A system for fluidized bed reduction of powdered iron ore. Use of high-gas-velocity processing accelerates iron ore reduction speed and greatly improves the gas-treatment capabilities of a unit-cross-sectional fluidized bed. Use of parallel connections involving reduced coal gas lessens the volume of gas passing through a single-stage fluidized bed. Use of serial/parallel-connection processing involving reduced coal gas increases the coal gas utilization rate. The invention achieves the highly-effective reduction of powdered iron ore in a fluidized bed under near-atmospheric pressure. A reduction method based on the present system is also disclosed.

A process and its relating plant for recycling zinc oxide residues. Thereby, zinc oxide residues are granulated to particles with a size of d.sub.80 between 0.3 and 5 mm, preferably between 0.5 and 2 mm. These particles are fed into a roaster where they are thermally treated at a temperature in the range of 500 and 1.200? C., preferably 800 to 1.100? C. in a fluidized bed to form a calcine. The zinc oxide residues are zinc oxide dusts with a particle size below d.sub.80 100 ?m, preferably below d.sub.80 75 ?m coming from kiln, submerges lances furnaces, ferric reduction furnaces, galvanizing and/or recycling processes, particularly recycling of steel, copper, lead, nickel and/or electronic scrap, and/or that the zinc oxide residues comes from foundry for lead and zinc, ashes and/or dross from a Zamac process, oxide zinc ash, catalysts, melting and casting of Zn and/or zinc slag.

A process and its relating plant for recycling zinc oxide residues. Thereby, zinc oxide residues are granulated to particles with a size of d.sub.80 between 0.3 and 5 mm, preferably between 0.5 and 2 mm. These particles are fed into a roaster where they are thermally treated at a temperature in the range of 500 and 1.200? C., preferably 800 to 1.100? C. in a fluidized bed to form a calcine. The zinc oxide residues are zinc oxide dusts with a particle size below d.sub.80 100 ?m, preferably below d.sub.80 75 ?m coming from kiln, submerges lances furnaces, ferric reduction furnaces, galvanizing and/or recycling processes, particularly recycling of steel, copper, lead, nickel and/or electronic scrap, and/or that the zinc oxide residues comes from foundry for lead and zinc, ashes and/or dross from a Zamac process, oxide zinc ash, catalysts, melting and casting of Zn and/or zinc slag.

A system and method for fluidized reduction of iron ore powder. Use of oxidation increases the iron ore reduction rate. Use of high-gas-velocity processing accelerates iron ore reduction speed and greatly improves the gas-treatment capabilities of a unit-cross-sectional fluidized bed. Use of parallel-connections involving reduced coal gas lessens the volume of gas passing through a single-stage fluidized bed. The invention achieves the highly-effective reduction of iron ore powder in a fluidized bed under near-atmospheric pressure.

A system and method for the fluidized direct reduction of iron ore concentrate powder. A two-phase fluidized bed is used for the direct reduction of iron ore concentrate powder. Each phase of the fluidized bed is formed by a bubbling bed and a circulating bed. Use of serial-connection processing involving gas and of high-gas-velocity processing of the circulating bed increase the gas utilization rate and the reduction efficiency of single-phase reduction. Once reduced gases are subjected to preheating, each gas is sent into an initial reduction phase and a final reduction phase so as to implement reduction of minerals. Use of mixed-connection processing involving gas appropriately reduces processing pressure. Hot flue gas produced by combustion in a gas heater is sent to a mineral pre-heating system that is used for pre-heating iron ore concentrate powder.

A method and a sensor device for evaluating residual Sulphur in a cement preheater of a cement kiln, wherein the residual Sulphur is based on the values of the fuel Sulphur content, the fuel rate of consumption, the hotmeal quality and the clinker Sulphur content. A method for evaluating blockage in a cement preheater includes evaluating the residual Sulphur in the cement preheater, determining an agglomeration rate of Sulphur compounds agglomerating on an inner surface of the cement preheater based on the residual Sulphur, and evaluating a level of blockage in at least one predetermined pathway of the cement preheater using a blockage evaluation unit, wherein the level of blockage is based on the agglomeration rate.

The invention concerns: A) An assembly to reduce the emission of CO.sub.2 in a plant for the production of clinkers comprising two calciners and a carbonator arranged between the two calciners, wherein one of the calciners is an integral part of a conventional clinker production system. Thanks to this assembly, the plant can continue to operate in the clinker production process even if the CO.sub.2 capture system which uses the carbonator and the other calciner of the assembly is disconnected due to malfunctions or maintenance characterized in that said carbonator is free of recirculation to both said two calciners. B) The relative plants comprising both the assembly and the actual clinker production plant in which the clinker production plant is of the conventional type existed before and already operational, or said plant is installed simultaneously with the assembly units. C) The clinker production process with reduction of CO.sub.2 emission conducted in the plants B.

The invention concerns: A) An assembly to reduce the emission of CO.sub.2 in a plant for the production of clinkers comprising two calciners and a carbonator arranged between the two calciners, wherein one of the calciners is an integral part of a conventional clinker production system. Thanks to this assembly, the plant can continue to operate in the clinker production process even if the CO.sub.2 capture system which uses the carbonator and the other calciner of the assembly is disconnected due to malfunctions or maintenance characterized in that said carbonator is free of recirculation to both said two calciners. B) The relative plants comprising both the assembly and the actual clinker production plant in which the clinker production plant is of the conventional type existed before and already operational, or said plant is installed simultaneously with the assembly units. C) The clinker production process with reduction of CO.sub.2 emission conducted in the plants B.

An apparatus for calcination of gypsum includes a gypsum calciner having an interior wall surface with a circular or annular configuration as seen in its plan view, and a tubular combustor positioned at a center part of a body of the calciner. Raw gypsum is calcined or dehydrated by a high temperature gas spouting flow (Hg) ejected from a lower portion of the combustor. The calciner has a stationary-vane-type or movable-vane-type auxiliary device, which circumferentially energizes the raw gypsum in the vicinity of the interior wall surface toward a circumferential direction of the calciner. The auxiliary device has a plurality of stationary vanes circumferentially arranged in an outer peripheral zone of a lower portion of the combustor and spaced apart from each other at an angular interval, or an agitator extending through a conical or inner circumferential surface defined by the interior wall surface.

An apparatus for calcination of gypsum includes a gypsum calciner having an interior wall surface with a circular or annular configuration as seen in its plan view, and a tubular combustor positioned at a center part of a body of the calciner. Raw gypsum is calcined or dehydrated by a high temperature gas spouting flow (Hg) ejected from a lower portion of the combustor. The calciner has a stationary-vane-type or movable-vane-type auxiliary device, which circumferentially energizes the raw gypsum in the vicinity of the interior wall surface toward a circumferential direction of the calciner. The auxiliary device has a plurality of stationary vanes circumferentially arranged in an outer peripheral zone of a lower portion of the combustor and spaced apart from each other at an angular interval, or an agitator extending through a conical or inner circumferential surface defined by the interior wall surface.