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: 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: 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: A process for producing a silica-alumina composite sol, which comprises mixing a silica hydrogel and an aluminum salt which, when dissolved in water, gives an acidic solution.

Abstract: A process for producing a silica-alumina composite sol, which comprises mixing a silica hydrogel and an aluminum salt which, when dissolved in water, gives an acidic solution.

Abstract: An alumina sol having an alumina solid content of at least 10 wt % and a viscosity of not higher than 5 Pa.s measured by a Brookfield viscometer and containing a cation other than a hydrogen ion in a total ion equivalent concentration in the range of from 2.0.times.10.sup.-4 to 1.0.times.10.sup.-1 N and a method of preparing the same.

Abstract: A process for producing zinc oxide-containing spherical silica, which comprises emulsifying, in an organic solvent containing a surfactant, a dispersion having zinc oxide with a particle size of from 0.005 to 0.5 .mu.m dispersed in an aqueous alkali metal silicate solution in an amount of from 10 to 70 wt % based on the total amount of zinc oxide and SiO.sub.2 in the aqueous alkali metal silicate solution, followed by gelation of the resulting emulsion with carbon dioxide gas.