Asahi Glass Company, Limited

Shintaro Kikuchi

Hisakazu Arima

Fumiaki Nakashima

Shigeru Sakurai

Hachiro Hirano

Kunio Tanaka

Hachirou Hirano

Takako Hirano, Legal Representative

Hidetomi Haga

Teiji Kawada

Yuriko Takahashi

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/(m&#xb7;24 h) (at 40&#xb0; 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&#xb0; 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.

Method for evaluating caking property of sodium hydrogencarbonate crystal particles

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 &#x3bc;m based on the mass to heat treatment at a temperature of from 70 to 95&#xb0; 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&#xd7;e&#xd7;R, where T (&#xb0; 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.

Process for producing sodium hydrogencarbonate crystal particles having low caking property

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.

Process for producing alkali metal hydrogencarbonate

Sodium hydrogencarbonate crystal particles, which comprise sodium hydrogencarbonate crystal particles having an average particle size of from 50 to 500 &#x3bc;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., which require no necessity to contain an anticaking agent, a process for producing them and a method for packaging them, can be provided.

Sodium hydrogencarbonate crystal particles having low caking property and process for producing them

A process for producing sodium salts, which comprises adding solid sodium carbonate to a first aqueous solution containing sodium carbonate and sodium hydrogencarbonate, to prepare a second aqueous solution, precipitating, separating and recovering from the second aqueous solution sodium sesquicarbonate crystals containing at least 50 mol % of the sodium hydrogencarbonate component contained in the second aqueous solution, and further recovering sodium carbonate from a mother liquor remaining after separating the sodium sesquicarbonate crystals from the second aqueous solution.

Process for producing sodium salts

A blasting medium composed of a granulated product which comprises a water-soluble inorganic salt as the main component and which has a weight average grain size of from 1 to 10 mm.

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Ibaraki, Japan

Shintaro Kikuchi