A rotary drum configuration for the efficient blending, cooling, and screening of granular products having an outer cylindrical shell, an intake end, and a discharge end. The rotary drum is normally rotated at a predetermined speed by means of a conventional drive package. Disposed on an inner surface of the cylindrical shell are a plurality of compound helical flights and scoops, configured to blend granular product as it cascades from the intake end to the discharge end of the rotary drum. A coaxially disposed cylindrical air passage adjacent the discharge end of the rotary drum directs a counter flow of cooling air through the rotary drum towards the intake end, cooling the cascading granular product as it approaches the discharge end, and plurality of discharge ports and grading screens in the surface of the outer cylindrical shell adjacent the discharge end provide a entrance for a second counter flow of cooling air while simultaneously providing passage for the granular product to drop downwards towards a outer coaxial discharge passage.