Patent ID: 8235219

Claim:
A plant for the heat treatment of feedstock having a pre-heater ( 200 ) for pre-heating the feedstock and a rotary tubular kiln ( 300 ) for burning the pre-heated feedstock, characterized in that a device ( 100 ) for separating or classifying feedstock ( 1 ) into at least two different grain fractions ( 2 , 3 ) is arranged between the pre-heater ( 200 ) and the rotary tubular kiln ( 300 ), the device having a screen device ( 5 ) which is formed by rotatable elements ( 8 ), at least one finer grain fraction ( 2 ) falling through between the rotatable elements and means ( 14 ) being provided for supplying a cooling medium to the rotatable elements ( 8 ), and wherein the rotatable elements ( 8 ) have a basic body ( 8 a ) and an outer casing ( 8 b ), the basic body ( 8 a ) having a duct ( 8 d ) which extends in the direction of its axis of rotation ( 8 e ) and which can be acted upon by a cooling medium and which is connected to the means ( 14 ) for supplying the cooling medium.