JP4435053B2 - Bitter salt removal method - Google Patents

Description

  The present invention relates to a method of freezing bitter juice, which is a remaining mother liquor from which salt has been removed from seawater, and further removing salt (sodium chloride) remaining in the bitter juice.

  Bitter juice contains a wide variety of useful minerals such as magnesium and potassium. In recent years, bitter juice has been focused on its usefulness, such as diet effects, supplementation of insufficient minerals, and efficiency and quality improvement of crop cultivation. It is effectively used in a wide range of fields, such as diluting it for use as a beverage or as an additive for food, cosmetics or agriculture. Here, bitter juice means “mother liquor remaining after boiling and salting seawater”, and its main component is magnesium chloride.

  In particular, bitter juice obtained from deep ocean water is drawing attention. This kind of deep ocean water is collected in Japan mainly off Cape Muroto and Toyama Bay in Kochi Prefecture, and is said to have excellent features such as eutrophication and cleanliness.

  The present applicant manufactures and sells natural salt in Muroto deep sea water, and bitter juice is obtained as a by-product. When this bitter juice is used for food or agriculture, a large amount of salt remains, which is problematic for practical use. That is, if it is used for eating and drinking as it is, it causes high blood pressure, and if it is used for agriculture such as fertilizer, it causes salt damage.

  As a method for removing the salt content from the bitter juice, generally, a method of further removing the salt by concentrating the bitter juice by heat treatment to precipitate the salt content is conceivable. According to this, there are advantages such as easy setting of the concentration factor and salt removal in a short time. However, when heat treatment is performed, potassium and calcium are also reduced, resulting in poor mineral balance, high equipment costs, poor product recovery, and too high Baume (concentration), it is necessary to dilute at the product manufacturing stage. There are disadvantages such as poor usability.

  Therefore, the present inventor has developed a desalination method using a refrigeration method that takes advantage of the property that minerals are precipitated by cooling the bitter juice and changing its temperature. Here, there are Patent Documents 1 and 2 as methods for cooling and desalinating seawater, bitter juice, and the like.

JP 2002-10754 (paragraph numbers 0013 to 0015, Table 2, FIG. 1) Japanese Patent Laid-Open No. 11-32726 (Table 1)

  In Patent Literature 1, bitter juice is cooled and partially frozen, and desalted by separating the frozen portion and the non-frozen solution. However, the frozen part is used here, and salt can be removed, but the content of useful minerals such as magnesium is also lowered accordingly, and the salt content is still higher and the mineral balance is better than other minerals. That's not true. In secondary frozen water, the salinity ratio is further increased. Although it is necessary to separate the frozen portion from the non-frozen water in a cooled state, in Patent Document 1, since the bitter juice is cooled in the freezer, the apparatus is increased in size in order to process a large amount of bitter juice. Cost and running cost are expensive.

  Patent Document 2 discloses a method of cooling bitter juice and collecting magnesium sulfate, but the specific method is unknown, and it is not a method of collecting (desalting) salt (sodium chloride) in the first place.

  Therefore, an object of the present invention is to provide a method for removing salt from bitter juice that can remove salt (sodium chloride) easily and at low cost while leaving each useful mineral contained in the bitter juice.

  In the method for removing salt from bitter juice of the present invention, the bitter juice, which is a mother liquor after the raw seawater has been dried and boiled and salted, is partially frozen while being left standing in a stationary state by a refrigeration apparatus and remains in the bitter juice. The salt is precipitated, and the remaining non-frozen liquid is separated and recovered from the frozen portion in this state.

  The bitter juice is cooled by a direct cooling method using a refrigeration apparatus, and the cooling temperature at that time is set to -25 ° C or lower. A Baume meter is arranged in the freezing apparatus, and when the bitter baume falls below 26 degrees, the unfrozen bitter juice may be recovered from the freezing apparatus. Deep sea water is suitable for the raw seawater.

  According to the salt removal method of the present invention, since the bitter juice is cooled in a stationary state, only the salt is surely precipitated to obtain a bitter juice having a low salt concentration while maintaining a good mineral balance. Although the clear theory is unknown, it is because when the bitter juice is rapidly cooled while stirring, only ice is produced first, and the salt does not precipitate smoothly, and a large amount of salt remains in the non-frozen solution. Moreover, it is because the malfunction that another useful mineral is contained in an ice part can also be avoided.

  Since this bitter juice is cooled directly, the non-frozen liquid can be separated and recovered while the frozen part is frozen while reducing the size of the refrigeration system, eliminating equipment and running costs. It can be purified at low cost. When the cooling temperature is set to −25 ° C. or lower, salt precipitation can be reliably ensured. Although it is difficult to visually check the state of bitter juice such as the amount of ice produced and the amount of salt deposited, a non-frozen liquid can be easily obtained simply by reading the Baume degree by placing a Baume meter on the refrigeration system. It is possible to confirm the separation and recovery time of When bitter juice obtained from deep ocean water is used, cleanliness and eutrophication can be expected as compared to bitter juice obtained from surface seawater.

  The bitter salt removal method according to the present invention is carried out using the apparatus shown in FIG. Specifically, a refrigeration apparatus 1 that uses a heat insulating material on the outer peripheral wall, a refrigerator 2 that cools the bitter juice in the refrigeration apparatus 1, a stock solution tank 3 that supplies undiluted juice into the refrigeration apparatus 1, and a refrigeration apparatus 1 And a recovery tank 4 for recovering a non-freezing liquid that has not been frozen.

  The undiluted juice is supplied from the undiluted solution tank 3 to the freezer 1 through the undiluted solution supply pipe 7, and the free juice in the freezer 1 is cooled to −25 ° C. or lower by the refrigerator 2. A refrigerant pipe 8 connected to the refrigerator 2 is spirally arranged in the refrigeration apparatus 1, and liquid refrigerant sent from the refrigerator 2 is circulated through the refrigerant pipe 8 to directly cool the bitter juice. There are no stirring wings in the refrigeration apparatus 1, and the bitter juice is slowly cooled in a stationary state.

  Accompanying the temperature decrease of the bitter juice, acicular ice begins to adhere around the refrigerant pipe 8, and at the same time, salt gradually precipitates from the lower side of the refrigeration apparatus 1 and begins to become a sherbet. Along with this, the degree of Baume decreases, and when the degree of Baume becomes 26 degrees or less, the non-frozen liquid is collected from the refrigeration apparatus 1 to the collection tank 4 via the collection pipe 9 disposed below the Baume degree. . At this time, a mesh-like metal filter (not shown) is arranged on the inlet side of the collection tube 9 to prevent the mixture of ice and precipitated salt, so that the non-frozen liquid is accurately separated. Can be recovered. Reference numeral 11 is an on-off valve for opening and closing the recovery pipe 9. The stock solution supply pipe 7 is also provided with an on-off valve 12 and a supply pump 13 as necessary.

<< Comparison Test 1 >>
Sodium salt in the demineralized bitter juice obtained by these methods is used to demineralize the bitter juice by a direct cooling method in which the bitter juice is directly cooled in the freezer 1 and a method in which the bitter juice is placed in a container and indirectly cooled in the freezer. The contents of potassium, calcium and magnesium were analyzed by atomic absorption spectrophotometry, ph by glass electrode method, and Baume by Baume meter, respectively. The analysis results are shown in Table 1.
Example 1
The cooling temperature by the 0.75 / Ps refrigerator 2 was set to −25 ° C., 40 liters of bitter juice was introduced into the freezer 1 and gradually cooled from room temperature (20 ° C.) for 7 days. Changes in temperature and Baume degree at this time are shown in FIG. As the raw sea water of bitter juice, the mother liquor remaining after refining the salt from the deep sea water in the pot was used.
(Example 2)
The same amount of bitter juice as in Example 1 was put into the refrigeration apparatus 1 and the cooling temperature by the refrigerator 2 was set to −40 ° C. The non-frozen solution was separated and recovered when the bitter baume became 26 degrees or less. The changes in temperature and Baume degree at this time showed almost the same changes as in Example 1.
(Comparative Example 1)
20 liters of bitter juice was stored in a cubiner, which was frozen for 3 days in a freezer set at −25 ° C., then taken out of the freezer, and the frozen portion and the non-frozen liquid were separated and collected by a centrifuge.
(Comparative Example 2)
The non-frozen liquid collected in Comparative Example 1 was again placed in a cubina and frozen in a freezer at −25 ° C. for 3 days, and the non-frozen liquid was collected in the same manner as in Comparative Example 1.
(Comparative Example 3)
It was made to be the same as that of the comparative example 1 except having made it freeze with a -40 degreeC freezer.
(Comparative Example 4)
It was made to be the same as that of the comparative example 2 except having made it freeze with a -40 degreeC freezer.

  According to FIG. 2, it can be seen that the baume gradually decreases as the temperature decreases, and finally the baume becomes constant at about 25.3 to 25.5 degrees. It can also be seen that if the cooling temperature is −24 ° C. or lower, Baume is 26 ° C. or lower.

  As is clear from Table 1, in Examples 1 and 2 of the direct cooling type, the amount of sodium was almost halved while leaving useful minerals as they were, and salted bitter juice with a good mineral balance was obtained. The reason why minerals other than sodium are increasing in Examples 1 and 2 is that some water is separated as ice and bitter juice is concentrated.

  On the other hand, in each comparative example, it turns out that salt removal is not so much. This can remove the deposited salt, but since the separation with the centrifuge is performed in a room temperature environment outside the freezer, part of the ice melts in the meantime, and at the same time the salt content in the ice also It is thought that it melted.

  Even if the desalted bitter juice once frozen and separated was frozen again, there was no significant difference in the mineral content in the first and second desalted bitter juice. There was no significant difference in the mineral content between the bitter juice frozen at -25 ° C and the bitter juice frozen at -40 ° C. This is considered to be due to the fact that there is no great difference in the amount of precipitated salt and the amount of ice produced even at −40 ° C.

<< Comparison Test 2 >>
Next, demineralized bitter juice that was slowly frozen while standing in a stationary state was compared with demineralized bitter juice that was rapidly cooled while stirring. The analysis items are the same as those in the previous comparative test 1. The analysis results are shown in Table 2.
(Example 3)
40 liters of bitter juice was put into the freezer 1 and the refrigerator 2 was set to −40 ° C., and when the baume became 26 degrees or less, the non-freezing liquid was collected.
(Comparative Example 5)
A stirring blade is installed in the same type of refrigeration apparatus as in Example 3, and the same process as in Example 3 is performed except that the bitter juice is rapidly cooled while stirring. Was also carried out in parallel at the same timing as in Example 3.

  As is clear from Table 2, it can be seen that in Comparative Example 5 in which stirring and quenching were carried out, salt removal was not so much. This is mainly due to the fact that only water was first frozen during freezing and the salt did not precipitate smoothly. Moreover, since other minerals also have a low value compared to Example 3, it can be seen that useful minerals are taken into ice by stirring.

Schematic diagram of bitter refrigeration equipment used in the present invention Chart showing changes in temperature and baume when freezing bitter juice

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigeration equipment 2 Refrigerator 3 Stock solution tank 4 Collection tank 8 Refrigerant pipe

Claims (2)

Bitter juice, the mother liquor after the raw seawater has been dried and boiled and salted, is partially frozen while slowly cooled in a stationary state by a freezing device to precipitate the salt remaining in the bitter juice, and the remaining non-frozen solution In the method for removing salt from bitter juice by removing salt from the frozen portion ,
The cooling of the bitter juice by the refrigeration apparatus is performed by a direct cooling method,
The cooling temperature of the bitter juice is set to −25 ° C. or lower,
A method for removing salt from bitter juice, characterized in that a baume meter is arranged in the freezer, and when the bitter baume falls below 26 degrees, the unfrozen bitter juice is recovered from the freezer.   The method for removing salt from bitter juice according to claim 1, wherein the raw sea water is deep sea water.

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