Patent ID: 8100351

Claim:
Method for grinding hot, wet raw material, including cement clinker, slag and aggregates, using a vertical mill ( 2 ) having a lower mill part ( 3 ) and an upper mill part ( 5 ) above the lower mill part ( 3 ), the upper mill part ( 5 ) including a grinding area ( 7 ), the lower mill part ( 3 ) having a nozzle ring therein, and the raw material having a plurality of components, the method comprising the steps of: feeding raw material components to the vertical mill ( 2 ), supplying only a hot gas ( 4 ) to the lower mill part ( 3 ) via the nozzle ring with a gas inlet temperature which is determined by the moisture content of the raw material component with the highest moisture level, creating a grinding material-hot gas mixture by grinding and simultaneously drying the raw material components in the upper mill part ( 5 ) with the aid of the hot gas ( 4 ) supplied via the nozzle ring to the lower mill part ( 3 ), and introducing a cooling gas ( 8 ) separately from the hot gas ( 4 ) into the grinding area ( 7 ) of the upper mill part ( 5 ) of the vertical mill ( 2 ) above the nozzle ring, and admixing the cooling gas ( 8 ) with the grinding material-hot gas mixture upstream of a classifier ( 6 ) above the upper mill part ( 5 ), wherein the cooling gas ( 8 ) serves as a cooling medium maintaining a predeterminable gas and product temperature downstream of the classifier ( 6 ) and also makes up a portion of the carrying gas which carries the grinding material-hot gas mixture to the classifier ( 6 ).