Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/301563
AGGREGATES MANAGER May 2014 10 appropriate solution for preventing larger materials from traveling into the hopper and through the screener. This hinged grid catches larger materials, and producers can clear them by manually tipping the grid via a remote control. Although this is an affordable option, it can become a chore, particularly in wet or dirty applica- tions where the tipping grid may become plugged frequently. The other option, a livehead, is essen- tially a vibrating screen that attaches to the hopper. This piece of equipment is suitable for heavy-duty applications with dirty, wet, and/or sticky material. The unit can be used for two purposes: to scalp dirty material off and eliminate the need for manual cleaning or to size mate- rial going into the machine so producers can produce an additional sized product. Although these units are designed to boost production and create an additional product, they become a hindrance if used in the wrong application. These are built with thick bars that limit the open area, so operations processing finer materials might discover material on the ground that should have been in the hopper. Further, screeners with 14-foot hoppers would not be used to the full potential, as the livehead measures 12 feet, leaving 2 feet of the hopper unusable. Apron feeder vs. belt feeder From the hopper, material is fed onto a standard belt feeder. The standard belt feeder works well for sand and gravel oper- ations. It is cost efficient and will hold up well in numerous applications. However, for producers working with metal, large rock, or any abrasive material, a standard belt feeder is likely to tear or break. These more heavy-duty applications require an apron feeder, which is essentially a belt made of metal. Screen media It seems there are just as many types of screen media as there are materials to screen. Most screens feature a typical wire mesh screen media for different sizing applications. However, there are a few heartier options for producers working with abrasive materials. First, operations working with abrasive materials may want to consider stainless steel as an alternative to regular wire mesh. Although the cost is nearly twice as much, stainless steel offers a higher wear resis- tance and longer wear life that is worth the extra cost. Another replacement for the standard screen for certain scalping jobs is bofar bars. Bofar bars, formed of long bars with spaces between, are designed for materials such as recycled concrete that commonly contain a lot of dirt and miscellaneous material. Although bofar bars do a certain amount of sizing, the process doesn't necessarily end with thoroughly sorted product. Punch plates are another option. These plates are essentially a piece of sheet metal with spaced holes for heavier applications. Punch plates are better for sizing in com- parison to bofar bars and are very durable, customizable, and affordable. Finally, finger decks work for reclama- tion, landfill jobs, or any other type of screening where clogging, blinding, or breakage may be an issue. Finger decks can Consider the number of decks on a potential screener. A three-deck screen offers an option to produce an additional product compared to more common two-deck units.