Abstract: An apparatus and method for the continuous processing of a granular material in a wet or dry state. The apparatus comprises first and second heating chambers, and the heating energy is provided by microwave energy. The first chamber preheats the granular material to lower the moisture content. The second chamber heats the granular material to the desired high temperature, for example, 800.degree. C. for the reactivation of carbon. The first and second chambers are arranged in a vertical orientation to allow gravity to assist in the flow of material through the chambers. The flow of material is controlled by a valve positioned at the outlet of the second chamber. The apparatus is suitable for the reactivation of metallurgical carbon and the heating of other granular materials such as ceramics and glass powders.