Spray-dried fabric washing detergent powders based on nonionic surfactants are prepared by a process involving the step of injecting a phosphoric acid ester into the high pressure line carrying slurry to the spray-drying tower. The phosphoric acid ester is dissolved or dispersed in a nonionic surfactant such as a long chain alcohol ethoxylate and injected into the pressurized slurry either using a venturi effect or by being pressurized to a higher pressure.
A process for the drying of water-containing materials which are suitable for use as wetting agents, detergents or cleaning products. An aqueous solution, emulsion or suspension of the materials is dried using superheated steam as the drying gas wherein the drying gas is recycled to the drying zone after removal therefrom of evaporated water and the energy required for the evaporation of water is supplied to the superheated steam by heat exchangers.
