The PRAYON filter is essentially made up of a series of individual filtration pans, fixed on a circular and horizontal frame which rotates around a central distributor. The pans receive the slurry to be filtered and the successive wash liquids by means of distributing troughs. Armored hoses connect the pans to a central distributor under vacuum, which allow filtrates to discharge and, after inverting of the pan, cake discharges with the help of air back-pressure.