TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Method: The inorganic particulate forming the reactor bed material (15) is treated with an oxygeneous gas in a separate oxidation unit comprising fluidized reactor (33). The material fed (18) in the oxidation unit is fluidized with an oxygeneous gas to burn off the combustion residue attached to the material. The material obtained is then recycled to the reactor.Preferred Product: The gas phase product after condensation is recycled in the form of circulation gas. The circulation gas is expressed as gas volume, 0.5-2-fold of the amount of the uncondensed processed product. The uncondensed gases produced by the process are also conducted into the oxidation unit, where they are at least partially combusted.Preferred Condition: The velocity of the fluidization gas in the reactor is maintained, which allows for fluidization in the regime of turbulent or rapid fluidization. Thus, the velocity ratio between the gas and the particles is smaller than 2 on the whole length of the riser space. The residence time in the reactor is 0.01-10 seconds. The average particles size of the solid matter is 50-120 micron.    TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Component: The oxidation unit is used as pneumatic conveyor. It comprises a circulating bed reactor, an internal circulation for adjustment of the residence time and the regeneration degree, and a bubbling bed reactor. It also includes a circulating fluidized bed reactor, dimensioned partially for achieving removal of combustion residue from the bed material and for producing heat needed by thermal treatment. The final burning-off of the combustion residue, recovery of excess heat, and treatment of flue gases are accomplished with another boiler unit (20). The separation unit for separating solid materials from gaseous materials comprises a multiport cyclones. It also includes cascade of cyclones comprising single inlet cyclones or multi-inlet cyclones. The cascade of cyclones includes first and second separation stages. The reactor and the oxidation unit are mounted together, thus heat needed in the reactor is brought through the common wall. The reactor includes internal vanes for increasing the turbulence of the reactor flow.