Abstract: A method for evaluating the caking property of sodium hydrogencarbonate crystal particles, characterized in that sodium hydrogencarbonate crystal particles are hermetically sealed in a packaging material having a water vapor transmission rate of at least 3 g/(m2·24 h) (at 40° C. with a relative humidity difference of 90%) as stipulated in JIS K7129 and left at rest at a temperature of from 17 to 35° C. at a carbon dioxide gas concentration of from 0.03 to 0.05 vol % at a relative humidity of from 40 to 95% for from 2 weeks to 3 months, and the proportion of agglomerated sodium hydrogencarbonate crystal particles is determined to evaluate the caking tendency. A novel test method for evaluating the caking property of sodium hydrogencarbonate crystal particles, capable of providing results of the caking property test with high reproducibility, quantitatively with high versatility, can be provided.

Abstract: A process for producing sodium hydrogencarbonate crystal particles having a low caking property, which entails subjecting sodium hydrogencarbonate crystal particles having an average particle size of from 50 to 500 ?m based on the mass to heat treatment at a temperature of from 70 to 95° C. by a heating gas having a carbon dioxide gas concentration of at most the concentration calculated by the formula: Carbon dioxide gas concentration=0.071×e(0.1×T)×R(?0.0005×T?0.9574), where T (° C.) is the temperature of sodium hydrogencarbonate crystals, and R (%) is the relative humidity around the crystals at the temperature of the crystals, provided that the upper limit of the carbon dioxide gas concentration is 100 vol % to form anhydrous sodium carbonate on the surface of the sodium hydrogencarbonate crystal particles with a content of anhydrous sodium carbonate of from 0.03 to 0.4 mass % in the sodium hydrogencarbonate crystals.

Abstract: To provide an agent for removing a halogen series gas and a method for removing a halogen series gas which is excellent in a removing ability of removing the present halogen series gas in a low concentration area, which prevents an adsorbent from generating heat, and which is capable of reducing formation of a solid waste. A method for removing a halogen series gas, which comprises bringing a gas to be treated which contains at least one member selected from the halogen series gas group consisting of F2, Cl2, Br2, I2, and compounds which generate a hydrogen halide or hypohalogeneous acid upon hydrolysis, into contact with a granule comprising, based on the total mass of the granule, from 45 to 99.85 mass % of an alkali metal salt, from 0.1 to 40 mass % of a carbonaceous material, and from more than 0 mass % to 15 mass % of an alkaline earth metal salt, in the presence of water.

Abstract: A process for producing an alkali metal hydrogencarbonate by reacting an aqueous solution containing alkali metal ions with carbon dioxide in a prescribed crystallizer to precipitate crystals of an alkali metal hydrogencarbonate, and in this process a part of a slurry containing the alkali metal hydrogencarbonate crystals in the aqueous solution is withdrawn from the crystallizer and, after dissolution of a part of the crystals, it is returned to the crystallizer.

Abstract: To provide an agent for removing a halogen series gas and a method for removing a halogen series gas which is excellent in a removing ability of removing the present halogen series gas in a low concentration area, which prevents an adsorbent from generating heat, and which is capable of reducing formation of a solid waste. A method for removing a halogen series gas, which comprises bringing a gas to be treated which contains at least one member selected from the halogen series gas group consisting of F2, Cl2, Br2, I2, and compounds which generate a hydrogen halide or hypohalogeneous acid upon hydrolysis, into contact with a granule comprising, based on the total mass of the granule, from 45 to 99.85 mass % of an alkali metal salt, from 0.1 to 40 mass % of a carbonaceous material, and from more than 0 mass % to 15 mass % of an alkaline earth metal salt, in the presence of water.

Abstract: Sodium hydrogencarbonate crystal particles, which comprise sodium hydrogencarbonate crystal particles having an average particle size of from 50 to 500 ?m based on the mass, and anhydrous sodium carbonate, and sodium carbonate monohydrate and/or Wegscheider's salt, present on the surface of the sodium hydrogencarbonate crystal particles in such amounts that the total content of anhydrous sodium carbonate, sodium carbonate monohydrate, Wegscheider's salt and sodium sesquicarbonate in the sodium hydrogencarbonate crystal particles is from 0.04 to 1 mass % as calculated as anhydrous sodium carbonate, anhydrous sodium carbonate accounts for at least 40 mass % of the total content, and sodium carbonate monohydrate and/or Wegscheider's salt accounts for from 5 to 60 mass % of the total content. Sodium hydrogencarbonate crystal particles having a low caking property, which are useful in the field of food products, pharmaceuticals, bath additives, etc.

Abstract: Sodium hydrogencarbonate crystal particles excellent in anti-caking property and anti-thermal decomposition property, and its production process, are provided. Sodium hydrogencarbonate crystal particles whose color 1 second after dropping of a phenolphthalein solution having a predetermined composition, is R=245 to 255, G=243 to 255 and B=245 to 255 in RGB 256 tone notation. The sodium hydrogencarbonate crystal particles are produced by subjecting sodium hydrogencarbonate crystal particles to a bicarbonation treatment in a humidified carbon dioxide gas atmosphere.

Abstract: A method for removing a halogen series gas, which comprises contacting a gas containing a halogen series gas forming at least one kind selected from the group consisting of HF, HCl, HBr and HI by water with a granule containing from 60 to 99.9 mass % of a solid base and from 0.1 to 40 mass % of a carbonaceous material to the total mass amount of the granule in the presence of water.

Abstract: To provide a method for removing a halogen series gas, which has high capability of treating a halogen series gas, can prevent ignition of an adsorbing agent, is free from formation of carbon dioxide and can reduce generation of wastes, and a removing agent to be used for the method. The method for removing a halogen series gas comprises bringing a gas comprising at least one halogen series gas selected from the group consisting of F2, Cl2, Br2, I2 and a compound which undergoes hydrolysis to form a hydrogen halide or hypohalogenous acid into contact with a granulated product comprising from 80 to 99.9 mass % of an alkali metal base and from 0.1 to 20 mass % of a thiosulfate based on the total mass of the granulated product, in the presence of water, to remove the halogen series gas.

Abstract: A process for producing sodium hydrogencarbonate crystals, which comprise subjecting sodium hydrogencarbonate crystal powder having an average particle size of from 50 to 500 ?m based on the mass to heat treatment at a temperature of from 70 to 95° C. by a heating gas having a carbon dioxide gas concentration of at most the concentration calculated by the following formula (1): Carbon dioxide gas concentration=0.07l×e(0.1×T)×R(?0.0005×T?0.9574)??(1) (wherein T is the temperature (%) of sodium hydrogencarbonate crystals, and R is the relative humidity (%), provided that the upper limit of the carbon dioxide gas concentration is 100 vol %) with reference to the graph of FIG. 1 wherein the horizontal axis (X-axis) represents the relative humidity and the vertical axis (Y-axis) represents the carbon dioxide gas concentration, to form anhydrous sodium carbonate on the surface of the sodium hydrogencarbonate crystal particles with a content of anhydrous sodium carbonate of from 0.03 to 0.

Abstract: A method for evaluating the caking property of sodium hydrogencarbonate crystal particles, characterized in that sodium hydrogencarbonate crystal particles are hermetically sealed in a packaging material having a water vapor transmission rate of at least 3 g/(m2·24h) (at 40° C. with a relative humidity difference of 90%) as stipulated in JIS K7129 and left at rest at a temperature of from 17 to 35° C. at a carbon dioxide gas concentration of from 0.03 to 0.05 vol % at a relative humidity of from 40 to 95% for from 2 weeks to 3 months, and the proportion of agglomerated sodium hydrogencarbonate crystal particles is determined to evaluate the caking tendency. A novel test method for evaluating the caking property of sodium hydrogencarbonate crystal particles, capable of providing results of the caking property test with high reproducibility, quantitatively with high versatility, can be provided.

Abstract: Sodium hydrogencarbonate crystal particles, which comprise sodium hydrogencarbonate crystal particles having an average particle size of from 50 to 500 ?m based on the mass, and anhydrous sodium carbonate, and sodium carbonate monohydrate and/or Wegscheider's salt, present on the surface of the sodium hydrogencarbonate crystal particles in such amounts that the total content of anhydrous sodium carbonate, sodium carbonate monohydrate, Wegscheider's salt and sodium sesquicarbonate in the sodium hydrogencarbonate crystal particles is from 0.04 to 1 mass % as calculated as anhydrous sodium carbonate, anhydrous sodium carbonate accounts for at least 40 mass % of the total content, and sodium carbonate monohydrate and/or Wegscheider's salt accounts for from 5 to 60 mass % of the total content. Sodium hydrogencarbonate crystal particles having a low caking property, which are useful in the field of food products, pharmaceuticals, bath additives, etc.

Abstract: To provide a process for easily obtaining an alkali metal hydrogencarbonate having a large crystal particle size in good yield by an industrially convenient installation by a crystallization method from an aqueous solution. A process for producing an alkali metal hydrogencarbonate, which comprises reacting an aqueous solution containing alkali metal ions with carbon dioxide in a prescribed crystallizer to precipitate crystals of an alkali metal hydrogencarbonate, characterized in that a part of a slurry containing the above crystals in the above aqueous solution, is withdrawn from the above crystallizer and, after a part of the above crystals is dissolved, returned to the above crystallizer.

Abstract: A method for removing a halogen series gas, which comprises contacting a gas containing a halogen series gas forming at least one kind selected from the group consisting of HF, HCl, HBr and HI by water with a granule containing from 60 to 99.9 mass % of a solid base and from 0.1 to 40 mass % of a carbonaceous material to the total mass amount of the granule in the presence of water.