Abstract: A rotary drying system for particulate material includes a rotary dryer of the multiple pass drum construction with a horizontal axis of rotation. A furnace is coupled to one end and a horizontally disposed centrifugal separator of the scroll type is coupled to the opposite end. A small cyclone separator is coupled to the scroll separator and connected in a closed loop system with the scroll separator for continuous recycling air therethrough. The rotary dryer has essentially the largest vertical dimension and therefore the profile of the system is minimized. The rotary dryer is formed with an inner cylinder of a conical taper with a relatively small inlet end and progressively increasing passageway diameter to a large discharge end coupled to an intermediate passageway between the inner cylinder and an intermediate constant diameter cylinder. The intermediate passageway continuously expands in cross-section to a final discharge passageway formed by an outer concentric cylinder.