(57) A vertical roller mill has a grinding table (1) with grinding rollers (3). Conveying air passes through nozzles (5) and entrains ground material which is carried into a separator (6) where fine material passes out through a top outlet (11). Coarse material falls through a bottom outlet (8) to the grinding table for further grinding. The adverse pressure difference across the outlet (8), impeding the flow of coarse material is counteracted by an ejector (12), which is fed from the source of conveying air and blows downwards through the outlet (8).