Abstract: The invention relates to apparatus and to a method for the heat treatment of fine-grained material using a multi-stage cyclone preheater and a combustion chamber supplied with tertiary air from the cooler, in which the branched part of the tertiary air pipe extends upwards and the material discharged from the second-lowest stage of the cyclone preheater is introduced into one branch pipe at a point which lies lower than the point at which this branch pipe is connected to the combustion chamber. In this way good dispersal of the material which is delivered pneumatically to the combusion chamber and excellent combustion conditions are achieved at the same time as a considerable reduction in the overall height of the entire cyclone preheater.

Abstract: A process for the heat-treatment of fine-grained material which is preheated in a cyclone preheater, deacidified by additional fuel in a precalcination zone, and subsequently calcined to completion in a revolving tubular kiln. The gas temperature in the cyclone preheater and the material temperature after passage through the precalcination zone are measured, the difference between these temperatures is determined and, when the temperature difference reaches a maximum or minimum value, regulation of the fuel supply to the precalcination zone is switched to manual operation. In this way, the amount of fuel is rapidly adapted to the particular circumstances prevailing in the event of disturbances.