Patent ID: 6644479
Filing Date: 2003-11-11
Classification: B07B

Abstract:
A method for grading comminuted charging material in a wind sifter having at least one driven sifting rotor, comprising the following steps of:introducing sifting air and charging material into a sifting chamber; separating coarse material substantially downwards from the sifting chamber and sucking a sifting air stream charged at least with fine material initially from the rotor circumference into the inside of the sifting rotor and then approximately axially at least one end face of the rotor into a stationary withdrawal duct; and blowing blocking air into a ring seal region in the transition region between the sifting rotor and the stationary withdrawal duct; wherein the grain size distribution in the discharged fine material is adjusted with the aid of a bypass stream, which flows in an alterable volume from the sifting chamber into the withdrawal duct and which is charged with sifter charging material or sifter grit, by controlling the volume of that bypass stream by adjustment of the blocking air supply in terms of its amount.