Abstract: A spray drying apparatus includes a chamber through which cyclonic flow of heated gas is maintained. A rotating spray head is located in the chamber adjacent to the heated gas inlet and aligned axially of the cyclonic flow so as to receive the hottest gas. The spray head has spiral vanes which define heated gas flow channels extending spirally in the axial flow direction. The slurry is introduced into the bottoms of these channels to flow in thin film fashion across the vanes whereby the hottest gas scrubs the thin films before the liquid is discharged in finely divided form from the edges of the vanes.