Process for producing light-weight aggregates having a low density

摘要

To produce a light-weight aggregate having a low density and to use fine-grained to fine pulverulent combustion residues formed in fluidised-bed furnaces, a process is employed according to which light cores such as, for example, granulated Styropor (rigid polystyrene foam) or spheres of foam material whose water absorption is very low and whose wetting with water is difficult under water-containing suspensions are made wettable by appropriate treatment processes using foam material formers. After wetting, the predominantly fine pulverulent mixtures of inorganic binders and thermally treated mineral materials are then applied in the form of a shell to these cores. The selection of the core-forming grain size is matched to the desired grain size of the aggregate. The shell thickness is determined by the duration of the application process as a function of the desired grain strength. Depending on the starting material or the field of application, binder in the form of cement or of lime is added or utilised. The grain formed in this way is cured or subjected to thermal curing by the lime-sand brick process.