Rock Products

APR 2018

Rock Products is the aggregates industry's leading source for market analysis and technology solutions, delivering critical content focusing on aggregates-processing equipment; operational efficiencies; management best practices; comprehensive market

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18 • ROCK products • April 2018 O ver the past several years, the filter press' popularity has increased dramatically, making it one of the more pop- ular methods to process and dewater tailings. Other outside factors are also pushing producers to invest in a filter press. Due to changes in regulation and permitting processes, it has become increasingly hard to obtain permits for settling ponds. Having enough space at a site can also be an issue. Set- tling ponds may not fit expansion plans because they prevent access to and use of saleable product. Additionally, equipment such as belt presses often produce a moister cake using chemicals, while filter presses can achieve the needed drier product and require no chemicals. To answer the question if you are ready to invest in a filter press, you should understand the different types along with how they work. Placing and sizing a filter press are crucial steps when deciding if a filter press is the correct solution for your site. Learning and being well equipped to maintain your filter press will keep your machine running stronger for longer. How Does a Filter Press Work? At its most basic level, the filtration cycle of a filter press consists of covering recessed plates with filter media, apply- ing enough force to create a seal between the filter plates perimeter surfaces, and then using a feed pump to supply the pressure necessary to pump the slurry into the cavities formed between the sealed plates. The filter cloth captures the slurry solids between the filter plates while allowing the filtrate water to pass through the cloth mesh and exit through ports in the filter plates. When the chamber becomes completely full, the feed pump stops and the pressure that seals the plates is released. The plates are separated allowing the dry cakes to emerge from the chamber and fall to the ground below. Most people think that the filter plates squeeze together to expel water, but the press never moves during the time of dewatering. The only movement by the press is when they are opened and closed to expel the dry cake or to begin a new process. Plates simply connect to form a seal; the feed pump supplies the necessary pressure to dewater the fine solids. Filter presses were designed for simple and limited move- ment. This design leads to high-levels of automation and reliability. The ability to select cycle times, cake thickness, feed pressures and plate styles are what allow filter presses to achieve much drier cakes than many competing technologies. Optimizing a Filter Press Like other machines in your operation, the filter press should be set up to maximize your output. You should consider these things when designing your filter press: •  Your Optimal Cake Thickness – Thinner cakes dewater faster than thicker ones. •  Permeability of Solids – The higher the permeability of the material, the easier for the water to pass through, leading to a quicker cycle. • Cake Moisture – Know your goal for moisture content and the amount of time to achieve that. • Solids Concentration in Your Feed – Less water and higher solids in your feed means, faster dewatering. •  Opening and Closing Speed – Find a happy medium between dewatering cakes and resetting the press can play a big role in the tons per hour capacity of your press. •  Test Your Material – Several characteristics can impact dewatering including: Filter Press Say Yes to a Filter Press If You Are Ready to Invest in a Filter Press You Should Understand the Different Types Along With How They Work. By Mark S. Kuhar

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