PURPOSE: To enable the perfect treatment of various kinds of dust materials which are capable of making trickle flow by introducing the power into a fluidizable heat medium made of refractory material and heating the dust then burning the same.

CONSTITUTION: A heating rod 36 is heated to drastically decrease a fluidizable air stream during the start-up of equipment. As a result, the heat medium 34 heated in a lower region and the heated air transmit temperature to the entire part of the material bed formed of the heat medium 34 until the entire part of the materiel bed attains the desired temperature by a fluidization effect and the resultant circulation motion. The dust which is ought to be made inert and is charged together with organic substances is then heated within a heat source 34. The heat medium 34 moving toward clockwise by the air stream from a transverse direction air nozzle 47 applies the heat thereof to the dust. When the dust attains an ignition temperature, the dust burns and the energy generated by the combustion of the dust is returned to the heat medium 34 particularly in the heated region of the bulk material bed of the heat medium, i.e., an upper region.