Sifter for sifting granular material and grinding system with insertion

Abstract

An energy-saving effective sifter used in interparticle crushing of brittle charging stock such as cement clinker in the nip of a high pressure roller press including a dynamic sifter having a rotating rod basket and laterally preceding the rotary rod basket sifter by a fluidized bed pre-sifting chamber having an admission opening at the top with a chamber defined between opposed porous walls to provide a pre-sifting zone with the walls formed by angularly adjustable baffles in one form, and passing air across the zone toward the rotary rod basket, removing a coarse grain fraction below the pre-sifting chamber, removing a medium grain fraction from beneath the rotary rod basket and removing fine material axially of the rotary rod basket passing the medium grain and coarse grain fraction into an interparticle crushing high pressure roller press having a nip pressure in excess of 2 t/cm of roller length, mixing the medium grain fraction and coarse grain fraction with a pre-comminuted pulverulent material such as cement clinker, passing the discharge of the interparticle crushing roller press to a deagglomerator and feeding the deagglomerated material into the sifted. In one form, the fine material rod basket is passed through a dust removal cyclone with the discharge of the cyclone and the medium grain discharge of the rod basket being passed to a tube mill.