JP3890512B2 - Spherical salt and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spherical salt mainly composed of sodium chloride or potassium chloride and a method for producing the same.
[0002]
[Prior art]
All naturally exposed rock salts, solar salts or salts produced by the ion exchange membrane method are usually cubic. Depending on the application, a salt with good fluidity is required for ease of use, and the fluidity of the salt is considered to be determined by the moisture on the crystal particle surface and the contact area between the crystal particles. The dry salt is better than the wet salt, the larger particles are smaller than the small particles, the particle size distribution is more uniform than the non-uniform, and the cubic shape is more fluid and less consolidated than the cubic crystals. It can be said to be salt. However, when a constant particle size and particle size distribution are required at a constant atmospheric temperature and humidity, the spherical salt that is in contact between the points becomes a freer salt than the cubic crystal that is in contact between the surfaces. It is clear that the fluidity is small and the fluidity is excellent. Therefore, various methods for producing spherical salts have been tried.
Conventionally, a method for producing a granular salt obtained by collecting and agglomerating a large amount of fine salt, or a spherical salt of monolithic particles from a supersaturated aqueous solution of sodium chloride (Japanese Patent Laid-Open No. 2-83002) is known. Is an aggregate of porous grains and is bulky, and the latter has a problem of poor productivity and lacks economic efficiency.
[0003]
[Means for solving problems]
As a result of diligent research, the present inventors have found a phenomenon in which melted spheroids are formed by high-temperature treatment of commercially available sodium chloride or potassium chloride particles under specific conditions, and the present invention has been completed. That is, in the present invention, sodium chloride or potassium chloride particles are brought into contact with a high-temperature flame or high-temperature gas in a suspended state for a short time at 1000 to 1300 ° C, and spheroidized by the surface tension of the particles simultaneously with partial dissolution. A spherical salt having a particle diameter of 0.01 to 1.0 mm, which is a particle close to a true sphere obtained by solidification, and a method for producing the same are provided.
[0004]
When trying to produce a spherical salt with a particle size of 0.01 mm or less, if the raw material particles are fine, it is difficult to disperse them completely in a flame or high-temperature gas, and the particle size increases due to contact between the molten particles. It tends to be a spherical salt with a larger particle size than the target. In order to prevent this, it is necessary to put raw material salt in small quantities in the flame or high-temperature gas, and there is a defect that is not economical. Conversely, when trying to produce a spherical salt with a particle size of 1.0 mm or more, contact the raw material particles with a particle size of 1.0 mm or more with a hotter flame or hot gas, It is necessary to make the contact time long, and steam generation due to salt vaporization is severe, and there is a limit in equipment technology.
[0005]
The details of the spherical salt of the present invention and the production method thereof will be described with reference to the production apparatus shown in FIG. The fuel for forming the flame or the high-temperature gas may be liquid fuel or gaseous fuel, but the fuel that is as clean as possible is required, and the gaseous fuel 3 such as natural gas, LPG, or butane gas is preferably used. At the same time, air 2 is blown into the salt supply pipe 1 at high pressure to assist combustion, and the temperature of the flame 6 inside the furnace body 5 or the hot gas 7 is maintained at 1000 to 1300 ° C., and the salt of the raw material fed pneumatically The particles are fed into the center of the hot flame through the salt supply pipe 1. It takes about 0.1 second for the salt particles to be exposed to the flame 6 or the high temperature gas 7 in a floating state. When the contact time is insufficient, the yield of the spherical salt is poor and a relatively small particle size, for example, A spherical salt of about 0.01 to 0.1 mm is obtained. Even when the temperature of the flame or hot gas is 800 ° C. or lower, only salt particles having the same particle size can be obtained.
[0006]
The degree of formation of such a spherical salt is almost the same with sodium chloride or potassium chloride, but in the case of a mixed salt consisting of sodium chloride and potassium chloride, the melting point is 680 to 750 ° C compared to a single cubic crystal. The yield of spherical salt tends to be slightly better.
It is stored in the first collection container 8 for recovering spheroidized salt particles treated with a flame or high temperature gas. Further, among the salt particles, those having a relatively small particle diameter are cooled to about 100 ° C. by blowing cooling air 10 into the transfer pipe 4, and collected by the back filter 12 through the cyclone 11. Spherical salt of about 0.05 mm or less is collected in the lower second collection container 9.
The structure of the furnace body 5 may be a horizontal type or a vertical type, but may be appropriately selected depending on the desired particle size of the spheroidized salt.
[0007]
[Action]
By bringing sodium chloride or potassium chloride particles into contact with a combustion burner flame or high-temperature gas in a floating state at a temperature of 1000 to 1300 ° C for a short time , spheroidization progresses due to the partial melting of the salt particles and the surface tension of the particles. The cooled and solidified salt particles can produce single particles having a glass-like particle size of 0.01 to 1.0 mm, which is close to a true sphere. When producing a spherical salt with a particle size of 0.01 mm or less, if the raw material particles are fine, it is difficult to completely disperse them in a flame or high-temperature gas. It tends to be a spherical salt with a larger particle size. Conversely, when trying to produce a spherical salt with a particle size of 1.0 mm or more, the raw material salt particles with a particle size of 1.0 mm or more are brought into contact with a hotter flame or hot gas, or the salt particle flame and hot gas are in contact with each other. The contact time needs to be long. In the granular salt produced by collecting and aggregating fine salt found in the prior art, a porous body containing a binder component is formed, but the spherical salt obtained by the present invention is a crystal grain having a specific particle size. Is melted or semi-molten and spheroidized, and the purity is maintained at the salt purity of the raw material, and a spherical salt composed of a monolithic single structure is formed. The spherical salt of the present invention has almost no voids inside the particle, the particle surface has smoothness, and has a bead shape close to a true sphere.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to examples.
[0009]
[Example 1]
Using a burner using butane gas 3 and high-pressure air 2 as fuel, the flame temperature inside the furnace 5 is maintained at 1,000 ° C., and then commercial sodium chloride particles are blown into the center of the flame 6 through the salt supply pipe 1. . The spheroidized sodium chloride particles were stored in the first collection container 8 at the bottom of the furnace body 5. Among the obtained salt particles, small particles having a particle diameter of 0.01 to 0.3 mm are spheroidized, and large particles having a particle diameter of 0.3 to 0.5 mm are rounded and spheroidized.
[0010]
[Example 2]
Using the same equipment as in Example 1, with the burner using butane gas as the fuel, the flame temperature inside the furnace was kept at 1,300 ° C, and then commercial sodium chloride granules were placed in the center of the flame through a salt supply pipe. Infuse. Spherical sodium chloride particles were taken out from the lower part of the furnace body. The particles obtained were all relatively small particles of 0.2 to 0.5 mm, and large particles of 0.5 to 1.0 mm were almost spheroidized.
[0011]
[Example 3]
Similarly, after maintaining the flame temperature inside the furnace body at 1,200 ° C with a burner using butane gas as fuel, commercial potassium chloride granules are blown into the center of the flame through a salt supply pipe. Spherical potassium chloride was taken out from the lower part of the furnace body. Of the obtained salt particles, those with a particle size of 0.1 to 0.5 mm were all spheroidized, and most of those with a particle size of 0.5 to 1.0 mm were spheroidized.
[0012]
[Comparative Example 1]
With a burner using butane gas as the fuel, the flame temperature inside the furnace is set to 750 ° C, and finely crushed sodium chloride particles are blown into the center of the flame through a salt supply pipe. Spherical sodium chloride was taken out from the lower part of the furnace and from the cyclone. Among the collected particles, small particles having a particle size of 0.01 to 0.10 mm were spheroidized, but relatively large particles of about 0.1 to 0.2 mm were insufficiently spheroidized.
[0013]
【The invention's effect】
The manufacturing method of the present invention in which particles of sodium chloride or potassium chloride salt are brought into spheroidization by bringing them into contact with a high-temperature flame or high-temperature gas in a suspended state is excellent in practicality and economy, and the obtained spherical shape. The application range of salt is wide.
In addition, the spherical salt obtained by this method is not a surface contact that comes from tetragonal crystals like conventional salts, but because the particles are in point contact with each other due to the spherical shape, the touch is smooth and fluid. It became clear that it became an excellent salt.
The spherical salt of the present invention is hard to consolidate even in a high humidity atmosphere, and it is easy to use as a table salt for seasonings, and when used for funerals, it is free flowing, so it is easy to wipe off, Does not stain clothes.
[Brief description of the drawings]
FIG. 1 shows an apparatus for producing a spherical salt of the present invention.
2 is a photomicrograph of the particle structure of the spherical salt obtained in Example 1. FIG.
3 is a photomicrograph of the particle structure of the spherical salt obtained in Example 2. FIG.
4 is a photomicrograph of the particle structure of the spherical salt obtained in Example 3. FIG.
5 is a photomicrograph of the particle structure of the spherical salt obtained in Comparative Example 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Salt supply pipe 2 Air 3 Fuel gas 4 Transfer pipe 5 Furnace 6 Flame 7 Hot gas 8 1st collector 9 2nd collector 10 Cooling air 11 Cyclone 12 Bag filter

Claims (2)

A spherical salt having a particle size of 0.01 to 1.0 mm, in which particles of sodium chloride and / or potassium chloride are floated in contact with a flame of a combustion burner or a high-temperature gas at 1000 to 1300 ° C. in a floating state. Sodium chloride and / or particles of potassium chloride into a flame or hot gas burner in suspension, are contacted with 1000 ~ 1300 ° C., producing spherical salt particle size 0.01~1.0mm characterized by melting spheroidizing Method.

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