JPS6036325A - Preparation of sodium carbonate - Google Patents

Abstract

PURPOSE:To obtain Na2CO3 having extremely low apparent specific gravity, and high dissolution rate in water, by blending NaHCO3, with Na2CO3(calculated as anhydrous state), and an aqueous solution containing sodium silicate or CMC in a given weight ratio to give a blend, uniforming and calcining the blend in given temperature ranges, respectively. CONSTITUTION:A blend is prepared in such a way that it has a ratio of NaHCO3:Na2CO3(calculated as anhydrous state):an aqueous solution containing sodium carbonate or carboxymethyl cellulose (CMC) of 1:(0.2-1.5):(0.1-0.8), especially 1:(0.3-1.5):(0.1-0.5) by weight. The blend is then stirred, kneaded, and uniformed at 40-105 deg.C, especially at 50-100 deg.C. The uniformed blend is then calcined at a sufficiently high temperature (100-300 deg.C, preferably 150-220 deg.C). Consequently, NaHCO3 is decomposed, and water containing sodium silicate or CMC is dehydrated, to give the desired Na2CO3. This Na2CO3 has 0.4-0.8 apparent viscosity, and <=40sec dissolution rate in water, and it is extremely advantageous as a raw material component especially for synthetic detergent.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an extremely useful and novel method for producing sodium carbonate, particularly as a raw material component for synthetic detergents.

More specifically, the present invention relates to a method for producing sodium carbonate, which has good apparent specific gravity and water solubility, which are not found in anhydrous sodium carbonate commercially available so far.

Conventionally, anhydrous sodium carbonate has been produced by the so-called ammonia-soda method and ammonium chloride-soda method, that is, by reacting carbon dioxide gas with ammoniacal saturated salt water. ~300°
It is produced by force firing at a temperature of C.

The anhydrous sodium carbonate obtained by this method is industrially referred to as light ash, and generally has an apparent specific gravity of about 0.8 and an average particle size in the range of 90μ to 110μ. This light ash is generally used as a raw material for chemical industries such as food additives and dyes.

On the other hand, anhydrous sodium carbonate, which is used as a raw material for plate glass, bottles, steel, detergents, and the chemical industry, and is industrially called reprint, is produced by adding water to the light ash obtained by the above manufacturing method. , sl/lium carbonate water salt CNa2CO
3.It20) and then drying it at a temperature such that the outlet temperature of the dryer is 110°C to 170°C. The reprints obtained in this way generally have an apparent specific gravity of 1 or more □ and an average particle size of 200/
It is in the range of 1 to 400/7. It is also possible to obtain a similar reprint by carbonating caustic soda.

As is well known, sodium carbonate is an indispensable and effective raw material for synthetic detergents.

Until now, when using sodium carbonate as a raw material for synthetic detergents, whether using light ash or reprinted material, sodium carbonate is mixed with other detergent raw materials to form a slurry, and then the slurry is In this method, detergent is obtained by simultaneously drying and granulating the detergent using a dryer. In this way, when using light ash and reprint, it is necessary to make it into a slurry once, and the main reason why it is not possible to add sodium carbonate after drying and granulation is that light ash has a small average particle size, This is because the hardness is low, and in reprinting, the apparent specific gravity is high, so it is easy to separate from other synthetic detergent raw materials. In addition, when using light ash and heavy version dissolved in water, the particle size of light ash is extremely small, and when added to water, it is easy to aggregate and form clumps.
On the other hand, the overprint has the disadvantage that it sinks to the bottom due to its large apparent specific gravity, and that it is necessary to increase the stirring intensity to aid dissolution.

In order to eliminate these drawbacks, the present invention eliminates the need to make a slurry during the manufacturing process of synthetic detergents, allows the addition of sodium carbonate even after drying and granulation, and allows the use of other detergent raw materials. The present invention was completed as a result of intensive research into a method for producing sodium carbonate that allows the addition ratio of sodium carbonate to be freely adjusted and at the same time is difficult to separate from other detergent raw materials.

The present invention provides an unprecedented method for producing sodium carbonate that has an extremely low apparent specific gravity and a high dissolution rate in water.

That is, in the present invention, an aqueous solution containing sodium bicarbonate:sodium carbonate (anhydrous equivalent):sodium silicate or carboxymethyl cellulose (hereinafter referred to as CMC) in a weight ratio of 1
:0.2 to 1.5 :o, adjusted to a ratio of 1 to 0.8, and the adjusted product was heated at 40°C to 10°C with a dissolution rate of 40°C.
This is a method for producing sodium carbonate in seconds or less.

In addition, the present invention can be carried out by appropriately mixing the assembled sodium carbonate and sodium carbonate or sodium carbonate hydrate obtained from the ammonia-soda method or the ammonium chloride-soda method as raw materials, but in that case, sodium bicarbonate : It is necessary to adjust the gravity/hi ratio of l/lium carbonate (in anhydrous terms) to l : 0.2 to 1.5.

In addition, sodium bicarbonate, monolithium carbonate hydrate, sodium carbonate, anhydrous salt or Sodium sesquicarbonate and the like can also be appropriately used as a raw material in the present invention.

What is important in the production method of the present invention is that the weight ratio of sodium bicarbonate: sodium carbonate (anhydrous equivalent): aqueous solution containing CMC covered with sodium silicate is 1:0.
2 to 1.5: o, i to 0.8, preferably 1: (1,
3 to 1.5:o, adjusted to a ratio of 1 to 0.5, and the adjusted product is heated to 40'C to 105C, preferably 50C to
The goal is to make it uniform by heating it at 100°C. If this condition is not met, the desired sodium carbonate will be j! I can't do it. For example, if the mixing temperature is less than 40'C, the particle hardness becomes weak, and if it exceeds 105C, the apparent specific gravity will be different from the target value and will be undesirable. In addition, these reactions are usually carried out within 10 minutes after mixing.
Although the process is completed in ~20 minutes, it is not desirable to stir too vigorously in the mixing operation P1 of the mixer. In order to reduce the particle size of sodium carbonate, vigorous stirring must be carried out carefully and with appropriate stirring in consideration of crystal growth.

Also, when the raw material contains sodium carbonate-hydrate salt, it is desirable to control the amount of aqueous solution used to a low level, but the total water content, that is, the sum of the water content as crystal water and the water content in the added aqueous solution. It is important that the amount is within the ranges mentioned above. Also, if you use too much sodium carbonate-water salt, the hardness of the crystals obtained may decrease slightly.Also, regarding the effect of adding sodium silicate or CMC, it is important to use only an aqueous solution. Sodium carbonate produced by the above method also has considerable properties, but when a small amount of sodium silicate or CMC is added to this aqueous solution, the powdering rate is further improved and hard sodium carbonate can be obtained.

As an example of a reaction operation, a case will be described in which sodium bicarbonate, sodium carbonate, and water to which sodium silicate or CMC is added are mixed.

In the present invention, for example, 60 parts of sodium carbonate and 30 parts of an aqueous solution containing sodium silicate or CMC are added to 60 parts of sodium bicarbonate and thoroughly mixed for 20 minutes. Since 60 parts of sodium bicarbonate is about 40 parts in terms of sodium carbonate equivalent, the mixing ratio of sodium bicarbonate and putoliuno carbonate is 1:1 by weight, and 2 = t/lium carbonate equivalent ratio.
It becomes 3. The same reaction will occur if the ratio of 5 parts of sodium carbonate is between 2:1 and 1:3 between sodium bicarbonate and sodium carbonate. This mixed substance is heated to a sufficiently high temperature (1
The target sodium carbonate is obtained by decomposing the botrium carbonate and dehydrating the water to which sodium silicate or CMC has been added by heating at a temperature of 0° C. to 300° C., preferably 5° C. to 220° C.).

The manufacturing method of the present invention is characterized by the fact that the average particle diameter is between 200μ and 60μ, although the reason for this has not been confirmed.
The sodium carbonate has an extremely large particle size of 0 tl, has unprecedented properties such as a pulverization rate of 8% or less in terms of particle hardness and a dissolution rate in water of 40 seconds or less.

What is even more surprising is that the surface of the particles of monolithium carbonate obtained by the present invention is completely different from that of light ash and molded particles obtained by conventional methods, and exhibits a state in which rod-shaped crystals are aggregated. be.

Note that the average particle diameter, apparent specific gravity, powdering rate, and dissolution rate in the present invention are values calculated by the following measurement method, and the same applies to the Examples and Comparative Examples shown below.

(Average particle size) 100g of the sample divided into tiW parts using a two-plate balance (scale m
200g), transferred to the top sieve of a stack of JIS standard sieves suitable for the particle size of the saucer and sample, covered with a lid, attached to a rotary tube shaker, and shaken for 7 minutes. After that, weigh the residue in the saucer and each sieve using an upper balance (it weighs 100g),
Calculate the cumulative percentage of the nominal size 71 of each sieve, and calculate the nominal 1 method μ of the sieve that is 50 iyt% or more.
is the average particle size.

(Appearance IJ weight) Weigh 5h of the sample, put it into an ifloOnl measuring cylinder (inner diameter 2.7cm), and tap it thoroughly on a thick rubber plate, being careful not to apply too much force, until it reaches the minimum The apparent specific gravity is calculated using the following formula.

The average particle size of the material to be measured is between 200μ and 600μ.
For μ samples, take 120g of the sample and mix it for a long time. Scales, weight (i1
g Put it in an intermediate saucer together with 15 aluminum disks with a diameter of 20 mm, shake it for 5 minutes in a shaker (do not use a sear at this time), and again the sieve amount of the above (average particle size) is 149 after operation - x 3. .11 pass Weigh the amount and calculate the percentage. Also, the average particle size of the material to be measured is 5
For those of about 0μ to 150μ, the corresponding correspondence is indicated by an asterisk.

(Dissolution rate) Pure water in a glass container with a diameter of 135 mm and a height of 1 Elomm
00mj! Thickness 25mm 1112mm length 58
A stirrer with 4 n+n+ stirring blades was rotated at 55 rpm, 200 g of sample was added at once, and 200 g was added every 5 seconds.
Sample the solution in mA increments and measure the time required for the dissolved sodium carbonate concentration to reach 240 g/7I by titration.

Examples will be shown below, but it goes without saying that the present invention is not limited thereto.

Example 1 Typed sodium carbonate and light ash obtained by the ammonia-soda method were simultaneously fed into a mixer in the ratio shown in the m1 table, and while stirring, a spray nozzle was used to add sodium silicate. 0
．． A 7% hot aqueous solution (60°C) was added. As the sodium silicate used here, No. 3 silica was used. At this time, the temperature inside the mixer was adjusted by the opening degree of the damper at the top of the mixer, and the residence time was adjusted by the feed rate of the raw materials to the mixer.

These mixtures were heated in the same manner to a temperature of 18
The average particle size, apparent specific gravity, pulverization rate, and dissolution rate of these sodium carbonates obtained by heating at 0° C. were measured. The results are shown in Table 1.

Example 2 In Example 1, instead of the sodium silicate aqueous solution, 0.2
Sodium carbonate was produced under the same conditions as in Example 1, except that an iyt% CMC warm aqueous solution was used.

The results are shown in Table 1.

Example 3 f11 obtained by carbonation of 48% caustic soda aqueous solution
Thorium carbonate, sodium carbonate hydrate, and sodium carbonate anhydrous salt were mixed in a mixer, and while stirring, a hot aqueous solution of 1.0 uL% sodium silicate (6
Sodium carbonate was produced under the same conditions as in Example 1, except that 35 kg of sodium carbonate (0°C) was used. The results are shown in Table 1.

Table 2 For reference, Table 2 shows a comparison of the physical properties of mold skin and light ash obtained by the conventional ammonia-soda method and sodium carbonate obtained by Example 1 of the method of the present invention.

Table 2

Claims (1)

[Claims] 1. Weight ratio of sodium bicarbonate: sodium carbonate (anhydrous dilution): aqueous solution containing sodium silicate or carboxymethyl cellulose: 0.2-1.5: 0.1-0
．． Adjust the ratio to be 8%, and heat the adjusted product at 40'C~
After homogenization at a temperature of 105-°C, the preparation was
A method for producing sodium carbonate having an apparent specific gravity of 0.4 to m and a dissolution rate in water of 40 seconds or less by calcining at a temperature of 'c to 30°C. 2. The manufacturing method according to claim 1, wherein the concentration of sodium silicate is 0.2 to 10%. 3. Concentration of carboxymethyl cellulose is 0.05-1
% of the manufacturing method according to claim 1.