Method for carbonating waste materials

A method for simultaneously drying and carbonating a mineral waste material, the mineral waste material comprising carbonatable calcium compounds and/or carbonatable magnesium compounds and/or silicate, aluminate or silicate-aluminate phases able to be converted into silica gel, alumina gel or silica-alumina gel respectively by carbonation, in a spray dryer, wherein

• a starting material slurry is provided comprising the mineral waste material in the form of particles with a D90≤500 μm and at least 30 wt.-% water,
• a hot gas is provided comprising at least 4 Vol.-% CO2 and fed into the spray dryer
• the starting material slurry is sprayed into the hot gas in the spray dryer wherein a temperature of ≥100° C. and a relative humidity of <50% at the outlet are adjusted in the spray dryer
• the starting material slurry is transformed into evaporated water and a dry, carbonated product comprising calcium and/or magnesium carbonate and/or at least one of silica gel or alumina gel or silica-alumina gel, and
• the dry, carbonated product is separated from the gas and evaporated water.