JP2018058010A - Purification method of boron eluent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a purification method of a boron eluent causing no outflow of a liquid containing boron and mineral acid from an anion exchange tower 4 when the boron eluent containing the mineral acid is purified by an anion exchange resin in the anion exchange tower 4.SOLUTION: When a boron eluent is passed through an anion exchange tower 4 filled with an anion exchange resin from a boron eluent tank 1, passing the liquid is stopped at a predetermined integrated flow rate before breakthrough of the anion exchange resin, and then water is passed from a water tank 2. Because all mineral acid contained in passed boron eluent is absorbed to the anion exchange resin, when post water is passed and a liquid containing boron remaining in the anion exchange tower 4 is extruded, only boron-containing liquid contained in the anion exchange tower 4 is flowed out and, on the other hand, no mineral acid absorbed by the ion exchange resin is leaked, the boron-containing liquid is recovered in a boron purification liquid recovery tank 5 without contaminating the mineral acid in the boron purification liquid.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for purifying a boron eluent containing a mineral acid and efficiently recovering a boron purified solution having a high boron purity.

  The nickel plating solution and the aluminum surface treatment solution generally contain a boron compound (boric acid or the like), and wastewater containing boron is generated in factories that handle these. Boron compounds are essential elements for plants, and it is well known that seawater contains about 4 to 5 mg / L. On the other hand, although the effect of boron on the human body is not necessarily clear, it has been pointed out that it may cause health problems such as a decrease in genital function when continuously ingested at a low concentration. In February 1999, 1 mg / L or less was announced as an environmental standard for boron, and in July 2001, 10 mg / L or less of boron was established as a uniform drainage standard (sea discharge was 230 mg / L or less). In the above factories that handle boron, it is necessary to remove boron from the process wastewater.

  Various methods have been proposed as a method for removing boron in waste water, and a method using a boron selective resin is also known. In this method, wastewater containing boron is passed through, for example, a boron selective adsorption tower filled with a boron selective adsorption resin having an N-methylglucamine group to adsorb boron to the boron selective adsorption resin, and does not contain boron. An operation of regenerating the resin by passing a mineral acid such as hydrochloric acid or sulfuric acid into the treated water and then adsorbing boron to the resin is performed. Along with this operation, boron eluent is also generated and recovered in the boron eluent recovery tank. The boron eluent contains a mineral acid together with boron.

  Proposals have been made to use the generated boron eluent as a boron resource. For example, in Patent Document 1, a boron eluent containing a mineral acid is passed through an acid adsorption tower packed with an OH-type weakly basic anion exchange resin, and a boron solution containing no mineral acid (hereinafter referred to as a mineral acid). A boron solution containing no boron and a mineral acid and a solution containing boron, and recovering the fractionated boron solution containing no mineral acid. Is disclosed. First, a boron solution containing no mineral acid flows out from the acid adsorption tower, and then a boron solution containing a mineral acid flows out. Since the pH of the boron-containing effluent containing no mineral acid (boron refining solution) is 6 to 7 and the pH of the mineral acid-containing effluent is 1 to 6, the fractionation time can be determined by installing a pH meter. Can be determined. Since the fractionated mineral acid solution contains boron, it is possible to effectively utilize the boron and mineral acid in the mineral acid solution by reusing the boron-selective resin that adsorbs boron for the elimination of boron. it can. Further, Patent Document 1 mentions that the mineral acid is sulfuric acid, and that the weakly basic anion exchange resin is a porous ion exchange resin based on a styrene-based crosslinked copolymer.

  Patent Document 2 discloses a method for purifying a boron eluent containing a root acid (mineral acid). By passing a mineral acid through a boron selective resin on which boron is adsorbed, a boron eluent containing a mineral acid is obtained. This boron eluent is selected from the group consisting of OH Form I type strongly basic anion exchange resin, OH Form II type strongly basic anion exchange resin, or OH form weakly basic anion exchange resin. Is passed through the ion exchange tower (anion exchange tower) filled with, and when the mineral acid leaks and the pH at the exit of the ion exchange tower falls, the passage of the liquid is stopped and a high purity boron purification liquid (boron purification liquid) ). After stopping the flow of boron eluent, pass water. Since the liquid recovered when water is passed contains mineral acid in addition to boron, it is used as a stock solution that passes through an anion exchange column. Thus, it is described that a high-purity boron purified solution can be recovered.

Japanese Patent No. 3913939 Japanese Patent No. 4733807

  In any of the methods described in Patent Documents 1 and 2, a boron eluent containing a mineral acid is passed through an acid adsorption tower (Patent Document 1) or an anion exchange tower (Patent Document 2) to purify the boron eluent. At the time, the start of outflow of mineral acid is detected by measuring the pH of the liquid flowing out from the acid adsorption tower (anion exchange tower), and the effluent is fractionated. The point in time when the pH of the liquid flowing out decreases means that the ion exchange resin in the anion exchange column has broken through. The liquid that has flowed out before the pH drop is used as a boron purified liquid, and the liquid that flows out after the pH drop is collected as a liquid containing mineral acid and boron. Continue to pass the boron eluent until the anion exchange resin breaks through, stop the flow after the mineral acid leaks into the effluent, and switch the collection destination of the effluent to perform fractionation. In this fractionation operation, the mineral acid is slightly mixed on the boron purification solution side at the time of switching, and the purity of the recovered boron purification solution is lowered.

  The boron eluent flow stoppage is controlled by a pH meter installed at the bottom of the ion exchange column, and the boron eluent flow stoppage is judged by judging that the mineral acid has leaked due to the rapid drop in pH. Its management becomes complicated.

  After the mineral acid has flowed out and the pH of the liquid has dropped, the operation of stopping the flow of the boron eluent containing the mineral acid and passing the water and extruding the liquid remaining in the anion exchange column is performed. At the time when the boron eluent phase liquid containing mineral acid is stopped, the liquid containing boron and mineral acid remains in the anion exchange column. Therefore, both the boron and the mineral acid are contained in the effluent after the start of water flow. If the generated boron acid-containing boron solution is discarded, the boron recovery rate is lowered, which is not preferable. On the other hand, in order to recover the boron in the liquid, a liquid tank for storing the fractionated mineral acid and boron-containing liquid is installed, and the boron eluent purification process (boron adsorption process) in the previous stage is installed. A returning process is required, and the processing process is increased by one step. A pipe that sends the liquid containing mineral acid and boron to the liquid tank that stores the boron eluent is installed. However, when returning to the purification process of boron eluent, an anion exchange resin is required as the amount of mineral acid increases. In the case of returning to the boron adsorption step, the amount of the boron component to be processed increases, and the amount of resin necessary for the processing increases. In any case, due to these factors, returning the liquid containing the mineral acid and boron to the previous step leads to an increase in cost.

  An object of this invention is to provide the purification method of the boron eluent which can solve the said problem.

The present invention solves the above problems, and the gist thereof is that before the anion exchange resin breaks through when the boron eluent containing a mineral acid is passed through an anion exchange column filled with the anion exchange resin. By stopping the flow of the boron eluent at the predetermined flow rate, all the mineral acid contained in the passed boron eluent is adsorbed to the anion exchange resin. When extruding the boron-containing liquid remaining in the ion exchange tower, only the boron-containing liquid contained in the anion exchange tower flows out, while the mineral acid adsorbed on the anion exchange resin does not leak at all, and the boron purified liquid There is a method in which no mineral acid is mixed in.
(1) The flow rate for passing a boron eluent containing a mineral acid through an anion exchange column is smaller than the flow rate for passing through the anion exchange resin by passing the boron eluent containing the mineral acid. A method for purifying a boron eluent, wherein a boron solution containing no mineral acid is recovered by passing at an integrated flow rate that is an amount.
(2) The method for purifying a boron eluent according to (1), wherein an integrated flow rate of the boron eluent containing the mineral acid is determined in advance based on the mineral acid content in the boron eluent.
(3) Group of type I strongly basic anion exchange resin adjusted to form OH, type II strongly basic anion exchange resin adjusted to form OH, and group of weakly basic anion exchange resins adjusted to form OH (hereinafter referred to as OH type) Using an ion exchange column (hereinafter referred to as “anion exchange column”) filled with an anion exchange resin selected from “anion exchange resin group”), boron anion containing mineral acid is eluted in the anion exchange column. The amount of liquid to be passed is determined in advance as the integrated flow rate of the boron eluent containing mineral acid, and the boron eluent containing mineral acid is passed through the anion exchange column to elute boron containing the mineral acid. When the flow rate of the liquid reaches or reaches the integrated flow rate of the boron eluent containing the predetermined mineral acid, the flow is stopped, and then water is passed through the anion exchange column to recover boron. Process and anion exchange after recovering the boron Method of purifying boron eluent, characterized in that the ionic form of the ion exchange resin filling the anion exchange column was passed through an alkaline solution to the column and a step of adjusting the OH form.
(4) In the step of arranging the cation exchange column filled with the strongly acidic cation exchange resin adjusted to the H form before the anion exchange column filled with the anion exchange resin group, and collecting the boron, The cation contained in the boron solution containing the cation and mineral acid is adsorbed on the ion exchange resin in the cation exchange tower, and then the regenerant is passed through the cation exchange tower and filled in the cation exchange tower. The method for purifying a boron eluent according to any one of (1) to (3), further comprising a step of adjusting an ion form of the ion exchange resin thus obtained to an H form.
(5) The method for purifying a boron eluent according to any one of (1) to (4), wherein the mineral acid is sulfuric acid.
(6) Any of (1) to (5), wherein the anion exchange resin group and the strongly acidic cation exchange resin are porous ion exchange resins based on a styrene-based crosslinked copolymer. The method for purifying a boron eluent as described in one of the above.
(7) The boron according to any one of (1) to (6), wherein the high-purity boron solution obtained in the step of recovering boron is concentrated and solidified to form a boric acid solid. Purification method of eluent.

  The effect brought about by the present invention is as follows. First, it is possible to obtain a high-purity boron purified liquid in which no mineral acid is mixed. Secondly, since the flow of boron eluent can be stopped by the integrated flow rate, management is easy. Thirdly, in the step of passing a boron eluent containing a mineral acid through an anion exchange tower and then passing water (step of recovering boron), the liquid flowing out of the anion exchange tower includes: Since no boron refining solution containing mineral acid is generated at all, the cost can be reduced by eliminating the corresponding processing steps.

It is a figure which shows the purification method of the boron eluent of this invention, (A) is the case where the cation exchange column is not arrange | positioned, (B) is the case where the cation exchange column is arrange | positioned. It is a figure which shows the reproduction | regeneration process of an anion exchange resin. It is a figure which shows the reproduction | regeneration process of a cation exchange resin. It is a figure which shows the component time change in the effluent from an anion exchange tower in the process of collect | recovering the boron of this invention. It is a figure which shows the component time change in the effluent from an anion exchange tower in the process of collect | recovering the boron of this invention. It is a figure which shows the component time change in the effluent from an anion exchange tower in the process of collect | recovering the boron of a comparative example.

  The present invention relates to a purification method in which a boron eluent containing a mineral acid is purified to obtain a boron purified solution containing no mineral acid. As described above, the boron eluent containing the mineral acid targeted by the present invention is generated by the following steps, for example.

  In a method using a boron selective resin as a method for removing boron contained in wastewater, the wastewater containing boron is passed through, for example, a boron adsorption tower packed with a boron selective resin having an N-methylglucamine group. Then, boron is adsorbed on the boron selective resin to obtain treated water containing no boron. Thereafter, a mineral acid such as hydrochloric acid or sulfuric acid is passed through the resin that has adsorbed boron to desorb the adsorbed boron from the resin, and caustic soda is passed through the resin from which boron has been desorbed to regenerate the resin. The operation is performed. Along with this desorption operation, a boron eluent containing a mineral acid is generated and collected in the boron eluent tank.

In the process of purifying the boron eluent, boric acid is dissolved as boric acid molecule H ₃ BO ₃ without being ionized in the acidic region, and adsorbed on the anion exchange resin adjusted to OH form. Therefore, after confirming from past examples that when boron eluent is passed through an anion exchange column packed with anion exchange resin, anions other than boric acid are adsorbed and only boric acid leaks. The present invention has been reached. In the present specification, boron is a generic term for boric acid and borates.

  In the present invention, for example, as shown in FIG. 1 (A) and FIGS. 2 to 3, a boron eluent tank 1, a working water tank 2, an anion exchange tower 4, a boron purified liquid recovery tank 5, a recycled water recovery tank 6, and caustic soda. It implements using the apparatus which has the tank 7, the process liquid discharge pipe 8, and the hydrochloric acid tank 9. FIG.

<< Step of recovering boron >>
The boron eluent contained in the boron eluent tank 1 is enriched in boron concentration, but contains ions that become impurities, and has a particularly high mineral acid concentration. For the purpose of recovering a high purity boron purified solution by removing the mineral acid from the boron eluent, the mineral acid is adsorbed and removed by passing the solution through an anion exchange resin using the above method.

  When a boron eluent containing a mineral acid is passed through the anion exchange column 4 filled with the anion exchange resin, the mineral acid in the solution is adsorbed by the anion exchange resin. It contains no mineral acid. As the liquid flow continues, adsorption of the mineral acid proceeds to the anion exchange resin. Eventually, the anion exchange resin cannot completely absorb the mineral acid, and when the ion exchange resin breaks through, the liquid containing the mineral acid flows out from the anion exchange tower thereafter. If mineral acid leaks, the pH in the liquid will drop. Conventionally, the pH of the effluent is detected, and when the pH drops, it is recognized that the anion exchange resin has passed through, and boron elution into the anion exchange column is performed. Stop liquid flow and start water flow. Moreover, since the mineral acid is hardly contained in the effluent before the pH is lowered, it is recovered as a boron purification solution. Since the effluent after the decrease in pH contains mineral acid and boron, it was recycled to the boron recovery process and recovered as described in Patent Document 1.

  The anion exchange tower is filled with an anion exchange resin, and a space exists above the anion exchange tower. Moreover, an anion exchange resin has a space | gap inside, Usually, the porosity will be about 30%. When the boron eluent is passed through the anion exchange column, the passed boron eluent is filled in the space between the upper space and the anion exchange resin. At the time when the anion adsorption ability of the anion exchange resin has not yet reached breakthrough, the effluent (treatment liquid) does not contain mineral acid and is recovered as a boron purified liquid. On the other hand, immediately after the anion exchange resin breaks through, the mineral acid begins to gradually leak into the treatment liquid. At this time, since the pH of the treatment liquid is lowered, at the same time in the conventional method, the liquid flowing through the anion exchange tower is switched from the boron eluent to the working water, and the recovery destination of the treatment liquid flowing out from the anion exchange tower is changed. Switching from the refined boron solution to the solution containing mineral acid and boron. For this reason, the recovered boron purification solution contains a slight amount of mineral acid. In addition, when extruding the charged water in the anion exchange tower after switching, both the boron and mineral acid filled in the space above the anion exchange tower and the void portion of the anion exchange resin were included. The liquid is discharged as a processing liquid.

  On the other hand, the present invention is characterized in that the flow of the boron eluent is stopped at a predetermined integrated flow before the ion exchange resin breaks through. When water is passed through the anion exchange column in this state, the liquid filling the space between the anion exchange column and the resin gap is pushed and moved, and the mineral acid is not yet adsorbed among the ion exchange resins. As it moves to the part, the mineral acid in the liquid is adsorbed on the anion exchange resin. Therefore, if the anion exchange resin has sufficient anion adsorption capability, the mineral acid contained in the passed boron eluent can be obtained by stopping the boron eluent flow and switching to water. Is adsorbed by the ion exchange resin and is contained in the liquid filled in the space of the anion exchange column and the space of the anion exchange resin when water is passed through and the boron-containing water remaining in the ion exchange column is pushed out. Since only the boron that flows out flows out and the mineral acid adsorbed on the anion exchange resin does not leak at all, a highly purified boron refining solution can be obtained. In the step of passing the boron eluent or water (step of recovering boron), the liquid flowing out from the anion exchange column does not contain any mineral acid. Conventionally, since a liquid containing boron and a mineral acid has flowed out, it has been necessary to recycle the liquid in order to effectively use the boron in the liquid. On the other hand, in the method of the present invention, the liquid containing both boron and mineral acid does not flow out until all boron contained in the boron eluent passed through the anion exchange column flows out. No need to recycle.

  The anion exchange column of the present invention comprises a group of type I strongly basic anion exchange resin, type II strongly basic anion exchange resin, and weakly basic anion exchange resin adjusted to OH type (anion exchange resin group). A) anion exchange resin selected from If it is an anion exchange resin selected from the above anion exchange resin group, by passing a boron eluent containing a mineral acid, the mineral acid can be separated efficiently and a high purity boron purification solution can be obtained. Because it can.

  In the present invention, the flow of boron eluent containing mineral acid is stopped at a predetermined integrated flow rate before the anion exchange resin breaks through, and then water is passed through the anion exchange tower. Recover boron. Specifically, the flow rate of boron eluent containing mineral acid until the boron eluent flow is stopped (cumulative flow rate of boron eluent containing mineral acid) flows out when water is passed after stopping. A predetermined time when no mineral acid is contained in the liquid.

The flow rate of the boron eluent can be determined as follows. That is, the flow rate (V ₀ ) (L / L-Resin) at which the ion exchange resin is saturated in advance is derived by calculation, and the ion exchange resin breakthrough occurs when it exceeds 90% of the saturated flow rate (V ₀ ). From the empirical prediction that mineral acid will occur, the flow rate of boron eluent (V) (L / L-Resin), which prevents mineral acids from leaking out, is specified and controlled by an integrating flow meter at the outlet of the anion exchange column To do. The standard of the flow rate (V) of the boron eluent in which the mineral acid does not leak out reliably is 60 to 90%, more preferably 80 to 90%, of the flow rate (Vo) at which the ion exchange resin is saturated. Further, the flow rate when the pH of the treatment liquid is lowered and the ion exchange resin breaks through is called V _C. The flow rate (V _C ) when this ion exchange resin breaks through is in the range of 90 to 100% of the flow rate (V ₀ ) up to the saturation point. Generally, there is a relationship V <Vc <Vo.

More preferably, in the present invention, the flow rate of boron eluent containing mineral acid until the boron eluent flow is stopped (the integrated flow rate of boron eluent containing mineral acid) is boron elution. It can be determined by the ionic load (eq / L) of the liquid. The ion load (eq / L) of the boron eluent is calculated from the ion concentration (mg / L) of the mineral acid contained in the boron eluent. For example, if the ion concentration of sulfuric acid contained in the boron eluent is 10,000 mg / L,
10,000 mg / L (concentration) ÷ 96 (molecular weight) × 2 (valence) /1000=0.21
Thus, the ion load of the boron eluent can be calculated as 0.21 eq / L. By comparing the ion load (eq / L) of the boron eluent with the adsorption capacity (eq / L-Resin) of the ion exchange resin, the liquid flow rate (V ₀ ) (L / L-Resin) at which the ion exchange resin is saturated ) Is required. Theoretically, the boron eluent of this liquid flow rate (L / L-Resin) is passed, and then water is passed to the space in the anion exchange tower and the void in the anion exchange resin. When the mineral acid in the liquid that has been filled is adsorbed by the anion exchange resin, the anion exchange resin breaks through and eventually reaches saturation. After grasping the amount of mineral acid filling the space in the anion exchange tower and the void in the anion exchange resin, the flow rate (V) of the boron eluent that does not allow the mineral acid to leak out is set to V < It is determined in advance within the range of Vo and is controlled by an integrating flow meter at the outlet of the anion exchange tower. The standard of the flow rate (V) of the boron eluent in which the mineral acid does not leak out reliably is 60 to 90%, more preferably 80 to 90%, of the flow rate (Vo) at which the ion exchange resin is saturated. The higher the mineral acid content in the boron eluent, the lower the amount of liquid (V ₀ ) at which the ion exchange resin is saturated.

Further, after the flow of the boron eluent is stopped, boron remains in the anion exchange column. If the regeneration of the ion exchange resin is started as it is, a problem arises in that the regeneration wastewater is mixed with boron, the boron recovery rate is lowered, and the boron concentration in the regeneration wastewater is increased, and therefore a boron removal treatment is necessary. Therefore, by passing the working water from the working water tank 2 to the anion exchange tower 4 before starting the regeneration process, the boron remaining in the ion exchange tower is pushed by water. In order to stop the flow of boron eluent containing mineral acid at a predetermined flow rate before the anion exchange resin breaks through, the anion exchange resin retains the ion adsorption capacity. The mineral acid in the liquid filled in the space in the anion exchange tower and the space of the anion exchange resin is adsorbed on the anion exchange resin, and the mineral acid adsorbed on the anion exchange resin does not leak out and functions as a molecule. Only the existing H ₃ BO ₃ is released from the lower part of the ion exchange column without being adsorbed by the ion exchange resin. This boron solution is sent to the boron purified liquid recovery tank 5 or the recycled water recovery tank 6 as it is.

The liquid that has passed through the anion exchange tower 4 is sent to a boron purified liquid recovery tank 5. The boron purification solution to be sent is a solution having a boron concentration of 10 mg / L or more and a mineral acid (SO ₄ ) concentration of 0.05 mg / L or less. A solution having a low boron concentration can be discharged as it is, but by providing a separate recycled water recovery tank 6, it can also be used as washing water in the subsequent anion exchange resin regeneration step.

After starting the flow of the boron eluent, the transition of the components contained in the treatment liquid was evaluated along with the transition of the flow rate. The components in the boron eluent are as shown in Table 1 below. The boron eluent was passed through 4BV (4 times the amount of the anion exchange resin), and then the working water was passed through. Note that the flow rate (V ₀ ) at which the ion exchange resin saturates is 4.4 BV, and the upper limit is 90% (V = V ₀ ×). 0.9BV = 4.0BV), and if the construction water is then passed, it has been confirmed in advance that no mineral acid is mixed in the effluent of the anion exchange tower. Further, if the boron eluent is continuously passed, the anion exchange resin will break through when the boron eluent passes through the ion exchange resin when the flow rate V _C = 4.2 BV. I have confirmed. Detailed test conditions are described in Example 1 below.

The result of the test is shown in FIG. In FIG. 4, the horizontal axis is the flow rate after the start of passing the boron eluent, the vertical axis (left) and the circle mark are the boron concentration in the treatment liquid, the vertical axis (right) and the white square mark are It is the mineral acid (SO ₄ ) concentration in the treatment liquid. As shown in FIG. 4, the boron concentration in the waste water starts to rise after a while since the start of the flow of the boron eluent. Thereafter, when the boron eluent flow rate reaches 4 BV, the flow is stopped, and after a while from the start of flowing the working water, boron is swept away and the boron concentration decreases. In the present invention, the treatment liquid discharged in the “boron purification liquid recovery section” in FIG. 4 is recovered in the boron purification liquid recovery tank 5. Table 1 shows the components of the recovered boron purification solution. Since the treatment liquid discharged in the “first discharge section” and “second discharge section” in FIG. 4 is low in both boron concentration and mineral acid (SO ₄ ) concentration, it should be used as recycled water or discharged as discharge water. Can do. The boron concentration in the first and second discharge sections is less than 200 mg / L.

  By adopting the above-described process of the present invention as a process for recovering boron, the following effects can be obtained. That is, in the conventional method of measuring the pH of the effluent from the anion exchange tower and stopping the flow of the boron eluent, it is possible to avoid the inclusion of mineral acid in the boron purified solution recovered water immediately before the stop of the flow. However, according to the present invention, it is possible to recover a high-purity boron purified liquid without any mixing of mineral acid in the recovered water for recovering boron. Further, since the flow of boron eluent can be stopped with the integrated flow rate, management becomes easy. Furthermore, since the liquid that flows out from the anion exchange tower does not generate any liquid containing both boron and mineral acid, it is not necessary to waste boron, and it is necessary to carry out recycling for effective use of boron. Therefore, the cost can be reduced.

《Cation adsorption process》
A large amount of cations may be contained in the boron eluent. In such a case, as shown in FIG. 1B, a cation exchange column 3 filled with a strongly acidic cation exchange resin adjusted to an H shape can be disposed in front of the anion exchange column 4. Thereby, cations such as Na and Ca are removed by adsorbing to the strongly acidic cation exchange resin, and a higher purity boron purified solution is obtained.

《Regeneration process》
The anion exchange resin that adsorbs the mineral acid and the strongly acidic cation exchange resin that adsorbs the cation are regenerated into the original OH form and H form by passing the regenerant. The regenerated anion exchange column can return to the “step of recovering boron” and pass the boron eluent again.

  As shown in FIG. 2, caustic soda is passed through the caustic soda tank 7 as a regenerant, and the adsorbed mineral acid is desorbed and regenerated into OH form. The mineral acid adsorbed on the anion exchange resin is ion-exchanged with OH ions of caustic soda (NaOH), and then reacts with Na ions to form a salt to be eluted from the anion exchange resin. After that, the boron eluent can be passed again by washing with water and washing away caustic soda and salt. At this time, the recycled water recovered in the recycled water recovery tank 6 can be used instead of the industrial water.

  As shown in FIG. 3, a mineral acid is passed as a regenerant from the mineral acid tank (hydrochloric acid tank 9) to the strongly acidic cation exchange resin adsorbing the cation to desorb the adsorbed cation. To play back in H shape. The cation adhering to the strongly acidic cation exchange resin is ion-exchanged with the H ion of the mineral acid and reacts with the mineral acid ion to form a salt to be eluted from the strongly acidic cation exchange resin. After that, by washing with industrial water and washing away the mineral acid and salt, the process returns to the “step of recovering boron” and the boron eluent can be passed again.

  Wastewater containing mineral acid and its sodium salt, potassium salt, or cation generated in the regeneration step can be sent to the treatment liquid discharge pipe 8 and discharged. At this time, if necessary, a pH adjustment tank is provided and discharged after pH adjustment. If there is a possibility that the treated water may contain heavy metals, etc., further treatment with chelate resin or post-treatment such as solid-liquid separation treatment by forming metal hydroxide with alkaline agent such as caustic soda or slaked lime It is preferable to discharge | release after attaching | subjecting to a process.

  In order to clean the water filled in the ion exchange tower and piping, which will be recovered as recycled water immediately after the start of the flow after completion of the regeneration process of the anion exchange tower 4 and the strong acid cation exchange tower 3, Water washing can also be performed in a state where two ion exchange towers are connected. Since the components of the wastewater generated at this time are close to industrial water, they can be sent to the recycled water recovery tank 6.

  In the regeneration process of the ion exchange resin, it is preferable to control the flow rate of the regenerant and the working water in accordance with the integrated flow meter, similarly to the control of the boron eluent flow end time described above. Specifically, the regenerant can be used in an amount capable of completely regenerating the resin adsorption capacity, and the industrial water can be used in an amount capable of completely washing the regenerator.

<Others>
In the present invention, when the mineral acid contained in the boron eluent is sulfuric acid, the present invention can be preferably used. Since sulfuric acid has higher adsorption efficiency than hydrochloric acid, the ion exchange resin can be regenerated more efficiently. In addition, since sulfuric acid is less corrosive than hydrochloric acid, a type of material that cannot be used when hydrochloric acid is used can be used for the equipment. However, since the corrosiveness of sulfuric acid varies greatly depending on temperature and concentration, it is necessary to examine and select a material suitable for the use environment.

  As the basic anion exchange resin and the acidic cation exchange resin, a porous ion exchange resin based on a styrene-based crosslinked copolymer can be used. Specifically, type I strongly basic anion exchange resin, type II strongly basic anion exchange resin, weakly basic anion exchange resin as basic anion exchange resin, and strong acidity as acidic cation exchange resin A cation exchange resin can be suitably used.

  The high-purity boron purified solution obtained in the step of recovering boron can be reused as it is or after being concentrated and solidified as necessary. Concentration and solidification methods include a dry solidification method that completely evaporates the obtained boron purified liquid, or a cooled crystal that cools the concentrated liquid after concentration to some extent, lowers the solubility of boric acid, and precipitates boric acid crystals. Conventional concentrated crystallization, such as precipitation, can be used.

  By installing two series of resin towers, the boron eluent purification step and the resin regeneration step used in the purification step can be performed simultaneously. In other words, while the boron eluent purification process is in progress, the resin tower used in the previous cycle is regenerated, so that the boron eluent flow can be resumed simply by switching the piping after the boron eluent flow is stopped. Can increase the daily processing cycle.

[Example 1]
The apparatus shown in FIG. An acrylic column having an inner diameter of 72 mm and a height of 1000 mm is prepared, and 2.4 L-Resin is packed with a strongly acidic cation exchange resin adjusted to an H shape to form a cation exchange column 3. Further, an acrylic column having an inner diameter of 150 mm and a height of 1000 mm is prepared, and 12 L-Resin is filled with a weakly basic anion exchange resin adjusted to an OH form to form an anion exchange column 4. The adsorption capacity of the ion exchange resin is 1.7 eq / L-Resin.
Further, by passing sulfuric acid through a boron selective adsorption resin having an N-methylglucamine group adsorbing boron, a boron eluent containing sulfuric acid was obtained and accommodated in the boron eluent tank 1. The components of the boron eluent were 2100 mg / L for boron and 18400 mg / L for SO ₄ concentration. The ion load of the boron eluent is 0.38 eq / L.
From the above, the liquid flow rate (V ₀ ) at which the ion exchange resin is saturated is
V ₀ = 1.7 (eq / L-Resin) /0.38 (eq / L) = 4.4 (L / L-Resin)
Is calculated. Since the unit (L / L-Resin) and the unit BV have the same meaning, V ₀ = 4.4 BV. Therefore, the liquid flow rate (V) at which the boron eluent never leaks is estimated to be 2.6 to 4.0 BV of 60 to 90% of V ₀ , more preferably 3.5 to 4.0 BV of 80 to 90%. Is done.
This time, V = 4.4 BV × 0.9 = 4 BV.

Next, the boron eluent contained in the boron eluent tank 1 is 4 L / h in the order of the cation exchange column 3 and the anion exchange column 4 in the order of 24 L / h. Double volume (4BV) was passed. After the end of the flow, the working water was further passed through 7 times the amount of the weak basic anion exchange resin (7 BV).
Of the liquid flowing out from the anion exchange tower 4, 6.5 BV liquid from 2.5 BV to 9 BV (“boron purification liquid recovery section” in FIG. 4) is recovered in the boron purification liquid recovery tank 5. The other parts were collected in the recycled water collection tank 6. As a result, the boron concentration of the boron purified liquid obtained by collecting in the boron purified liquid recovery tank 5 is 1,130 mg / L, and the boron recovery rate is
{1130 (mg / L) × 6.5 (BV)} / {2100 (mg / L) × 4 (BV)} × 100 = 87.4 (%)
was. Moreover, the sulfuric acid concentration of the boron purified solution was less than 0.1 mg / L. The results are shown in Table 1.

[Example 2]
The apparatus shown in FIG. A glass column having an inner diameter of 14 mm and a height of 550 mm is prepared, and 30 mL-Resin of a strongly acidic cation exchange resin adjusted to an H shape is packed into a cation exchange tower 3. Further, a glass column having an inner diameter of 26 mm and a height of 550 mm is prepared, and 150 mL-Resin is filled with a weakly basic anion exchange resin adjusted to an OH form to form an anion exchange column 4. The adsorption capacity of the ion exchange resin is 1.7 eq / L-Resin.
Further, by passing sulfuric acid through a boron selective adsorption resin having an N-methylglucamine group adsorbing boron, a boron eluent containing sulfuric acid was obtained and accommodated in the boron eluent tank 1. The components of the boron eluent were 2200 mg / L boron and 18400 mg / L SO ₄ concentration. The ion load of the boron eluent is 0.38 eq / L.
From the above, the flow rate (V ₀ ) until the ion exchange resin is saturated is
V ₀ = 4.4 (L / L-Resin) = 1.7 (eq / L-Resin) /0.38 (eq / L)
Is calculated. Since the unit (L / L-Resin) and the unit BV have the same meaning, V ₀ = 4.4 BV. Therefore, the liquid flow rate (V) at which the boron eluent never leaks is estimated to be 2.6 to 4.0 BV of 60 to 90% of V ₀ , more preferably 3.5 to 4.0 BV of 80 to 90%. Is done.
This time, V = 4.4 BV × 0.9 = 4 BV.

  Next, the boron eluent contained in the boron eluent tank 1 is charged in the order of 0.3 L / h in the order of the cation exchange column 3 and the anion exchange column 4, and the resin amount of the weakly basic anion exchange resin. 4 times the amount (4 BV) was passed. After the end of the flow, the working water was further passed in an amount 8 times the amount of the weakly basic anion exchange resin (8 BV).

The results are shown in FIG. The vertical axis and horizontal axis in FIG. 5 are the same as those in FIG. 4. The vertical axis (left) and circles indicate the boron concentration in the treatment liquid, the vertical axis (right) and white square marks indicate the mineral acid ( SO ₄ ) concentration. The behavior of the boron concentration and the behavior of the sulfuric acid concentration after the start of liquid flow show the same behavior as in FIG. Of the liquid flowing out from the anion exchange tower 4, 6BV liquid from the start of liquid flow to 2BV to 8BV ("boron purified liquid recovery section" in FIG. 5) is recovered in the boron purified liquid recovery tank 5, and the others The portion (“first discharge section” and “second discharge section” in FIG. 5) was recovered in the recycled water recovery tank 6. As a result, the boron concentration of the boron purified liquid obtained by collecting in the boron purified liquid recovery tank 5 is 1460 mg / L, and the boron recovery rate is
{1460 (mg / L) × 6 (BV)} / {2200 (mg / L) × 4 (BV)} × 100 = 99.5 (%)
was. Moreover, the sulfuric acid concentration of the boron purified solution was less than 0.1 mg / L. The results are shown in Table 2.

[Comparative Example 1]
The same cation exchange column, anion exchange column and boron eluent as in Example 2 were prepared. The components of the boron eluent were 2200 mg / L boron and 18400 mg / L SO ₄ concentration. The ion load of the boron eluent is 0.38 eq / L. The liquid flow rate (V ₀ ) at which the ion exchange resin saturates is V ₀ = 4.4 BV, as in Example 2. The boron eluent was passed through the cation exchange column 3 and the anion exchange column 4 in this order at a rate of 0.3 L / h, and the pH of the purified boron solution discharged from the anion exchange column outlet was lowered. After confirming this, the liquid passing was finished. Since the liquid flowed until the ion exchange resin broke through, the liquid flow volume (V) = the liquid flow volume when the ion exchange resin broke through (V _C ), and the liquid flow volume was measured. The amount was 4.2 times the amount of the weakly basic anion exchange resin (4.2 BV). After the end of the flow, the working water was further passed 5 times the amount of the weak basic anion exchange resin (5 BV).

The results are shown in FIG. The vertical axis and horizontal axis in FIG. 6 are the same as those in FIG. 4. The vertical axis (left) and circles indicate the boron concentration in the treatment liquid, the vertical axis (right) and white square marks indicate the mineral acid ( SO ₄ ) concentration. The concentration of boron is high at 2 BV to 8.2 BV from the start of liquid flow, and the mineral acid (SO ₄ ) concentration is increased as a result of the mixing of mineral acid into the treatment liquid (effluent) at 4.2 BV from the start of liquid flow. In addition, the pH decreases. Of the liquid flowing out from the anion exchange tower 4, 2.2 BV of liquid from the start of liquid flow to 2 BV to 4.2 BV (“boron purified liquid recovery section” in FIG. 6) is recovered in the boron purified liquid recovery tank 5. 4 BV liquid from 4.2 BV to 8.2 BV ("mineral acid recovery section" in FIG. 6) is individually recovered as sulfuric acid recovery liquid, and the other parts ("first discharge section in FIG. 6" The “second discharge section”) was recovered in the recycled water recovery tank 6. As a result, the boron concentration of the boron purified solution recovered in the boron purified solution recovery tank 5 is 1270 mg / L, and the boron recovery rate is
{1270 (mg / L) × 2.2 (BV)} / {2200 (mg / L) × 4.2 (BV)} × 100 = 30.2 (%)
was. Further, the sulfuric acid concentration of the purified boron solution was 120 mg / L. Since the end of the flow of boron eluent was performed after exceeding the flow rate until the ion exchange resin broke through (V _C = 4.2 BV), boron was contained in the sulfuric acid recovery liquid. The concentration of boron recovered in the sulfuric acid recovery solution was 1600 mg / L, the concentration of sulfuric acid was 9300 mg / L, and the boron recovery rate recovered in the solution was
{1600 (mg / L) × 4 (BV)} / {2200 (mg / L) × 4.2 (BV)} × 100 = 69.3 (%)
was. In order to separate and effectively use the boron recovered in the sulfuric acid solution, it is necessary to recycle the solution to an anion exchange column as in the prior art. The results are shown in Table 3.

DESCRIPTION OF SYMBOLS 1 Boron elution tank 2 Industrial water tank 3 Cation exchange tower 4 Anion exchange tower 5 Boron refined liquid collection tank 6 Recycled water collection tank 7 Caustic soda tank 8 Treatment liquid discharge pipe 9 Hydrochloric acid tank

Claims (7)

  The amount of flow through which the boron eluent containing the mineral acid is passed through the anion exchange column is smaller than the amount of flow through which the anion exchange resin breaks through the flow of the boron eluent containing the mineral acid. A method for purifying a boron eluent, wherein the solution is passed at an integrated flow rate and a boron solution containing no mineral acid is recovered.   2. The method for purifying a boron eluent according to claim 1, wherein an integrated flow rate of the boron eluent containing the mineral acid is predetermined based on a mineral acid content in the boron eluent. A group of type I strongly basic anion exchange resins adjusted to form OH, type II strongly basic anion exchange resins adjusted to form OH, and weakly basic anion exchange resins adjusted to form OH (hereinafter referred to as “anions”). An ion exchange tower (hereinafter referred to as “anion exchange tower”) filled with an anion exchange resin selected from the “exchange resin group”),
A liquid flow rate for passing a boron eluent containing a mineral acid through an anion exchange column is determined in advance as an integrated flow rate of a boron eluent containing a mineral acid,
When a boron eluent containing a mineral acid is passed through an anion exchange column and the flow rate of the boron eluent containing the mineral acid reaches or reaches the integrated flow rate of the boron eluent containing the predetermined mineral acid A step of recovering boron by stopping the process before passing, and then passing water through the anion exchange tower;
And a step of adjusting an ion form of an ion exchange resin filled in the anion exchange column to an OH form by passing an alkaline solution through the anion exchange tower after recovering the boron. The method for purifying a boron eluent according to claim 1 or 2.   In the step of recovering the boron, a cation exchange column filled with a strongly acidic cation exchange resin adjusted to H-shape is arranged in front of the anion exchange column filled with the anion exchange resin group, Ions that are adsorbed on the ion exchange resin in the cation exchange column by adsorbing the cation contained in the boron solution containing the mineral acid, and then filling the cation exchange column by passing a regenerant through the cation exchange column The method for purifying a boron eluent according to any one of claims 1 to 3, further comprising a step of adjusting the ion form of the exchange resin to an H form.   The method for purifying a boron eluent according to any one of claims 1 to 4, wherein the mineral acid is sulfuric acid.   6. The anion exchange resin group and the strongly acidic cation exchange resin are porous ion exchange resins based on a styrene-based crosslinked copolymer as claimed in any one of claims 1 to 5. A method for purifying the boron eluent as described.   The boron eluent according to any one of claims 1 to 6, wherein the boron solution obtained in the step of recovering boron is concentrated and solidified to form a boric acid solid. Purification method.