Treatment of granular solids in an annular fluidized bed with microwaves

Abstract

This invention relates to a method for the thermal treatment of granular solids in a fluidized-bed reactor ( 1 ), in which microwave radiation from a microwave source ( 2 ) is fed into the reactor ( 1 ), and to a corresponding plant. To improve the utilization of energy and the introduction of the microwave radiation, a first gas or gas mixture is introduced from below through a preferably central gas supply tube ( 3 ) into a mixing chamber ( 7 ) of the reactor, the gas supply tube ( 3 ) being at least partly surrounded by a stationary annular fluidized bed ( 8 ) which is fluidized by supplying fluidizing gas. The microwave radiation is supplied to the mixing chamber ( 7 ) through the same gas supply tube ( 3 ).

Description

technical field [0001] The present invention relates to a process for the thermal treatment of granular solids in a fluidized bed reactor, wherein microwave radiation is fed into the reactor from a microwave source. Background technique [0002] Such a method is known from US5972302 in which sulphide ores are subjected to an oxidation reaction supported by microwaves. The method mainly involves sintering pyrite in a fluidized bed, where microwaves introduced into the fluidized bed promote the formation of hematite and elemental sulfur, and suppress SO 2 Formation. The fixed fluidized bed used is irradiated by a microwave source placed directly above. The microwave source or point of microwave introduction must be in contact with gases, vapors and dust rising from the fluidized bed. [0003] Examples where a microwave source can be coupled to a mixing chamber are: open waveguides, slot antennas, coupling rings, diaphragms, coaxial antennas filled with gas or other dielectr...

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