JPH0348128B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention particularly provides raw materials for synthetic detergents.
The present invention provides an extremely useful and novel method for producing sodium carbonate. 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, in which crude sodium bicarbonate obtained by reacting ammoniacal saturated brine with carbon dioxide gas is heated to a calcining machine outlet temperature of 100°C to 300°C. It is manufactured by calcination at a temperature that 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 heavy ash, is produced by adding water to the light ash obtained by the above manufacturing method. Sodium carbonate-water salt (Na ₂ CO ₃ H ₂ O), and then
It is manufactured by drying it at a temperature such that the outlet temperature of the dryer is 110°C to 170°C. The heavy ash thus obtained generally has an apparent specific gravity of 1 or more and an average particle size in the range of 200μ to 400μ. It is also possible to obtain similar heavy ash by carbonation of 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 light ash or heavy ash was used, sodium carbonate was mixed with other detergent raw materials to form a slurry, and then the mixture was mixed. This method involves simultaneously drying and granulating the slurry using a dryer to obtain a detergent. The main reason why light ash and heavy ash have to be made into a slurry once and sodium carbonate cannot be added after dry granulation is that light ash has a small average particle size, This is because the hardness is low, and because heavy ash has a high apparent specific gravity, it is easy to separate from other synthetic detergent raw materials. In addition, when using light ash and heavy ash dissolved in water, light ash has an extremely small particle size and tends to aggregate and form lumps when added to water, while heavy ash has a low apparent specific gravity. Disadvantages include that it sinks to the bottom due to its large size and that it is necessary to increase the stirring intensity to aid in 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, the present invention uses sodium bicarbonate: sodium carbonate (anhydrous equivalent): sodium silicate or carboxymethyl cellulose (hereinafter referred to as CMC) in a weight ratio.
The ratio of the aqueous solution containing
This is a method for producing sodium carbonate, which has an apparent specific gravity of 0.4 to 0.8 and a dissolution rate in water of 40 seconds or less, by homogenizing at a temperature of 100°C to 300°C. Note that the present invention can be carried out by appropriately mixing crude sodium bicarbonate and sodium carbonate or sodium carbonate hydrate obtained from the ammonia-soda method or the ammonium chloride-soda method as raw materials; in this case, sodium bicarbonate: It is necessary to adjust the weight ratio of sodium carbonate (anhydrous equivalent) to 1:0.2 to 1.5. In addition, sodium bicarbonate, sodium carbonate hydrate, obtained by carbonating a caustic soda solution or carbonating an electrolyte from a diaphragm salt water electrolyzer, or by treating natural soda ash,
Anhydrous sodium carbonate or sodium sesquicarbonate can also be used as appropriate 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 sodium silicate or CMC is 1:0.2-1.5:0.1-0.8, preferably 1:0.3-0. The ratio of 1.5:0.1 to 0.5 is adjusted, and the adjusted product is heated to 40℃ to 105℃, preferably 50℃ to 100℃.
It is to homogenize under the temperature of ℃. Unless this condition is satisfied, the desired sodium carbonate cannot be obtained. For example, if the mixing temperature is less than 40°C, the particle hardness will be weakened, and if it exceeds 105°C, the apparent specific gravity will be different from the target value and will be undesirable. Further, although these reactions usually complete within 10 to 20 minutes after mixing, it is not desirable to use a mixer to stir the mixture too vigorously. 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 the aqueous solution used to a low level, but the total amount of water, that is, the total amount of water as crystal water and the water in the added aqueous solution. It is important that the value be within the above range. Furthermore, if the amount of sodium carbonate-hydrate used is too large, the hardness of the resulting crystals may be slightly reduced. Regarding the effect of adding sodium silicate or CMC, we investigated the effect of adding sodium silicate or CMC to an aqueous solution containing sodium bicarbonate and sodium carbonate.
Sodium carbonate produced without CMC 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, sodium silicate or CMC per 60 parts of sodium bicarbonate.
Add 30 parts of an aqueous solution containing and mix thoroughly for 20 minutes. Since 60 parts of sodium bicarbonate is about 40 parts of sodium carbonate equivalent, the mixing ratio of sodium bicarbonate and sodium carbonate is 1:1 by weight and 2:3 by weight. The same reaction occurs if the ratio of sodium carbonate equivalents is between 2:1 and 1:3 between sodium bicarbonate and sodium carbonate. This mixed substance is heated to a sufficiently high temperature (100℃~
Sodium silicate or
The water to which CMC has been added is dehydrated to obtain the desired sodium carbonate. Further features of the production method of the present invention are:
The reason for this is not confirmed, but the average particle size
Sodium carbonate with an extremely large particle size of 200μ to 600μ can be obtained, and the obtained sodium carbonate has a small apparent specific gravity of 0.4 to 0.8 and a powderization rate (the higher this value, the lower the hardness of the particles). ) is less than 8%, and the dissolution rate in water is less than 40 seconds, which is an unprecedented property. What is even more surprising is that the surface of the particles of the sodium carbonate obtained by the present invention is completely different from that of light ash and heavy ash obtained by conventional methods, and exhibits a state in which rod-shaped crystals are aggregated. In this specification, the values of average particle size, apparent specific gravity, powdering rate and dissolution rate in water for particles with an average particle size of 200 to 600μ are as follows (average particle size), (apparent specific gravity), ( It is determined by the method described in the sections ``Powderization rate'' and ``Dissolution rate'', and the same applies to the Examples and Comparative Examples shown below. (Average particle size) Correctly weigh 100g using a top balance (weighing 200g), and measure the appropriate JIS particle size according to the particle size of the saucer and sample.
Transfer the standard sieve to the top sieve in the stack.
Place the lid on a rotary shaker and shake for 7 minutes, then weigh the residue on the saucer and each sieve using an upper balance (weighing 100 g), and calculate the cumulative percentage of the nominal size μ of each sieve. Calculate,
Nominal size μ of sieve where 50wt% or more
is the average particle size. (Apparent specific gravity) Weigh 50g of the sample, place it in a graduated cylinder with a capacity of 100ml (inner diameter approx. 2.7cm), and pound it thoroughly on a thick rubber plate, being careful not to apply too much force, until the minimum volume of Aml is reached. and calculate the apparent specific gravity using the following formula. Apparent specific gravity = 50 (g)/A (ml) (Powdering rate) The powdering rate of particles with an average particle size of 200 to 600 μm is determined by measuring as follows. That is, from 250
Sieve through 500μ, take 50g of sample, weigh 1g,
Place in an intermediate saucer together with 15 aluminum discs with a diameter of 20 mm, and shake without beating for 5 minutes in a shaker. After completion, the sample in the saucer is sieved again for 7 minutes through a sieve with a mesh size of 149μ, the amount passed through is measured, and the percentage is calculated. For particles whose average particle size is outside the above range of 200 to 600μ, the same procedure is carried out by changing the mesh size of the sieve. For example, those with an average particle size of 50 to 150μ,
The mixture is sieved through a 74-149μ sieve, shaken with an aluminum disk in the same manner as above, and then sieved through a 44μ sieve to determine the percentage. (Dissolution rate) 800ml of pure water in a glass container with a diameter of 135mm and a height of 180mm.
A stirrer with four stirring blades 25 mm thick, 12 mm wide, and 58 mm long was rotated at 550 rpm, 200 g of the sample was added at once, and 2 ml of the solution was sampled every 5 seconds, and dissolved by titration. Sodium carbonate concentration is 240
Measure the time required to reach g/. Examples will be shown below, but it goes without saying that the present invention is not limited thereto. Example 1 Crude sodium bicarbonate and light ash obtained by the ammonia-soda method were simultaneously fed into a mixer in the proportions shown in Table 1, and while stirring, a warm aqueous solution of 0.7% sodium silicate ( 60℃) 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. Each of these mixtures was similarly calcined in a calcining machine at a temperature of 180°C, and the average particle size, apparent specific gravity, powdering rate, and dissolution rate of the sodium carbonate obtained were measured. The results are shown in Table 1. Example 2 Sodium carbonate was produced under the same conditions as in Example 1, except that a 0.2 wt% CMC warm aqueous solution was used in place of the sodium silicate hot aqueous solution. The results are shown in Table 1. Example 3 Sodium bicarbonate, sodium carbonate hydrate, and anhydrous sodium carbonate obtained by carbonation of a 48% aqueous solution of caustic soda were mixed in a mixer, and while stirring, 1.0 wt of sodium silicate was added using a spray nozzle.
Sodium carbonate was produced under the same conditions as in Example 1, except that 35 kg of a warm aqueous solution (60° C.) of 10% was used.
The results are shown in Table 1.

[Table] Reference Example For reference, Table 2 shows a comparison of the physical properties of heavy ash 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】

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Claims (1)

[Claims] 1. Sodium bicarbonate: Sodium carbonate (anhydrous equivalent): Aqueous solution containing sodium silicate or carboxymethyl cellulose in a weight ratio of 1:0.2 to 1.5:
Adjust the ratio to be 0.1 to 0.8, and add the adjusted product.
The apparent specific gravity obtained by homogenizing at a temperature of 40°C to 105°C and then calcining the preparation at a temperature of 100°C to 300°C.
0.4-0.8, a method for producing sodium carbonate whose dissolution rate in water is 40 seconds or less. 2. The manufacturing method according to claim 1, wherein the concentration of sodium silicate is 0.2 to 10%. 3 Concentration of carboxymethylcellulose is 0.05~
1% of the manufacturing method according to claim 1.