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.

A calcination unit able to decarbonate raw materials intended for clinker production, the unit including: a main duct in which the raw materials circulate according to a first movement direction, the raw materials being calcined in the main duct; a solid fuel supply duct opening onto the main duct via a fuel outlet, the solid fuel moving according to a second movement direction; a retaining device located in the main duct and arranged opposite the solid fuel outlet so that the solid fuel arriving in the main duct via the fuel outlet passes through the retaining device.

A calcination unit able to decarbonate raw materials intended for clinker production, the unit including: a main duct in which the raw materials circulate according to a first movement direction, the raw materials being calcined in the main duct; a solid fuel supply duct opening onto the main duct via a fuel outlet, the solid fuel moving according to a second movement direction; a retaining device located in the main duct and arranged opposite the solid fuel outlet so that the solid fuel arriving in the main duct via the fuel outlet passes through the retaining device.

A method for reducing metal oxide containing charge materials (1): reducing the metal oxide containing charge materials (1) in at least two fluidized bed units (RA,RE) by means of a reduction gas (2), wherein at least some of the resulting off-gas (3) is recycled and wherein the metal oxide containing charge materials (1) are conveyed into the fluidized bed unit RE by a propellant gas. Also, apparatus for carrying out the method according to the invention is disclosed.

A method for reducing metal oxide containing charge materials (1): reducing the metal oxide containing charge materials (1) in at least two fluidized bed units (RA,RE) by means of a reduction gas (2), wherein at least some of the resulting off-gas (3) is recycled and wherein the metal oxide containing charge materials (1) are conveyed into the fluidized bed unit RE by a propellant gas. Also, apparatus for carrying out the method according to the invention is disclosed.

A process for calcining a feed material can include passing a solid particulate material through a burner or adjacent a burner for being pass through a flame formed by the burner to facilitate calcination of the material. The material can be emitted from the flame of the burner within a calciner for passing through a body of the calciner to an outlet for further calcination of the material so the material has a pre-selected residence time as it is passed through the flame and calciner to an outlet. The residence time can be 20 seconds to 30 seconds, 1-3 minutes, less than 5 minutes in some embodiments. Some embodiments can facilitate calcination of a CaCO.sub.3 material so the calcined solid material output from a calciner is comprised of Ca(OH).sub.2 (e.g. is mostly Ca(OH).sub.2, is over 90 weight percent Ca(OH).sub.2, etc.).

A process for calcining a feed material can include passing a solid particulate material through a burner or adjacent a burner for being pass through a flame formed by the burner to facilitate calcination of the material. The material can be emitted from the flame of the burner within a calciner for passing through a body of the calciner to an outlet for further calcination of the material so the material has a pre-selected residence time as it is passed through the flame and calciner to an outlet. The residence time can be 20 seconds to 30 seconds, 1-3 minutes, less than 5 minutes in some embodiments. Some embodiments can facilitate calcination of a CaCO.sub.3 material so the calcined solid material output from a calciner is comprised of Ca(OH).sub.2 (e.g. is mostly Ca(OH).sub.2, is over 90 weight percent Ca(OH).sub.2, etc.).

A calcination unit able to decarbonate raw materials intended for clinker production, the unit including: a main duct in which the raw materials circulate according to a first movement direction, the raw materials being calcined in the main duct; a solid fuel supply duct opening onto the main duct via a fuel outlet, the solid fuel moving according to a second movement direction; a retaining device located in the main duct and arranged opposite the solid fuel outlet so that the solid fuel arriving in the main duct via the fuel outlet passes through the retaining device.

A calcination unit able to decarbonate raw materials intended for clinker production, the unit including: a main duct in which the raw materials circulate according to a first movement direction, the raw materials being calcined in the main duct; a solid fuel supply duct opening onto the main duct via a fuel outlet, the solid fuel moving according to a second movement direction; a retaining device located in the main duct and arranged opposite the solid fuel outlet so that the solid fuel arriving in the main duct via the fuel outlet passes through the retaining device.