A method and a corresponding plant for denitrifying bypass exhaust gases in a cement clinker production plant. Raw meal is sintered in a rotary kiln and deacidified in a calciner. A rotary kiln inlet chamber is connected to the calciner directly or by a riser duct. Bypass exhaust gas is drawn off near the inlet chamber. This exhaust gas is guided into a first mixing chamber, in which the exhaust gas is cooled to between 800 and 950 C., then the exhaust gas is guided through a reaction pipeline segment, wherein the dwell time is between 0.5 and 3 seconds and ammonia, aqueous ammonia solution, or ammonia-releasing substances are injected for denitrification. Then the exhaust gas is guided into a second mixing chamber, in which the exhaust gas is cooled to between 150 to 250 C. Then the exhaust gas is guided to a filter for dust removal.

A method and a corresponding plant for denitrifying bypass exhaust gases in a cement clinker production plant. Raw meal is sintered in a rotary kiln and deacidified in a calciner. A rotary kiln inlet chamber is connected to the calciner directly or by a riser duct. Bypass exhaust gas is drawn off near the inlet chamber. This exhaust gas is guided into a first mixing chamber, in which the exhaust gas is cooled to between 800 and 950 degrees C., then the exhaust gas is guided through a reaction pipeline segment, wherein the dwell time is between 0.5 and 3 seconds and ammonia, aqueous ammonia solution, or ammonia-releasing substances are injected for denitrification. Then the exhaust gas is guided into a second mixing chamber, in which the exhaust gas is cooled to between 150 250 degrees C. Then the exhaust gas is guided to a filter for dust removal.

A method and a corresponding plant for denitrifying bypass exhaust gases in a cement clinker production plant. Raw meal is sintered in a rotary kiln and deacidified in a calciner. A rotary kiln inlet chamber is connected to the calciner directly or by a riser duct. Bypass exhaust gas is drawn off near the inlet chamber. This exhaust gas is guided into a first mixing chamber, in which the exhaust gas is cooled to between 800 and 950 degrees C., then the exhaust gas is guided through a reaction pipeline segment, wherein the dwell time is between 0.5 and 3 seconds and ammonia, aqueous ammonia solution, or ammonia-releasing substances are injected for denitrification. Then the exhaust gas is guided into a second mixing chamber, in which the exhaust gas is cooled to between 150 250 degrees C. Then the exhaust gas is guided to a filter for dust removal.

A method for manufacturing clinker includes sintering raw meal in a kiln to clinker, preheating the raw meal (prior to sintering the raw meal) in a preheater using a main flue gas stream from the kiln as heat source, dedusting the main flue gas downstream of the preheater at a temperature below the boiling point of mercury (thereby obtaining mercury loaded dust) and withdrawing a bypass flue gas stream from the kiln. The method is configured to efficiently remove mercury from the manufacturing process if mercury in the bypass flue gas is vaporized by injecting of at least a fraction of the mercury-loaded dust into the bypass flue gas stream. Subsequently, the bypass flue gas is dedusted and cooled down. Thereby, the mercury can be adsorbed by injecting an adsorbent (such as activated charcoal) into the bypass flue gas. With subsequent removal of the adsorbent, mercury is finally removed from the manufacturing process.

A method for manufacturing clinker includes sintering raw meal in a kiln to clinker, preheating the raw meal (prior to sintering the raw meal) in a preheater using a main flue gas stream from the kiln as heat source, dedusting the main flue gas downstream of the preheater at a temperature below the boiling point of mercury (thereby obtaining mercury loaded dust) and withdrawing a bypass flue gas stream from the kiln. The method is configured to efficiently remove mercury from the manufacturing process if mercury in the bypass flue gas is vaporized by injecting of at least a fraction of the mercury-loaded dust into the bypass flue gas stream. Subsequently, the bypass flue gas is dedusted and cooled down. Thereby, the mercury can be adsorbed by injecting an adsorbent (such as activated charcoal) into the bypass flue gas. With subsequent removal of the adsorbent, mercury is finally removed from the manufacturing process.

A process for producing a pozzolan from a starting material. The starting material is size-reduced and incorporated into an aqueous slurry. The size-reduction can be carried out before or after incorporation into the aqueous slurry. Pressurized gas containing carbon dioxide is supplied to the aqueous slurry, and the aqueous slurry is mixed in the presence of the pressurized gas for a treatment period.

A process for producing a pozzolan from a starting material. The starting material is size-reduced and incorporated into an aqueous slurry. The size-reduction can be carried out before or after incorporation into the aqueous slurry. Pressurized gas containing carbon dioxide is supplied to the aqueous slurry, and the aqueous slurry is mixed in the presence of the pressurized gas for a treatment period.

Provided is a calcium carbonate generation method and system in which calcium carbonate having a high purity can be generated using a calcium-containing waste. Provided is a calcium carbonate generation method of generating calcium carbonate from a calcium-containing waste, the calcium carbonate generation method including: a calcium dissolution step of adding aqueous hydrochloric acid to a calcium-containing waste and dissolving calcium to generate an aqueous solution containing a calcium ion; a separation step of adjusting a hydrogen ion concentration index of the aqueous solution containing a calcium ion and separating a component containing at least one selected from the group consisting of Si, Al, Mg, and heavy metal from the aqueous solution; and a calcium carbonate collection step of generating calcium carbonate using an aqueous solution obtained in the separation step and an aqueous solution containing potassium carbonate and/or sodium carbonate.

A method for industrial refining of coal ash created in power plants and carbonaceous ashes produced in other combustion processes by separating coal from said ashes and returning it to use and by recovering a substantially coal-free ash fraction obtained in the refining. In the method, coal ash and at least one ash fraction created by gasification technique in combustion plants are carefully proportioned in relation to one another and formed into a slurry mixture by means of an efficient dispersion technique, the slurry being then led to a flotation step, where a fraction rich in coal and a siliceous fraction poor in coal and a fraction dissolving in the process water are separated by flotation. The coal ash is arranged to have the highest proportion in the mixture to be taken to flotation, the ashes from combustion plants being dosed into said mixture in an amount that does not cause the maximum amounts of harmful substances to be exceeded in the qualities of the carbonaceous product and the silicate product poor in coal to be obtained.

A method for industrial refining of coal ash created in power plants and carbonaceous ashes produced in other combustion processes by separating coal from said ashes and returning it to use and by recovering a substantially coal-free ash fraction obtained in the refining. In the method, coal ash and at least one ash fraction created by gasification technique in combustion plants are carefully proportioned in relation to one another and formed into a slurry mixture by means of an efficient dispersion technique, the slurry being then led to a flotation step, where a fraction rich in coal and a siliceous fraction poor in coal and a fraction dissolving in the process water are separated by flotation. The coal ash is arranged to have the highest proportion in the mixture to be taken to flotation, the ashes from combustion plants being dosed into said mixture in an amount that does not cause the maximum amounts of harmful substances to be exceeded in the qualities of the carbonaceous product and the silicate product poor in coal to be obtained.