JP2002233773A - Method for recovering high-purity boron-containing water and apparatus for treating boron eluate eluted from boron selective adsorption resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device therefor which can recover water containing high purity boron by making a resin selectively adsorbing boron adsorb boron in waste water and by treating a boron eluting solution containing cations and anions obtained by eluting the adsorbed boron with a mineral acid. SOLUTION: The boron eluting solution eluted with the mineral acid from the resin selectively adsorbing boron firstly passes through a cation exchange column filled with a strongly acidic cation exchange resin modified to H type, and then passes through an anion exchange column filled with a I-type or II-type strongly basic anion exchange resin modified to OH type, or a weakly basic anion exchange resin modified to OH type.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for treating a boron eluate obtained by treating and eluting wastewater containing boron with an ion exchange resin, and more particularly to a method for treating boron contained in a boron selective adsorption resin. The present invention relates to a method for recovering high-purity boron-containing water by treating a boron eluate obtained by eluting the same with a mineral acid, and a treatment apparatus therefor.

[0002]

2. Description of the Related Art Generally, a nickel plating solution or an aluminum surface treatment solution contains a boron compound (boric acid, etc.), and a factory that handles these generates cleaning wastewater containing boron. Plants that use boron, such as glass, glazes, and aluminum capacitors, also generate factory wastewater containing boron.

It is well known that boron is an essential trace element for plants and that seawater contains about 4 to 5 mg / l. On the other hand, although the effects of boron on the human body are not always clear, it has been pointed out that continuous ingestion of low concentrations may cause health problems such as reduced reproductive function. In February 1999, 1 mg / l or less was announced as an environmental standard for boron, and it is expected that a effluent standard will be set in the future.Therefore, it is necessary to remove boron from factory wastewater containing these boron. ing.

[0004] Therefore, it is desired to establish a technique for efficiently removing boron from factory wastewater containing boron and regenerating the removed boron into a reusable form such as boric acid. As a means for this, wastewater containing boron is adsorbed on an anion exchange resin or a boron selective adsorption resin, thereby purifying the wastewater (JP-A-2-32952).
In addition to this, a method is known in which boron adsorbed on a resin is eluted with an acid or an alkali, and an acid salt or an alkali, which is an anion, is removed from the eluate to obtain highly pure boron-containing water.

[0005] Among these, the method of performing adsorption treatment with a boron selective adsorption resin is characterized in that the resin has the characteristic of being capable of adsorbing boron even from an aqueous solution containing ions other than boron, for example, seawater, in wastewater. There is an advantage that it can be used even in a place where the salt concentration is high.

[0006]

However, according to the study of the present inventors, the boron selective adsorption resin is used to adsorb boron in waste water, and the resin is subjected to an elution treatment with a mineral acid such as sulfuric acid or hydrochloric acid. At that time, it became clear that cations such as Na, Ca, and Mg existed in the eluate at a considerably high concentration in addition to the boron compound. Although the cause is not necessarily clear, it is presumed that these elements are also adsorbed to the boron selective adsorption resin having an N-methylglucamine group. Furthermore, when passing through factory effluent after neutralizing and precipitating heavy metals such as Cr (III) and Ni (II), a small amount of hydroxides of these heavy metals adhere to the ion exchange resin,
When eluted with a mineral acid, they become ions and are present in the eluate. Therefore, even if only anions are removed from the eluate obtained by this method using, for example, an ion-exchange resin, the purity of the boron-containing water is low, so that there is a problem that a high-purity boron raw material cannot be obtained.

According to the present invention, the eluent containing cations and anions obtained by adsorbing boron in waste water by using such a boron selective adsorption resin and eluting the same with a mineral acid is treated to obtain high purity. It is an object of the present invention to propose a method and an apparatus for recovering boron-containing water.

[0008]

In the process of purifying such a boron eluent containing a cation and an anion, the present inventors have found that boric acid is not ionized in an acidic region, and boric acid molecules (H ₃ BO ₃ ), which is dissolved as a molecule without being adsorbed by both the strongly acidic cation exchange resin adjusted to the H-form and the anion exchange resin adjusted to the OH-form. Na ions, Ca ions, Mg ions, and cations of heavy metals in the eluent are adsorbed and removed by passing the solution through an ion exchange column filled with a strongly acidic cation exchange resin adjusted to It has been confirmed that anions are adsorbed and removed by passing the solution through the column, and that boric acid leaks as it is without being adsorbed to any ion exchange resin.

That is, in the method for recovering high-purity boron-containing water of the present invention, a boron eluent eluted from a boron selective adsorption resin having adsorbed boron with a mineral acid is first converted into an H-type strongly acidic cation exchange solution. Pass the solution through a cation exchange column packed with resin, and then anion exchange packed with an I- or II-type strongly basic anion exchange resin adjusted to OH type or a weakly basic anion exchange resin adjusted to OH type The liquid is passed through the tower.

After passing the solution through the above cation exchange column and then into the anion exchange column, a strongly acidic cation exchange resin adjusted to H-form and a strongly basic anion exchange resin of type I or II adjusted to OH-type or It is preferable to mix a weakly basic anion exchange resin adjusted to OH type and pass the mixture through a mixed bed ion exchange column filled with the resin. Further, it is preferable that the mixed bed ion exchange tower is constituted by a plurality of ion exchange towers of the same type connected in series, and these are operated by a progressive exchange method.

Further, the apparatus for treating a boron eluate eluted from a boron selective adsorption resin with a mineral acid according to the present invention comprises a strongly acidic solution adjusted to H-type in order from the inflow side of the boron eluate eluted from the boron selective adsorption resin. A cation exchange tower packed with an ion exchange resin and an anion exchange tower packed with a strongly basic anion exchange resin of type I or II adjusted to OH type or a weakly basic anion exchange resin adjusted to OH type are provided. It is set up.

In the above treatment apparatus, a strongly acidic cation exchange resin adjusted to H-form and an I-form adjusted to OH-form are provided at the subsequent stage of the anion exchange tower provided following the cation exchange tower.
It is preferable that a mixed-bed ion exchange column filled with a mixture of a weakly basic anion exchange resin adjusted to a type or type II strongly basic anion exchange resin or an OH type is preferably provided, It is preferable that the mixed-bed ion exchange tower be one in which a plurality of ion exchange towers of the same type are connected in series.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described specifically. The eluent to be treated in the present invention is a boron eluent eluted from a boron selective adsorption resin with a mineral acid. A typical example of the boron selective adsorption resin is a boron selective adsorption resin having an N-methylglucamine group, and elution of the boron-adsorbed resin is performed with a mineral acid such as hydrochloric acid or sulfuric acid. The eluent contains, for example, B: 2-3 g / l, SO ₄ ions and Cl ions as anions, Na ions: 1-3 g / l as impurities, Ca ions: 0.5-2 g / l, and Mg ions: About 0.3g
Various impurities such as about / l are included. Therefore, in order to obtain a high-purity boron raw material, it is necessary to remove not only anions but also cations such as Na, Ca and Mg, which are impurities.

For this purpose, the above eluent is first passed through a cation exchange column filled with a strongly acidic cation exchange resin adjusted to H-form. Thereby, cations such as Na and Ca are adsorbed and removed. However, boric acid is dissolved in the form of boric acid molecules (H ₃ BO ₃ ) because the pH of this solution is low and in the acidic region, and is leaked out without being adsorbed by the cation exchange resin.

Subsequently, the solution is passed through an anion exchange column filled with an I- or II-type strongly basic anion exchange resin adjusted to OH type or a weakly basic anion exchange resin adjusted to OH type. Thereby, anions such as SO ₄ ions are adsorbed and removed. However, also in this case, the solution is in an acidic or neutral region, and boric acid dissolves as boric acid molecules and is not ionized, and thus leaks without being adsorbed by the anion exchange resin. If ions to be removed leak from the anion exchange tower, a sudden change in pH or electrical conductivity occurs.Therefore, installing a pH meter or electrical conductivity meter at the outlet pipe on the head side allows water to flow. End point management becomes easy.

By the above operation, cations and anions other than boron are completely removed from the eluate, and a highly pure boron solution containing very few impurities can be obtained. However, in the above operation, when the cation exchange resin charged in the cation exchange column or the anion exchange resin charged in the anion exchange column is saturated, the cation or anion other than boron, which is a component in the eluent, is saturated. There is a concern that ions may leak. Further, Na in NaOH used for regeneration of the anion exchange resin slightly remains after washing, and may be mixed into the boron solution. In order to cope with such a problem, it is effective to further pass the solution through the mixed bed ion exchange column after the above operation is completed.

The mixed bed ion exchange column is provided with a strongly acidic cation exchange resin adjusted to H form, a strong basic anion exchange resin of type I or II adjusted to OH form, or a weakly basic cation exchange resin adjusted to OH form. The two types of anion exchange resins are mixed and packed, and by passing through this mixed bed ion tower, the above contaminants (cations and anions) are completely removed, resulting in extremely high purity. A high boric acid solution can be obtained. In the mixed bed ion exchange column, a strongly acidic cation exchange resin adjusted to H-type and an anion exchange resin adjusted to OH-type (type I or II strongly basic anion exchange resin or a weak base adjusted to OH-type) Anionic exchange resin)
Is preferably 1: 1 in consideration of ease of mixing.

Although the above-mentioned structure makes it possible to obtain a boric acid solution of extremely high purity in a stable manner, a practical problem is that the end point of the mixed bed ion exchange column is incorrectly controlled by the cation or the anion. Risk of leakage. In the present invention, as a countermeasure, two or more mixed bed ion exchange towers of the same type are prepared and connected in series. Accordingly, even if cations or anions from the head of the mixed bed ion exchange column of mixed bed ion exchange column connected in series to leak, it is removed by the ion exchange column for subsequent isomorphic. As a result, no ions leak from the final mixed bed ion exchange tower.

The management of a group of ion exchange towers formed by connecting the same type of ion exchange towers in series can be performed by a so-called progressive exchange method. This progressive exchange method means that, when a plurality of ion exchange towers of the same type are connected in series and operated, when the ion species to be removed starts to leak from the leading ion exchange tower, the operation is temporarily stopped. The system is interrupted, the leading ion exchange tower is removed, the subsequent ion exchange tower is applied, and a newly adjusted ion exchange tower is installed after the subsequent ion exchange tower. By adopting this method, the capacity of the ion exchange column can be completely used, and economic operation can be achieved. Also, if ions to be removed leak from the ion exchange tower on the head side, a sudden change in pH or electrical conductivity occurs. Water end point management becomes easy.

Representative examples of plant configurations suitable for implementing the present invention are shown in FIGS. In FIG. 1, a cation exchange column 1 filled with a strongly acidic cation exchange resin adjusted to H-type and a type I or II type adjusted to OH-type are sequentially arranged from the inflow side of boron elution eluted from the boron selective adsorption resin. An anion exchange column 2 packed with a basic anion exchange resin or a weakly basic anion exchange resin adjusted to an OH type is provided, thereby achieving the basic object of the present invention. In this configuration, a pH meter 4 was connected to the outlet pipe of the anion exchange tower 2.
Is attached. An electric conductivity meter 5 can be provided instead of or in addition to the pH meter 4.

In FIG. 2, a mixed-bed ion exchange column 3 is added to the configuration shown in FIG. Thereby, even if the cation exchange tower 1 or the anion exchange tower 2 is saturated, leakage of cations and anions can be prevented. The one shown in FIG. 3 has a configuration in which a plurality of ion exchange columns 3A and 3B of the same type are connected in series to a mixed bed ion exchange column. Thereby, leakage of cations and anions can be more completely prevented. In this configuration, a pH meter 4 was connected to the outlet pipe of the top one of the mixed bed ion exchange towers.
Is attached. An electric conductivity meter 5 can be provided instead of or in addition to the pH meter 4.

[0022]

[Example] An acrylic column with an inner diameter of 34 mm and a height of 1000 mm was used.
I prepared three. The first one was filled with 300 ml of a strongly acidic cation exchange resin adjusted to H-form to form a cation exchange column. The second tube was filled with 300 ml of a weakly basic anion exchange resin adjusted to OH type to form an anion exchange column. In the third column, 150 ml of the strongly acidic cation exchange resin adjusted to the H type and 150 ml of the weakly basic cation exchange resin adjusted to the OH type were sufficiently mixed and filled to form a mixed bed ion exchange column. . These cation exchange tower, anion exchange tower, and mixed bed ion exchange tower were connected to form a boron eluent treatment apparatus according to the present invention.

Ion-exchanged water at a flow rate of 3000 ml
/ h for 1 h to extract the drug remaining in the ion exchange resin,
After washing, dehydrate with compressed air.
The boron eluent shown in 1 was passed at a flow rate of 3000 ml / h.

[0024]

[Table 1]

FIG. 4 is a diagram showing the relationship between the B and SO ₄ ion concentrations and the pH of the treated water at the outlet side of the anion exchange tower and the flow rate (BV). As shown here, in the anion exchange column, SO ₄ ions are completely removed until the flow rate reaches approximately 4 BV, and a boric acid solution with high purity can be recovered.
When the SO ₄ ions start to leak, the pH sharply drops at the outlet of the anion exchange tower, so that the end point of the flow can be controlled. In the cation exchange column, since the concentration of Na ion and Ca ion is lower than the concentration of SO ₄ ion, no leakage of these components is observed at the above flow rate, but the stage where SO ₄ ion does not leak Then, when Na ions and Ca ions leak from the cation exchange tower, the pH at the anion exchange tower outlet rises. Thereby, the end point of the flow can be managed.

However, when cations leak from the cation exchange tower and anions leak from the anion exchange tower, in order to prevent these ions from being mixed into the boric acid solution and obtain high-purity boron-containing water, the above description is made. Need to be passed through a mixed bed tower.

FIG. 5 is a graph showing the relationship between the B concentration, the SO ₄ concentration, the pH, the electric conductivity, and the flow rate (BV) of the treated water at the outlet of the mixed bed ion exchange column. As shown here, no leakage of cations or anions from the mixed-bed ion exchange column was observed. If cations start to leak from the mixed-bed ion exchange column, an increase in the electrical conductivity occurs with an increase in the pH, so that the end point control of the flow can be easily performed. In addition, when the anion starts to leak, the electrical conductivity increases as the pH decreases, so that the end point management of the liquid passing can be easily performed as in the case described above.

As described above, according to the present invention, Na, Ca
Cations and Cl, the extremely high purity boron-containing water from the boron eluate containing anions such SO ₄ can be recovered and the like. Therefore, by concentrating and crystallizing this, for example, a raw material boric acid for producing high-purity boron-based ferroalloys can be easily obtained. The levels of impurities when the boric acid obtained according to the present invention was crystallized are shown in Table 2, and all components were extremely low.
It can be suitably used as a raw material for a glass raw material, a reactor control material, and the like.

[0029]

[Table 2]

[0030]

According to the present invention, an extremely high-purity boric acid-containing aqueous solution containing few impurities can be efficiently recovered from the boron eluate eluted from the boron selective adsorption resin as described above. From the obtained recovered liquid, high-purity boric acid can be obtained, and as a raw material for boron-based ferroalloys,
It can be used for the production of glass, aluminum capacitors, glazes and reactor control materials.

[Brief description of the drawings]

FIG. 1 is a basic plant layout diagram used in the present invention.

FIG. 2 is a basic plant layout diagram used in the present invention.

FIG. 3 is a basic plant layout diagram used in the present invention.

FIG. 4 is treated water at the outlet side of the anion exchange tower
FIG. 4 is a diagram illustrating the relationship between B, NaOH concentration and pH, and the flow rate (BV).

FIG. 5: Treated water at the outlet side of the mixed bed ion exchange tower
FIG. 4 is a diagram illustrating the relationship between B concentration, pH, and electric conductivity, and the flow rate (BV).

[Explanation of symbols]

 1: Cation exchange tower 2: Anion exchange tower 3: Mixed bed ion exchange tower 4: pH meter 5: Electric conductivity meter

Claims (6)

[Claims] 1. A boron eluent eluted from a boron selective adsorption resin with a mineral acid is first passed through a cation exchange column packed with a strongly acidic cation exchange resin adjusted to H-form,
High-purity boron content characterized by passing through an anion-exchange column packed with a type I or type II strongly basic anion exchange resin adjusted to OH type or a weakly basic anion exchange resin adjusted to OH type Water recovery method. 2. After passing through a cation exchange column and then an anion exchange column, a strongly acidic cation exchange resin adjusted to H type and a strongly basic anion exchange resin type I or II adjusted to OH type. The method for recovering high-purity boron-containing water according to claim 1, wherein the mixture is passed through a mixed-bed ion exchange column packed with a weakly basic anion exchange resin adjusted to OH type and filled. 3. The multi-bed ion exchange tower according to claim 2, wherein the mixed bed ion exchange tower is constituted by a plurality of ion exchange towers of the same type connected in series, and these are operated by a progressive exchange system. A method for recovering water containing pure boron. 4. A cation exchange column packed with a strongly acidic cation exchange resin adjusted to H-form, in order from the inflow side of the boron eluent eluted from the boron selective adsorption resin with a mineral acid.
Selective boron adsorption characterized by comprising an anion exchange column packed with a type I or II type strongly basic anion exchange resin adjusted to a type or a weakly basic anion exchange resin adjusted to an OH type Processing equipment for boron eluent eluted from resin. 5. A strongly acidic cation exchange resin adjusted to H-form and a type I or II strong basic anion adjusted to OH after the anion exchange tower provided following the cation exchange tower. 5. A mixed bed ion exchange column packed with a mixture of an exchange resin or a weakly basic anion exchange resin adjusted to an OH type, and eluted from the boron selective adsorption resin according to claim 4. Processing equipment for boron eluent. 6. The apparatus for treating a boron eluent eluted from a boron selective adsorption resin according to claim 5, wherein the mixed bed ion exchange column is formed by connecting a plurality of ion exchange columns of the same type in series. .