Abstract: The invention relates to a roller mill having a grinding table, at least one grinding roller and at least two drives with a rotor winding for driving the roller mill and at least one adjustment device for adjusting the motor torque of at least one drive, the adjustment device being connected to the rotor winding of at least one drive in order to influence the rotor current.

Abstract: The invention relates to a method for monitoring the load state of a grinding system having rotating grinding elements, the dynamic forces exerted by the grinding stock on the grinding elements being detected in a first frequency range which contains the fundamental oscillation of the grinding elements, and in a second frequency range in which the first harmonic of the fundamental oscillation occurs, and measures for reducing the load state being introduced when the first harmonic exceeds a predetermined threshold value in relation to the magnitude of the fundamental oscillation. Such a method permits very reliable and accurate monitoring of the load state of the grinding system.

Abstract: The invention relates to a method for monitoring the load state of a grinding system having rotating grinding elements, the dynamic forces exerted by the grinding stock on the grinding elements being detected in a first frequency range which contains the fundamental oscillation of the grinding elements, and in a second frequency range in which the first harmonic of the fundamental oscillation occurs, and measures for reducing the load state being introduced when the first harmonic exceeds a predetermined threshold value in relation to the magnitude of the fundamental oscillation. Such a method permits very reliable and accurate monitoring of the load state of the grinding system.

Abstract: The invention relates to a roller mill having a grinding table, at least one grinding roller and at least two drives with a rotor winding for driving the roller mill and at least one adjustment device for adjusting the motor torque of at least one drive, the adjustment device being connected to the rotor winding of at least one drive in order to influence the rotor current.

Abstract: A method of grading comminuted charging material in a wind sifter having a sifting rotor. The sifting air and the charging material are introduced into a sifting chamber and blocking air is blown into a ring seal region in the transition region between the sifting rotor and a stationary withdrawal duct. In order to be able to adjust the grain size distribution range in the fine material/end product in a reliable manner and with relatively little structural outlay, the grain size distribution in the discharged fine material is adjusted in a selective manner with the aid of a bypass stream, which flows in an alterable volume from the sifting chamber into the withdrawal duct and which is charged with sifter charging material or sifter grit, by controlling the supply of blocking air.

Abstract: Fresh raw material is delivered to a crushing zone for crushing. Beforehand, fine particles are separated from the raw material by means of an airstream and directed into the housing of the crusher where they are entrained by an independent gas stream that conveys crushed fines upwardly to a separator also located within the housing. The separator removes fine particles from the system and returns the remaining, relatively course tailings material to the crushing zone through a tailings return chute. At least a portion of the material exiting the tailings return chute is subjected to a secondary separation treatment to capture additional quantities of fine particles before entering the crushing zone. The captured tailings material may be mixed with the fresh raw material else reintroduced into the top of the separator to receive the secondary separation treatment.

Abstract: The invention relates to the comminution of material for grinding, particularly for the production of cement, wherein the material for grinding is comminuted in a mill and the comminution product is classified in a classification zone into fines and oversize material and the oversize material is returned to the mill. With a view to effective influencing of the breadth of the particle size distribution as well as a relatively low specific energy consumption the comminution product is classified in the classification zone in at least two air separators which are connected one behind the other in series, and a proportion of the oversize material from the first air separator is returned directly to the mill, the remaining proportion being delivered to the second air separator.

Abstract: The invention relates to a roll mill having at least one pair of grinding rollers bearing against a substantially horizontal surface of a grinding table which is rotatable about a vertical axis. The rollers are mounted at one end of a roller support the opposite end of which is guided by guide lugs slidable vertically in guides and linked to the roller support by a tension rod. In order to achieve particularly smooth running of the grinding rollers on the grinding surface, the guides and the guide lugs lie approximately at the level of the grinding surface.

Abstract: The invention relates to a method and to apparatus for crushing material for grinding, in which the material for grinding first of all passes in multiple circulation through a grinding stage which operates on the pressure crushing principle and then without further grinding is delivered to a classification stage consisting of two classification assemblies set to different degrees of fineness, the streams of fines from the two classification assemblies being mixed together. By the combination of these two measures a desired flattening of the particle size distribution of the end product is achieved.

Abstract: The invention relates to a sifter in which the spiral for delivery of the air for sifting is divided into a plurality of channels lying one above another in which elements for setting the quantity of sifting air delivered to the individual channels are provided. In such a sifter the quantity of sifting air in the individual regions of the sifting chamber can be optimally adapted to the requirements, which leads to a substantial improvement in the degree of separation.