Abstract: A treatment process of a gas containing zero-valent mercury and a mercury separation system, by which the amount of an iodine compound used can be reduced when the zero-valent mercury is separated from the gas containing the zero-valent mercury by using the iodine compound. The process has a step of oxidizing the zero-valent mercury contained in the gas with a first liquid phase containing an alkali metal iodide, thereby obtaining a second liquid phase containing a divalent mercury ion and an iodide ion; a step of separating the divalent mercury ion as mercury sulfide by adjusting the pH of the second liquid phase; and a step of circulating a third liquid phase which is obtained by separating the mercury sulfide in the mercury separation step to use the third liquid phase as the first liquid phase in the mercury oxidation step.

Abstract: This desulfurization device is for desulfurizing a discharge gas which contains sulfur oxides and which was discharged from a device for sulfuric acid production that includes a concentrated-sulfuric-acid production step in which sulfur trioxide gas obtained by oxidizing sulfur dioxide gas is absorbed in an aqueous sulfuric acid solution while supplying water thereto to thereby produce sulfuric acid having a concentration as high as 90 wt % or more but less than 99 wt %, the desulfurization device comprising: a desulfurization tower in which the sulfur oxides are removed from the discharge gas and, simultaneously therewith, dilute sulfuric acid is formed from the sulfur oxides; and a dilute sulfuric acid mixer which, in the concentrated-sulfuric-acid production step, mixes the dilute sulfuric acid with the aqueous sulfuric acid solution.

Abstract: A treatment process of a gas containing zero-valent mercury and a mercury separation system, by which the amount of an iodine compound used can be reduced when the zero-valent mercury is separated from the gas containing the zero-valent mercury by using the iodine compound. The process has a step of oxidizing the zero-valent mercury contained in the gas with a first liquid phase containing an alkali metal iodide, thereby obtaining a second liquid phase containing a divalent mercury ion and an iodide ion; a step of separating the divalent mercury ion as mercury sulfide by adjusting the pH of the second liquid phase; and a step of circulating a third liquid phase which is obtained by separating the mercury sulfide in the mercury separation step to use the third liquid phase as the first liquid phase in the mercury oxidation step.

Abstract: This desulfurization device is for desulfurizing a discharge gas which contains sulfur oxides and which was discharged from a device for sulfuric acid production that includes a concentrated-sulfuric-acid production step in which sulfur trioxide gas obtained by oxidizing sulfur dioxide gas is absorbed in an aqueous sulfuric acid solution while supplying water thereto to thereby produce sulfuric acid having a concentration as high as 90 wt % or more but less than 99 wt %, the desulfurization device comprising: a desulfurization tower in which the sulfur oxides are removed from the discharge gas and, simultaneously therewith, dilute sulfuric acid is formed from the sulfur oxides; and a dilute sulfuric acid mixer which, in the concentrated-sulfuric-acid production step, mixes the dilute sulfuric acid with the aqueous sulfuric acid solution.

Abstract: An exhaust gas treating method removes sulfur dioxide from exhaust gas containing at least sulfur dioxide and mercury by bringing the exhaust gas into contact with absorption liquid. Persulfate is added into the absorption liquid or alternatively, iodine gas is added to the exhaust gas before the exhaust gas is brought into contact with the absorption liquid. A high removal rate for both sulfur dioxide and mercury is stably maintained if the load of power generation and the composition of exhaust gas fluctuate.

Abstract: A carbon-based catalyst for flue gas desulfurization is brought into contact with a flue gas containing at least SO2 gas, oxygen and water vapor so that the SO2 gas can react with the oxygen and the water vapor to form sulfuric acid which is to be recovered. On a surface of the carbon-based catalyst, iodine, bromine or a compound thereof is added, ion exchanged or supported and a water-repellent treatment is applied. The carbon-based catalyst can also be used as a mercury adsorbent for flue gas treatment for adsorbing and removing metallic mercury from a flue gas containing metallic mercury, SO2 gas, oxygen and water vapor.

Abstract: A carbon-based catalyst for flue gas desulfurization is brought into contact with a flue gas containing at least SO2 gas, oxygen and water vapor so that the SO2 gas can react with the oxygen and the water vapor to form sulfuric acid which is to be recovered. On a surface of the carbon-based catalyst, iodine, bromine or a compound thereof is added, ion exchanged or supported and a water-repellent treatment is applied. The carbon-based catalyst can also be used as a mercury adsorbent for flue gas treatment for adsorbing and removing metallic mercury from a flue gas containing metallic mercury, SO2 gas, oxygen and water vapor.

Abstract: An exhaust gas treating method removes sulfur dioxide from exhaust gas containing at least sulfur dioxide and mercury by bringing the exhaust gas into contact with absorption liquid. Persulfate is added into the absorption liquid or alternatively, iodine gas is added to the exhaust gas before the exhaust gas is brought into contact with the absorption liquid. A high removal rate for both sulfur dioxide and mercury is stably maintained if the load of power generation and the composition of exhaust gas fluctuate.