JPH0352649A - Method for regenerating ion exchange resin - Google Patents

Abstract

PURPOSE:To reduce cost and to shorten the time required to regenerate an ion exchange resin by blowing steam into a layer of the resin from the top when the resin is regenerated after a soln. contg. a water soluble org. solvent having a lower b.p. than water is treated by passing through the layer. CONSTITUTION:When an ion exchange resin is regenerated after a soln. contg. a water soluble org. solvent having a lower b.p. than water is treated by passing through a layer of the resin to remove cations or anions in the soln., the feed of the soln. to be treated is stopped and steam is blown into the layer from the top. A regenerating soln. is then passed through the layer to regenerate the resin and the used regenerating soln. in the tower is drawn out. Water is further passed through the layer to wash the resin and the used water in the tower is drawn out. By this method, cost is considerably reduced and the time required to regenerate the ion exchange resin is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improved method for regenerating ion exchange resins. [Prior art and problems to be solved by the invention] Ion exchange resins include cation exchange resins and anion exchange resins.
When the treatment liquid (referred to as "treatment liquid") is passed through a column (ion exchange tower) packed with ion exchange resin, the cations and anions in the treatment liquid are replaced by other ions, such as hydrogen ions, in the ion exchange resin. Alternatively, it is removed by exchanging with hydroxyl ion. Therefore, this ion exchange capacity gradually decreases as the processing solution passes through the resin, and eventually ion exchange ceases, so the ion exchange resin must be regenerated at an appropriate point. The regeneration of ion exchange resins is usually performed using the following method. In other words, stopping the flow of the processing solution, draining the processing solution, cleaning before regeneration, draining the washing water, regeneration, draining the regenerated solution, cleaning after regeneration, draining the washing water, and stopping the passing of the processing solution. It is done in order. The purpose of cleaning before regeneration is to recover the treated liquid impregnated into the ion exchange resin, and the process of passing regular water through the ion exchange tower or filling and draining water is repeated several times to recover the treated liquid. After washing, continue rinsing with water if necessary (discard after rinsing). However, although this method achieves the purpose of recovering the processing solution, it produces a considerable amount of dilute processing solution. This dilute processing solution must be concentrated by some method, and the loss of energy cannot be ignored. To solve this problem, there is a method in which the processing solution is collected in multiple stages. Although this method reduces the amount of dilute processing solution generated compared to the above method, it has the disadvantage that the cleaning time becomes longer. Therefore, the present inventors have developed a regeneration method that first eliminates the generation of dilute processing solution and reduces the time required before regeneration, that is, the processing solution is passed through an ion exchange resin layer to remove cations or anions in the processing solution. When regenerating the ion-exchange resin after deionizing the ion-exchange resin, the inventors invented a method in which water vapor is blown into the ion-exchange resin layer from the bottom of the resin layer after the treatment solution is drained from the ion-exchange resin layer (Japanese Patent Application No. 1986- 1776
No. 57). However, this method had the disadvantage of requiring a large amount of steam, since the remaining organic solvent had to be completely evaporated with steam. In addition, in order to reduce water vapor as much as possible, it was necessary to drain the liquid in advance. [Means for Solving the Problems] The present inventors have conducted intensive studies on a method for reducing the amount of water vapor used when regenerating ion exchange resins, and have found that when blowing water vapor into the ion exchange resin layer, ion It was discovered that the amount of water vapor used could be significantly reduced by blowing from the top of the exchange resin layer, which led to the completion of the present invention. That is, the method for regenerating an ion exchange resin of the present invention involves using a solution (processing liquid) containing an organic solvent that is soluble in water and has a boiling point lower than that of water.
is passed through an ion exchange resin layer to deionize cations or anions in the treated solution, and then the ion exchange resin is regenerated, the method comprising blowing steam from above the ion exchange resin layer. This is a distinctive method for regenerating ion exchange resins. [Detailed Disclosure of the Invention] The present invention will be explained in more detail. The regeneration order of the ion exchange resin in the present invention is usually carried out as follows. l) Stop the flow of the processing solution to the ion exchange resin layer. 2
) Steam is blown into the ion exchange resin layer from above.

3) Pass the regeneration solution through the ion exchange resin layer to regenerate the ion exchange resin. 4) After regeneration, drain the regenerated liquid from the ion exchange tower. 5)
Water is passed through the ion exchange resin layer to wash the ion exchange resin. 6) Drain the water in the ion exchange tower. 7) Pass the processing solution through the ion exchange resin layer. The treatment liquid targeted by the present invention is a solution containing an organic solvent that is water-soluble and has a boiling point lower than water (unless otherwise specified, an organic solvent that is water-soluble and has a boiling point lower than water is simply referred to as an organic solvent).
In other words, it is a three-component solution consisting of an organic solvent, water, and a solute, or a two-component solution consisting of an organic solvent and a solute. If the solute is non-volatile or has a higher boiling point than water, the next step is to blow steam into the ion exchange resin layer, which will recover the organic solvent impregnated in the ion exchange resin layer, but the solute will remain intact. Therefore, in order to completely recover the solute, it is preferable to wash the ion exchange resin layer with an organic solvent before blowing water vapor into the ion exchange resin layer. It is even more preferable if it is the same as the organic solvent contained therein. It is also preferable if the washed organic solvent can be used as is. A suitable example of such a process is a wet phosphoric acid purification process using a molar solvent, as shown in the examples below. The ion exchange resin layer is washed with an organic solvent in a down flow manner. If the boiling point of the solute is lower than that of water, the solute can be evaporated and recovered together with the organic solvent by blowing water vapor into the ion exchange resin layer, which will be described later. Therefore, washing with the organic solvent described above is not necessary. If the content of the ion-exchange resin layer is low, washing with the ion-exchange resin layer makes it easier to perform the subsequent step of blowing water vapor into the ion-exchange resin layer. The blowing of steam in the present invention will be explained. After stopping the flow of the treated liquid to the ion exchange resin layer, water vapor is blown into the ion exchange resin column from the top of the column, and the treated liquid in the column is pushed out from the bottom by the pressure of the steam. Next, the upper part of the resin layer is heated by water vapor, and the organic solvent impregnated in the resin evaporates. This organic solvent vapor transfers heat to the resin at the bottom, condenses, and flows out while transferring heat to the resin at the bottom. The organic solvent impregnated into the resin in this way is temporarily evaporated by water vapor, but can be extracted as a condensate while there is a resin layer below that can exchange heat. but,
As the resin temperature at the bottom of the column rises, the organic solvent vapor is not condensed within the column and is recovered using a condenser outside the system. When water vapor is blown into the ion-exchange resin layer in this way, the organic solvent impregnating the upper part of the ion-exchange resin layer evaporates at first, but it quickly evaporates and is recovered as a condensate. The temperature of the gaseous portion recovered at the bottom of the column does not change. Thereafter, the temperature of this part indicates the azeotropic point of the organic solvent and water. Continuing further, as the organic solvent evaporates, the temperature of the area rises rapidly. At this point, you can stop blowing steam. The pressure of the water vapor blown into the ion exchange resin layer is 0.5 Kg/c+w"・G ~5 Kg/cm" in gauge pressure.
・G level is preferable. If the pressure is less than 0.5 kg/am''·G, the organic solvent impregnated in the ion exchange resin will not be sufficiently evaporated, which is undesirable, and if the pressure is too high, it will be difficult to control the amount of water vapor blown into the resin, which is undesirable. The amount of water vapor blown into the ion exchange resin varies slightly depending on the particle size of the ion exchange resin, but it is preferably about 200 to 300 kg/h per ion exchange resin layer 11. If the amount is more than this, the rectification effect will be weakened, and the resulting organic This is not preferable because the solvent concentration will be low, and if it is less than this, the time required will be longer, which is not preferable.Ion exchange resins can be regenerated using sulfuric acid, hydrochloric acid, etc. at a concentration of 5 to 10% by weight for cation exchange resins. mineral acid aqueous solution,
For anion exchange resins, this is carried out by a method known per se in which a caustic alkali such as caustic soda at a concentration of 5 to 10% by weight is passed through an ion exchange column. When the injection of steam into the ion exchange resin layer is thus completed, the ion exchange resin may be regenerated with a regenerating liquid and washed with water after regeneration by a method known per se. In addition, since the present invention blows water vapor into the ion exchange resin layer in this way, it is naturally preferable that the ion exchange resin has heat resistance of 100° C. or higher. Examples of such heat-resistant ion exchange resins include cation exchange resins such as Revatit SP112 and Revatit SP-12 manufactured by Bayer AG, West Germany.
0, C-111 and C-132 made by Kurita Kogyo ■, and A-168 made by Kurita Kogyo ■ for anion exchange resins. [Example] The present invention will be specifically explained below with reference to Examples and Comparative Examples. In the Examples and Comparative Examples, % indicates weight %. Example 1 Isopropyl alcohol was added to a wet phosphoric acid solution with hOs 1 degree 54.3%, the free M phosphoric acid content in the wet phosphoric acid was extracted, and the first
An extract with the composition shown in the table was obtained. Table 1: An ion exchange column (ion exchange resin filling height: 4.5+ m) with a column diameter of 1.5 m and a column height of 6.4 m filled with cation exchange resin Revati SP-112 (manufactured by Bayer AG, West Germany).
The extract having the composition shown in Table 1 was passed through upflow at a fit of 16 m"/h to deionize the contained Na ions. After passing for 7.5 hours, the ion exchange processing capacity decreased. Therefore, the flow of liquid was stopped.After that, using isobrobyl alcohol with a concentration of 87%,
The ion exchange resin was washed with downflow for 2 hours at a flow rate of 15IIl3/h. Next, 500 kg of water vapor with a gauge pressure of 1.5 kg/c1・G was pumped from the top of the ion exchange tower.
g/h, and was separated by a gas-liquid separator installed at the outlet of the lower part of the ion exchange tower, and an effluent 91 and an "iflla" obtained by condensing the vapor in a cooler were recovered.

The temperature of the steam section of the gas-liquid separator was initially 50°C, but 30 minutes after the start of steam injection, it rose to 80°C, and 70 minutes later, this temperature reached 95°C. Stopped blowing steam (steam usage: approx. 580
kg). The atc of the liquid recovered by steam condensation was 83% isobrobyl alcohol (the remainder was water), and the composition of the liquid flowing out from the gas-liquid separator was 87% isobrobyl alcohol (the remainder was water). The recovered isobrobyl alcohol could be reused as a solvent for wet phosphoric acid extraction. Next, after filling the ion exchange tower with water by upflow,
A sulfuric acid aqueous solution with a concentration of 9.5% 16 points is downflowed to 20
n? The ion exchange resin was regenerated by passing liquid through it for 50 minutes at a speed of /h. After regeneration, the ion exchange resin was thoroughly washed with tap water. It should be noted that almost no isopropyl alcohol was present in the regenerated liquid after regeneration, and the loss of isopropyl alcohol was negligible.

A portion of the thus regenerated cation exchange resin was observed using an electron microscope, but no change was observed in the shape of the ion exchange resin particles. Comparative Example 1 In the same manner as in Example 1, the flow of the extract was stopped and stopped. After that, using isopropyl alcohol with a concentration of 87%,
After washing the ion exchange resin with a down flow at a flow rate of 51/h for 2 hours, the isobrobyl alcohol in the ion exchange tower was drained into the solvent tank using nitrogen gas (drainage time required: 30 minutes). Next, water vapor with a gauge pressure of 1.5 Kg/cm'・G was introduced from the bottom of the ion exchange resin column at 1200 g.
The steam generated from the top of the ion exchange column was condensed in a cooler and recovered. The temperature at the top of the ion exchange column was initially 80'C, which was the boiling point of an azeotrope of isopropyl alcohol and water. It was about 70 minutes after the start of steam injection that the temperature reached 95°C and the steam injection was stopped (approx. 1400 kg of steam was used). The liquid recovered from the above condensation had an isopropyl alcohol concentration of approximately 86% (the remainder was water). Next, in the same manner as in Example 1, the ion exchange column was filled with water in an upflow manner, and then 161 sulfuric acid aqueous solution with a concentration of 9.5% was poured in a downflow manner at a speed of 20 m''/h for 5 minutes.
The ion exchange resin was regenerated by passing liquid through it for 0 minutes. The regenerated ion exchange resin was thoroughly washed with clean water. [Effects of the Invention] As described in detail above, the method of the present invention eliminates the use of water vapor, which was conventionally required in large amounts, when regenerating ion exchange resin. We were able to significantly reduce the amount. In addition, because the liquid draining operation that was required before blowing in steam could be omitted, the nitrogen gas used at that time was no longer needed. That is, the present invention significantly reduces costs and shortens the time required for regenerating the ion exchange resin, which has great economic effects.

Claims (3)

[Claims] (1) A solution (treatment liquid) containing an organic solvent that is water-soluble and has a boiling point lower than water is passed through the ion exchange resin layer to deionize the cations or anions in the treatment liquid, and then the ion exchange resin 1. A method for regenerating an ion exchange resin, the method comprising blowing steam from above the ion exchange resin layer. (2) The method according to claim 1, characterized in that, prior to blowing water vapor into the ion exchange resin layer, the ion exchange resin is washed with an organic solvent that is water soluble and has a boiling point lower than water. (3) The method according to claim 2, wherein the water-soluble organic solvent with a boiling point lower than water for washing the ion exchange resin is the same organic solvent as the organic solvent contained in the treatment liquid. .