Abstract: In the method according to the invention for increasing the calorific value of a material flow containing carbon, preferably a material flow of renewable raw materials, the material flow is brought in direct contact with at least one low-oxygen, inert hot gas flow in a reactor, wherein the hot gas flow is formed at least 50%, preferably at least 80%, by exhaust gas of a process for thermally processing cement raw meal and/or lime and/or an ore, wherein at least part of a preheater exhaust gas for preheating the cement raw meal and/or lime and/or ore is used as the hot gas flow.

Abstract: The roller mill according to the invention consists substantially of two grinding rollers which are driven in opposite directions and form between them a grinding gap for comminuting material to be ground, and a delivery chute via which the material to be ground is fed to the grinding gap. Furthermore, there is provided in the delivery chute a pressure sensor for measuring the static gas pressure, which pressure sensor is connected to a control or regulating device, which changes the circumferential speed of the grinding rollers in dependence on the measured static gas pressure. In the method according to the invention for operating the above roller mill, the static gas pressure in the delivery chute is measured and used to control or regulate the circumferential speed of the grinding rollers.

Abstract: The roller mill according to the invention consists substantially of two grinding rollers which are driven in opposite directions and form between them a grinding gap for comminuting material to be ground, and a delivery chute via which the material to be ground is fed to the grinding gap. Furthermore, there is provided in the delivery chute a pressure sensor for measuring the static gas pressure, which pressure sensor is connected to a control or regulating device, which changes the circumferential speed of the grinding rollers in dependence on the measured static gas pressure. In the method according to the invention for operating the above roller mill, the static gas pressure in the delivery chute is measured and used to control or regulate the circumferential speed of the grinding rollers.

Abstract: The invention relates to the preparation of a material mixture consisting of a plurality of mineral raw material components which are delivered individually proportioned, are ground and homogenised, wherein samples are periodically analysed and determined ACTUAL values are compared with predetermined DESIRED values in order if appropriate to carry out corrective control interventions on the proportioning of raw material components by way of a laboratory computer. In relatively short time periods evaluations of the material samples and re-homogenisation of the ground mixture can be carried out very reliably with relatively low expenditure on construction if the material samples are analysed on the spot by means of a rapid analysis arrangement and the determined ACTUAL values from this analysis are passed to the laboratory computer, the homogenisation being carried out in a mixing zone with relatively small receiving capacity which is separated from the storage zone.

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.