JPH11207151A - Method for separating minerals in solution - Google Patents

Abstract

(57) [Object] To reduce the amount of Na ions and Cl ions remaining in a solution containing monovalent ions and polyvalent ions. SOLUTION: A solution 1 to be separated, which is wet-oxidized urine,
Monovalent ions such as Na, K, Cl and Ca, Mg, S
Polyvalent ions such as O ₄ and PO ₄ are contained as mineral components. The solution 1 to be separated is mixed with a solid or an aqueous solution of KCl 2 in a mixing tank 3. The solution 1 to be separated in the mixing tank 3 is supplied to an electrodialysis device 4 and, by electrodialysis,
It is separated into a desalted solution 5 from which monovalent ions have been removed and a monovalent ion concentrate 6. If KCl is added to increase the amount of K remaining in the desalted solution, the limit monovalent cation concentration at which multivalent ion permeation starts can be reduced as compared to before KCl addition. As a result, the amount of Na remaining after electrodialysis is reduced, and at the same time, Cl ions are reduced in order to satisfy the electrically neutral condition in the solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for separating minerals, and more particularly to a method for separating minerals suitable for establishing material recycling in a closed system.

[0002]

2. Description of the Related Art Monovalent ions such as Na, K and Cl, and C
a, a method for separating and recovering NaCl required for human survival and ions required for plant growth from a solution (for example, human urine) containing multivalent ions such as Mg, SO ₄ , and PO ₄ as a mineral component For example, Japanese Unexamined Patent Application Publication No. 7-39728 discloses a method.

[0003]

In the prior art, since the solution to be separated is subjected to electrodialysis as it is, for example, monovalent cations are excessive in comparison with monovalent anions, such as human urine. In the case where minerals are separated and recovered from a solution having a large amount of Na ions as compared with K ions, the following problems occur. First, a large amount of Na ions and Cl ions remain in a solution to be separated after electrodialysis (hereinafter, referred to as a desalted solution). Where Na
If electrodialysis is continued for a long time so as not to leave Cl and Cl, divalent ions are removed together with monovalent ions (FIG. 10). Second, the monovalent ion concentrate generated by electrodialysis contains K ions necessary for plant growth, and is extracted in the form of KCl by temperature difference crystallization.

In a closed system, a desalted solution obtained by removing monovalent ions from urine is usually used as it is as a nutrient solution for plant cultivation. However, when a large amount of Na ions and Cl ions are present in the desalted solution, salt damage is caused. However, in a desalinated solution from which divalent ions have been removed by excessive electrodialysis,
Mineral components such as Ca, Mg, S, and P, which are indispensable for plant growth, are deficient. In order to recycle K ions, which are extracted as KCl and are essential minerals for plant growth, to plant cultivation without causing salt damage, a complex process for separating K ions and Cl ions is required. Is needed.

An object of the present invention is to provide a method for recovering minerals in a solution that can reduce the amount of Na ions and Cl ions remaining in a solution containing monovalent ions and polyvalent ions.

[0006]

A first aspect of the present invention for achieving the above object is as follows.
A feature of the invention is a method for separating minerals in a solution containing monovalent ions and polyvalent ions as a mineral component by electrodialysis of the monovalent ions and the polyvalent ions, wherein KCl is contained in the solution. And electrodialysis as described above. Na, K, C as monovalent ions
and polyvalent ions such as Ca, Mg, S
O ₄ , PO ₄ and the like.

When Na and K are permeated by electrodialysis using a monovalent cation selective permeable membrane, K has higher permeability to polyvalent ions than Na. In other words, if Na is used, K easily penetrates the membrane selectively, even under conditions where polyvalent ions are present in a relatively large amount, so that multivalent ions permeate the membrane. Therefore, if KCl is added to increase the amount of K remaining in the desalted solution, the limit monovalent cation concentration at which multivalent ions start to permeate can be reduced as compared to before KCl addition. In the electrodialysis method used in the present invention using a monovalent cation-selective permeable membrane and a monovalent anion-selective permeable membrane, the amount of residual monovalent cations such as Na after electrodialysis is reduced. In order to satisfy the electric neutral condition in the solution, a monovalent anion, that is, Cl ion corresponding to the decrease in the residual amount of the monovalent cation passes through the monovalent anion-selective permeable membrane. The amount of monovalent ions remaining after dialysis can be reduced.

[0008] The features of the second invention for achieving the above object are as follows.
The monovalent ions and the polyvalent ions in the solution containing a valence ion and a polyvalent ion as a mineral component are separated by electrodialysis, and K and Na are separated from a solution containing Na ions and K ions taken out after the electrodialysis. KCl and NaC
In a method for recovering a mineral in a solution to be separated and recovered in the form of 1, the recovered KCl is recycled to means for separating monovalent ions and polyvalent ions by electrodialysis.

Since the recovered KCl is reused, the amount of new KCl to be added to the solution for electrodialysis can be reduced.

A third feature of the present invention that achieves the above object is that the amount of KCl added to the solution is determined by the amount of the recovered KCl.
Is to make it equal to the quantity.

Since KCl added to the solution is all recovered KCl, KCl newly added from the outside becomes unnecessary.

[0012] The features of the fourth invention for achieving the above object are as follows.
In the method for recovering a monovalent ion and a polyvalent ion in a solution containing a valence ion and a polyvalent ion as a mineral component in a solution in which the monovalent ion and the polyvalent ion are separated by electrodialysis, the residual solution after the solution is electrodialyzed It is to perform electrodialysis further by adding KCl.

The residual solution is a desalted solution. By adding KCl to the residual solution and performing electrodialysis, the amount of Na ions contained in the desalted solution obtained by the electrodialysis is significantly reduced.

A fifth feature of the present invention to achieve the above object is that a concentrated solution of monovalent ions generated by each dialysis is separated and recovered into KCl and NaCl, and the recovered KC
Part of 1 is used as KCl added to the residual solution.

The fifth invention has the same function and effect as the second invention.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Example 1) A solution (urine) subjected to wet oxidation treatment contains trace amounts of polyvalent ions (Ca ²⁺ , Mg ³⁺ , SO _4).
^2- , PO ₄ ^3-, etc.) and a large amount of monovalent ions (Na ⁺ , K ⁺ ,
Cl ^- etc.). Na ⁺ and Cl ^- molar concentration of substantially equal. A method for separating minerals in a solution, which is a preferred embodiment obtained by applying the present invention to a system for removing NaCl from urine subjected to wet oxidation treatment, will be described with reference to FIG. The solution 1 to be separated, which is wet-oxidized urine, is mixed with a solid or aqueous solution of KCl 2 in the mixing tank 3.
The solution 1 to be separated in the mixing tank 3 is supplied to an electrodialysis device 4 and separated into a desalted solution 5 from which monovalent ions have been removed and a monovalent ion concentrate 6 by electrodialysis.

As shown in FIG. 2, for example, the electrodialysis apparatus 4 comprises monovalent cation-selective permeable membranes 4 arranged alternately.
It has a plurality of solution chambers 45 and 46 separated by a mono- and monovalent anion-selective permeable membrane 42. These solution chambers 45 and 46 are arranged alternately. Each solution chamber 46 is connected to the mixing tank 3 by an inlet pipe 23 and an outlet pipe 24. A circulation pump 22 is provided on the inlet side pipe 23. Each solution chamber 45 is connected to the tank 21 by an inlet pipe 26 and an outlet pipe 27. Circulation pump 25
Is installed in the inlet side pipe 26. A desalted liquid discharge pipe 31 having a valve 32 is connected to the mixing tank 3. Valve 3
The monovalent ion concentrate discharge pipe 33 provided with the
Connected to.

A negative electrode 44 is disposed in a solution chamber 46 on the rightmost side in FIG. In contact with the monovalent cation selective permeable membrane 41 located on the leftmost side in FIG.
7 are present. A positive electrode 43 is arranged in the anode chamber 47. The anode chamber 47 is connected to the tank 29 by the circulation pipe 30. A circulation pump 28 is provided on the circulation pipe 30. These solution chambers 45 and 46 are arranged alternately.

The solution 1 to be separated and KCl 2 are mixed and supplied into the mixing tank 3. This mixed solution is supplied to the solution chamber 46 by driving the circulation pump 22. Solution chamber 45
, The solution in the tank 21 is supplied by the circulation pump 25. A DC voltage is applied between the positive electrode 43 and the negative electrode 44. Therefore, monovalent anions (such as Cl ⁻ ) contained in the mixed solution permeate through the monovalent anion-selective permeable membrane 42 and move into the solution chamber 45 adjacent on the positive electrode side. Further, monovalent cations (Na ⁺ , K ^+, etc.) permeate through the monovalent cation selective permeable membrane 43 and are adjacent to the solution chamber 4 on the negative electrode side.
Move to within 5. The number of moles of monovalent anions and monovalent cations transferred from the solution in the solution chamber 46 to the solution in the solution chamber 45 is the same. The solution in the solution chamber 46 circulates between the solution chamber 45 and the mixing tank 3, and the solution in the solution chamber 45 is
5 and the tank 21. The solution in the solution chamber 46 reduces the concentration of monovalent anions and monovalent cations while circulating, and relatively increases the concentration of polyvalent ions. The solution in the solution chamber 46 in which the concentrations of the monovalent anion and the monovalent cation are reduced becomes a desalted solution. On the other hand, the solution chamber 45
The solution within increases the concentration of monovalent anions and monovalent cations during circulation. The light passes through the selective permeable membrane 42 and moves into the adjacent solution chamber 45 on the positive electrode side.

K and N at the monovalent cation selective permeable membrane 41
Assuming that the transport numbers of a are t _K and t _Na , respectively, the relative transport number of K to Na is represented by t _K / t _Na (this is R). The value of this relative transport number is kept almost constant as long as the concentration of either K or Na is sufficient. Note that the transport number is an index indicating how easily the ions permeate the monovalent cation selective permeable membrane 41. The relative transport number is an index of how easily the ion to be compared passes through the membrane with respect to the ion to be compared.

_Assuming that the amount of K ions contained in the solution 1 to be separated before desalting is N _K0 and the amount of Na ions is N _Na0 , the total amount of K ions and Na ions contained in the desalted solution 1 to be separated When N becomes N, the ion amount of Na ion changes mainly with N _K0 , N _Na0 and R. When N _Na0 is constant, it decreases as N _K0 increases. Since N _K0 increases by the addition of KCl, when comparing the N _Na before and after the addition of KCl after each electrodialysis so that N is equal, it at KCl added N _Na is reduced. Therefore, by adding KCl, the amount of Na ions permeating through the monovalent cation selective permeable membrane 41 is increased, and the recovery rate of Na ions recovered from the solution 1 to be separated is improved. Naturally, N remaining in the solution 1 to be separated
The amount of a ions decreases more.

In this embodiment, the mixing tank 3 and the solution chamber 46
FIG. 3 shows a change in concentration of each cation contained in the solution circulating between and with respect to the dialysis time, and FIG. 4 shows a concentration change of each anion contained in the solution with respect to the dialysis time. The concentrations of K, Na and Cl all decreased almost in proportion to the dialysis time. Further, the reduction rate of K is higher than that of Na.

In the present embodiment, KCl is added to 5380 mg per 1 kg of the solution to be separated and electrodialysis is performed. In the same manner as in the prior art, electrodialysis is performed without adding KCl. FIG. 5 shows a comparison of the amount of monovalent ions. Although the residual amount of K is about three times that of the conventional case, the amounts of Na ions and Cl ions are greatly reduced to two thirds of the conventional case. The effect of reducing Na ions and Cl ions is as follows.
The larger the amount of 1 added, the larger and the smaller the added amount, the smaller. In addition, the time required for completing the electrodialysis (desalting treatment) increases with the addition amount of KCl, provided that the configuration of the electrodialysis device 4 is the same and the amount of current flowing is equal.

(Embodiment 2) A method for separating minerals in a solution according to another embodiment of the present invention will be described with reference to FIG. In this embodiment, a temperature difference crystallization device 7 is provided in the first embodiment, and KCl 2 separated and eliminated by the temperature difference crystallization device 7 is supplied to the mixing tank 3. Other configurations of the present embodiment are the same as those of the first embodiment.
The electrodialysis device 4 in the present embodiment has the configuration shown in FIG. The monovalent ion concentrated solution discharge pipe 33 shown in FIG. 2 is connected to the temperature difference crystallization device 7.

In the present embodiment, the separation target solution 1 which is wet-oxidized urine is treated similarly to the first embodiment. In the present example, the monovalent ion concentrate 6 obtained in Example 1 is separated into KCl and NaCl using a temperature difference crystallization apparatus 7, and KCl is reused as described above.

The treatment of the monovalent ion concentrate 6 performed in the temperature difference crystallizer 7 will be described below. The monovalent ion concentrate 6 obtained in this example is different from a monovalent ion concentrate obtained by electrodialysis of wet-oxidized urine as it is,
KCl is in excess. The operation of the temperature difference crystallization apparatus 7 in such a state will be described with reference to FIG.

The high temperature section (90
° C) and a low temperature part (20 ° C). KCl is precipitated in a high temperature part and KCl is precipitated in a low temperature part. For this reason, as shown in step a of FIG. 7, the KCl and NaCl contained in the monovalent ion concentrate 6 in the high-temperature portion reach the saturation concentration with respect to the eutectic point in the high-temperature portion, and the KCl The monovalent ion concentrate 6 is circulated between the low temperature portion and the high temperature portion while evaporating the water in the monovalent ion concentrate 6 in the high temperature portion until KCl precipitates, and depositing KCl in the low temperature portion.

In the following processes (1) to (3), N
Since aCl is deposited, it is necessary to prevent excessive evaporation of water in the monovalent ion concentrate 6 in the high temperature part so as not to precipitate KCl in the high temperature part.

(1) While precipitating NaCl in the high temperature part, water is evaporated until the concentration ratio of KCl and NaCl in the monovalent ion concentrate 6 reaches the concentration ratio corresponding to the eutectic point in the high temperature part. .

(2) The concentrated solution in which the concentration ratio of KCl and NaCl reaches the concentration ratio corresponding to the eutectic point in the high temperature part is sent to the low temperature part to precipitate KCl, and then sent to the high temperature part (FIG. 7 c).

(3) The steps (1) and (2) are repeated until the amount of the monovalent ion concentrate 6 becomes less than the set amount.

The monovalent ion concentrate 6 remaining after the above-mentioned treatment is mixed with the monovalent ion concentrate 6 supplied to the temperature difference crystallization device 7 and treated again as described above. By using the temperature difference crystallizer 7, KCl2 and Na
Cl8 is recovered. The recovered KCl2 is mixed in mixing tank 3
And mixed with the monovalent ion concentrate 6 for reuse.

KCl is added to the monovalent ion concentrate 6 in the mixing tank 3.
Is added for two reasons. The first reason is to improve the recovery rate of Na ions recovered from the solution 1 to be separated and reduce the amount of Na ions remaining in the solution 1 to be separated as described above. The second reason is to efficiently separate and recover K and Na from the solution 1 to be separated. Na and K are very difficult to separate and cannot be separated effectively except for temperature crystallization using NaCl and KCl.
In order to remove both monovalent cations and anions from the solution to be separated, it is desirable that the same number of monovalent cations and anions be present. Therefore, divalent anions such as K ₂ SO ₄ are preferable. The use of salts containing is inappropriate. In the present embodiment, the same effects as in the first embodiment can be obtained. Further, in the present embodiment, KCl 2 recovered from the monovalent ion concentrate 6 is reused, so that KCl 2 newly added to the solution 1 to be separated is used.
Can be reduced.

(Example 3) A method for separating minerals in a solution according to another embodiment of the present invention will be described below. In this embodiment, in the second embodiment shown in FIG. 6, the amount of KCl added to the solution 1 to be separated in the mixing tank 3 is adjusted so as to be equal to the amount of KCl recovered in the temperature difference crystallizer 7. Is what you do. By such adjustment, K ions are left in the desalting solution 5 without Cl, and NaCl contained in urine is removed.
Only (apparently) can be recovered. For example, when 1280 mg of K ions are contained in 1 kg of the solution 1 to be separated, 85% of K ions are transferred to the monovalent ion concentrate 6 by the electrodialyzer 4 and 95% by the temperature difference crystallization device 7. When the K ions are precipitated in the low temperature part as KCl, if the amount of KCl 2 added in the mixing tank 3 is 10.25 g per 1 kg of the solution to be separated, the added KCl and the recovered KCl are balanced. At this time, when the amount of K ions contained in the separation target solution 1 decreases, the amount of recovered KCl decreases, and when the amount of K ions increases, the amount of recovered KCl increases. However, if the change is temporary during daily operation, the amount of recovered KCl gradually returns to the original state.

This embodiment has the same effect as the second embodiment.

If this embodiment is applied to a system that maintains a closed material cycle, only the mineral components that need to be returned to the plant nutrient solution in the desalted solution 5 exist in the form of an aqueous solution that can be easily transferred. In addition, the salt consumed by animals is present as solid NaCl, which makes handling very easy.

(Embodiment 4) A method for separating minerals in a solution according to another embodiment of the present invention will be described with reference to FIG. In the present embodiment, electrodialysis apparatuses 4A and 4A having the configuration of FIG.
B, a temperature difference crystallization device 7 and an evaporation / filtration device 9 are provided.

In this embodiment, the separation target solution 1, which is wet oxidized urine, is treated in the same manner as in the first embodiment. In this embodiment, though not shown, KCl is added to the solution 1 to be separated and supplied to the electrodialysis apparatus 4A. As KCl, a part of KCl2 recovered by a temperature difference crystallization apparatus 7 described later may be used as in Example 2. Similarly to the electrodialysis device 4 of the first embodiment, the separation target solution 1 is processed by the electrodialysis device 4A to obtain the monovalent ion concentrated solution 6A and the desalted solution 5A. The temperature-difference crystallization apparatus 7 is provided with Na
Recover Cl8 and KCl2. The recovered KCl2 is led to the electrodialysis device 4B together with the desalted solution 5A. All of the KCl supplied to the electrodialysis apparatus 4B does not need to be KCl2 recovered by the temperature difference crystallization apparatus 7, and it is desirable to introduce KCl from the outside especially at the beginning of the treatment.

The electrodialysis apparatus 4B converts the desalted solution 5A, from which the monovalent ions in the solution 1 to be separated have been almost removed, with KCl
Is electrodialyzed with the addition of. For this reason, the amounts of Na ions and Cl ions in the desalted solution 5B obtained by the electrodialysis device 4B are further reduced as compared with the desalted solution 5 obtained in Examples 1 and 2. The monovalent ion concentrate 6B obtained by the electrodialysis device 4B contains a large amount of K ions and Cl ions and a small amount of Na ions. The monovalent ion concentrate 6B is supplied to the evaporating / filtering device 9, and is heated to a predetermined temperature to evaporate water. In the evaporator / filter 9, the solubility of KCl is lower than that of NaCl, so that only KCl selectively precipitates when the concentration exceeds the saturation concentration (see FIG. 7). When KCl contained in the monovalent ion concentrate 6B precipitates and the KCl concentration and the NaCl concentration in the monovalent ion concentrate approach the eutectic point, the evaporation of the water in the evaporator / filter 9 is stopped. Evaporation / filtration device 9
Solution 10 discharged from is supplied to the temperature difference crystallization device 7.

In this embodiment, KCl is added to each solution supplied to the electrodialysis devices 4A and 4B. This effect will be described.

The effect obtained by the addition of KCl is not only when KCl is added to the solution 1 to be separated as in Examples 1 and 2 at once, but also as in this example. Can also be obtained by adding KCl in portions during the electrodialysis process. This can be explained for the same reason as described in Example 1 if the amount of Na ions at the time of KCl addition is considered to be N _Na0 . Here, the difference from the case of batch addition is that the amount of KCl added in the processing stage in the electrodialysis apparatus 4A is reduced. In the initial stage of the electrodialysis performed by the electrodialysis apparatus 4A, since the amount of Na ions in the desalted solution is large, even if KCl is added, the effect of reducing the ratio of Na ions to the total amount of monovalent ions is small. In addition, in the initial dialysis stage in the electrodialysis apparatus 4A, the total amount of monovalent ions contained in the solution 1 to be separated is sufficient even if the addition of KCl is reduced, so There is no need to prevent permeation through the monovalent selective permeable membrane. As the electrodialysis proceeds, the amount of Na ions contained in the desalted solution 5A decreases. If the amount of KCl added at one time is the same, KCl
The ratio of K ions to the amount of Na ions at the time of addition gradually increases. Therefore, in the latter half of the electrodialysis process, that is, by further adding KCl to the desalted solution 5A supplied to the electrodialyzer 4B with the total amount of monovalent ions reduced,
While preventing permeation of multivalent ions through the monovalent selective permeable membrane,
The amount of Na ions in the desalted solution 5B can be reduced by adding less KCl than in the batch addition.

In the fourth embodiment, the amount of KCl added to the solution 1 supplied to the electrodialyzer 4A may be set to zero.
This is an extreme case in which KCl is added to each of the solutions supplied to the electrodialyzers 4A and 4B as in Example 4. The KCl added to the solution 1 supplied to the electrodialyzer 4A is set to 0. KCl is added to the solution supplied to the electrodialysis apparatus 4B corresponding to the final stage of dialysis. In this case, the amount of Na contained in the desalting solution 5B is significantly smaller than when KCl is added to the solution supplied to the electrodialyzer 4A.

This embodiment has the same effect as the second embodiment. In this embodiment, the desalting solution 5A is prepared by adding KCl to the desalting solution 5A.
Since A is electrodialyzed, a desalted solution having a remarkably low concentration of NaCl can be obtained. Further, the obtained NaCl8 also has high purity.

(Embodiment 5) A method for separating minerals in a solution according to another embodiment of the present invention will be described with reference to FIG. In the present embodiment, the electrodialysis apparatuses 4A and 4B of the fourth embodiment are shared, and the system is simplified. This embodiment includes an electrodialysis device 4, a temperature difference crystallization device 7, an evaporation / filtration device 9, and valves 11, 12, 13, 14, and 15.

First, with the valve 12 closed, the valve 1
1 is opened, and the solution 1 to be separated, which is wet-oxidized urine, is supplied to the electrodialysis device 4. Valve 15 is closed. By this electrodialysis, a monovalent ion concentrate 6 and a desalted solution 5 are generated. The monovalent ion concentrate 6 is guided to the temperature difference crystallizer 7 by opening the valve 13. At this time, the valve 14 is closed. After the monovalent ion concentrate 6 is introduced into the temperature difference crystallizer 7, the valves 12, 15 are opened.
Valve 11 is closed. The KCl separated and recovered by the temperature difference crystallizer 7 is mixed with the desalting solution 5 to form an electrodialysis device 4.
Supplied to The desalted solution 5 containing KCl is electrodialyzed by the electrodialysis device 4. Na and Cl remaining in the desalted solution 5 move to the monovalent ion concentrate 6 together with the added KCl. The monovalent ion concentrate (corresponding to the monovalent ion concentrate 6B of Example 4) is supplied to the evaporator / filter 9 by opening the valve 14 (the valve 13 is closed). The evaporating / filtering device 9 precipitates KCl and filters the same as in Example 4. The residual solution 10 discharged from the evaporation / filtration device 9 is sent to the temperature difference crystallization device 7 and mixed with the monovalent ion concentrate obtained by electrodialysis of the solution 1 to be separated next time to be treated. It is processed in the differential crystallization device 7. The KCl precipitated in the evaporator / filter 9 is added to the desalted liquid 5 supplied to the electrodialyzer 4 and used.

This embodiment produces the same effect as the fourth embodiment.
Further, the configuration can be simplified since only one electrodialysis device is required as compared with the fourth embodiment.

In this embodiment, the evaporation / concentration device 9 can be substituted by changing the operation method of the temperature difference crystallization device 7 without providing the valves 13 and 14 and the evaporation / concentration device 9. At this time, the temperature difference crystallization device 7 performs a known temperature difference crystallization operation when Na ions are larger than K ions, such as a monovalent ion concentrate generated by electrodialysis of the solution 1 to be separated, When the amount of K ions is larger than that of Na ions as in the case of the monovalent ion concentrate in the desalted solution after the addition of KCl, the operation is performed as shown in step a in FIG. With such a configuration, the device configuration can be further simplified, and the reliability increases.

Embodiments 1 to 5 are examples applied to the separation and recovery of minerals from urine. The same configuration is used to separate domestic wastewater and factory wastewater also composed of monovalent ions and polyvalent ions. It can be applied to recovery of minerals and ions.

[0049]

According to the first invention, the amounts of Na ions and Cl ions remaining in the solution containing monovalent ions and polyvalent ions can be reduced.

According to the second and fifth aspects of the present invention, since the recovered KCl is reused, the amount of new KCl added to the electrodialyzed solution for performing electrodialysis can be reduced.

According to the third aspect, KCl newly added from the outside becomes unnecessary.

According to the fourth aspect of the present invention, the amount of Na ions contained in the desalted solution obtained by the electrodialysis is significantly reduced by adding KCl to the residual solution as the desalted solution and performing electrodialysis. Become.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an apparatus for separating minerals in a solution to which a method for separating minerals in a solution according to a preferred embodiment of the present invention is applied.

FIG. 2 is a detailed configuration diagram of the electrodialysis apparatus of FIG.

FIG. 3 is a characteristic diagram showing a change in cation concentration with respect to an electrodialysis time of a solution to be separated to which KCl is added.

FIG. 4 is a characteristic diagram showing a change in cation concentration with respect to an electrodialysis time of a solution to be separated to which KCl is added.

FIG. 5 is an explanatory diagram showing a comparison of the amount of monovalent ions remaining in a desalted solution after electrodialysis.

FIG. 6 is a configuration diagram of a device for separating minerals in a solution to which a method for separating minerals in a solution according to another embodiment of the present invention is applied.

FIG. 7 is a KCl-NaCl solubility curve illustrating a process of temperature difference crystallization performed in the temperature difference crystallizer of FIG.

FIG. 8 is a configuration diagram of an apparatus for separating minerals in a solution to which a method for separating minerals in a solution according to another embodiment of the present invention is applied.

FIG. 9 is a configuration diagram of an apparatus for separating minerals in a solution to which a method for separating minerals in a solution according to another embodiment of the present invention is applied.

FIG. 10 is a characteristic diagram showing a change in cation concentration in urine subjected to wet oxidation treatment with electrodialysis.

[Explanation of symbols]

3: Mixing tank, 4, 4A, 4B: Electrodialyzer, 7: Temperature difference crystallization device, 9: Evaporation / filtration device, 11, 12, 13,
14, 15 ... valve, 41 ... monovalent cation selective permeable membrane, 42 ... monovalent anion selective permeable membrane, 43 ... anode, 4
4: Cathode, 45, 46: Solution chamber.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takayuki Matsumoto 7-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture Within the Power & Electricity Development Division, Hitachi, Ltd. (72) Inventor Masayoshi Kondo Omika-cho, Hitachi City, Ibaraki Prefecture 7-2-1, Hitachi, Ltd. Power and Electricity Development Division (72) Inventor Satoshi Sugawara 3-1-1, Sachimachi, Hitachi, Ibaraki Pref. Hitachi, Ltd. Hitachi Plant, Hitachi Ltd. (72) Inventor New Keiji Ta 7-23, Hachimancho, Higashikurume-shi, Tokyo

Claims (5)

[Claims] 1. A method for separating minerals from a solution containing monovalent ions and polyvalent ions as a mineral component by electrodialysis, wherein KCl is added to the solution. A method for separating minerals in a solution, wherein the method further comprises performing the electrodialysis after addition. 2. The method according to claim 1, wherein said monovalent ion and said polyvalent ion in a solution containing monovalent ions and polyvalent ions as mineral components are separated by electrodialysis, and include Na ions and K ions extracted after said electrodialysis. A method for recovering minerals in a solution for separating and recovering K and Na from the solution in the form of KCl and NaCl, wherein the recovered KCl is recycled to means for separating monovalent ions and polyvalent ions by electrodialysis. A method for separating minerals in a solution. 3. The method for separating minerals in a solution according to claim 2, wherein the amount of KCl added to the solution is equal to the amount of KCl recovered. 4. A method for recovering minerals from a solution containing monovalent ions and polyvalent ions as a mineral component, wherein the monovalent ions and the polyvalent ions are separated by electrodialysis, wherein the solution is electrodialyzed. A method for separating minerals in a solution, wherein KCl is added to the remaining solution after that and electrodialysis is further performed. 5. A concentrated solution of monovalent ions generated by each dialysis is separated and recovered into KCl and NaCl, and a part of the recovered KCl is added to the residual solution.
5. The method for separating minerals in a solution according to claim 4, which is used as l.