Planetary roller mill for processing high moisture feed material

A planetary roller mill for processing a feed material includes a vessel with a grinding ring having an opening therethrough and a first area. The grinding ring is in sealing engagement with the inside surface of the vessel assembly. At least two non-circular support plates are secured to a rotatable shaft. Each plate has an axially facing surface. A plurality of rollers rotatably are mounted to and positioned between the two support plates. Each of the plurality of rollers are in grinding communication with the grinding surface. The planetary roller mill includes an air supply system having an outlet in communication with the opening in the grinding ring. Areas of the two support plates are of magnitudes which configure a flow area through the opening of at least 30 percent of the first area to provide a predetermined quantity of heated air to remove moisture from the feed material in the grinding assembly.