In a spray drying process utilizing a spray dryer having internal gas filters and an internal fluidized bed and comprising an after-treatment of the product in a separate unit outside the spray drying chamber, which treatment produces a particle-loaded gas stream, said particle-loaded gas stream is conducted from the separate unit to the spray drying chamber. The stream passes, together with the spent drying gas in the drying chamber, the filters integrated in said chamber. Several plant modifications are suggested for performing the process which involves substantial savings by making external particle collectors superfluous.