JP2004345949A - Hydrofluoric acid regeneration method and apparatus - Google Patents

Abstract

【Task】
Using an adsorbent that has been treated to adsorb fluorine from wastewater and wastewater containing fluorine, this adsorbent is reacted with a sulfuric acid solution and separated by distillation to obtain pure hydrofluoric acid even from hydrofluoric acid wastewater and wastewater containing various impurities. Acid can be regenerated, and a large amount of hydrofluoric acid can be regenerated in a short time without depending on the purity of hydrofluoric acid waste liquid. It is an object of the present invention to provide a hydrofluoric acid regenerating method and apparatus capable of performing treatment and reusing the adsorbent.
[Solution]
Hydrofluoric acid regeneration by adsorbing fluorine from wastewater and wastewater containing fluorine with a ceramic adsorbent A containing activated alumina and silicon dioxide as main components, and regenerating hydrofluoric acid using the adsorbent A after the adsorption treatment A distillation means for reacting an adsorbent A with a sulfuric acid solution B to separate fluorine from the adsorbent A, and liquefying hydrogen fluoride gas generated by a manual distillation operation to form hydrofluoric acid And a cooling means 16 that performs cooling.
[Selection diagram] Fig. 1

Description

The present invention is intended to reduce harmful substances such as fluorine contained in industrial wastewater and wastewater (hazardous substances such as fluorine, arsenic, chromium, phosphorus, lead, etc., which are regulated substances of the wastewater standard defined by the Water Pollution Control Law). The present invention relates to a method and an apparatus for regenerating hydrofluoric acid in which an adsorbent is subjected to an adsorption treatment, fluorine is recovered from the adsorbed adsorbent, liquefied and regenerated as hydrofluoric acid (HF + H ₂ O).

Conventionally, in order to release fluorine contained in wastewater and wastewater and recover the fluorine, fluorine ions in the wastewater are converted into calcium fluoride (CaF ₂ ) based on a recrystallization precipitation principle called a crystallization method. The method of taking out is common.

In addition, there is no method or apparatus for removing and recovering fluorine ions from wastewater and wastewater in which a plurality of harmful substances are mixed, and regenerating hydrofluoric acid (hydrofluoric acid). A conventional technique for removing and recovering only fluorine to generate calcium fluoride (CaF ₂ ) will be described.

In the process of etching a silicon wafer of a semiconductor product, highly pure hydrofluoric acid containing no impurities is used.
This hydrofluoric acid is high-purity (99.999% purity) hydrofluoric acid containing no impurities. After etching and cleaning silicon wafers, remove fluorine and discharge it to rivers or the like as wastewater. Or collected as waste liquid.

Since this hydrofluoric acid waste liquid contains more than the effluent standard value stipulated by the Water Pollution Control Law, to discharge it to rivers, sea areas, etc. as effluent and effluent, the fluorine must be less than the above effluent standard. Although removal treatment is required, the apparatus shown in FIG. 4 is used as a pre-step treatment of the method of recovering the fluorine ions contained in the hydrofluoric acid waste liquid and regenerating it into the original hydrofluoric acid from the viewpoint of recycling recycling. Fluorine is recovered and regenerated to produce high-purity calcium fluoride (CaF ₂ ).

  In the hydrofluoric acid recycling apparatus based on the crystallization method shown in FIG. 4, the hydrofluoric acid waste liquid 80 is supplied via a pipe 81 to a crystallization furnace 82 such as a fluidized bed crystallizer. A sheet material (a seed material for crystallizing fluorine ions) as a crystallization accelerator for accelerating crystallization is supplied from a seed agent tank 83 to the crystallization furnace 82. As is well known, this seed agent can crystallize and precipitate fluorine ions from hydrofluoric acid waste liquid on the surface of the seed agent.

Next, the crystallized fluorine and the seed agent are separated, calcium chloride (CaCl ₂ ) is supplied from the calcium chloride tank 84, and reacted with the crystallized fluorine to obtain calcium fluoride (CaF ₂ ) (FIG. 4). (See reference numeral 85).

A circulating tank 86 provided at the next stage of the crystallization furnace 82 supplies circulating water to the crystallization furnace 82 through a circulation line 87 in order to crystallize the waste water that could not be crystallized again, and performs crystallization and circulation. By repeating the treatment a plurality of times, calcium fluoride (CaF ₂ , so-called fluorite) having a high purity of 80% or more is generated.

  On the other hand, the circulating water is guided to the neutralization tank 88 as wastewater every plural times, and the fluoride ion concentration is reduced to below the wastewater standard value.

The calcium fluoride (CaF ₂ ) generated in the above-mentioned crystallization furnace 82 is used by a chemical manufacturer or the like as an industrial hydrofluoric acid production raw material.
The above-described conventional method and its apparatus have the following various problems.

In other words, calcium fluoride (CaF ₂ ) used as a raw material for producing industrial hydrofluoric acid cannot be used unless its purity is not less than 80%, and the concentration of impurities other than fluorine is higher than the environmental standard value (drainage standard). (1/10 or less of the value) makes it difficult to crystallize in the crystallization furnace 82 and is not suitable for industrial hydrofluoric acid production raw materials.

Therefore, in many cases, only high-purity hydrofluoric acid waste liquid used in semiconductor production is suitable, and it is impossible to regenerate industrial hydrofluoric acid from wastewater / waste liquid containing a plurality of impurities even in trace amounts.
In addition, a seed agent used for crystallization is expensive, and a large amount of a chemical agent such as calcium chloride (CaCl ₂ ) is used, so that the running cost of producing high-purity calcium fluoride (CaF ₂ ) increases. There was a problem.

Furthermore, since the above-mentioned crystallization is due to a chemical reaction, an extremely long reaction time is required to produce high-purity calcium fluoride (CaF ₂ ), and the amount of produced high-purity calcium fluoride increases. For this purpose, parallel processing by a plurality of crystallization furnaces 82 is required, which causes an increase in running cost and initial cost of the apparatus, and also has a problem that the apparatus is enlarged.

In short, in order to produce high-purity calcium fluoride (CaF ₂ ), impurities other than fluorine cannot be regenerated from wastewater and wastewater containing them, and are limited to high-purity hydrofluoric acid wastewater used in semiconductor production. Moreover, it was not possible to regenerate inexpensive general industrial hydrofluoric acid.

  In addition, in order to regenerate hydrofluoric acid from the recovered calcium fluoride, it is necessary to transport calcium fluoride to a chemical manufacturer, which naturally requires transportation and regeneration costs, and is economically viable. There were no problems.

Moreover, in order to regenerate hydrofluoric acid from waste water and waste liquid containing fluorine, first, a pre-stage treatment for generating calcium fluoride (CaF ₂ ) from waste water and waste liquid, and a post-stage treatment for regenerating hydrofluoric acid from calcium fluoride There was a problem that hydrofluoric acid could not be regenerated unless a separate two-step process was performed.

On the other hand, Patent Document 1 discloses that the above-mentioned calcium carbonate-filled layer is used for removing fluorine in the fluorine-containing water and recovering calcium fluoride while passing fluorine-containing water through the calcium carbonate-filled layer in an upward flow. Means of passing water until the fluorine concentration or the pH of the inlet liquid and the outlet liquid are substantially the same are disclosed. However, to regenerate hydrofluoric acid from high-purity calcium fluoride recovered by this means, Similarly, post-stage processing is required.
JP-A-5-253578

  Accordingly, the present invention provides a hydrofluoric acid wastewater containing various impurities by reacting the adsorbent with a sulfuric acid solution by distillation using an adsorbent obtained by absorbing fluorine from wastewater and wastewater containing fluorine. Pure hydrofluoric acid can be regenerated from the waste liquid, a large amount of hydrofluoric acid can be regenerated in a short time without depending on the purity of the hydrofluoric acid waste liquid, and the hydrofluoric acid regeneration process can be unified, It is an object of the present invention to provide a hydrofluoric acid regenerating method and apparatus capable of performing batch processing in the same business site and reusing the adsorbent.

  The hydrofluoric acid regenerating apparatus according to the present invention is a ceramic-based adsorbent containing activated alumina and silicon dioxide as main components, which absorbs fluorine from waste water and waste liquid containing fluorine, and uses the adsorbent after the adsorption treatment. A hydrofluoric acid regenerating apparatus for regenerating an acid, comprising: a distilling means for reacting an adsorbent with a sulfuric acid solution to separate fluorine from the adsorbent; and hydrofluoric acid by liquefying hydrogen fluoride gas generated by the distillation operation. And cooling means for forming

The above-mentioned adsorbent is obtained by removing and adsorbing a plurality of harmful substances including fluorine from wastewater and wastewater, and a used adsorbent whose adsorbent has reached adsorption saturation may be used. However, it is in a state of silicon tetrafluoride (SiF ₄ ) as a compound in which silicon dioxide (SiO ₂ ) and F (fluorine), which are components of the adsorbent, are bonded, and fluorine alone easily binds to other metals. Is in the condition of the compound (SiF ₄ ), and is under the condition that it is not easily connected to other metals.

According to the above configuration, the distillation means reacts the adsorbent with the sulfuric acid solution to separate fluorine from the adsorbent, and the cooling means liquefies the hydrogen fluoride gas generated by the distillation operation to hydrofluoric acid (that is, hydrofluoric acid). Acid).
Since regeneration by distillation is a physical means for selectively separating and liquefying a pure substance from a mixture, even if there are impurities other than fluorine in the adsorbent, only hydrogen fluoride gas is selectively removed. , Can regenerate pure hydrofluoric acid. In short, it is possible to regenerate pure hydrofluoric acid from hydrofluoric acid wastewater and wastewater containing various impurities without being limited to pure semiconductor hydrofluoric acid wastewater containing no impurities at all. It is possible to regenerate a large amount of hydrofluoric acid in a short time without dependence.

The above-mentioned distillation separation is performed by the following chemical formula.
SiF ₄ + H ₂ SO ₄ → 2HF + SiSO ₄ + F ₂
That is, the fluorine (F ₂ ) adsorbed on the adsorbent is linked with silicon dioxide (SiO ₂ ) as a component of the adsorbent, and exists as silicon tetrafluoride (SiF ₄ ), and the solution of sulfuric acid (H ₂ SO ₄ ) Reacting silicon tetrafluoride (SiF ₄ ) is decomposed to generate hydrogen fluoride (2HF), and the gaseous hydrogen fluoride is liquefied by cooling means to be hydrofluoric acid.

  In addition, since hydrofluoric acid is regenerated by distilling the adsorbent that has absorbed fluorine from wastewater and wastewater containing fluorine, the hydrofluoric acid regeneration process can be centralized and batch processing can be performed at the same business site. Since the cost can be reduced and the adsorbent itself is regenerated, the regenerated adsorbent can be reused.

  Furthermore, unlike the conventional method using a large amount of a drug such as calcium chloride or a crystallization accelerator (seed agent), the cost of the drug can be significantly reduced, and the chemical reaction time is not required, so that The efficiency of hydrofluoric acid regeneration is improved, and the running cost can be significantly reduced.

  In addition, the use of adsorbents that adsorb and remove fluorine from hydrofluoric acid waste liquids used in various industrial fields regenerates hydrofluoric acid by selectively separating only fluorine, greatly expanding its versatility. Can be planned. For example, hydrofluoric acid is also used in glass manufacturers and liquid crystal manufacturers, and hydrofluoric acid is also used for cleaning printed circuit boards and electronic components. Therefore, application to such various technical fields is possible.

In one embodiment of the present invention, a purge means for purging the hydrogen fluoride gas to the cooling means with water vapor is provided.
As the above-mentioned steam, pure water steam may be used.
According to the above configuration, the hydrogen fluoride gas can be reliably sent to the cooling means with water vapor, and the hydrogen fluoride gas can be prevented from stagnating in the middle of the path.

In one embodiment of the present invention, the heating temperature in the distillation operation is set at 100 to 200 ° C.
According to the above configuration, only hydrogen fluoride (HF) having a low boiling point can be reliably vaporized, and vaporization of other harmful substances such as heavy metals can be prevented.

  That is, the boiling points of the substances are different, the boiling point of lead is 1740 ° C, the boiling point of zinc is 907 ° C, the boiling point of mercury is 356 ° C, the boiling point of cadmium is 766 ° C, the boiling point of chromium is 2200 ° C, and the boiling point of diarsenic trioxide is Is 278 ° C., and the boiling point of hydrofluoric acid (50 wt%) is 106 ° C.

  By setting the heating temperature of the distillation operation in the above range of 100 ° C. to 200 ° C., only hydrogen fluoride can be reliably vaporized with the minimum necessary heat energy, and vaporization of other harmful substances can be prevented. .

In one embodiment of the present invention, the cooling means liquefies the hydrogen fluoride gas at normal temperature or lower to form hydrofluoric acid.
The above-mentioned liquefaction may be set to water cooling using industrial water or pure water.
According to the above configuration, the hydrogen fluoride gas as a gas can be cooled by the cooling means, liquefied reliably, and hydrofluoric acid can be formed. In other words, since hydrofluoric acid can be formed mainly by heating during distillation and cooling during liquefaction, unlike the conventional crystallization method, a large amount of a seed agent or calcium chloride is not required, and it is decomposed as a chemical. Since only sulfuric acid for promotion is sufficient, the running cost can be significantly reduced.

  In one embodiment of the present invention, there is provided at least one concentration means for concentrating the hydrofluoric acid liquefied by the cooling means to a predetermined hydrofluoric acid concentration according to the purpose of use.

According to the above configuration, the regenerated and liquefied hydrofluoric acid can be concentrated to a predetermined hydrofluoric acid concentration according to the purpose of use.
The above concentration can be set to an arbitrary concentration by evaporating a predetermined amount of water from hydrofluoric acid in the state of HF + H ₂ O.

The hydrofluoric acid regenerating method according to the present invention is a ceramic-based adsorbent containing activated alumina and silicon dioxide as main components, which absorbs fluorine from waste water and waste liquid containing fluorine, and uses the adsorbent after the adsorption treatment. A hydrofluoric acid regenerating method for regenerating an acid, comprising reacting an adsorbent with a sulfuric acid solution to separate fluorine from the adsorbent,
And a cooling step of liquefying the hydrogen fluoride gas generated by the distillation operation to form hydrofluoric acid.

  According to the above configuration, in the distillation step, the adsorbent reacts with the sulfuric acid solution to separate fluorine from the adsorbent, and in the cooling step, hydrogen fluoride gas generated by the distillation operation is liquefied to hydrofluoric acid ( That is, hydrofluoric acid is formed.

  Since the regeneration by distillation separation is a physical means for selectively separating and liquefying a pure substance from a mixture, even if there is an impurity in the adsorbent, only hydrogen fluoride gas is selectively taken out, and pure hydrogen is removed. Hydrofluoric acid can be regenerated. In short, it is possible to regenerate pure hydrofluoric acid from hydrofluoric acid wastewater and wastewater containing various impurities without being limited to pure semiconductor hydrofluoric acid wastewater containing no impurities at all. It is possible to regenerate a large amount of hydrofluoric acid in a short time without being dependent on it, and to exhibit the same operation and effect as the hydrofluoric acid regenerating device.

  According to the present invention, since the adsorbent and the sulfuric acid solution are reacted and separated by distillation using the adsorbent obtained by absorbing fluorine from wastewater and wastewater containing fluorine, hydrofluoric acid containing various impurities is used. Pure hydrofluoric acid can be regenerated from wastewater and wastewater, and a large amount of hydrofluoric acid can be regenerated in a short time without depending on the purity of hydrofluoric acid wastewater. It is possible to carry out batch processing in the same business establishment, and it is possible to reuse the adsorbent.

Embodiments of the present invention will be described below in detail with reference to the drawings.
The drawings show a hydrofluoric acid regenerating method and an apparatus thereof. First, the structure of the hydrofluoric acid regenerating apparatus will be described with reference to FIG.
In FIG. 1, a distillation column 1 as a distillation means is provided. Inside the distillation column 1, a heating furnace 2 and a raw material charging passage 3 communicating with the heating furnace 2 are provided. A spiral passage 4 for supplying steam which communicates with one upper side, and a spiral passage 5 for delivering hydrogen fluoride gas which communicates between the heating furnace 2 and the other upper side of the distillation column 1 are provided. .

  The raw material charging passage 3 is connected to a raw material charging port 8 via an on-off valve 6 and a hopper 7, and the above-described passage 4 is connected to a steam generating tank 10 via an on-off valve 9.

  The steam generating tank 10 heats the pure water to generate pure water steam. The steam is supplied from the passage 4 into the heating furnace 2 to purge the hydrogen fluoride gas flowing through the passage 5.

As a raw material to be charged from the above-described raw material charging port 8, a solid adsorbent A described below is used.
That is, the adsorbent A is made of activated alumina (this activated alumina is a non-quality alumina having a large specific surface area and having a high adsorptive power) and silicon dioxide (SiO ₂ ). A ceramic-based adsorbent to be used as a component, and a plurality of harmful substances including fluorine in the wastewater / waste liquid are filtered by an adsorption / filtration method using hydrofluoric acid wastewater / wastewater in which a plurality of harmful substances such as heavy metals are mixed by the adsorbent. The adsorbent A under the adsorption saturated state removed simultaneously or stepwise is used.

That is, the adsorbent A is in a state of silicon tetrafluoride (SiF ₄ ) as a compound in which silicon dioxide (SiO ₂ ) as its component and F (fluorine) are bonded. Although the above-mentioned elemental fluorine is easily bound to other metals, it is not easily bound to other metals because it is in a state of silicon tetrafluoride (SiF ₄ ) as a compound.

On the other hand, a sulfuric acid tank 11 storing sulfuric acid (H ₂ SO ₄ ) is provided, and a sulfuric acid supply line 13 in which the sulfuric acid tank 11 opening / closing valve 12 is interposed is connected so that the line 13 faces the heating furnace 2. ing.

  In this heating furnace 2, a fixed amount of adsorbent A supplied through a hopper 7, an opening / closing valve 6, and a material charging passage 3 from a material charging port 8, and a switching valve 12 and a sulfuric acid supply line 13 from a sulfuric acid tank 11. There is a sulfuric acid solution B supplied via.

In the heating furnace 2, the adsorbent A and the sulfuric acid solution B in the state of SiF ₄ react with each other, so that hydrogen fluoride gas is generated by the following chemical formula.
SiF ₄ + H ₂ SO ₄ → 2HF + SiSO ₄ + F ₂
When the heating temperature in the heating furnace 2 is set to 100 to 200 ° C., desirably 130 ° C. to 155 ° C., and more desirably 145 ° C., hydrogen fluoride gas is used under the condition that vaporization of other harmful substances such as heavy metals is prevented. (2HF) occurs.

This hydrogen fluoride gas is sent out by the steam for purge supplied from the passage 4 and is expelled to the upstream part through the passage 5.
A cooling tower 16 as a cooling means is connected to a delivery end of the hydrogen fluoride gas delivery passage 5 via a communication passage 15 provided with a check valve 14.

The cooling tower 16 liquefies the hydrogen fluoride gas generated by the distillation operation to form hydrofluoric acid (HF + H ₂ O). The cooling tower 16 has an inner pipe for flowing down the hydrogen fluoride gas from the upper end thereof. 17 and a cooling coil 18 which is spirally wound around the outer circumference of the inner pipe 17 and through which cooling water (industrial water or pure water) flows.

  Although the cooling temperature of the cooling tower 16 is set to a normal temperature of 20 ° C. or lower, a cooling temperature may be set to about −10 ° C. by using a refrigerant instead of the cooling water flowing through the cooling coil 18. That is, the cooling temperature of the cooling tower 16 may be set in the range of -10 to + 20 ° C.

  Here, the above-mentioned check valve 14 is connected to the upper end side of the inner pipe 17 to prevent the back flow of hydrogen fluoride gas from the cooling tower 16 due to the pressure difference caused by the temperature decrease when the distillation is stopped. Therefore, a check valve with a check valve may be used instead of the check valve 14.

While the hydrogen fluoride gas flows down the inside of the inner pipe 17 of the cooling tower 16 from upstream to downstream, the hydrogen fluoride gas and pure water vapor are liquefied together, and hydrofluoric acid (HF + H ₂ O) and Become.

  A storage tank 21 is connected to a lower end of the inner pipe 17 via an on-off valve 19 and a line 20, and the storage tank 21 is configured to store liquefied hydrofluoric acid.

Concentration towers 25, 26, and 27 as a plurality of concentration means are connected to the next stage of the storage tank 21 via an on-off valve 22, a line 23, and an on-off valve 24.
The above-mentioned concentrating towers 25, 26, and 27 are concentrating means for concentrating the hydrofluoric acid liquefied in the cooling tower 16 to a predetermined hydrofluoric acid concentration corresponding to the purpose of use, and include hydrofluoric acid (HF + H ₂ O). The concentration of hydrofluoric acid can be easily adjusted by evaporating a predetermined amount of water as a solvent therein. Here, the concentration of hydrofluoric acid in each of the above-described concentration towers 25, 26, and 27 may be different. Further, H ₂ O evaporates at 100 ° C. and the boiling point of HF is 108 ° C. Therefore, the HF is heated and concentrated at 100 ° C. or less.

A line 29 provided with a relief valve 28 having a check valve structure for releasing steam into the atmosphere at the time of concentration is provided above the concentration towers 25, 26, and 27.
Further, storage tanks 32, 33, and 34 for storing hydrofluoric acid concentrated to a predetermined concentration are provided below the concentration towers 25, 26, and 27 via a line 30 and an on-off valve 31.

  By the way, a sealed waste liquid tank 37 is provided at the bottom of the heating furnace 2 in the above-mentioned distillation column 1 via a line 35 and an on-off valve 36. The above-mentioned line 35 allows the adsorbent A to pass therethrough. It is set in a solid-liquid separation passage which allows only the waste liquid to flow down to the waste liquid tank 37. The solid-liquid separation passage may be formed by a mesh-like passage, or may be constituted by providing a filter above the line 35.

Next, a method for regenerating hydrofluoric acid using the hydrofluoric acid regenerating apparatus having the above configuration will be described.
The adsorbent A after the adsorption of the harmful substance (used) under the condition of SiF ₄ is directly charged into the raw material inlet 8 as a raw material. The adsorbent A falls into the heating furnace 2 via the hopper 7, the on-off valve 6, and the passage 3.

Since the sulfuric acid solution B corresponding to the weight of the adsorbent A is previously injected into the heating furnace 2, the used adsorbent A reacts with the sulfuric acid solution B.
As the solution B of sulfuric acid (H ₂ SO ₄ ) reacts with the adsorbent A in the state of silicon tetrafluoride (SiF ₄ ), as shown by the chemical formula of SiF ₄ + H ₂ SO ₄ → 2HF + SiSO ₄ + F ₂ Is decomposed into hydrogen fluoride (2HF) and silicon sulfide (SiO ₄ ).

  When the heating temperature of the heating furnace 2 is set in the range of 100 to 200 ° C., hydrogen fluoride (2HF) having a low boiling point is vaporized, hydrogen fluoride gas is generated, and evaporation of harmful substances such as heavy metals having a high boiling point is prevented. Can be prevented (distillation step).

  The above-mentioned hydrogen fluoride gas is sent to the cooling tower 16 via the passages 5 and 15 and the check valve 14 with pure water vapor generated from the water vapor generating tank 10 and enters the inner pipe 17 thereof.

  While the hydrogen fluoride gas and the water vapor for purging flow down the inner pipe 17, both of them are cooled to room temperature or lower by the cooling coil 18 to liquefy, and the hydrogen fluoride is dissolved in the water. Since it has properties, it quickly dissolves in pure water and becomes hydrofluoric acid (hydrofluoric acid) (cooling step).

  Here, the results obtained by comparing experimentally the hydrofluoric acid recovery rate (hydrofluoric acid regeneration rate) of both the used adsorbent A and a commercially available virgin hydrofluoric acid solution having a concentration of 2% with the distillation operation are shown. It is shown in FIG.

The used adsorbent A, which has adsorbed 460 ppm of fluorine at 5 g, is distilled and regenerated using sulfuric acid at a distillation temperature of 145 ° C. by the method of the above embodiment, and the hydrofluoric acid concentration becomes 440 ppm, and hydrofluoric acid is regenerated from hydrofluoric acid wastewater and waste liquid. The recovery (hydrofluoric acid regeneration rate) was 95.7%.
When industrial hydrofluoric acid having an initial concentration of 2.1% was distilled under the same conditions as described above, the concentration after recovery was 2.0%, and the recovery was 95.2%.

In other words, hydrofluoric acid was able to be regenerated from hydrofluoric acid wastewater / waste liquid at a recovery rate equivalent to that of a commercially available pure hydrofluoric acid.
By the way, when the hydrofluoric acid liquefied by the cooling tower 16 is temporarily stored in the storage tank 21 and supplied to the concentration towers 25, 26, and 27 via the on-off valve 22, the line 23, and the on-off valve 24, For example, the concentration is adjusted to a predetermined hydrofluoric acid concentration desired by the user (concentration step).

To illustrate the adjustment of the hydrofluoric acid concentration, when 100 liters of hydrogen fluoride gas is liquefied with respect to 1900 liters of pure water, hydrofluoric acid having a concentration of 5% is formed.
By evaporating 1000 liters of water in a concentration tower, 100 / (900 + 100) × 100 = 10% hydrofluoric acid can be obtained, and the hydrofluoric acid concentration can be doubled.
That is, by evaporating only the amount of water, the concentration of hydrofluoric acid can be arbitrarily concentrated.
FIG. 4 shows the results of actual measurement of the concentration of the regenerated hydrofluoric acid accompanying the concentration operation of the regenerated hydrofluoric acid. When the initial concentration of the regenerated hydrofluoric acid is 0.40% with respect to 250 liters of water, the water content is reduced to 1%. When the is reduced to 50 liters, a concentration about 5 times is theoretically obtained and the concentration becomes about 2.0%, but the actual concentration concentrated in the concentration tower of FIG. 1 is 1.8. %. That is, only about 10% of the theoretical value was lost.

  As described above, even when the treatment for concentrating the concentration of the regenerated hydrofluoric acid is performed, the concentration is only about 10%, so that the concentration can be achieved without losing most of the concentration of the regenerated hydrofluoric acid. The result was.

The concentration column shown in FIG. 1 may be, for example, only one concentration column if there is only one type of hydrofluoric acid concentration desired by the user.
As described in detail above, the hydrofluoric acid regenerating apparatus of the above embodiment is a ceramic adsorbent A containing activated alumina (Al ₂ O ₃ ) and silicon dioxide (SiO ₂ ) as main components and containing fluorine F. A hydrofluoric acid regenerating apparatus for adsorbing fluorine from waste water and waste liquid and regenerating hydrofluoric acid using the adsorbent A after the adsorption treatment, wherein the adsorbent A reacts with a sulfuric acid (H ₂ SO ₄ ) solution B. A distillation column 1 for separating fluorine from the adsorbent A, and a cooling tower 16 for liquefying hydrogen fluoride gas generated by the distillation operation to form hydrofluoric acid.

  According to this configuration, the distillation tower 1 reacts the adsorbent A with the sulfuric acid solution to separate fluorine from the adsorbent A, and the cooling tower 16 liquefies the hydrogen fluoride gas generated by the distillation operation and converts the hydrogen fluoride gas into hydrogen fluoride. Form acids (ie hydrofluoric acid).

  Since this regeneration by distillation is a physical means for selectively separating and liquefying a pure substance from a mixture, even if there are impurities other than fluorine in the adsorbent A, only hydrogen fluoride gas is selectively taken out. Thus, pure hydrofluoric acid can be regenerated. In short, it is possible to regenerate pure hydrofluoric acid from hydrofluoric acid wastewater and wastewater containing various impurities without being limited to pure semiconductor hydrofluoric acid wastewater containing no impurities at all. It is possible to regenerate a large amount of hydrofluoric acid in a short time without dependence.

The above-mentioned distillation separation is performed by the following chemical formula.
SiF ₄ + H ₂ SO ₄ → 2HF + SiSO ₄ + F ₂
That is, the fluorine (F ₂ ) adsorbed on the adsorbent A is combined with silicon dioxide (SiO ₂ ) as a component of the adsorbent A and exists as silicon tetrafluoride (SiF ₄ ), and sulfuric acid (H ₂ SO ₄ ) Silicon tetrafluoride (SiF ₄ ) that reacts with the solution is decomposed to generate hydrogen fluoride (2HF), and gaseous hydrogen fluoride is liquefied in the cooling tower 16 to be hydrofluoric acid.

  In addition, since the hydrofluoric acid is regenerated by distilling the adsorbent A that has adsorbed fluorine from the wastewater and wastewater containing fluorine, the hydrofluoric acid regeneration process can be centralized and batch processing can be performed within the same business site. The running cost can be reduced, and the adsorbent A can be taken out of the heating furnace 2 and the regenerated adsorbent A can be reused.

  Furthermore, unlike the conventional method using a large amount of a drug such as calcium chloride or a crystallization accelerator (seed agent), the cost of the drug can be significantly reduced, and the chemical reaction time is not required, so that The efficiency of hydrofluoric acid regeneration is improved, and the running cost can be significantly reduced.

  In addition, the use of adsorbent A, which adsorbs and removes fluorine from hydrofluoric acid waste liquid used in various industrial fields, selectively separates only fluorine to regenerate hydrofluoric acid, greatly expanding its versatility. Can be achieved.

Further, a purge means (see the steam generation tank 10 and the passage 4) for purging the hydrogen fluoride gas to the cooling tower 16 with steam is provided.
According to this configuration, the hydrogen fluoride gas can be reliably sent to the cooling tower 16 with the steam, and the hydrogen fluoride gas can be prevented from stagnating in the middle of the path (see the passage 5). .

In addition, the heating temperature of the distillation operation is set at 100 to 200 ° C.
According to this configuration, only hydrogen fluoride (HF) having a low boiling point can be reliably vaporized, and vaporization of other harmful substances such as heavy metals can be prevented.

  In this way, by setting the heating temperature of the distillation operation in the above-mentioned range of 100 ° C. to 200 ° C., only the hydrogen fluoride is reliably vaporized with the minimum necessary heat energy, and the vaporization of other harmful substances is prevented. can do.

The cooling tower 16 liquefies the hydrogen fluoride gas at room temperature or lower to form hydrofluoric acid.
According to this configuration, the hydrogen fluoride gas as a gas can be cooled in the cooling tower 16 and liquefied reliably to form hydrofluoric acid. In other words, since hydrofluoric acid can be formed mainly by heating during distillation and cooling during liquefaction, unlike the conventional crystallization method, a large amount of a seed agent or calcium chloride is not required, and it is decomposed as a chemical. Since only sulfuric acid (H ₂ SO ₄ ) for promotion is required, the running cost can be significantly reduced.

  In addition, at least one concentrating tower (at least one of the concentrating towers 25, 26, 27) for concentrating the hydrofluoric acid liquefied in the cooling tower 16 to a predetermined hydrofluoric acid concentration according to the purpose of use is provided. It is provided.

According to this configuration, the regenerated and liquefied hydrofluoric acid can be concentrated to a predetermined hydrofluoric acid concentration according to the purpose of use.
The above concentration can be set to an arbitrary concentration by evaporating a predetermined amount of water from hydrofluoric acid in the state of HF + H ₂ O.
On the other hand, the hydrofluoric acid regeneration method of the above embodiment uses a ceramic-based adsorbent A containing activated alumina (Al ₂ O ₃ ) and silicon dioxide (SiO ₂ ) as main components to remove fluorine from waste water and waste liquid containing fluorine. This is a hydrofluoric acid regenerating method for performing an adsorption treatment and regenerating hydrofluoric acid using the adsorbent A after the adsorption treatment, wherein the adsorbent A is reacted with a sulfuric acid (H ₂ SO ₄ ) solution B, and the fluorine is converted from the adsorbent A to fluorine. And a cooling step of liquefying hydrogen fluoride gas generated by the distillation operation to form hydrofluoric acid.

According to this configuration, in the distillation step, the adsorbent A reacts with the solution B of sulfuric acid (H ₂ SO ₄ ) to separate fluorine from the adsorbent A, and in the cooling step, hydrogen fluoride generated by the distillation operation The gas is liquefied to form hydrofluoric acid (ie, hydrofluoric acid).
Since this regeneration by distillation is a physical means for selectively separating and liquefying a pure substance from a mixture, even if there are impurities other than fluorine in the adsorbent A, only hydrogen fluoride gas is selectively taken out. Thus, pure hydrofluoric acid can be regenerated. In short, it is possible to regenerate pure hydrofluoric acid from hydrofluoric acid wastewater and wastewater containing various impurities without being limited to pure semiconductor hydrofluoric acid wastewater containing no impurities at all. It is possible to regenerate a large amount of hydrofluoric acid in a short time without dependence.
In other respects, the same operation and effect as those of the hydrofluoric acid regenerating apparatus of the above embodiment can be obtained.

In correspondence between the configuration of the present invention and the above-described embodiment,
The distillation means of the present invention corresponds to the distillation column 1 of the embodiment,
Similarly,
The cooling means corresponds to the cooling tower 16,
The purging means corresponds to the steam generation tank 10 and the passage 4,
The enrichment means corresponds to at least one of the enrichment towers 25, 26, 27,
The present invention is not limited only to the configuration of the above embodiment.

FIG. 1 is a system diagram showing a hydrofluoric acid regeneration method and an apparatus for the same according to the present invention. Explanatory drawing which shows the hydrofluoric acid collection rate accompanying a distillation operation. Explanatory drawing which shows the hydrofluoric acid concentration loss accompanying the concentration operation. The system diagram which shows the hydrofluoric acid recycling apparatus by the conventional crystallization method.

Explanation of reference numerals

1. Distillation tower (distillation means)
4. Passage (purge means)
10. Steam generation tank (purge means)
16. Cooling tower (cooling means)
25-27 ... Concentration tower (concentration means)
A: Adsorbent B: Sulfuric acid solution

Claims (6)

A hydrofluoric acid regenerating device that absorbs fluorine from wastewater and wastewater containing fluorine, and regenerates hydrofluoric acid using the adsorbent after the adsorption treatment. So,
A distillation means for reacting the adsorbent with the sulfuric acid solution and separating fluorine from the adsorbent,
A hydrofluoric acid regenerating apparatus comprising: cooling means for liquefying hydrogen fluoride gas generated by a distillation operation to form hydrofluoric acid.   2. The hydrofluoric acid regeneration apparatus according to claim 1, further comprising a purging means for purging the hydrogen fluoride gas to a cooling means with water vapor. The hydrofluoric acid regeneration apparatus according to claim 1 or 2, wherein a heating temperature of the distillation operation is set to 100 to 200 ° C. The hydrofluoric acid regenerating apparatus according to any one of claims 1 to 3, wherein the cooling unit liquefies the hydrogen fluoride gas at normal temperature or lower to form hydrofluoric acid. The hydrofluoric acid regenerating apparatus according to any one of claims 1 to 4, further comprising at least one concentrating means for concentrating the hydrofluoric acid liquefied by the cooling means to a predetermined hydrofluoric acid concentration in accordance with the purpose of use. . This is a hydrofluoric acid regeneration method that uses a ceramic-based adsorbent containing activated alumina and silicon dioxide as main components to adsorb fluorine from wastewater and wastewater containing fluorine, and regenerate hydrofluoric acid using the adsorbent after the adsorption treatment. So,
A distillation step of reacting the adsorbent with the sulfuric acid solution and separating fluorine from the adsorbent;
A cooling step of liquefying hydrogen fluoride gas generated by the distillation operation to form hydrofluoric acid.

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