Spray drying process for producing anhydrous alkali sulfide

Process for producing anhydrous alkali sulfide, comprising spray drying a liquid substance preparation selected from the group consisting of an alkali sulfide solution, alkali sulfide suspension, alkali sulfide dispersion and alkali sulfide water of crystallisation melt, into a chamber and atomizing said liquid substance preparation in contact with a hot gas stream consisting of inert drying gas loaded with pure superheated water vapour, and optionally, an inert drying gas, to dry said preparation and thereby produce anhydrous alkali sulfide and recycling exhaust gas without introduction of additional inert gas and drying in pure superheated water vapour.