filter aids

Many wet process phosphoric acid plants use filtration aids to improve gypsum slurry filtration and hence increase production rates and recovery. Filtration aids are based on the principle of producing larger and more homogeneous particles or gypsum crystals to allow for faster drainage. The size and shape of gypsum crystals directly impact filtration rates, which in turn, influence production rates.

OAN provides polymeric filtration aids specifically designed to coalesce small gypsum crystals into much larger particles creating significantly larger void spaces in the filter cake. The larger void spaces allow for faster liquid drainage time on phosphoric acid filters.

OAN filtration aids can be formulated to improve any phosphoric acid plant production rate by adjusting molecular weight and/or charge to meet the particular operating conditions of each individual operation as well as the unique characteristics of the particular phosphoric acid/gypsum slurry being delivered from the reactors to the filters. Therefore, filtration aid selection and performance are plant-specific. OAN filtration aids have shown the ability to improve filtration rates and improve filtration capacity. Fine solid impurities less than 5 m must be removed from liquids in many chemical processes. Clarification or polishing filtration is used when the suspended particles level is low, often less than 1% by weight, and the goal is to produce a clean liquid product. Catalyst recovery, polymer and resins, active medicinal components, elimination of unreacted compounds and byproducts, and grey water polishing are all common applications. Solids in polishing applications are either very tiny or amorphous, making filtering challenging. When solids are filtered, they form a thin impermeable coating on the filter medium, reducing the filtration rate to an unsatisfactory level.

OAN ’s technical experts work closely with customers to develop and supply the right filtration aids as well as make down and delivery systems for optimal phosphoric acid production and recovery.