Abstract: The invention relates to a method for comminuting fertiliser slugs or slug pieces in a two-roll mill (3) in the course of producing granular fertiliser material, wherein the two-roll mill (3) has two rotatingly driven grinding rolls, the roll surfaces of which are provided with a profiling, wherein the slug or slug pieces is/are placed on the two-roll mill (3) and comminuted into granular material in the roll nip formed between the grinding rolls, wherein the grinding rolls rotate at a circumferential speed of more than 5 m/s. This e method is characterised in that the surfaces of the grinding rolls are cooled during operation.