Patent ID: 7662351

Claim:
A process for producing metal oxide from a metal compound in which the metal compound is conveyed into a reactor with fluidized bed, heated there to a temperature of 650 to 1150° C. by combustion of fuel, and metal oxide is generated, comprising introducing a first gas or gas mixture from below through a gas supply tube into a mixing chamber of the reactor located above the orifice region of the gas supply tube, the gas supply tube being at least partly surrounded by a stationary annular fluidized bed which is fluidized by supplying fluidizing gas, wherein the gas flowing through the gas supply tube entrains solids from the fluidized bed into the mixing chamber when passing though the upper orifice region of the gas supply tube, and adjusting the gas velocities of the first gas or gas mixture as well as of the fluidizing gas for the annular fluidized bed such that the Particle-Froude numbers in the gas supply tube lie between 1 and 100, in the annular fluidized bed between 0.02 and 2, and in the mixing chamber between 0.3 and 30.