KR20090071552A - Process and equipment for the recovery of phosphoric acid from phosphoric acid-containing water - Google Patents

Abstract

A process and equipment which make it possible to recover high-purity phosphoric acid useful as a recycled matter in the form of a portable high-concentration liquid from phosphoric acid-containing water at high efficiency by simple constitution and operation. The process comprises subjecting phosphoric acid-containing water to both cation exchange and anion exchange, subjecting the resulting water to reverse osmosis under the condition of pH of 3 or below, preferably under the conditions of pH of 3 or below and a phosphoric acid concentration of 1 to 15wt%, to transmit acids (except phosphoric acid) and water to a permeating fluid chamber side with phosphoric acid concentrated on a concentrated fluid chamber side, desalting the permeating fluid with an ion exchanger to recover pure water, and evaporating the concentrated fluid with an evaporator to remove volatile components and water and recover a concentrated phosphoric acid solution.

Description

PROCESS AND EQUIPMENT FOR THE RECOVERY OF PHOSPHORIC ACID FROM PHOSPHORIC ACID-CONTAINING WATER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for recovering phosphoric acid from a phosphoric acid-containing water by means of a reverse osmosis device, in particular, valuables such as phosphoric acid and treated water from a washing wastewater containing phosphoric acid after etching a liquid crystal substrate, a wafer or other electronic device. A method and apparatus for recovering phosphoric acid suitable for recovery of phosphorus pure water.

An etching solution containing phosphoric acid is used for etching liquid crystal substrates, wafers and other electronic devices. Although a high concentration of the waste etching solution generated in the etching process is recovered and used, the electronic equipment after etching is washed with pure water, and a low concentration of washing waste water is generated in large quantities. In addition to phosphoric acid, nitric acid, acetic acid, other acid components, etc., which are components of the cutting solution, such washing drainage includes impurities such as metal ions and others eluted by etching, most of which are pure water.

Such etch cleaning waste water is conventionally treated by mixing with other waste water. Agglomeration sedimentation treatment is mentioned as a wastewater treatment technique containing general phosphoric acid and hydrofluoric acid (HF). However, in the case of performing coagulation precipitation treatment of phosphoric acid or hydrofluoric acid, there are problems of using a large amount of chemicals, increasing treatment costs due to a large amount of sludge generation, and increasing load on the environment. In addition, the increase in the water-soluble ions by the agent added in a large amount in the flocculation precipitation treatment increases the operating cost due to the increase in operating pressure of the reverse osmosis membrane process, deterioration of the treated water quality, generation of scale, and the like. The ion exchange method is associated with an increase in the amount of regenerant used.

In Japanese Patent Laid-Open No. 2006-75820, an ion exchange resin removes ions such as phosphoric acid and nitric acid, and recovers pure water and phosphate. However, according to this method, it is recovered as phosphate (sodium dihydrogen phosphate, etc.), but since there is little market for phosphate, and the sodium salt of phosphate has low solubility, the content of phosphoric acid is low in liquid phase and difficult to transport. In order to make it into salt, caustic rays are expensive. In addition, a method of passing through an H-type cationic resin to disclose sodium dihydrogen phosphate is disclosed, but acid such as hydrochloric acid is consumed in regeneration of the cationic resin, and sodium hydroxide used in regeneration of the anion resin is also used. There was a flaw such as being discharged without.

SUMMARY OF THE INVENTION An object of the present invention is a method and apparatus for recovering phosphoric acid, which can be transported in a high concentration liquid phase by a simple configuration and operation, and recovers high-purity phosphoric acid useful as a recovered product from phosphoric acid-containing water at low cost and with excellent efficiency. To provide.

The present invention relates to a method and apparatus for recovering phosphoric acid from phosphate ion-containing water as follows.

(1) A method for recovering phosphoric acid from phosphoric acid-containing water, wherein the phosphoric acid-containing water is supplied to a reverse osmosis apparatus under a condition of pH 3 or less, and a reverse osmosis treatment is performed to permeate an acid other than phosphoric acid to the permeate chamber together with water. And recovering the phosphoric acid concentrate by concentrating the phosphoric acid to the concentrate chamber side.

(2) A method for recovering phosphoric acid from phosphoric acid-containing water, wherein the phosphoric acid-containing water is supplied to a reverse osmosis apparatus under a condition of pH 3 or less and phosphoric acid concentration of about 1 to 15% by weight to carry out membrane separation treatment, and phosphoric acid A method for recovering phosphoric acid, wherein other acids are permeated with the water to the permeate chamber and the phosphoric acid is concentrated to the concentrate chamber to recover the phosphoric acid concentrate.

(3) recovering the phosphoric acid according to (1) or (2) above, wherein the concentrated liquid is taken out and circulated to the concentrated liquid chamber, and the reverse osmosis treatment is performed by adding the treated phosphoric acid-containing water to the circulating concentrated liquid. Way.

(4) A method for recovering phosphoric acid according to the above (1) or (2), which comprises taking out the concentrate of the concentrate chamber and circulating it to the concentrate chamber, wherein dilution water is added to the circulated concentrate to perform membrane separation treatment.

(5) The method according to the above (1) or (2), wherein impurities such as cation and / or anion are removed as pretreatment before the phosphoric acid-containing water is supplied to the reverse osmosis apparatus.

(6) The method for recovering phosphoric acid according to (1) or (2), wherein pure water is recovered by removing impurities including acid from the permeate of the reverse osmosis device.

(7) A method for recovering phosphoric acid according to (6), wherein the removal of impurities is performed by an ion exchange device.

(8) A method for recovering phosphoric acid according to (1) or (2), wherein an acid other than phosphoric acid is removed and purified from the phosphoric acid concentrate by anion exchange.

(9) A method for recovering phosphoric acid according to the above (1) or (2), wherein the phosphoric acid concentrate is evaporated and concentrated to remove volatile components with water.

(10) An apparatus for recovering phosphoric acid from phosphoric acid-containing water, wherein the phosphoric acid-containing water is subjected to membrane separation under a condition of pH 3 or less, permeate an acid other than phosphoric acid with water to the permeate chamber and concentrate the phosphoric acid to the concentrate chamber side. A reverse osmosis device, a raw water supply part for supplying phosphoric acid-containing water to the concentrate chamber side of the reverse osmosis membrane device under a condition of pH 3 or less, a permeate extraction part for extracting permeate from the permeate chamber side of the reverse osmosis device, and a reverse osmosis device A phosphoric acid recovery device including a concentrated phosphoric acid liquid extracting unit that extracts the concentrated phosphoric acid liquid from the concentrated liquid chamber side.

(11) An apparatus for recovering phosphoric acid from phosphoric acid-containing water, wherein the phosphoric acid-containing water is subjected to membrane separation under conditions of pH 3 or less and phosphoric acid concentration of about 1 to 15% by weight, and permeate acid other than phosphoric acid with water. A reverse osmosis device for permeating the liquid chamber side and concentrating phosphoric acid to the concentrated liquid chamber side; a phosphoric acid-containing water supply unit for supplying phosphoric acid-containing water to the concentrated liquid chamber side of the reverse osmosis apparatus under a condition of pH 3 or less and a phosphoric acid concentration of about 1 to 15% by weight; The permeate extraction part which extracts permeate liquid from the permeation liquid chamber side of a reverse osmosis apparatus, the concentrated phosphoric acid extraction part which extracts concentrated phosphoric acid liquid from the concentrate liquid chamber side of a reverse osmosis apparatus, and the concentrated phosphoric acid liquid extracted from the concentrated phosphoric acid liquid extraction part A phosphoric acid recovery device having a circulation path that circulates to the concentrate chamber side.

(12) The phosphoric acid recovery apparatus according to (10) or (11), including a dilution water supply unit for adding dilution water to a concentrate circulating in a circulation path.

(13) The phosphoric acid recovery device according to (10) or (11), further comprising a raw water supply unit having a pretreatment device for removing impurities including cationic and / or anion.

(14) The phosphoric acid recovery apparatus according to (10) or (11) above, further comprising an impurity removal device for removing impurities including acid from the permeate of the reverse osmosis device.

(15) The phosphoric acid recovery device according to (14), wherein the impurity removal device is an ion exchange device.

(16) The phosphoric acid recovery device according to (10) or (11) above, further comprising a purification device for removing an acid other than phosphoric acid from the phosphoric acid concentrate by anion exchange.

(17) The phosphoric acid recovery apparatus according to (10) or (11) above, further comprising an evaporation and concentrating device for evaporating and concentrating the phosphate concentrate to remove volatile components with water.

In the present invention, the phosphoric acid-containing water to be treated may be any object in the case of water containing phosphoric acid, but it may contain about 50 to 10,000 mg / L of phosphate ions, particularly about 50 to 2,000 mg / L, The pH is 3 or less, especially about 2.8 or less, and in any case, acidic water having a pH of 1 or more, particularly about 1.8 or more is preferable for treatment, and in addition to phosphate ions, acid components such as nitrate ions and acetate ions, other anions and metals Cation, such as an ion, and other impurities may be contained. The present invention is particularly suitable for removing other acid components such as nitrate ions and acetate ions from phosphoric acid-containing water containing other acid components such as nitrate ions and acetate ions and recovering high purity phosphoric acid.

Particularly preferred phosphoric acid-containing water as a treatment target is a low concentration washing waste water generated when pure water washing is performed after etching with a phosphoric acid-containing etching liquid of a liquid crystal substrate, a wafer or other electronic device. Examples of the washing drainage after such etching include about 50 to 2,000 mg / L of phosphate ions, about 10 to 500 mg / L of nitrate ions, about 5 to 300 mg / L of acetate ions, and an acid having a pH of about 1.8 to 2.8. Number.

According to the present invention, in order to recover the phosphoric acid from the phosphoric acid-containing water, the phosphoric acid-containing water is supplied to the reverse osmosis membrane device under a condition of pH of about 3 or less and phosphoric acid concentration of about 1 to 15% by weight to perform membrane separation treatment. It is preferable. Further, according to the present invention, it is preferable to perform removal of the aliquots containing cationic and / or anion as pretreatment before supplying the phosphoric acid-containing water to the reverse osmosis membrane device. In this case, removal of solids by precipitation separation, filtration, etc., removal of cations such as metal ions by cationic exchange resins, and removal of anions such as perchloric acid, molybdic acid, and organic acid complexes by an anion exchange resin can be performed. have. As a pretreatment apparatus used for such a pretreatment process, the general apparatus which can be applied to the objective of this invention mentioned above can be used.

Metal ions such as indium, iron, and aluminum contained in the washing drainage after etching cause clogging of the reverse osmosis (RO) membrane in the membrane separation process, and perchloric acid and molybdic acid, etc., cause membrane damage at high concentrations. Therefore, by removing these cations and anions, clogging or damage of the membrane can be prevented, which is preferable. Strongly acidic or weakly acidic cation exchange resins can be used as the cation exchange resin. However, when the H-type strongly acidic cation exchange resins are used and these cations are exchanged and removed, the treatment liquid increases the acid component and becomes easier to adjust to pH 3 or less. It is preferable because of that. The cation exchange resin may be a chelate resin. The anion exchange resin can use a strong or weakly basic cationic exchange resin. The anion exchange resin is used in acid form such as phosphoric acid type, and passes through phosphoric acid, nitric acid, acetic acid and the like to remove other impurity anions.

The reverse osmosis apparatus in the membrane separation process according to the present invention is also called a reverse osmosis (RO) apparatus, and is partitioned into a permeate chamber and a concentrate chamber by a reverse osmosis (RO) membrane, and the phosphoric acid-containing water is used under a condition of about pH 3 or less. In addition, preferably, a reverse osmosis membrane treatment is performed by supplying to the concentrate chamber side under a phosphoric acid concentration of about 1 to 15% by weight, permeating acid other than phosphoric acid to the permeate chamber side with water and simultaneously phosphoric acid to the concentrate chamber side. It is configured to concentrate. On the concentrated liquid chamber side of the reverse osmosis membrane apparatus, a phosphoric acid-containing water supply portion for supplying phosphoric acid-containing water and a concentrated phosphoric acid liquid extracting portion for taking out the concentrated phosphoric acid liquid are formed. The permeate extraction part which takes out a permeate liquid is formed in the permeate chamber side of a reverse osmosis membrane apparatus. Between the concentrated phosphoric acid extraction part and the phosphoric acid containing water supply part, a circulation path for circulating the concentrated phosphoric acid liquid taken out from the concentrated phosphoric acid liquid extraction part to the concentrated liquid chamber side is formed. The reverse osmosis membrane is a semi-permeable membrane which permeates water by the infiltration pressure or, conversely, pressurizes it at a higher pressure than the infiltration pressure to supply the liquid to be treated and permeates the water by reverse osmosis while preventing salts, organic substances, and other solutes without permeation. .

The material of the reverse osmosis membrane is not particularly limited as long as it has the above-described characteristics, and examples thereof include a polyamide permeable membrane, a polyimide permeable membrane, a cellulose permeable membrane, and the like. Composite reverse osmosis membranes are preferred in which an active skin layer having substantially selective separability is formed on a microporous support. The reverse osmosis device can be provided with such a reverse osmosis membrane, but it is preferable to include a membrane module in which the reverse osmosis membrane, the support mechanism, the collecting mechanism, and the like are integrated. There is no restriction | limiting in particular as a membrane module, For example, a tubular membrane module, a planar membrane module, a spiral membrane module, a hollow fiber membrane module, etc. are mentioned. As a reverse osmosis apparatus provided with these, a well-known thing can be used and the high permeability thing operated at low pressure is preferable.

In the membrane separation process according to the present invention, the phosphoric acid-containing water is used under conditions of about pH 3 or less, and preferably, under conditions of about 1 to 15% by weight of phosphoric acid, more preferably about 2 to 10% by weight. The membrane is subjected to a membrane separation (reverse osmosis) treatment under the condition of. When phosphoric acid containing water is obtained in the state of about pH3 or less, it can supply to a reverse osmosis membrane apparatus without adjusting pH as it is, but pH can also be adjusted by addition of pH adjusters, such as hydrochloric acid and nitric acid, as needed. The same applies to the case where the pH is adjusted to 3 or less by carrying out removal of cationics such as metal ions by the cationic exchange resin in pretreatment. Since the washing drainage after etching of a liquid crystal substrate or a wafer is usually obtained at a pH of 3 or less, it can be supplied to the reverse osmosis membrane device without adjusting the pH, and even when the pH is adjusted, the amount of the pH adjuster added is small. Lose.

When the phosphoric acid-containing water is obtained at a phosphoric acid concentration of about 1 to 15% by weight, membrane separation may be performed as it is to perform separation by reverse osmosis. However, when the phosphoric acid concentration is less than about 1% by weight, the concentrate is concentrated through a circulation path. By carrying out the membrane separation treatment while circulating, the phosphoric acid concentration can be concentrated to about 1% by weight or more. Alternatively, the concentration treatment may be performed in advance by a concentration apparatus such as a reverse osmosis (RO) apparatus separately formed, or the recovered high concentration phosphoric acid solution may be added.

When the concentration of phosphoric acid is concentrated to about 1% by weight or more by performing the membrane separation process while circulating the concentrate through a circulation path, the concentration of the phosphoric acid containing water at low concentration is circulated, and the concentration of phosphoric acid is about 1% by weight or more. Although a batch treatment may be performed to replace the circulating fluid at this point, the concentrated liquid is circulated by adding a low concentration of the treated phosphoric acid-containing water to the circulating concentrate while circulating the concentrated solution having a concentration of about 1 to 15% by weight. It is preferable to take out partly as a phosphoric acid concentrate because it can perform a daily food processing in appearance. In the process of taking out the concentrate of the concentrate chamber and circulating it into the concentrate chamber, dilution water is added to the circulated concentrate to perform reverse osmosis, whereby the removal rate of acids other than phosphoric acid can be increased. As dilution water, the recovery water which removed the impurity from permeate water can be used.

When phosphoric acid-containing water is supplied to the reverse osmosis apparatus under a condition of about pH 3 or less, and the membrane separation treatment is performed, acids other than phosphoric acid such as nitric acid and acetic acid pass through the reverse osmosis membrane together with water, and move to the permeate chamber, whereby It is taken out from the side. Since phosphoric acid is impeded from permeation of the reverse osmosis membrane and remains on the concentrate chamber side, it can be recovered as a phosphoric acid concentrate from the concentrate chamber side. The concentrated liquid on the concentrated liquid chamber side may be passed through a daily meal or may be circulated to increase the concentrated rate. When phosphoric acid-containing water is supplied to the reverse osmosis apparatus under the condition of about pH 3 or less (also less than about 1% by weight of phosphoric acid) and the membrane separation treatment is performed, the pressure of the phosphoric acid-containing water supplied to the reverse osmosis apparatus is about 0.3 It is about 3 MPa, Preferably it is about 0.5-1.5 MPa.

Although a small amount of acid other than phosphoric acid remains in the concentrate, if the membrane separation treatment is carried out under a condition in which the phosphoric acid concentration is about 1 to 15% by weight, the blocking rate of acids other than phosphoric acid is lowered and the permeability is increased. It can be recovered. When the phosphoric acid-containing water is supplied to the reverse osmosis apparatus under the condition of about pH 3 or less and the phosphoric acid concentration is about 1 to 15% by weight and the membrane separation treatment is performed, the pressure of the phosphoric acid-containing water supplied to the reverse osmosis apparatus is about It may be about 0.3 to 5 MPa, preferably about 0.5 to 3 MPa.

Comparing the permeation rate of the ionic material and the nonionic material in the permeation of the reverse osmosis membrane, the reverse osmosis membrane blocking rate is known to be overwhelmingly inhibited by the ionic material as compared with the nonionic material even at the same molecular weight. However, the present inventors have repeatedly studied, unlike the common sense, if the reverse osmosis membrane treatment under the conditions of pH 3 or less difficult to elute phosphoric acid, the blocking rate of phosphoric acid is overwhelmingly higher than that of nitric acid or acetic acid, such as nitric acid or acetic acid It was found that acids other than phosphoric acid and phosphoric acid can be separated and recovered. The reason why the phosphoric acid is strongly inhibited by the reverse osmosis membrane at low pH is because the phosphoric acid is in the form of heavy phosphoric acid, the molecular weight is increased, and the blocking rate is increased.

The blocking rate of acids other than phosphoric acid such as nitric acid and acetic acid under the condition of pH 3 or lower is low, and the blocking rate in the case of treating a conventional phosphoric acid-containing etching solution is about 1% or less, but the higher the concentration of phosphoric acid, The blocking rate is lowered and the blocking rate of acids other than phosphoric acid becomes negative at a phosphoric acid concentration of about 1% by weight or more. Here, the blocking rate is a rate at which the reverse osmosis membrane blocks the permeation of the solute, and is represented by the following formula (1).

[Equation 1]

Blockage percentage (%) = (1-C ₃ / (C ₁ , C ₂ ) ^1/2 ) × 100

In Equation 1, C ₁ represents the solute concentration of the feed liquid inlet, C ₂ represents the solute concentration of the concentrate outlet, and C ₃ means the solute concentration of the permeate.

In formula 1, ((C ₁ · C ₂ ) ^1/2 ) represents a rising average, and (C ₃ / (C ₁ · C ₂ ) ^1/2 ) represents the solute of the concentrate. (Raise) The ratio of the solute concentration of the permeate to the average concentration is shown. For this reason, the lower the blocking rate, the more the solute is permeated to the permeate side. In general, it is easy to recognize that the blocking rate does not become negative. However, in the formula 1, the blocking rate may be negative from the composition of the formula. In this case, the solute concentration of the permeate is higher than the solute concentration of the concentrate, It has been shown to transmit at high transmittance.

When the phosphoric acid concentration is about 1% by weight or more, the blocking rate of acids other than phosphoric acid becomes negative, when the phosphoric acid concentration is about 1% by weight or more, particularly about 2% by weight or more, the acid concentration other than phosphoric acid remaining in the concentrate is lowered. This means that a high purity phosphoric acid concentrate is obtained. If the concentration of phosphoric acid in the concentrate is too high, the membrane treatment cannot be performed in relation to the penetration pressure, so that the upper limit of the concentration of phosphoric acid in the concentrate is about 15% by weight, preferably about 10% by weight. While circulating the concentrated solution of the phosphoric acid concentration, the treated phosphoric acid-containing water is added to the circulating concentrated solution, and the concentrated solution is taken out as a phosphate concentrated solution to carry out the daily food treatment. Can be done.

When the membrane treatment is performed while circulating the concentrate, the more the number of cycles of the concentrate is circulated, the more the acid other than phosphoric acid comes into contact with the reverse osmosis membrane, and the lower the concentration of the acid other than phosphoric acid in the concentrate is. At this time, if the phosphoric acid concentration exceeds about 15% by weight, the permeation pressure (operation pressure) becomes so high that the membrane treatment cannot be performed, so that dilution water is added to the concentrate, diluted to circulate, and the reverse osmosis treatment is performed. The concentration of acids other than phosphoric acid can be lowered, and a high purity phosphoric acid concentrate can be recovered. As dilution water, the recovery water which removed the impurity from permeate water can be circulated and used.

Since the permeated water of the reverse osmosis membrane device taken out from the permeate liquid chamber side contains permeated acids such as phosphoric acid, nitric acid, and acetic acid, impurities such as these acids and others are removed from the permeated water of the reverse osmosis membrane device by an impurity removal device. Thus, pure water can be recovered. In this case, as an impurity removal apparatus, the ion exchange apparatus using ion exchange resin can be employ | adopted. By passing the permeate water through the anion exchange resin layer, these acids and other anions are removed, and the water is passed through the cation exchange resin layer and the anion exchange resin layer, or a mixed phase thereof. Acids other than phosphoric acid, such as acetic acid and nitric acid, other anions, and residual cation can be removed and pure water can be recovered. As the anion exchange resin used here, an OH type strong basic or weak base anion exchange resin is preferable, and as the cation exchange resin, an H type strongly acidic cation exchange resin is preferable.

In the general ion exchange apparatus, acid is used for regeneration of the ion exchange resin and alkali is used for regeneration of the anion exchange resin, and in this regeneration method, a regeneration agent is required, and a regeneration waste liquid is generated. Since there are disadvantages, it is preferable to employ an electrically regenerative ion exchange device. An electrically regenerative ion exchange device is a device in which an ion exchange resin layer is partitioned into a cation exchange resin film and an anion exchange resin film, and cathodes and anodes are disposed at both ends. While passing through to perform ion exchange. In this case, no special operation and regenerant for regeneration are necessary, and impurities other than acid can be continuously taken out and pure water can be recovered. If the ion exchange resin used in the electrically regenerative ion exchange device is only intended to remove acid and other anions, the ion exchange resin can be filled with only an anion exchange resin. The mixed phase of a cationic exchange resin and an anion exchange resin can be filled. The acid concentrated liquid discharged by regeneration is made into a concentrated liquid such as phosphoric acid, nitric acid, acetic acid and the like, and can be treated by a biological denitrification method.

On the other hand, the phosphoric acid concentrated liquid taken out from the concentrate chamber side is removed most of the acid other than phosphoric acid such as nitric acid or acetic acid, but can be purified by post-treatment to remove these to increase the purity, concentration of the recovered phosphoric acid solution . As purification by post-treatment, an acid other than phosphoric acid can be removed and purified by anion exchange from the phosphoric acid concentrate. In this case, an anion exchanger is formed as a purification device, the concentrate is passed through the anion exchange resin layer to remove strong acid ions such as nitric acid from the concentrate, and a high concentration of phosphoric acid containing almost no strong acid ions such as nitric acid is removed. It can be recovered. When the reverse osmosis apparatus performs concentration by circulating the concentrate, the purification apparatus may be formed in the concentrate circulation line of the reverse osmosis apparatus, which is preferably formed in the line which extracts the concentrate from the circulation line. The anion exchange resin is preferably a strong basic anion exchange resin of OH type or PO ₄ type.

If acetic acid remains in the phosphoric acid concentrate, acetic acid cannot be completely removed by an anion exchange resin. Therefore, in order to remove volatile components such as acetic acid and increase the purity and concentration of the recovered phosphoric acid solution, the phosphoric acid concentrate is transferred to an evaporation concentrator. By evaporating to remove volatile components with water and concentrating, high concentration of phosphoric acid containing almost no volatile components such as acetic acid can be recovered. As an evaporation concentration apparatus, well-known apparatuses, such as a rotary evaporator, can be used.

The phosphoric acid recovered by the above is useful as a recovered product, can be transported in a high concentration liquid phase, and can be recovered as a high purity concentrated phosphoric acid. In this case, the reverse osmosis treatment is carried out under the condition of pH 3 or lower. Since the phosphoric acid-containing water as raw water is usually obtained in an acidic state of about pH 3 or lower, it can be easily adjusted by injecting a pH adjuster such as hydrochloric acid.

In addition, the method and apparatus for recovery can be recovered as a phosphate concentrate by reverse osmosis treatment under a condition of about pH 3 or less, and in some cases about 1 to 15% by weight, by a simple configuration and operation. Do. As a result, the amount of the regenerant and the amount of waste generated can be reduced, the treatment cost can be lowered, and the concentrated phosphoric acid and pure water of high purity can be recovered.

As described above, according to the present invention, the phosphoric acid-containing water is supplied to the reverse osmosis apparatus under the condition of pH 3 or less to perform reverse osmosis treatment, and acids other than phosphoric acid are permeated to the permeate chamber side with water, and phosphoric acid is transferred to the concentrate chamber side. By concentrating and recovering the phosphoric acid concentrate, high-purity phosphoric acid which can be transported in a high concentration liquid phase by simple constitution and operation, can be recovered from the phosphoric acid-containing water at low cost and excellent efficiency.

In addition, according to the present invention, phosphoric acid-containing water is supplied to the reverse osmosis apparatus under conditions of about pH 3 or less and phosphoric acid concentration of about 1 to 15% by weight, and reverse osmosis treatment is performed to permeate acids other than phosphoric acid with water. By permeating to the liquid chamber side and concentrating phosphoric acid to the concentrated liquid chamber side to recover the phosphoric acid concentrate, it is possible to transport high-purity phosphoric acid from the phosphoric acid-containing water, which can be transported in a high concentration liquid phase by simple configuration and operation. Can be recovered.

1 is a block diagram of a method and apparatus for phosphoric acid recovery according to embodiments of the present invention.

2 is a block diagram of a phosphoric acid recovery method and apparatus according to other embodiments of the present invention.

3 is a graph showing the results according to the experimental examples of the present invention.

Embodiments of the present invention will be described with reference to FIG. 1. 1 is a flow diagram of a phosphoric acid recovery device according to embodiments of the present invention. In Fig. 1, reference numeral 1 denotes a raw water tank, and stores raw water 1a. Reference numeral 2 is a cationic exchange column, and has a cationic exchange resin layer 2a. Reference numeral 3 is a concentrate tank, and stores the concentrate 3a. Reference numeral 4 is a reverse osmosis device, and is divided into a permeate chamber 4b and a concentrated liquid chamber 4c by the reverse osmosis membrane 4a. Reference numeral 5 is an anion exchange tower, and includes an anion exchange resin layer 5a. Reference numeral 7 denotes a recovery tank, and stores the recovery water 7a. Reference numeral 5b is a second anion exchange tower, and includes an anion exchange resin layer 5c. Reference numeral 8 is an evaporation concentrator, and the volatile components are separated by distillation with water by distillation to concentrate the phosphoric acid solution. Reference numeral 9 is a recovery phosphoric acid tank and stores the recovery phosphoric acid solution 9a.

In Fig. 1, reference numeral P denotes a pressure pump, and constitutes a raw water supply unit together with a raw water tank 1, a cation exchange tower 2, and a concentrate solution 3, of which the cationic exchange tower 2 is a pretreatment apparatus. Configure The anion exchange tower 5 and the recovery tank 7 constitute a permeate extraction part, and the anion exchange tower 5 constitutes an impurity removal device. In addition, the second anion exchange tower 5b, the evaporation concentrator 8, and the recovery phosphate tank 9 constitute a concentrated phosphoric acid extracting unit, among which the second anion exchange tower 5b and the evaporation concentrator ( 8) constitutes a purification device.

In the above-described phosphoric acid recovery device, raw water 1a (phosphate ion-containing water) from which impurities are removed by precipitation separation, filtration, or the like is introduced into the raw water tank 1 from the line L1. The raw water 1a of the raw water tank 1 is introduced through the line L2 into the cationic exchange tower 2, passed through, and subjected to cationic exchange in the cationic exchange resin layer 2a, and includes aluminum, indium, and the like contained in the raw water. Cationics such as metal ions are removed by exchange adsorption. It is preferable to use H-type strongly acidic cationic exchange resin for the cation exchange resin layer 2a. When the cation exchange resin layer 2a is saturated, a regenerant containing an acid such as hydrochloric acid is passed through the line L3 to be regenerated, and the eluted cation is recovered from the line L4.

The decaching water which is the treated water of the kathion exchange tower 2 is introduced into the concentrate tank 3 from the line L5 and stored. Phosphoric acid-containing water as raw water is usually obtained in an acidic state of pH 3 or less, and even when the pH is high, acid is generated by the cationic exchange as a pretreatment and becomes a state of pH 3 or less. What is necessary is just to supply it to the reverse osmosis apparatus 4 as it is. In the case of adjusting the pH of raw water having a high pH, since the phosphoric acid-containing water is obtained in a state close to pH 3, it can be easily adjusted by injecting a pH regulator such as hydrochloric acid into the line L5 or the concentration tank 3.

The decaccion water (concentrate 3a) of the concentrate tank 3 is pressurized by the pressure pump P, introduced from the line L6 into the concentrate chamber 4c of the reverse osmosis device 4, and the reverse osmosis membrane 4a. Reverse osmosis treatment is carried out, and an acid other than phosphoric acid such as nitric acid and acetic acid is permeated to the permeate chamber 4b side with water, and the phosphoric acid is concentrated to the concentrate chamber 4c side. When the phosphoric acid-containing water is neutralized and subjected to reverse osmosis treatment in a neutral state, salts of acids other than phosphoric acid such as nitric acid and acetic acid and the salts of phosphoric acid are concentrated to the concentrate chamber 4c without passing through the reverse osmosis membrane 4a. do. On the other hand, when neutralizing the phosphoric acid-containing water and introducing into the reverse osmosis apparatus 4 under the condition of pH 3 or less, and performing the reverse osmosis treatment, phosphoric acid is impeded by the reverse osmosis membrane 4a and the concentrated liquid chamber 4c. ), But an acid other than phosphoric acid, such as nitric acid or acetic acid, permeates to the permeate chamber 4b side with water and is separated. Since the phosphoric acid-containing water introduced into the reverse osmosis device 4 is decaching, there is no blockage of the reverse osmosis membrane 4a, and the efficiency of the reverse osmosis treatment is maintained high.

The permeate that has permeated through the permeate chamber 4b of the reverse osmosis device 4 is introduced into the anion exchange column 5 from the line L7 and passed through the anion exchange resin layer 5a to be anion exchanged. Thereby, anion other than phosphate ions, such as nitric acid and acetic acid, contained in the permeate is removed by exchange adsorption to purify the purified water, and the treated water is taken out from the line L8 to the recovery tank 7 and the recovered water ( 7a). The anion exchange tower 5 uses an anion exchange resin layer 5a filled with an OH-type strong basic anion exchange resin, and adopts a multi-layer or mixed phase with an H-type cation exchange resin, and other than anion. The impurities may be removed. When the anion exchange resin layer 5a is saturated with anions other than phosphate ions, a regenerant including an alkali such as an aqueous alkali solution of about 2 to 10% by weight, such as sodium hydroxide and potassium hydroxide, is supplied from line L9. Is recycled and the eluted salt is discharged from the line (L10). In the case of using a cationic exchange resin, the regenerant containing an acid is passed through and regenerated.

The concentrated liquid concentrated in the concentrate chamber 4c of the reverse osmosis device 4 is introduced into the second anion exchange column 5b from the line L11 and passed through, and anion exchanged in the anion exchange resin layer 5c. And anion other than phosphate ions such as nitric acid and acetic acid remaining in the concentrate are removed by exchange adsorption, and purification is performed. In this case, the anion exchange resin layer 5c uses a strong basic anion exchange resin of OH type or PO ₄ type. Since the selectivity of anions other than phosphate ions, such as nitric acid, to anion exchange resin is higher than phosphate ions in a low pH range, separation with phosphate ions is easy. When the anion exchange resin layer 5c is saturated with anions other than phosphate ions, the regenerant containing alkali is passed through the line L12 for regeneration, and the eluted salt is discharged from the line L13.

When the phosphate solution from which anions other than phosphate ions are removed as the second anion exchange column 5b contains volatile components such as acetic acid, it is introduced into the evaporation concentrator 8 from the line L14 and distilled into water. And volatile components are evaporated to separate and discharged from line (L15). The phosphate concentrate obtained by removing the volatile components in the evaporation concentrator 8 is concentrated into the recovery phosphate tank 9 from the line L16 and stored as the recovered phosphoric acid solution 9a. As the evaporation concentration apparatus 8, well-known evaporation concentration apparatus, such as a rotary evaporator, can be used. The concentrated liquid in the concentrated liquid chamber 4c of the reverse osmosis device 4 can be circulated from the line L17 or L18 to the concentrated liquid tank 3 to increase the concentration rate, and stored as the concentrated liquid 3a.

The phosphoric acid solution 9a recovered by the above-described method is useful as a recovered product and can be transported practically since it is recovered in a high concentration liquid phase, and can be recovered as high-purity concentrated phosphoric acid. In this case, the reverse osmosis treatment is carried out under the condition of pH 3 or lower, but the phosphoric acid-containing water as raw water is usually obtained in an acidic state of pH 3 or lower, and even if the pH is high, the state of pH 3 or lower is obtained by the exchange of cationic as pretreatment. Therefore, in order to process on the conditions of pH 3 or less, what is necessary is just to supply, and it does not need to adjust pH especially. Reagents such as acids and alkalis are limited to regenerants for cation in the cation exchange tower 2 and regenerants for anions in the anion exchange tower 5 and the second anion exchange column 5b, It is not necessary for phosphoric acid recovery. In addition, the method and apparatus for recovery can be recovered as a phosphoric acid concentrate by reverse osmosis treatment under a condition of pH 3 or less by a simple configuration and operation. As a result, it is possible to recover high-purity concentrated phosphoric acid and pure water by reducing the amount of regenerant used and the amount of waste generated, and reducing the processing cost.

As described above, the phosphoric acid-containing water is supplied to the reverse osmosis apparatus 4 under the condition of pH 3 or less and the reverse osmosis treatment is performed by the reverse osmosis membrane 4a, and an acid other than phosphoric acid is added together with water to the permeate chamber ( 4b) is permeated to concentrate the phosphoric acid to the concentrate chamber 4c, and the pure water and phosphoric acid concentrate are recovered, so that it is transportable in a high concentration liquid phase by simple configuration and operation, and phosphoric acid of high purity which is useful as a recovered product is phosphoric acid. It can recover with low cost and excellent efficiency from containing water.

Next, other embodiments of the present invention will be described with reference to FIG. 2. Figure 2 is a flow diagram of a phosphoric acid recovery method and apparatus according to other embodiments of the present invention. In Fig. 2, reference numeral 1 denotes a raw water tank, and stores raw water 1a. Reference numeral 2 is a cationic exchange tower, and includes a cationic exchange resin layer 2a. Reference numeral 3 is a concentrate tank, and stores the concentrate 3a. Reference numeral 4 is a reverse osmosis device, and is divided into a permeate chamber 4b and a concentrated liquid chamber 4c by the reverse osmosis membrane 4a. Reference numeral 5 is an anion exchange tower, and includes an anion exchange resin layer 5a. Reference numeral 6 denotes an electric regenerative ion exchange device, which is partitioned into anion exchange membrane 6c rather than a desalination chamber 6a and a concentration chamber 6b, and a cathode is formed by a cationic exchange membrane 6d outside the desalination chamber 6a. The chamber 6e is partitioned, and the anode chamber 6g is partitioned by the cationic exchange membrane 6f on the outside of the concentration chamber 6b, and the mixed phase ion exchange layer (6a) and the concentration chamber 6b in the desalination chamber 6a. 6h and 6i are formed, and a cathode (-) is formed in the cathode chamber 6e and an anode (+) is formed in the anode chamber 6g. Reference numeral 7 denotes a recovery tank, and stores the recovery water 7a. Reference numeral 8 is an evaporation concentrator, and the volatile components are separated by evaporation with water by distillation to concentrate the phosphoric acid solution. Reference numeral 9 is a recovery phosphoric acid tank and stores the recovery phosphoric acid solution 9a. Reference numeral 10 is a biodenitrification device.

In Fig. 2, reference numeral P denotes a pressure pump, and together with the raw water tank 1, the cation exchange tower 2, the anion exchange tower 5, and the concentrate tank 4, the feed water supply part is formed, among which the cationic The exchange tower 2 and the anion exchange tower 5 constitute a pretreatment device. The pre-regeneration ion exchange device 6 and the recovery water tank 7 constitute a permeate extraction part, and the electro-regeneration ion exchange device 6 constitutes an impurity removal device. In addition, the evaporation concentration apparatus 8 and the recovery phosphate tank 9 comprise a concentrated phosphoric acid extracting part, among which the evaporation concentration apparatus 8 constitutes a purification apparatus.

In the above-described phosphoric acid recovery apparatus, raw water 1a (phosphate ion-containing water) from which impurities are removed by precipitation separation, filtration, or the like is introduced into the raw water tank 1 from the line L21. The raw water 1a of the raw water tank 1 is introduced through the line L22 to the cationic exchange tower 2 and passed therethrough, and is subjected to cationic exchange in the cationic exchange resin layer 2a, and the aluminum, indium, and the like contained in the raw water. Cationics such as metal ions are removed by exchange adsorption. It is preferable to use H-type strongly acidic cationic exchange resin for the cation exchange resin layer 2a. When the cation exchange resin layer 2a is saturated, a regenerant containing an acid such as hydrochloric acid is passed through the line L23 to be regenerated, and the eluted cation is recovered from the line L24.

The decaching water, which is the treated water of the cationic exchange tower 2, is introduced into the anion exchange tower 5 from the line L25 and passed through, and anion exchange is carried out in the anion exchange resin layer 5a, which is contained in the raw water. Anions such as perchloric acid, molybdate and organic acid complexes are removed by exchange adsorption. It is preferable to use phosphoric acid type strong base anion exchange resin for the anion exchange resin layer 5a. When the anion exchange resin layer 5a is saturated, the regenerant containing alkali, such as sodium hydroxide, is passed through line L26, and it regenerates, and eluted anion is collect | recovered from the line L27. Thereafter, an acid such as phosphoric acid is passed through the line L26, and the anion exchange resin is made into a phosphoric acid type.

The treated water of the anion exchange tower 5 is introduced into the concentrate tank 3 from the line L28. Phosphoric acid-containing water as raw water is usually obtained in an acidic state of pH 3 or lower, and may be supplied directly to the reverse osmosis apparatus 4 in order to perform reverse osmosis treatment under conditions of pH 3 or lower. In the case of adjusting the pH of raw water having a high pH, since the phosphoric acid-containing water is obtained in a state close to pH 3, it can be easily adjusted by injecting a pH regulator such as hydrochloric acid into the line L28 or the concentration tank 3.

Phosphoric acid-containing water in the concentrate tank 3 is pressurized by the pressure pump P, introduced from the line L31 into the concentrate chamber 4c of the reverse osmosis apparatus 4, and membrane separation is carried out by the reverse osmosis membrane 4a. Reverse osmosis treatment), an acid other than phosphoric acid such as nitric acid and acetic acid is permeated to the permeate chamber 4b side with water, and the phosphoric acid is concentrated to the concentrate chamber 4c side. When the phosphoric acid-containing water is neutralized and the reverse osmosis treatment is performed in a neutral state, all of salts and phosphates of acids other than phosphoric acid such as nitric acid and acetic acid are concentrated on the concentrated liquid chamber 4c side without permeating the reverse osmosis membrane 4a. On the other hand, without neutralizing the phosphoric acid-containing water, when introduced into the reverse osmosis apparatus 4 under the condition of pH 3 or less and performing the reverse osmosis treatment, phosphoric acid is prevented from permeating by the reverse osmosis membrane 4a and the concentrated liquid chamber ( Although concentrated to 4c) side, acids other than phosphoric acid, such as nitric acid and acetic acid, permeate | transmit to permeate chamber 4b side with water, and are isolate | separated. Since the phosphoric acid-containing water introduced into the reverse osmosis device 4 is decaching, there is no blockage of the reverse osmosis membrane 4a, and the efficiency of the reverse osmosis treatment is maintained high.

When the phosphoric acid-containing water as raw water obtained from the line L28 is obtained at about 1 to 15% by weight of phosphoric acid, membrane separation may be performed as it is and separation by reverse osmosis may be performed. However, when the phosphoric acid is less than about 1% by weight. The concentration of the phosphoric acid extracted from the concentrate chamber 4c through the line L32 is circulated from the line L33, which is a circulation path, to the concentrate tank 3, to thereby carry out a membrane separation treatment, thereby increasing the phosphoric acid concentration to about 1% by weight or more. Can be concentrated. In this case, a low concentration phosphoric acid-containing water may be concentrated while circulating, and a batch treatment may be performed in which the circulating fluid is exchanged when the phosphoric acid concentration is concentrated to about 1% by weight or more, but the concentration of phosphoric acid is about 1 to 15% by weight. It is preferable to add a low concentration of the treated phosphoric acid-containing water to the circulating concentrate while circulating the concentrated concentrate, and to take out the concentrate as part of the phosphoric acid concentrate from the line L34, so that the apparent daily food treatment can be performed.

The permeate that has permeated through the permeate chamber 4b of the reverse osmosis apparatus 4 is introduced from the line L35 into the desalting chamber 6a of the electro regenerative ion exchanger 6, and is positive and negative electrodes (-). Desalting by ion exchange while applying voltage and regenerating electricity. Thereby, anion, such as phosphoric acid, nitric acid, acetic acid, and the like, which are contained in the permeate, is removed by exchange adsorption, and purification is performed. The treated water is taken out from the line L36 to the recovery tank 7 and recovered. It stores as water 7a. In the desalting chamber 6a, it permeates into the concentration chamber 6b through an anion-exchange membrane 6c such as an acid adsorbed to the interphase ion exchange layer 6h, and enters the interphase ion exchange layer 6i. Since it adsorb | sucks, a part of permeate flows from the line L37 to the concentration chamber 6b, and elutes the anion adsorbed by regeneration, and sends it to the biological denitrification apparatus 10 from the line L38 for biodenitrification. Since the cation adsorbed to the mixed phase ion exchange layer 6h passes through the cathode chamber 6e, the electrode solution flows from the anode chamber 6g to the cathode chamber 6e through the line L39 and is discharged from the line L40. do.

A part of the concentrated liquid which is concentrated in the concentrated liquid chamber 4c of the reverse osmosis apparatus 4 and taken out from the line L34 is introduced into the evaporative concentration apparatus 8 and distilled, and the volatile components such as acetic acid are evaporated with water. It separates and discharges from the line L41. The phosphate concentrate obtained by removing the volatile components in the evaporation concentrator 8 and concentrated is introduced into the recovery phosphate tank 9 from the line L42 and stored as the recovered phosphate 9a. As the evaporation concentration apparatus 8, well-known evaporation concentration apparatus, such as a rotary evaporator, can be used.

Membrane separation (reverse osmosis treatment) in the reverse osmosis apparatus 4 is carried out under conditions in which the phosphoric acid-containing water is about pH 3 or less and the phosphoric acid concentration is about 1 to 15% by weight, so that acids other than phosphoric acid are highly transmitted. Permeation can be made and the purity of phosphoric acid can be increased, but in order to lower the concentration of acids other than phosphoric acid in the concentrate, the concentrate can be circulated to increase the chance of membrane separation, thereby increasing the permeation rate of these acids and increasing the permeability. have. In this case, water permeation also occurs, so that the circulating fluid is concentrated. For this reason, the removal rate of acids other than phosphoric acid can be improved by adding dilution water to the circulating concentrate and performing reverse osmosis treatment. As dilution water, the recovery water which removed the impurity from permeate water can be used.

For this reason, in FIG. 2, the recovery water 7a is supplied as the dilution water from the recovery water tank 7 to the concentrate tank 3 through the line L43 by the pump P2, and the circulating concentrate 3a is diluted. By performing the reverse osmosis treatment, the concentration of acids other than phosphoric acid can be lowered again, and a high purity phosphoric acid concentrate can be recovered. The amount of the recovered water 7a supplied to the concentrate tank 3 is an amount such that the concentrated solution circulated maintains about 1 to 15% by weight of phosphoric acid. Thereby, the permeation efficiency of acids other than phosphoric acid due to high concentration of the circulating concentrate is prevented from being lowered, and the phosphoric acid purity of the concentrate can be increased.

The recovered phosphoric acid solution 9a recovered by the above-described method is useful as a recovered product and can be transported practically since it is recovered in a high concentration liquid phase, and can be recovered as a high-purity concentrated phosphoric acid. In this case, the reverse osmosis treatment is performed under the condition of pH 3 or lower. Since the phosphoric acid-containing water as raw water is usually obtained in an acidic state of pH 3 or lower, it may be supplied as it is, and there is no need to adjust the pH in particular. Agents such as acids and alkalis are limited to the regeneration agent for the cation in the cation exchange column 2 and the regenerating agent for the anion in the anion exchange column 3, and are used for phosphoric acid recovery and purification of permeate. It is not necessary as. In addition, the method and apparatus for recovery can be recovered as a phosphoric acid concentrate by reverse osmosis treatment under a condition of pH 3 or less and about 1 to 15% by weight of phosphoric acid by a simple configuration and operation. As a result, it is possible to reduce the amount of chemicals used and the amount of waste generated, to lower the processing cost, and to recover the concentrated phosphoric acid and pure water of high purity.

In the phosphoric acid recovery method and apparatus shown in Fig. 2, phosphoric acid-containing water is supplied to the reverse osmosis apparatus 4 under conditions of pH 3 or less and phosphoric acid concentration of about 1 to 15% by weight to reverse osmosis membrane 4a. The reverse osmosis treatment was carried out, the acid other than phosphoric acid was permeated to the permeate chamber 4b side with water, the phosphoric acid was concentrated to the concentrated liquid chamber 4c side, and the pure water and the phosphoric acid concentrated liquid were recovered. High-purity phosphoric acid and pure water which can be transported in a high concentration liquid phase and which are useful as a recovered product can be efficiently recovered from the phosphoric acid-containing water at low cost.

Embodiments of the present invention are not limited to FIGS. 1 and 2, for example, in order to further increase the purity of the recovered phosphoric acid solution in FIG. 2, the second anion exchange column is evaporated to concentration of the line L34. It may be formed at the front end of the device (8). In addition, in the embodiments of the present invention, an anion exchange membrane (not the desalination chamber 6a and the concentration chamber 6b) is an electro regenerative ion exchange apparatus 6 for purifying a permeate from the reverse osmosis apparatus 4. A simple electric regenerative ion exchange device partitioned by 6c) is used, but anion exchange membrane and cation exchange membrane are alternately arranged between the cathode chamber and the anode chamber to form a desalting chamber and a concentration chamber, and an ion exchanger in the desalting chamber. It is also possible to use a conventional electric deionizer packed with.

Hereinafter, experimental examples and comparative examples of the present invention will be described. In each experimental example,% represents weight% other than a blocking rate and a special label.

Experimental Example 1 and Comparative Example 1

<Reverse osmosis treatment>

Raw water having a conductivity of 122 mS / m and pH 2.4 containing 550 mg / L phosphoric acid, 50 mg / L nitric acid and 50 mg / L of acetic acid was passed through the reverse osmosis membrane ES-20 produced by Ildong Electric Co., Ltd. at 0.7 MPa. The reverse osmosis treatment was carried out to obtain a concentrated solution (blind) of 6-fold concentration (Experimental Example 1). On the other hand, an aqueous sodium hydroxide solution was injected into the raw water to adjust the pH to 6 and tested in the same manner (Comparative Example 1). The results of the inhibition rates of phosphoric acid, nitric acid, and acetic acid are shown in Table 1. In Experimental Example 1, phosphoric acid was removed and nitric acid and acetic acid were permeated and separated, whereas in Comparative Example 1, all were removed and not separated. have.

Table 1: removal rate

Experimental Example 1 Comparative Example 1 pH 2.4 6 Phosphoric Acid (%) 97.8 99.6 nitric acid(%) 10 99.5 Acetic acid (%) 4 99.0

Experimental Example 2

Recovery of Phosphoric Acid and Pure Water

Figure 1 shows the cleaning drainage after etching a liquid crystal substrate having a conductivity of 122 mS / m, pH 2.4, including 550 mg / L phosphoric acid, 50 mg / L nitric acid, 50 mg / L acetic acid, 0.3 mg / L indium, and 1 mg / L sodium. The phosphoric acid and pure water were recovered by treatment in an apparatus. The cationic exchange tower 2 was filled with 10 L of H-type strongly acidic cationic exchange resin (manufactured by Mitsubishi Chemical Corporation, DiaionSK1B), and regenerated with hydrochloric acid. The anion exchange tower 5 was filled with 10 L of an OH type strong basic anion exchange resin (manufactured by Mitsubishi Chemical Corporation, Diaion SA11A), and regenerated with sodium hydroxide. The second anion exchange column 5b is filled with 10 L of PO ₄ type strong basic anion exchange resin (Diaion SA11A, manufactured by Mitsubishi Chemical Co., Ltd.), regenerated with OH type with sodium hydroxide, and then concentrated with PO _{4 using a} phosphoric acid concentrate. It was set as the type. As the reverse osmosis device 4, the device having the spiral membrane module of the reverse osmosis membrane ES-20 manufactured by Ildong Electric Co., Ltd. was passed through at 0.7 MPa to carry out reverse osmosis treatment, and concentrated 6 times. As the evaporation concentration apparatus 8, it concentrated by 75% of phosphoric acid concentration using the rotary evaporator. Table 2 shows the concentration of each component in each step.

TABLE 2

pH Phosphoric Acid nitric acid Acetic acid Kazion unit - (Mg / L) (Mg / L) (Mg / L) (Mg / L) Enemies (1a) 2.4 550 50 50 1> Talcachion Water (3a) 2.3 550 50 50 1> Permeate (L7) 2.4 20 45 47 1> Recovered water (7a) 6.7 1> 1> 1> 1> Concentrate (L11) 2.2 3,300 45 47 1> Second anion exchange liquid (L14) 2.2 3,300 0.3 47 1> Recovered Phosphate (9a) 1.7 75 (%) 1,000> 1,000> 100>

Reference Example 1 and Reference Example 2

<Reverse osmosis treatment>

Raw water having a conductivity of 122 mS / m and pH 2.4 containing 550 mg / L phosphoric acid, 50 mg / L nitric acid and 50 mg / L acetic acid was 0.7 MPa in reverse osmosis membrane ES-20 manufactured by Ildong Electric Co., Ltd. The solution was passed through a reverse osmosis treatment to obtain a 5-fold concentrate (blind) (reference example 1). On the other hand, the aqueous solution of sodium hydroxide was injected into raw water to adjust the pH to 6, and tested in the same manner (Reference Example 2). The results of the inhibition rates of phosphoric acid, nitric acid and acetic acid are shown in Table 3. In Reference Example 1, phosphoric acid was blocked, while nitric acid and acetic acid were permeated, while in Reference Example 2, it was found that all were blocked and not permeated. .

[ Table 3 ] Blocking rate

Reference Example 1 Reference Example 2 pH 2.3 6 Phosphoric Acid (%) 97.8 99.6 nitric acid(%) Less than 1 99.5 Acetic acid (%) Less than 1 99.0

Experimental Example 3

In Reference Example 1, the relationship between the change in the concentration of phosphoric acid in the concentrate and the inhibition rate of nitric acid when the circulation of the concentrate was increased to increase the recovery is shown in FIG. 3.

3 shows that the concentration of phosphoric acid in the concentrate is 1% by weight or less, the rate of nitric acid is negative, and the linear decrease, and in particular, the permeation of nitric acid is promoted to 2% by weight or less and 4% by weight or less of phosphoric acid. Able to know. The same result was obtained also for acetic acid.

Experimental Example 4 and Experimental Example 5

In the apparatus of Fig. 2, a cationic exchange tower and phosphoric acid filled with H-type strongly acidic cationic exchange resin (Mitsubishi Chemical Co., Ltd., DiaionSK1B) were filled with the same phosphoric acid-containing water as that of Reference Example 1 using the same reverse osmosis membrane as that of Reference Example 1. After treatment in an anion exchange tower packed with a type of anxious anion exchange resin (manufactured by Mitsubishi Chemical Corporation, DiaionWA30), the membrane was subjected to membrane separation while circulating without diluting the concentrate by supplying it to a reverse osmosis device, and performing 100 times the membrane separation. The concentrated water (Experimental Example 4) and the recovered water desalted by the electro regenerative ion exchanger were supplied to the concentrate tank as dilution water (20 vol% of the amount of feed water supplied), and the membrane was separated while diluting the concentrate with circulation. The concentration of the solute in the concentrate when concentrated 100 times (Experimental Example 5) is shown in Table 4. It is assumed that the concentrate obtained in Reference Example 1 was concentrated 100 times in total by distillation, and the solute concentration determined by the calculation is described together as Reference Example 1.

TABLE 4 solute concentration

Experimental Example 4 Experimental Example 5 Reference Example 1 Phosphoric Acid (%) 5.4 5.4 5.3 Nitric Acid (mg / L) 160 30 310 Acetic acid (mg / L) 170 40 380

From Table 4, by performing the reverse osmosis treatment under the condition that the concentration of phosphoric acid in the concentrate is 1% by weight or more, the acid concentration other than phosphoric acid in the concentrate is lowered, and the reverse osmosis treatment is carried out while diluting and circulating the concentrate to concentrate the concentrate in the concentrate. It can be seen that acid concentrations other than phosphoric acid are further lowered to recover a high purity phosphoric acid concentrate.

The present invention provides a method and apparatus for recovering phosphoric acid and pure water from phosphoric acid-containing water, in particular, recovering phosphoric acid such as phosphoric acid and phosphoric acid suitable for recovery of valuable water such as phosphoric acid and treated water from the washing drainage after etching a liquid crystal substrate, a wafer or other electronic device. It is available to methods and apparatus.

Although the above has been described with reference to embodiments of the present invention, those skilled in the art may variously modify the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. It will be appreciated that it can be changed.

Claims (17)

In the method of recovering phosphoric acid from the phosphoric acid-containing water, Supplying the phosphoric acid-containing water to the reverse osmosis apparatus under a condition of pH 3 or less to perform reverse osmosis treatment, permeate an acid other than phosphoric acid to the permeate chamber with water, and concentrate the phosphoric acid to the concentrate chamber to recover the phosphoric acid concentrate. A method for recovering phosphoric acid, which is characterized by the above-mentioned. In the method of recovering phosphoric acid from the phosphoric acid-containing water, Phosphoric acid-containing water was supplied to the reverse osmosis apparatus under a pH of 3 or less and a phosphoric acid concentration of 1 to 15% by weight to carry out membrane separation treatment. An acid other than phosphoric acid was permeated to the permeate chamber with water to concentrate the phosphoric acid to the concentrate chamber. Recovering the phosphoric acid concentrate. The method according to claim 1 or 2, And extracting the concentrated liquid from the concentrated liquid chamber and circulating the concentrated liquid chamber, and performing reverse osmosis by adding the treated phosphoric acid-containing water to the circulated concentrated liquid. The method according to claim 1 or 2, Extracting the concentrated liquid from the concentrated liquid chamber and circulating the concentrated liquid chamber, and adding dilution water to the circulating concentrated liquid to perform membrane separation. The method according to claim 1 or 2, Before the phosphoric acid-containing water is supplied to the reverse osmosis apparatus, a method for recovering phosphoric acid, characterized in that impurities such as cationic and / or anion are removed as a pretreatment. The method according to claim 1 or 2, A method for recovering phosphoric acid, wherein pure water is recovered by removing impurities including acid from the permeate of the reverse osmosis device. The method of claim 6, The removal method of the said impurity is performed by the ion exchange apparatus. The method according to claim 1 or 2, A method for recovering phosphoric acid, characterized in that an acid other than phosphoric acid is purified by anion exchange from the phosphoric acid concentrate. The method according to claim 1 or 2, The phosphoric acid concentrate is evaporated and concentrated to remove the volatile components with water to concentrate the phosphoric acid. In the apparatus for recovering phosphoric acid from the phosphoric acid containing water, A reverse osmosis device for separating the phosphoric acid-containing water under a condition of pH 3 or less, permeating an acid other than phosphoric acid with water to the permeate chamber, and concentrating the phosphoric acid to the concentrate chamber side; A raw water supply unit for supplying phosphoric acid-containing water to the concentrate chamber side of the reverse osmosis apparatus under a condition of pH 3 or less; A permeate extracting unit for extracting the permeate from the permeate chamber side of the reverse osmosis apparatus; And And a concentrated phosphate extracting unit for extracting the concentrated phosphate solution from the concentrated liquid chamber side of the reverse osmosis device. In the apparatus for recovering phosphoric acid from the phosphoric acid containing water, A reverse osmosis unit for separating phosphoric acid-containing water under a condition of pH 3 or less and phosphoric acid concentration of 1 to 15% by weight to permeate an acid other than phosphoric acid with water to the permeate chamber side, and to concentrate the phosphoric acid to the concentrate chamber side; A phosphoric acid-containing water supply unit for supplying phosphoric acid-containing water to a concentration chamber side of the reverse osmosis apparatus under a condition of pH 3 or less and phosphoric acid concentration of 1 to 15% by weight; A permeate extracting unit for extracting the permeate from the permeate chamber side of the reverse osmosis apparatus; A concentrated phosphoric acid extracting unit for extracting a concentrated phosphoric acid solution from the concentrated liquid chamber side of the reverse osmosis device; And And a circulation path for circulating the concentrated phosphoric acid liquid taken out from the concentrated phosphoric acid liquid extraction part to the concentrated liquid chamber side. The method of claim 10 or 11, And a dilution water supply unit for adding dilution water to the concentrate circulating in the circulation path. The method of claim 10 or 11, And a pretreatment device for removing impurities including cationic and / or anion. The method according to claim 10, wherein And an impurity removal device for removing impurities including acid from the permeate of the reverse osmosis device. The method of claim 14, And the impurity removal device is an ion exchange device. The method of claim 10 or 11, And a purification device for removing an acid other than phosphoric acid from the phosphoric acid concentrate by anion exchange. The method of claim 10 or 11, And an evaporating and concentrating device for evaporating and concentrating the phosphate concentrate to remove and concentrate volatile components together with water.

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