A method of producing a synthetic carbonated mineral component in a cement manufacturing plant, includes providing a carbonatable substance from an external source, introducing the carbonatable substance into an exhaust gas installation of the cement manufacturing plant for contacting the carbonatable substance with CO.sub.2 enriched exhaust gas, carbonating the carbonatable substance by reacting the carbonatable substance with CO.sub.2 contained in the CO.sub.2 enriched exhaust gas, thereby obtaining the synthetic carbonated mineral component, and removing the synthetic carbonated mineral component from the exhaust gas installation.

A method for operating a plant for producing cement clinker from raw meal having, as viewed in the materials flow direction, at least one calciner for deacidifying the raw meal, and at least one rotary kiln for sintering the deacidified raw meal to form cement clinker. The deacidified raw meal, after passing through the calciner, flows via a cyclone preheating stage into the rotary kiln. Exhaust gases are guided from the rotary kiln into a reactor, arranged between the rotary kiln and the calciner, with fuel being fed into the reactor superstoichiometrically in relation to the dwell time of the exhaust gases in the reactor, so that carbon dioxide in the exhaust gases is reduced to form carbon monoxide. The carbon monoxide is used as a reducing agent for nitrogen oxides, which are chemically reduced in the reactor independently of the short dwell time in the calciner.

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.

The present invention relates to a rotary kiln for burning carbonate-containing material, in particular limestone or dolomite, including a rotary tube having an inlet end for feeding the material to be burned and an outlet end for discharging the burnt material, and a burner unit arranged in the region of the outlet end, the rotary tube having an inlet zone at its inlet end and an outlet zone at its outlet end, a preheating zone and a combustion zone being arranged between the inlet zone and outlet zone in the direction of transport of the material. The rotary kiln is characterized according to the invention in that at least one projection is arranged in the outlet zone of the rotary tube, the at least one projection having a contour tapering in the direction of rotation of the rotary tube. The present invention further relates to a method for burning carbonate-containing material, in particular limestone or dolomite.

A process and device separate off a volatile component from the off-gases in cement clinker production. Raw materials for cement clinker production are passed through a preheater with heat exchange with the off-gases and are then burnt in a rotary kiln. Owing to the heating in the preheater, the volatile component bound in the raw materials is vaporized and separated off. A first raw material stream having a relatively high concentration of the volatile component is applied to a first line of the preheater and a second raw material stream having a lower concentration of the volatile component is applied to a second line. The volatile component is separated off from the first substream of the off-gases. The first raw material stream heated to a temperature of at least 250 C. with the first substream of the off gases in the first line is combined with the second raw material stream.

A process and device separate off a volatile component from the off-gases in cement clinker production. Raw materials for cement clinker production are passed through a preheater with heat exchange with the off-gases and are then burnt in a rotary kiln. Owing to the heating in the preheater, the volatile component bound in the raw materials is vaporized and separated off. A first raw material stream having a relatively high concentration of the volatile component is applied to a first line of the preheater and a second raw material stream having a lower concentration of the volatile component is applied to a second line. The volatile component is separated off from the first substream of the off-gases. The first raw material stream heated to a temperature of at least 250 C. with the first substream of the off gases in the first line is combined with the second raw material stream.

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.

In a process for the production of cement clinker, in which raw meal is preheated in a preheater (3) using the hot exhaust gases from a clinker kiln, and the preheated raw meal, which is optionally calcined in a calciner (4), is burned to clinker in the clinker kiln (2), wherein the preheater (3) includes at least one string of a plurality of cyclone suspension-type heat exchangers (8, 9, 10), through which the kiln exhaust gas successively flows and in which the raw meal is preheated in stages, a partial stream of the kiln exhaust gas is diverted such that only a remaining residual stream of the kiln exhaust gas is utilized for preheating the raw meal.

In a process for the production of cement clinker, in which raw meal is preheated in a preheater (3) using the hot exhaust gases from a clinker kiln, and the preheated raw meal, which is optionally calcined in a calciner (4), is burned to clinker in the clinker kiln (2), wherein the preheater (3) comprises at least one string of a plurality of cyclone suspension-type heat exchangers (8, 9, 10), through which the kiln exhaust gas successively flows and in which the raw meal is preheated in stages, a partial stream of the kiln exhaust gas is diverted such that only a remaining residual stream of the kiln exhaust gas is utilized for preheating the raw meal.

A process and device separate off a volatile component from the off-gases in cement clinker production. Raw materials for cement clinker production are passed through a preheater with heat exchange with the off-gases and are then burnt in a rotary kiln. Owing to the heating in the preheater, the volatile component bound in the raw materials is vaporized and separated off. A first raw material stream having a relatively high concentration of the volatile component is applied to a first line of the preheater and a second raw material stream having a lower concentration of the volatile component is applied to a second line. The volatile component is separated off from the first substream of the off-gases. The first raw material stream heated to a temperature of at least 250 C. with the first substream of the off gases in the first line is combined with the second raw material stream.