product, it is important to examine the entire crushing and processing system. Burke suggests reviewing the system from fi nished product all the way back as far as the initial phase of processing. "Good blasting technique is just as important as proper crusher operation to produce more of a desired product," Burke says. "People want good screen effi ciency, but the product may not be there to be recovered. Regardless of how well a screen is set up, if the product you want is not in the feed coming to the screen, it can't be produced." Another consideration is the combination and type of screen being used for the various decks. Open area is "king" for more throughput, but sometimes must be sacrifi ced for longevity and limited footprint. "You need to optimize the screen system design," explains Sam Durnavich, regional sales manager for Polydeck and a former plant manager for another top producer. A "mixed approach" — such as heavy-duty panels on the hot spots of the screen and high open area and lower-duty panels on non-heavy-duty screens — may be used to maxi- mize throughput and achieve producer goals. Even if the screen system is meeting throughput goals, producers need to make sure this doesn't become all for naught in the fi nished product piles coming off the screens. "If you have a dedicated fi nished stockpile, try to load out of it so new production falls to one side," says Michael Vacchi, quarry manager of PJ Keating's Cranston (Rhode Island) Quarry. "If you have large stockpiles, it can contam- inate the fi nished product. You want to manage potential contamination." Vacchi suggests digging out a half-moon fi nished stock- pile so material always falls down instead of covering the entire cone. "That way you are only contaminating one side instead of the whole stockpile," Vacchi says. "A lot of plants have dedicated stacking conveyors, but it may put you at risk of contaminating the entire stockpile. A radial stacker can help." Material science advances are enabling screen customization for maximum throughput. To ensure the screen deck has been properly set up, check the acceleration, displacement, and all technical aspects of the screen when it is running. If one side moves differently than the other or the G-Force is set too high or too low, it can affect the performance of the screen media. If improper set up causes these problems, a screen performance evaluation should be conducted. Multiple readings of several places on the machine should be taken to determine if it needs to be tweaked and if it is running as effi ciently as possible. 1