Abstract: A drying apparatus has a generally conical upwardly flared housing having an upper end provided with a cover and a lower end provided with an outlet, a mixing auger mounted on and extending upward from the lower housing end in the housing and rotatable to mix particulate material in the housing, and a magnetron mounted at the upper housing end and directed downward inside the housing to irradiate and heat the particulate material in the housing. The magnetron can be mounted directly on the cover. An adapter ring can be provided on the upper end of the housing between the housing and the cover with the magnetron mounted on this adapter ring. This ring is releasably connected to the cover and housing, and it is possible for the ring to carry a plurality of such magnetrons each provided with a respective coaxial wave guide extending through the ring and into the housing.