The invention relates to a method for the direct reduction of oxidic iron carrier particles to a reduction product in a fluidized bed through which a reduction gas containing 30-100 mol % hydrogen H.sub.2 flows in crossflow. At least 90% by mass of oxidic iron carrier particles introduced into the fluidized bed have a particle size of less than or equal to 200 micrometers. The superficial velocity U of the reduction gas flowing through the fluidized bed is set between 0.05 m/s and 1 m/s such that, for the particle size d equal to d.sub.30 of the oxidic iron carrier particles introduced into the fluidized bed, it is above the theoretical suspension velocity U.sub.t and is less than or equal to U.sub.max.

The invention relates to a method for the direct reduction of oxidic iron carrier particles to a reduction product in a fluidized bed through which a reduction gas containing 30-100 mol % hydrogen H.sub.2 flows in crossflow. At least 90% by mass of oxidic iron carrier particles introduced into the fluidized bed have a particle size of less than or equal to 200 micrometers. The superficial velocity U of the reduction gas flowing through the fluidized bed is set between 0.05 m/s and 1 m/s such that, for the particle size d equal to d.sub.30 of the oxidic iron carrier particles introduced into the fluidized bed, it is above the theoretical suspension velocity U.sub.t and is less than or equal to U.sub.max.

Plants for regenerating foundry sand are provided having a combustion chamber, which has at least one inlet for introducing sand to be regenerated into the combustion chamber, nozzles for feeding combustible gas into the combustion chamber, nozzles for injecting air so as to maintain a heated fluidized bed of sand in the combustion chamber, a cooling chamber for cooling sand coming from the combustion chamber, the cooling chamber having nozzles for blowing air in order to maintain a fluidized bed of sand in the cooling chamber, refrigerating pipes arranged above the air nozzles, a communicating duct which connects the combustion chamber with the cooling chamber, the communicating duct including a vertical or inclined lower end portion which is at least partially surrounded by or adjacent to a plurality of the refrigerating pipes in the cooling chamber, and wherein the lower end portion has a bottom outlet arranged at a lower level with respect to at least one of the refrigerating pipes.

Plants for regenerating foundry sand are provided having a combustion chamber, which has at least one inlet for introducing sand to be regenerated into the combustion chamber, nozzles for feeding combustible gas into the combustion chamber, nozzles for injecting air so as to maintain a heated fluidized bed of sand in the combustion chamber, a cooling chamber for cooling sand coming from the combustion chamber, the cooling chamber having nozzles for blowing air in order to maintain a fluidized bed of sand in the cooling chamber, refrigerating pipes arranged above the air nozzles, a communicating duct which connects the combustion chamber with the cooling chamber, the communicating duct including a vertical or inclined lower end portion which is at least partially surrounded by or adjacent to a plurality of the refrigerating pipes in the cooling chamber, and wherein the lower end portion has a bottom outlet arranged at a lower level with respect to at least one of the refrigerating pipes.

The disclosure discloses a method for preparing calcium oxide using multistage suspension preheater kiln. The steps of the method are: (1) the limestone powder is fed to the multistage suspension preheater kiln for preheating to 800 C. to 900 C.; (2) A preheated material is fed to a decomposition furnace, and calcined at 900 C. to 1100 C. for 25 s to 35 s; (3) A calcined material is fed to a rotary kiln, and calcined at 1100 C. to 1300 C. for 25 to 35 minutes, and finally cooled to obtain calcium oxide.

The disclosure discloses a method for preparing calcium oxide using multistage suspension preheater kiln. The steps of the method are: (1) the limestone powder is fed to the multistage suspension preheater kiln for preheating to 800 C. to 900 C.; (2) A preheated material is fed to a decomposition furnace, and calcined at 900 C. to 1100 C. for 25 s to 35 s; (3) A calcined material is fed to a rotary kiln, and calcined at 1100 C. to 1300 C. for 25 to 35 minutes, and finally cooled to obtain calcium oxide.

A counter-current catalyst regenerator with at least two stages of counter-current contact along with a regenerator riser is proposed. Each stage may comprise a permeable barrier that allows upward passage of oxygen-containing gas and downward passage of coked catalyst into each stage, but inhibits upward movement of catalyst to mitigate back mixing and approximate true counter-current contact and efficient combustion of coke from catalyst. The regenerator riser may provide a passage to transport the catalyst and may serve as a secondary stage for coke combustion to provide the regenerated catalyst.

A counter-current catalyst regenerator with at least two stages of counter-current contact along with a regenerator riser is proposed. Each stage may comprise a permeable barrier that allows upward passage of oxygen-containing gas and downward passage of coked catalyst into each stage, but inhibits upward movement of catalyst to mitigate back mixing and approximate true counter-current contact and efficient combustion of coke from catalyst. The regenerator riser may provide a passage to transport the catalyst and may serve as a secondary stage for coke combustion to provide the regenerated catalyst.

A device and a method for producing high-purity nano molybdenum trioxide are provided. The device comprises a raw material bin (1), a feeding machine (2), a subliming furnace (7), a first vent tube (24), a second vent tube (25), a spraying device (23) and a filtering assembly. The sublimated molybdenum trioxide is cooled with clean and dehumidified air so as to finally obtain the nano molybdenum trioxide, and the recycling mode is reliable, pollution-free and high in efficiency.

A device and a method for producing high-purity nano molybdenum trioxide are provided. The device comprises a raw material bin (1), a feeding machine (2), a subliming furnace (7), a first vent tube (24), a second vent tube (25), a spraying device (23) and a filtering assembly. The sublimated molybdenum trioxide is cooled with clean and dehumidified air so as to finally obtain the nano molybdenum trioxide, and the recycling mode is reliable, pollution-free and high in efficiency.