Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/661453
by Brian Prenatt, P.E. EQUIPMENT MANAGEMENT 22 AGGREGATES MANAGER / April 2016 F ilter presses are becoming one of the most popular methods of processing and dewatering tail- ings. In the aggregates industry, there are several factors that have driven the need for these pieces of equipment. First, it has become more difficult to get permits for new settling ponds due to changes in regulation and permitting pro- cesses. Second is the issue of space. Many facilities are running out of space, and, often, settling ponds do not fit expansion plans because they prevent access to and use of useable product. Finally, producers are looking to create drier cakes and use fewer chemicals to reduce operating costs, leading them to look into replacing belt presses with newer style filter presses that can often achieve the needed drier product while using fewer chemicals. How they work At its most basic level, the filtration cycle of a filter press consists of covering two plates with filter media, applying enough force to create a seal between the two filter plates, and then using a feed pump to supply the pressure necessary to pump the slurry into the cavities formed between the two sealed plates. The filter cloth prevents solids from escaping from the plates, while allowing the filtrate to pass through the openings in the filter media. Once the chamber is packed full of solids, the feed pump stops, the pressure sealing the plates is released, and the filter plates are pulled apart from each other, allowing the dewatered cakes to discharge via gravity. It is a common misconception that filter presses squeeze plates in order to dewater the cakes. In actuality, there is no move- ment of the press during the dewatering of the filter cakes. Plates connect together to form a seal, and the feed pump supplies the necessary pressure to dewater the fine solids. The only movements of the press during operation are typically for opening Filter Press 101 As filter presses gain popularity among producers, it's important to understand the basics on how to operate and maintain them.