Abstract: The invention relates to a rotary tube mill and to a method of comminuting lumpy mill feed material, in which at least a first and a second grinding chamber as well as a co-rotating partition disposed between the grinding chambers are used. The material ground in the first grinding chamber is divided in the partition into first and second part-quantities of mill feed material, whereby at least a part of the second part-quantity of mill feed material proceeds into the second grinding chamber and at least the first part-quantity of the mill feed material is discharged separately from the tube mill.

Abstract: The invention relates to a rotary tube mill and to a method of comminuting lumpy mill feed material, in which at least a first and a second grinding chamber as well as a co-rotating partition disposed between the grinding chambers are used. The material ground in the first grinding chamber is divided in the partition into first and second part-quantities of mill feed material, whereby at least a part of the second part-quantity of mill feed material proceeds into the second grinding chamber and at least the first part-quantity of the mill feed material is discharged separately from the tube mill.

Abstract: A method of grading comminuted charging material in a wind sifter having a sifting rotor. The sifting air and the charging material are introduced into a sifting chamber and blocking air is blown into a ring seal region in the transition region between the sifting rotor and a stationary withdrawal duct. In order to be able to adjust the grain size distribution range in the fine material/end product in a reliable manner and with relatively little structural outlay, the grain size distribution in the discharged fine material is adjusted in a selective manner 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 supply of blocking air.