In a first stage fresh material (7) is supplied to the rolling mill (1) while at least the major part of the pulverised material (9) is sent back to a collecting bunker (10) until a predetermined filling volume is reached. Then in a second state the supply of fresh material is switched off and the mill is then only fed with the already ground material from the collecting bunker. This returned ground material is then recirculated until pulverised to a further predefined product fineness. In a third stage on reaching this fineness the pulverised material is directed off from the mill and the bunker emptied to a predetermined minimum filling level (18). When this is reached the supply of fresh material is started up again to the mill and the pulverised material from this grinding is sent back to the collecting bunker. Two controllable dosing conveyors (6,8) are provided for controlling the flow.
