JP2005239455A - Production method for sodium chloride particulate excellent in caking prevention effect - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method for sodium chloride particulates (with an average particle size of 50 μm or less) excellent in caking prevention effect. <P>SOLUTION: The production method for sodium chloride having an average particle size of 50 μm or less has a step wherein a ferrocyanide solution is sprayed on and mixed with sodium chloride having an average particle size of 100-2,000 μm and the resultant mixture is pulverized. Otherwise, the production method for sodium chloride having an average particle size of 50 μm or less has a step wherein a ferrocyanide solution is sprayed on and mixed with sodium chloride having an average particle size of 100-2,000 μm and then sodium chloride having an average particle size of 100-2,000 μm is further added and mixed and a step for pulverizing the resultant mixture. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing fine-particle sodium chloride, which has an excellent anti-caking effect and has little variation in caking strength.

  Sodium chloride repeatedly absorbs and releases moisture at the surface of the crystal when the temperature and humidity in the storage environment change, absorbs moisture at high humidity and dissolves the crystal surface, and moisture crystallizes at low humidity. It is known that a salt microcrystal is newly released from the surface and released, and the precipitated microcrystal is solidified by crosslinking between the crystals. (Refer nonpatent literature 1). The environmental humidity at the boundary where the phenomenon of moisture absorption and desorption on the crystal surface at 25 ° C is switched is 75% relative humidity (hereinafter referred to as 75% RH). In Japan, the relative humidity is above and below this relative humidity. doing. For this reason, the caking phenomenon of sodium chloride is often observed. Also, this phenomenon tends to occur earlier and more firmly as the particles become smaller. Since the commercial property of sodium chloride is impaired when solidification occurs, various anti-caking means have been proposed so far, and the development of microparticle sodium chloride that does not solidify has been desired.

  Examples of anti-caking means include addition of substances that have an effect of preventing contact such as basic magnesium carbonate and fine silicon dioxide (see Patent Document 1), and addition of substances that have a humidity-controlling effect such as magnesium chloride and calcium chloride. Addition of hygroscopic substances such as magnesium sulfate (see Patent Document 2), silica gel and disodium hydrogen phosphate, inhibits crystal growth of salts such as ferrocyanide and ammonium iron citrate, and refines them The addition of a substance exhibiting a crystallizing action has been proposed, and some of them are actually used.

Ferrocyanide, in particular, has a great effect in a small amount, but until recently it was not approved as a food additive in Japan. However, in July 2002, the standard of use was 20 ppm or less (concentration in terms of sodium salt: all ferrocyanides below) The concentration was determined in terms of sodium salt) and was approved for use as a food additive. However, since fine particle sodium chloride has a large surface area and strong caking action, even if the ferrocyanide solution is sprayed on the fine particle sodium chloride so that it is 20 ppm or less, which is the above-mentioned standard of use, it has an anti-caking effect. It was insufficient. That is, when high-concentration ferrocyanide solution is sprayed on fine particle sodium chloride, due to the absolute lack of water, some of them are lumpy and others are not in contact with the ferrocyanide solution and are not evenly dispersed. Spraying a ferrocyanide solution at a concentration increases the water fraction and, moreover, makes it easier for sodium chloride to dissolve in the ferrocyanide solution, resulting in a sticky sodium chloride. Thus, the manufacturing method of the fine particle sodium chloride with the caking prevention effect by using a ferrocyanide is not clarified.
JP-A-5-229815 JP 63-109755 A DW KAUFMANN Edi. Director of Salt Science Research Foundation; “Sodium Chloride”, 468 (1993)

  An object of this invention is to provide the manufacturing method of the fine particle sodium chloride which has the outstanding caking prevention effect.

  As a result of intensive studies in view of the above-mentioned problems of the prior art, the inventor sprayed a ferrocyanide solution onto sodium chloride having a specific average particle diameter, and pulverized this sodium chloride to prevent caking. It was found that sodium chloride having an average particle size of 50 μm or less could be produced, and the present invention was completed.

That is, this invention provides the following manufacturing method and sodium chloride.
Item 1. A method for producing sodium chloride having an average particle size of 50 μm or less, comprising the steps of spraying and mixing a ferrocyanide solution on sodium chloride having an average particle size of 100 to 2000 μm and pulverizing the mixture.
Item 2. A step of spraying and mixing a ferrocyanide solution on sodium chloride having an average particle size of 100 to 2000 μm, mixing and further adding sodium chloride having an average particle size of 100 to 2000 μm to the mixture, and a step of pulverizing the resulting mixture A method for producing sodium chloride having an average particle size of 50 μm or less.
Item 3. Item 3. The method for producing sodium chloride according to Item 1 or 2, wherein the amount of the ferrocyanide solution is 0.1 to 3% by weight of the sprayed sodium chloride.
Item 4. Item 4. Sodium chloride having an average particle size of 50 μm or less produced by the production method according to any one of items 1 to 3.

  The production method of the present invention is characterized by having a step of spraying and mixing a ferrocyanide solution on sodium chloride having an average particle diameter of 100 to 2000 μm and pulverizing the mixture.

  Further, the production method of the present invention is a step of spraying and mixing a ferrocyanide solution to sodium chloride having an average particle size of 100 to 2000 μm, further adding sodium chloride having an average particle size of 100 to 2000 μm to the mixture, and mixing the mixture. And crushing the resulting mixture.

  In the present specification, “fine particle sodium chloride” refers to sodium chloride having an average particle diameter of about 0.1 to 50 μm.

  It is important that the average particle diameter of sodium chloride sprayed with the ferrocyanide solution is about 100 to 2000 μm. By making the average particle diameter of sodium chloride sprayed with the ferrocyanide solution within the above range, fine particle sodium chloride having excellent anti-caking effect and less variation in caking strength can be produced. More preferably, the particle size is about 300 to 1000 μm.

Ferrocyanides sprayed onto sodium chloride include potassium ferrocyanide (K ₄ [Fe (CN) ₆ ] · 3H ₂ O), sodium ferrocyanide (Na ₄ [Fe (CN) ₆ ] · 10H ₂ O), Calcium Russianide (Ca ₂ [Fe (CN) ₆ ] · 12H ₂ O) or the like can be used. Preference is given to potassium ferrocyanide and sodium ferrocyanide. The ferrocyanide solution is preferably an aqueous ferrocyanide solution. The amount of ferrocyanide solution sprayed is preferably such that the amount of ferrocyanide adhering to sodium chloride mixed after spraying is about 1 to 10000 ppm, preferably about 1 to 1000 ppm relative to sodium chloride. More preferred. In addition, in this specification, the density | concentration of ferrocyanide is shown by the value converted into sodium ferrocyanide.

  The amount by which the spray amount of the ferrocyanide solution is 0.1 to 3% by weight with respect to sodium chloride is preferred, and the amount that is 0.1 to 1% by weight is more preferred.

  As a method of spraying the ferrocyanide solution, a method of spraying using a spray, an electric sprayer or the like can be used. Other spraying conditions (temperature, etc.) follow the usual method.

  Sodium chloride sprayed with the ferrocyanide solution is mixed by a known method such as a kneader mixer or a drum mixer. The mixed sodium chloride is dried as necessary. When the amount of water added by spraying is small, there is no need to provide a drying step. In the case of drying, it is dried by a known method using a fluid dryer, a shelf dryer or the like.

  If necessary, sodium chloride having an average particle size of 100 to 2000 μm is added to and mixed with the obtained dried product. Hereinafter, this mixing step may be referred to as trituration. Here, the particle diameter of sodium chloride to be added is preferably about the same as that of sodium chloride to which ferrocyanide is attached. For example, the average particle size of sodium chloride to be added is preferably about 0.2 to 2 times, preferably about 0.5 to 1.5 times the average particle size of sodium chloride to which ferrocyanide is attached. Furthermore, it is desirable to be in the range of 300 to 1000 μm.

  Here, the amount of sodium chloride to be added is about 1 to 1000 times, preferably about 10 to 100 times the weight of sodium chloride to which ferrocyanide is attached. When determining the amount of sodium chloride to be added, the ferrocyanide concentration of sodium chloride to which ferrocyanide is added is measured, and the ferrocyanide concentration of fine particle sodium chloride obtained after addition of sodium chloride is desired. The theoretical amount to be the concentration can be used as the sodium chloride addition amount. For example, when the ferrocyanide concentration of sodium chloride to which ferrocyanide is added is 500 ppm, if it is attempted to produce fine particle sodium chloride having a ferrocyanide concentration of 20 ppm, the concentration of sodium chloride to which ferrocyanide has been added is 24. A double amount of sodium chloride may be added.

  The ferrocyanide concentration is measured by measuring the absorbance of ferric ferrocyanide formed by dissolving sodium ferritide adsorbed with ferrocyanide in water and adding an iron (II) sulfate reagent to this solution. Can be determined by

  Next, the dried product obtained by drying or the mixture obtained by trituration is pulverized to a fine particle size. The method of pulverization is not particularly limited, and for example, a method of pulverization using a classification pulverizer, a hammer pulverizer or the like can be employed. When producing microparticles having an average particle size of 20 μm or less, it is preferable to use a classification pulverizer.

  In addition, trituration is advantageous because it is industrially inexpensive and can quickly produce sodium chloride of the desired ferrocyanide concentration. For example, a case where 10000 kg of sodium chloride having a ferrocyanide concentration of 20 ppm is produced using a mixer and dryer having a maximum capacity of 1000 kg of sodium chloride will be compared below.

No doubling (Method A):
A ferrocyanide aqueous solution is sprayed on sodium chloride so that the ferrocyanide concentration is 20 ppm, mixed and dried, and finally pulverized to produce 20 ppm of sodium chloride. In this case, since the capacity of the mixer and the dryer is 1000 kg of sodium chloride, in order to produce 10000 kg of sodium chloride, the spraying process, the mixing process and the drying process are repeated 10 times in total.

With doubling (Method B):
After spraying ferrocyanide aqueous solution to 400 kg of sodium chloride so that the ferrocyanide concentration becomes 500 ppm, mixing and drying, 40 kg of 1000 kg of the obtained dried product is put into a mixer, and further 24 times amount of sodium chloride is added. And mixed (doubled), and then pulverized to produce 1000 kg of 20 ppm sodium chloride. Thereafter, similarly, the process of triturating 40 kg of the dried product is repeated 9 times to produce 10000 kg of sodium chloride.

  Comparing the above methods A and B, the method A requires 10 spray mixing steps, the drying step 10 times and the pulverization step 10 times. In the method B, the spray mixing step 1 time, the drying step 1 time, and the times 10 dispersion steps and 10 grinding steps are required. In general, the drying process is a process in which the fuel cost is increased, and rebounds on the cost. For this reason, the method B (doubled) with fewer drying steps is advantageous in terms of cost.

  Next, it will be explained below that trituration can quickly produce sodium chloride of the desired ferrocyanide concentration. For example, suppose a case in which 5000 kg of sodium chloride having a ferrocyanide concentration of 100 ppm and 5000 kg of sodium chloride having a ferrocyanide concentration of 10 ppm are produced using a mixer and dryer having a maximum capacity of 1000 kg of sodium chloride. In Method A (no trituration), 1000 kg of 100 ppm sodium chloride is produced, and this is repeated to produce 5000 kg of 100 ppm sodium chloride. Similarly, 1000 kg of sodium chloride of 10 ppm is manufactured and manufactured to 5000 kg. In Method B (with trituration), 400 kg of 500 ppm sodium chloride is produced by spraying, mixing and drying, and 40 kg of this is triturated with 24 times the amount of sodium chloride to produce 1000 kg of 100 ppm sodium chloride. To produce 5000 kg of sodium chloride. For 10 ppm sodium chloride, 5000 kg of sodium chloride is produced by repeating trituration five times.

  Comparing method A and method B, the method A requires 5 spray mixing steps, 5 drying steps and 5 pulverization steps to produce each concentration of sodium chloride. The process 10 times, the drying process 10 times, and the pulverization process 10 times are required. In the method B, since the trituration process is repeated, the spray mixing process and the drying process only need to be performed once. 1 time, drying process 1 time, trituration process 10 times and grinding process 10 times are required.

  Also in this comparison, the method B with fewer drying steps is advantageous in terms of cost. Furthermore, spraying, mixing, and drying produce sodium chloride with a high ferrocyanide concentration and stock it, so that if there is a demand for sodium chloride with various ferrocyanide concentrations, It is advantageous to be able to produce various concentrations of sodium chloride quickly (only by trituration and grinding steps).

  Thus, the manufacturing method which has a trituration process is advantageous at manufacturing cost and quickness.

  Sodium chloride produced by the production method of the present invention is sodium chloride having an average particle size of about 0.1 to 50 μm, preferably about 10 to 50 μm, and preventing caking. Since the production method of the present invention can produce sodium chloride having a ferrocyanide concentration of 20 ppm or less, sodium chloride having a ferrocyanide concentration of 20 ppm or less produced according to the present invention is edible chloride such as salt. It can be used as sodium.

  According to the production method of the present invention, sodium chloride having an average particle size of 50 μm or less, in which consolidation is suppressed, can be produced. Further, the production method of the present invention can produce sodium chloride having an average particle size of 50 μm or less with little variation in consolidation strength. The fine particle sodium chloride obtained by the production method of the present invention can be advantageously used as edible sodium chloride because caking is suppressed even when the ferrocyanide concentration is 20 ppm or less.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Example 1
500 g of sodium chloride having an average particle size of about 450 μm was placed in a plastic bag, and an aqueous potassium ferrocyanide solution was sprayed (about 30 mL capacity) in the concentration and amount shown in Table 1 and mixed well. In the control (sample 6), only water was sprayed. The obtained ferrocyanide-added sodium chloride was pulverized with a hammer-type pulverizer (Bantam Mill AP-1, manufactured by Hosokawa Micron Corporation) so that the average particle size was about 20 to 30 μm. The ferrocyanide concentration in the obtained sodium chloride was measured by the method shown below.
<Creation of calibration curve>
(Create a calibration curve)
About 0.2 g of potassium ferrocyanide trihydrate is weighed accurately, and water is added to make exactly 100 mL to make a standard stock solution. Weigh accurately 5 mL of this stock solution and make exactly 100 mL with water to make a standard solution. (1 mL of this solution contains about 50 μg of ferrocyanic ions). 2.5 g of sodium chloride is weighed in each of three 50 mL volumetric flasks, 40 mL of water is added and dissolved, and 0, 600, and 2000 μL of standard solutions are added thereto, and 2.5 mL of iron (II) sulfate test solution is further added. Make exactly 50 mL with water. Shake well and let stand for 30 minutes to make a standard solution for calibration curve. (The standard solution 1 mL for the calibration curve contains 0, 0.6, and 2 μg of ferrocyan ions, respectively).
<Sample preparation>
About 5 g of a sample is accurately weighed into a 100 mL volumetric flask and dissolved by adding 80 mL of water. To this is added 5 mL of iron (II) sulfate reagent solution, and water is added to make exactly 100 mL. After shaking well, leave for 30 minutes to make a sample for absorbance measurement.
<Measurement method>
Each standard curve standard solution is placed in a cell with an optical path length of 50 mm, and the absorbance at a wavelength of 720 nm is measured with a spectrophotometer using water as a control. Similarly, the absorbance of the sample solution is measured, and the ferrocyan ion concentration in the sample solution is determined from the calibration curve.
<Calculation method>
Ferrocyan ion content (mg / kg) = C x 100 / W
C: Ferrocyan ion concentration (μg / mL) in the sample solution
W: Amount of sample collected (g)

Sodium ferrocyanide (mg / kg) = ferrocyanic ion content (mg / kg) × 1.43
<Reagent>
Iron (II) sulfate test solution: 3 g of iron (II) sulfate heptahydrate is dissolved in 80 mL of water, 1 mL of sulfuric acid is added, and the mixture is accurately made up to 100 mL with water. This solution is prepared at the time of use.

比較例１
平均粒径が約２０〜３０μｍの塩化ナトリウム５００ｇをポリ袋に入れ、表２に示した濃度及び量でフェロシアン化カリウム水溶液をスプレーで噴霧し、よく混合した。なお、コントロール（試料12）では水のみを噴霧した。得られた塩化ナトリウム中のフェロシアン化物濃度を実施例１と同様な方法で測定した。

Comparative Example 1
500 g of sodium chloride having an average particle size of about 20 to 30 μm was put in a plastic bag, and an aqueous potassium ferrocyanide solution was sprayed at a concentration and amount shown in Table 2 and mixed well. In the control (sample 12), only water was sprayed. The ferrocyanide concentration in the obtained sodium chloride was measured by the same method as in Example 1.

Test Example 1: Measurement of consolidated strength The consolidated strength was measured for the samples (n = 5) produced in Example 1 and Comparative Example 1. Table 3 shows the measurement results. The measurement method is as follows. 4 g of the sample is put into a 25 mL polystyrene stick bottle (manufactured by Inoue Seieido: cylindrical plastic container, height 5.8 cm, diameter 2.8 cm), and a powder reduction measuring instrument (TPM-1-P, Tsutsui Riken Instrument Co., Ltd.) (Made by company) 100 times, 40 ° C., 75% R.D. H. For 3 days, a sample having a diameter of about 2.1 cm and a thickness of about 1 cm was prepared. The strength of the sample was measured with a particle strength measuring device (Grano, manufactured by Okada Seiko Co., Ltd.), and the consolidation strength was calculated from the following equation (p: peak value, π: circumference, D: thickness). Table 3 shows the consolidation strength.

Consolidation strength = 4p / (π × D ² )

平均値の比較より、フェロシアン化物添加量が同じであれば、本発明の微小粒子塩化ナトリウムの方が固結防止力が強い（固結強度が小さい）ことが確認できる。このため、同じ固結防止力の微小粒子塩化ナトリウムを得るのに必要なフェロシアン化物量は、本発明の方が少なくてすむ。また、標準偏差の比較より、本発明の微小粒子塩化ナトリウムの方が固結防止力のばらつきの小さい、すなわちより均質な微小粒子となっていることが確認できる。

From the comparison of the average values, if the ferrocyanide addition amount is the same, it can be confirmed that the fine particle sodium chloride of the present invention has a stronger anti-caking force (lower caking strength). For this reason, the amount of ferrocyanide necessary for obtaining fine particle sodium chloride having the same anti-caking force is smaller in the present invention. Further, from the comparison of standard deviations, it can be confirmed that the fine particle sodium chloride of the present invention has smaller variation in anti-caking force, that is, more uniform fine particles.

Example 2
500 g of sodium chloride having an average particle diameter of about 450 μm was put in a plastic bag, and an aqueous potassium ferrocyanide solution was sprayed at a concentration and amount shown in Table 4 and mixed well. Samples 21 to 25 were dried at 80 ° C. for 2 hours in order to keep the moisture content between the samples constant. The ferrocyanide concentration of these dried products was measured in the same manner as in Example 1. The obtained ferrocyanide-added sodium chloride has an amount of sodium chloride having an average particle diameter of 450 μm that is close to the theoretical amount of the additive amount shown in Table 1 (the target ferrocyanide concentration (measured concentration of sample 21 is 12 ppm)). ) And mixed, and pulverized with a hammer-type pulverizer so that the average particle size is about 20 to 30 μm. The ferrocyanide concentration in the obtained sodium chloride was measured by the same method as in Example 1.

Comparative Example 2
Sample 26: Ferrocyanide-free sodium chloride 500 g of sodium chloride having an average particle size of about 450 μm was pulverized with a hammer-type pulverizer so that the average particle size was about 20 μm. The obtained sample is designated as Sample 26.
Sample 27: Sodium phosphate added with calcium phosphate To 500 g of sodium chloride having an average particle diameter of about 450 μm, 2% by weight of calcium phosphate, which is generally used as an anti-caking agent, is added and mixed. The sample was pulverized with a hammer type pulverizer under the same conditions as the sample 26, but the average particle size of the obtained particles was about 15 μm, which was slightly smaller. The obtained sample is designated as Sample 27.

Test example 2
The consolidation strength of Samples 21 to 27 produced in Example 2 and Comparative Example 2 was calculated in the same manner as in Test Example 1. The results are shown in Table 5.

Claims (4)

  A method for producing sodium chloride having an average particle size of 50 μm or less, comprising the steps of spraying and mixing a ferrocyanide solution on sodium chloride having an average particle size of 100 to 2000 μm and pulverizing the mixture.   Spraying and mixing ferrocyanide solution into sodium chloride having an average particle diameter of 100 to 2000 μm, further adding sodium chloride having an average particle diameter of 100 to 2000 μm to the mixture, and mixing the obtained mixture, and pulverizing the resulting mixture A method for producing sodium chloride having an average particle size of 50 μm or less.   The method for producing sodium chloride according to claim 1 or 2, wherein the amount of the ferrocyanide solution is 0.1 to 3% by weight of the sodium chloride to be sprayed.   Sodium chloride having an average particle size of 50 µm or less, produced by the production method according to any one of claims 1 to 3.