JPS59121117A - Production of low-density sodium carbonate - Google Patents

Abstract

PURPOSE:To obtain a granular low-density sodium carbonate having excellent solubility and handleable without dusting, by reacting hydrated sodium carbonate or a mixture of sodium bicarbonate and sodium carbonate with carbon dioxide gas in the presence of water. CONSTITUTION:Hydrated sodium carbonate and/or a mixture of sodium bicarbonate and sodium carbonate, e.g. sodium sesquicarbonate, etc. obtained by the carbonation of sodium hydroxide, etc. is made to react with carbon dioxide gas having an arbitrary concentration in the presence of about 0.5-45wt% of water to convert about >=40% of the sodium carbonate to bicarbonate. The product is calcined at about 140-500 deg.C to convert the bicarbonate to sodium carbonate and obtain the objective low-density sodium carbonate. The concentration of the carbon dioxide gas is adjusted by the ratio of air, etc., added to the gas, and a sodium carbonate having desired low density can be obtained by controlling the concentration of carbon dioxide gas.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing low-density soda carbonate, and particularly to a method for producing soda carbonate that is granular and has good solubility and does not generate dust when handled.

Industrially, soda carbonate is produced by burning bicarbonate of soda obtained by the Tsurubei method, ammonia soda method, etc. to produce light ash, which is then calcined after water use to obtain what appears to be a dense electric charge. There is.

Among these, light ash has conventionally been used exclusively for applications where it is relatively easy to dissolve in water.

However, light ash generally has a high dust-generating property, is finely granular, has a tendency to form nodules, has poor fluidity, and is not necessarily difficult to handle.

In view of these points, the inventor of the present invention conducted various research and examinations with the aim of obtaining granular soda carbonate that does not generate dust and is easily soluble. No matter how the means for obtaining the carbonate is adjusted, the object of the present invention cannot be achieved, and it is necessary to first obtain the soda carbonate by any means and then process the soda by a specific means to reduce the density. It has been found that the above object can be achieved.

Thus, the present invention involves reacting sodium carbonate hydrate and/or a mixed salt of sodium bicarbonate and sodium carbonate with carbon dioxide gas at an arbitrary concentration in the presence of water, bicarbonating at least a portion of it, and then baking it. Another object of the present invention is to provide a method for producing low-density soda carbonate, which is characterized in that the density is reduced in accordance with the carbon dioxide concentration.

In the present invention, it has been found that similar results can be obtained by using not only sodium carbonate hydrate but also a mixed salt of sodium bicarbonate and soda carbonate, typified by sodium sesquicarbonate, as the raw material for the soda carbonate that lowers the density.

Sodium carbonate hydrate and I2 used as raw materials may be, for example, monohydrate or heptahydrate, and there are no particular restrictions on their production methods, such as carbonation of caustic soda, Truvay method, ammonia soda method, etc. means may be adopted. Also, mixed salts of baking soda and soda carbonate (hereinafter referred to as mixed salts) such as sodium sesquicarbonate may be appropriately prepared by known means.

Furthermore, the particle size of the low-density soda carbonate finally obtained according to the present invention is determined by the particle size of the above-mentioned hydrated sodium carbonate salt or mixed salt that is normally used as a raw material. Furthermore, the sodium carbonate hydrate and mixed salt used in the present invention may be crystallized or not.

These sodium carbonate hydrates and mixed salts are first reacted with carbon dioxide gas in the presence of moisture.

Strictly speaking, the amount of water present at this time varies somewhat depending on the amount of water used for soda carbonate, the mixed salt, etc., but in general, approximately α5 to 45 weight is appropriate. If the water content deviates from the above range, the progress of the reaction may be slowed down and caking between particles may occur, which is not preferable.

Among these ranges, it is particularly preferable to adopt a water content of about 5 to 20% by weight because the reaction rate is fast and handling is easy.

The amount of carbon dioxide gas reacted in the presence of water is determined by the degree of density reduction, required dissolution rate, etc.

In particular, it has been found that the carbon dioxide concentration greatly affects the degree of density reduction, and in general, the lower the carbon dioxide concentration, the lighter the bulk specific gravity of the final product, sodium carbonate, and the faster the dissolution rate. was discovered. Therefore, by adjusting the carbon dioxide concentration, it is possible to obtain soda carbonate of any desired low density. Such specific examples will be easily understood from the examples described below.

Further, the concentration of carbon dioxide gas can be adjusted, for example, by adjusting the mixing ratio with gases such as air and nitrogen gas.

If the generality in bicarbonation is too low, the industrial equipment will become complicated, and conversely, if the atb is too high, the reaction rate of the bicarbonation reaction may decrease, which is undesirable. Generally, it is appropriate to adopt a temperature of 0 to 80°C.

Thus, at least a portion of the sodium carbonate hydrate or mixed salt is bicarbonated. The degree of bicarbonation is determined by the degree of low density and the required dissolution rate, but it is generally effective to use 40% by weight or more of the sodium carbonate in the sodium carbonate hydrate or mixed salt. It is.

The bicarbonate thus obtained is then converted to soda carbonate by calcining it. As the waist condition to be adopted at this time, it is appropriate to adopt a temperature of about 140 to 500°C. If these firing conditions are deviated from, it is not preferable because there is a risk that problems such as insufficient density reduction and dissolution rate may not be obtained, and strength, especially abrasion resistance, may be reduced.

Next, the present invention will be explained using examples.

The dissolution rate measurement method adopted in the following examples is 5.
Pour 200 liters of 50°C water into an oocc beaker, and
Sample 60f was placed in a stirrer stirred with a magnetic stirrer at 0 to 300 r, p, m, and the time required for complete dissolution was measured. In addition, the fluidity index is based on the powder tester of the Wire Powder Engineering Research Institute.

Claims (1)

[Claims] 1. Reacting sodium carbonate hydrate and/or a mixed salt of sodium bicarbonate and sodium carbonate with carbon dioxide gas at an arbitrary concentration in the presence of 1 minute of water, bicarbonating at least a portion of it, and then exploding it. A method for producing low-density carbonated soda, which is characterized by lowering the density according to the carbon dioxide concentration.