JPH039774B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL FIELD The present invention relates to an improved method for regenerating ion exchange resins. (Prior art and problems) There are two types of ion exchange resins: cation exchange resins and anion exchange resins. ), the cations or anions in the treatment solution are exchanged with other ions, such as hydrogen ions or hydroxyl ions, in the ion exchange resin and removed. Therefore, this ion exchange ability gradually decreases as the processing solution passes through the resin, and eventually ions no longer exchange, so the ion exchange resin must be regenerated at an appropriate point. Regeneration of ion exchange resins is usually carried out in the following manner. 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 that, washing with water is continued if necessary (the washing liquid is discarded). However, although this method achieves the purpose of recovering the processing liquid,
Generates 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. In order to solve this problem, there is a method in which the processing liquid is recovered in multiple stages. Although this method reduces the amount of dilute processing liquid generated to some extent compared to the above-mentioned method, it has the disadvantage that the cleaning time becomes longer. (Means for Solving the Problems) The present inventors have been researching for many years how to reduce the amount of dilute treatment liquid generated during the regeneration of ion exchange resins and to shorten the cleaning time before regeneration as much as possible. As a result of extensive research, we found that by blowing steam into the ion exchange resin layer from which the processing solution has been drained, it is possible to virtually completely recover the active ingredients in the processing solution impregnated in the ion exchange resin. Moreover, they discovered that the required time can be significantly shortened compared to the conventional washing time, leading to the completion of the present invention. That is, the method for regenerating an ion exchange resin of the present invention involves passing a solution (treatment liquid) containing an organic solvent that is water-soluble and has a boiling point lower than water through an ion exchange resin layer to remove cations or anions in the treatment liquid. A method for regenerating the ion exchange resin after deionization, the method comprising:
This method is characterized in that after the treatment liquid is drained from the ion exchange resin layer, water vapor is blown into the ion exchange resin layer. The present invention will be explained in more detail. The regeneration order of the ion exchange resin in the present invention is generally carried out as follows. (1) Stop flowing the processing solution to the ion exchange resin layer. (2) Drain the treated liquid from the ion exchange tower. (3) Blowing water vapor into the ion exchange resin layer. (4) Pass the regeneration solution through the ion exchange resin layer to regenerate the ion exchange resin. (5) After regeneration, drain the regeneration liquid from the ion exchange tower. (6) Wash the ion exchange resin by passing water through the ion exchange resin layer. (7) Drain the water from the ion exchange tower. (8) Pass the processing solution through the ion exchange resin layer. To regenerate ion exchange resins, use a mineral acid aqueous solution such as sulfuric acid or hydrochloric acid with a concentration of 5 to 10% by weight for cation exchange resins, and use an aqueous solution of mineral acids such as sulfuric acid or hydrochloric acid at a concentration of 5% by weight for anion exchange resins.
~10% by weight of caustic alkali, such as caustic soda,
This is carried out by a method known per se, in which the liquid is passed through an ion exchange column. 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). That is, the solution 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 nonvolatile or has a boiling point higher than water, the organic solvent impregnated into the ion exchange resin layer is recovered by the next step, which is blowing steam into the ion exchange resin layer. In order to completely recover the solute, it is preferable to wash the ion exchange resin layer once or twice with an organic solvent before blowing water vapor into the ion exchange resin layer. It is more preferable that the organic solvent used for washing is the same as the organic solvent contained in the treatment liquid. Further, it is preferable that the washed organic solvent can be used as it is. Suitable examples of such a process include a wet phosphoric acid purification process using an organic solvent and a purification process in formalin production, as shown in Examples described later. Washing of the ion exchange resin layer with an organic solvent is carried out by applying an organic solvent to the ion exchange resin layer and draining it. 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, so washing with the organic solvent is not necessary, but the treatment When the content of organic solvent in the liquid is small, cleaning with an organic solvent makes it easier to perform the subsequent step of blowing water vapor into the ion exchange resin layer. The method of blowing water vapor into the ion exchange resin layer in the present invention is as follows. Steam is injected from the bottom of the ion exchange tower, but since the ion exchange resin is usually packed on a shelf such as a wire mesh installed at the bottom of the ion exchange tower, pressurized steam is injected through a dispersion nozzle, etc. It can be sufficiently dispersed and blown into the ion-exchange resin layer without using. In the present invention, since the boiling point of the organic solvent impregnated in the ion exchange resin is lower than that of water, the water vapor blown into the ion exchange resin layer rises through the ion exchange resin layer and evaporates the organic solvent impregnated therein. (The pressurized steam becomes condensed water and is impregnated into the ion exchange resin.) This evaporated organic solvent is led out of the system from the top of the ion exchange tower and can be recovered by condensing it using a condenser or the like. I can do it. In the present invention, the pressure of the water vapor blown into the ion exchange resin layer must be 0.5 kg/cm ² or more in terms of gauge pressure.
If the pressure is less than 0.5 Kg/cm ² ·G, the organic solvent impregnated in the ion exchange resin will not be sufficiently evaporated. However, if the pressure is too high, it will be difficult to control the amount of water vapor blown into it, so the upper limit of the pressure is about 5 kg/cm ² ·G. Naturally, the amount of water vapor blown into the ion exchange resin layer must be such that the blown water vapor does not blow through the ion exchange resin layer. The amount varies slightly depending on the diameter of the ion exchange tower and the height of the ion exchange resin layer, but it is ⁵⁰⁰
~1000Kg/h is appropriate. When steam is blown into the ion-exchange resin layer in this way, the organic solvent impregnated in the ion-exchange resin layer or the mixture of the organic solvent and a solute with a boiling point lower than that of water evaporates (the organic solvent is mixed with water). (When making an azeotropic composition, the organic solvent naturally becomes an azeotropic composition.) Therefore, the top temperature of the ion exchange resin column indicates the boiling point of the above organic solvent, etc., but the boiling point of the organic solvent or organic solvent and water is higher than that of the organic solvent. If the solute with a low temperature evaporates, the temperature at the top of the ion exchange column will rise rapidly at this point, so the injection of steam can be stopped at this point. The great effect of the present invention is that the ion exchange resin in the ion exchange column plays the role of packing in the rectification column, and the organic solvent or organic solvent impregnated into the ion exchange resin layer by steam injection. Only solutes with boiling points lower than that of water are rectified and discharged from the top of the ion exchange column as steam and are discharged from the system. This should never occur. However, if the organic solvent forms an azeotropic composition with water, the recovered organic solvent will have this azeotropic composition. When the injection of water vapor 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 the present invention, since water vapor is blown into the ion exchange resin layer in this manner, it is preferable that the ion exchange resin has heat resistance of 100° C. or higher. Among such heat-resistant ion exchange resins, among the cation exchange resins, there is Lewacht, manufactured by Bayer AG, West Germany.
SP-112, Revachit SP-120, Kurita Industries Co., Ltd. C
-111, C-132, Kurita Industries for anion exchange resins
There are A-168 manufactured by Co., Ltd., etc. (Effects of the Invention) The present invention is a method as described above, and makes it possible to substantially eliminate the dilute processing solution that is generated in considerable amounts during the regeneration of ion exchange resins, which has been a problem in the past. Moreover, the effective components in the treatment liquid impregnated into the ion exchange resin can be substantially completely recovered. In addition, it is possible to significantly shorten the time required before regenerating the ion exchange resin (cleaning time in conventional methods, steam blowing time in the method of the present invention).
There are great economic effects. (Example) The present invention will be specifically described 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 a P ₂ O ₅ concentration of 54.3% to extract the free phosphoric acid content in the wet phosphoric acid solution to obtain an extract having the composition shown in Table 1.

[Table] Ion exchange tower with a tower diameter of 1.5 m and tower height of 6.4 m filled with cation exchange resin Levachit SP-112 (manufactured by Bayer AG, West Germany) (ion exchange resin filling height: 4.5 m)
Next, an extract having the composition shown in Table 1 was passed through the tube at a flow rate of 20 m ³ /h to deionize the Na ions contained therein. After 12 hours of liquid passage, the ion exchange processing capacity decreased, so the liquid passage was stopped, and the extract in the ion exchange column was drained to the extract liquid tank. After draining the extract, the concentration up to the resin layer of the ion exchange tower
The ion exchange resin was washed by performing two operations of adding and draining 87% isopropyl alcohol (azeotropic composition with water). The isopropyl alcohol used for this washing was reused as a solvent for wet phosphoric acid extraction. Then, the gauge pressure is increased from the bottom of the ion exchange resin column.
Steam of 1.5 kg/cm ² ·G was blown in at a flow rate of 1200 kg/h, and the steam generated from the top of the ion exchange column was condensed and recovered in a cooler (collected amount: 3.7 m ³ ). The temperature at the top of the ion exchange column was initially 80°C, which was the boiling point of the azeotropic composition of isopropyl alcohol and water, but this temperature reached 95°C approximately 1 hour and 10 minutes after the start of steam injection. , the steam injection was stopped. The composition of the liquid recovered by the above condensation had an isopropyl alcohol concentration of about 86% (the remainder was water), which was almost the same composition as the isopropyl alcohol azeotropic composition. The recovered isopropyl alcohol could also be reused as a solvent for wet phosphoric acid extraction. Next, 16 m ³ of an aqueous sulfuric acid solution with a concentration of 9.5% was circulated through the ion exchange column at a rate of 20 m ³ /h for 50 minutes with upflow to regenerate the ion exchange resin. The regenerated 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 part of the thus regenerated cation exchange resin was observed by electron micrograph photography, but no change was observed in the shape of the particles of the ion exchange resin. Example 2 Formalin (formaldehyde 43.2%, methanol 3.9 %,formic acid
0.012%, the remainder being water) was passed down-flow at a flow rate of 1.5 m ³ /h to deionize and remove the formic acid contained therein. After 27 hours of liquid passage, the ion exchange processing capacity decreased, so the liquid passage was stopped, and the formalin in the ion exchange column was drained into a crude formalin tank. After removing the formalin, the ion exchange resin was washed by filling the resin layer of the ion exchange tower with methanol and removing the liquid twice. The methanol used for this washing was used as raw material methanol for formalin synthesis. Then, the gauge pressure from the bottom of the ion exchange tower is 1.2.
Blow in Kg/ ^cm2・G of steam at a flow rate of 600Kg/h,
The steam generated from the top of the ion exchange tower was condensed and recovered using a cooler. Initially, the temperature at the top of the ion exchange column was approximately
The boiling point of methanol was 65°C, but this temperature reached 90°C approximately 30 minutes after the start of steam injection, so the steam injection was stopped. The composition of the liquid recovered by the above condensation has a purity of approximately
It was 98.5% methanol. (Amount recovered: 660 kg) The recovered methanol was also used as raw material methanol for formalin synthesis. Next, 12 m ³ of NaOH aqueous solution with a concentration of 9.3% was circulated through the ion exchange tower at a rate of 1.5 m ³ /h for 2 hours with upflow to regenerate the ion exchange resin. The regenerated ion exchange resin was thoroughly washed with tap water. It should be noted that almost no methanol was present in the regenerated liquid after passing through the ion exchange tower, and the loss of methanol was substantially zero. A portion of the thus regenerated cation exchange resin was observed using electron microscopy photography as in Example 1.
No change was observed in the shape of the ion exchange resin particles. Comparative Example 1 In Example 1, the concentration to the ion exchange resin layer was 87
The ion exchange resin was prepared in the same manner as in Example 1, except that the ion exchange resin layer was washed with water and drained three times instead of the solution filling and washing with % isopropyl alcohol and the blowing of water vapor. was played. The amount of the washing liquid was 14.8 m ³ and the concentration of isopropyl alcohol was 12.1%. The regenerated solution after regeneration also contained 1.2% isopropyl alcohol. Comparative Example 2 Similar to Comparative Example 1, in Example 2, instead of filling and washing the ion exchange resin layer with methanol and blowing water vapor into it, the ion exchange resin layer was filled with water and cleaned by draining water. The ion exchange resin was regenerated in the same manner as in Example 2, except that the regeneration was repeated twice. The amount of the cleaning solution and the formaldehyde concentration in the cleaning solution were 2.2 m ³ and about 6%.

Claims (1)

[Scope of Claims] 1. An ion exchange resin after a treatment liquid containing an organic solvent that is soluble in water and has a boiling point lower than water is passed through an ion exchange resin layer to deionize cations or anions in the treatment liquid. In the method for regenerating the ion exchange resin, the treatment liquid is drained from the ion exchange resin layer, the regeneration liquid is passed through the ion exchange resin layer, and before the regeneration, water vapor is blown into the ion exchange resin layer to remove the organic solvent. How to play. 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 soluble in water and has a boiling point lower than water. 3. The method according to claim 2, wherein the water-soluble organic solvent having a boiling point lower than water and used to wash the ion exchange resin is the same organic solvent as the organic solvent contained in the treatment liquid.