TWI465280B - Separation method and separation device - Google Patents

Description

Separation method and separation device

The present invention relates to a separation method and a separation apparatus.

Since the past, as the etching liquid, those containing hydrofluoric acid and ammonium fluoride have been known. Further, a technique for recovering hydrofluoric acid (fluorine) from such an etching liquid and for etching waste liquid after etching is also known (for example, refer to Patent Document 1).

Patent Document 1 describes that high-purity calcium fluoride having a small content of cerium oxide is prepared by reacting calcium carbonate in an etching solution containing hydrofluoric acid and ammonium fluoride. A method of recovering hydrofluoric acid for etching liquid from the recovered calcium fluoride.

However, in this method, hydrofluoric acid cannot be directly separated and recovered from the etching solution. That is, after the calcium fluoride is produced and recovered, the process of preparing the calcium fluoride into hydrofluoric acid is required, and efficient recovery cannot be performed. Further, there are many processes for etching the waste liquid until a new etching liquid (hydrofluoric acid) is produced, and a large amount of secondary waste liquid is generated in the middle. Therefore, there are also problems of poor environmental protection. Moreover, since there are many processes, there is also a problem that the device is large and complicated.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 5-170435

An object of the present invention is to provide a separation method and a separation apparatus which can easily separate high-purity hydrofluoric acid from a mixed acid containing at least hydrofluoric acid, ammonium hydrogen fluoride, hydrazine and water.

The present invention has been made in order to solve at least a part of the above problems, and can be realized by the following forms or application examples.

[Application Example 1]

The separation method of the present invention is characterized in that the hydrofluoric acid is separated from a mixed acid containing at least hydrofluoric acid, ammonium hydrogen fluoride, hydrazine and water, and the method comprises the steps of: recovering the distillate by distilling the mixed acid; a liquid containing a first liquid of the hydrofluoric acid and water, and a first distillation step of recovering the second liquid containing the ammonium hydrogen fluoride and the ruthenium as a bottom residue; and discharging the first liquid from the above In the first liquid, the water is mainly separated, and a second distillation step in which the concentration of the hydrofluoric acid as the bottom residue is higher than the third liquid of the first liquid is recovered.

Thereby, high-purity hydrofluoric acid can be easily separated and recovered from the mixed acid at a relatively high concentration.

[Application Example 2]

In the separation method of the present invention, it is preferred that the heating temperature of the first liquid in the second distillation step is lower than a set temperature of a heating temperature of the mixed acid in the first distillation step.

Thereby, when water is removed from the first liquid, the amount of hydrofluoric acid mixed in the removed distillate and removed together with the water can be reduced. Therefore, the yield of hydrofluoric acid can be increased.

[Application Example 3]

In the separation method of the present invention, it is preferred that the solid containing the ammonium hydrogen fluoride and the ruthenium is crystallized from the second liquid, and the solid is separated from the second liquid by the first step. The fourth liquid is treated together with the above mixed acid.

Thereby, more hydrofluoric acid can be separated and recovered from the mixed acid.

[Application Example 4]

In the separation method of the present invention, it is preferred that the first distillation step be carried out while stirring the mixed acid.

Thereby, crystallization in the distillation tank is suppressed.

[Application 5]

In the separation method of the present invention, it is preferred to include a separation step of separating the above ammonium hydrogen fluoride from the above solid.

Thereby, ammonium hydrogen fluoride can be further separated and recovered from the mixed acid.

[Application Example 6]

In the separation method of the present invention, it is preferred that the ammonium hydrogen fluoride is separated from the solid by a crystallization method in the separation step.

Thereby, the separation of ammonium hydrogen fluoride can be easily performed.

[Application Example 7]

In the separation method of the present invention, preferably, in the separating step, the method comprises the steps of: preparing a solution in which the solid solution is dissolved, and cooling the solution to a specific temperature to perform a first crystallization step; The second crystallization step is carried out at the temperature of the first crystallization temperature.

Thereby, ammonium fluoride of higher purity can be separated and recovered.

[Application Example 8]

In the separation method of the present invention, it is preferred that the mixed acid is an etching waste liquid which is produced by etching a material containing ruthenium.

Thereby, the etching waste liquid can be reused, and the etching process can be reduced in cost. Moreover, since the amount of waste liquid to be discarded can be reduced, it is excellent in terms of environment.

[Application Example 9]

The separation device of the present invention is characterized in that it has the separation method of the present invention.

Thereby, a device for separating and recovering high-purity hydrofluoric acid or ammonium hydrogen fluoride from the mixed acid can be provided.

Hereinafter, the separation method and separation apparatus of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

1 is a schematic view of a separation apparatus according to a preferred embodiment of the present invention, and FIG. 2 is a schematic view for explaining a separation method according to a preferred embodiment of the present invention, and FIGS. 3 to 5 are diagrams for explaining the embodiment. .

Separation device

First, the configuration of the separation device 1 will be described.

The separating apparatus 1 shown in Fig. 1 is exemplified by a distillation apparatus which extracts the distillate obtained from the distillation apparatus of each step into the recovery vessel 300, or extracts the bottom residue from the distillation tank, and extracts the distillate The batch separation method in which the bottom residue is moved to the supply unit of the distillation apparatus of the next step will be described below as an example. In this case, a separation method may be constructed in which a plurality of such distillation apparatuses are arranged, connected between the apparatuses by an infusion tube, and separated by an in-line method by a valve operation.

The separation device 1 is used in a mixed acid 100 containing hydrofluoric acid [HF], ammonium hydrogen fluoride [(NH ₄ )HF ₂ ], hydrazine [Si], and water [H ₂ O], respectively, in high purity and A device for separating and recovering hydrofluoric acid and ammonium hydrogen fluoride at a relatively high concentration (distillation device). Further, the above lanthanum is present in the mixed acid 100 in the form of a ruthenium compound, specifically, ammonium fluoroantimonate [(NH ₄ ) ₂ SiF ₆ ].

The mixed acid 100 is, for example, an etching waste liquid. Specifically, for example, a waste liquid obtained by etching a member containing ruthenium using an etchant containing hydrofluoric acid or ammonium hydrogen fluoride. Examples of the member containing the crucible include various glasses, crystals, and the like.

In such a mixed acid 100, hydrofluoric acid and ammonium hydrogen fluoride which are not reacted in the etching treatment remain in a considerable amount of respective components. Therefore, it can be reused as a component of the etching liquid by separately recovering these.

In this way, the unreacted etching component can be separated from the etching waste liquid, and the etching waste liquid can be reused, and the etching process can be reduced in cost. Further, since the amount of the etching waste liquid which has been disposed of is reduced, it is possible to exhibit excellent environmental protection.

The concentration of the hydrofluoric acid before the separation in the mixed acid 100 is not particularly limited, and is, for example, about 10 to 20% by weight. Further, the concentration of ammonium hydrogen fluoride before the separation in the mixed acid 100 is not particularly limited, and is, for example, about 25 to 35 wt%. Further, the concentration of the ruthenium before the separation in the mixed acid 100 is not particularly limited, and is, for example, about 0.1 to 1.0 wt%.

Here, the concentration of hydrofluoric acid, ammonium hydrogen fluoride, and hydrazine in the mixed acid 100 can be determined as follows.

(Measurement of concentration of sputum)

Characterization and quantification of metal elements contained in mixed acid 100 using an ICP luminescence analyzer (Inductive Coupled Plasma Spectrometer) (for example, manufactured by Shimadzu Corporation, product name "ICPS-7510") analysis. Thereby, since the metal atom in the mixed acid 100 is only ruthenium, the concentration A (mol/l) of ruthenium in the mixed acid 100 can be obtained by this.

(Measurement of the concentration of ammonium hydrogen fluoride)

An indophenol blue spectrophotometry is carried out using an ultraviolet-visible spectrophotometer (for example, manufactured by Shimadzu Corporation, product name "IUV-1240"), whereby ammonium hydrogen fluoride in the mixed acid 100 can be obtained. And the total concentration B (mol/l) of (NH ₄ +) which the ammonium fluoroantimonate has. As described above, since the ruthenium in the mixed acid 100 exists in the form of ammonium fluoroantimonate, the (NH ₄ +) concentration 2A which is obtained by subtracting the ammonium fluoroantimonate from the total concentration B can be obtained. The concentration C (mol/l) of ammonium hydrogen fluoride in the mixed acid 100 is obtained. That is C=B-2A.

(Measurement of the concentration of hydrofluoric acid)

The acid concentration of the mixed acid 100 is measured using a potential difference automatic titration device (for example, manufactured by Kyoto Electronics Manufacturing Co., Ltd., product name "AT-510"). Specifically, the acid concentration of the mixed acid 100 was measured by neutralization titration with a 0.1 mol/dm ³ aqueous sodium hydroxide solution. Thereby, the total acid concentration D of hydrofluoric acid, ammonium hydrogen fluoride, and ammonium fluoroantimonate in the mixed acid 100 can be determined. Since the concentration of ammonium fluoroantimonate A and the concentration B of ammonium hydrogen fluoride in the mixed acid 100 are known above, the acid concentration 4A of ammonium fluoroantimonate and the ammonium hydrogen fluoride can be subtracted from the total acid concentration D. The acid concentration B was obtained, and the hydrofluoric acid concentration E (mol/l) in the mixed acid 100 was determined. That is, E=D-4A-B.

As described above, an example of a method for measuring the concentration of hydrofluoric acid, ammonium hydrogen fluoride, and hydrazine in the mixed acid 100 will be described.

As shown in Fig. 1, the separation apparatus 1 of the present embodiment includes a distillation tank (distillation vessel) 11, a supply unit 12 for supplying the mixed acid 100 to the distillation tank 11, a heating unit 13 for heating the distillation tank 11, and a stirring distillation tank 11. The stirring mechanism 14 of the mixed acid 100 cools the steam generated by the distillation tank 11 to obtain the cooling unit 15 of the distillate 200, the recovery unit 16 that recovers the distillate 200, and the exhaust gas treatment mechanism 17.

In each of the portions constituting the separation device 1, each of the contacts with the mixed acid 100 has acid resistance. In the present embodiment, acid resistance is imparted by forming a portion in contact with the mixed acid 100 with polytetrafluoroethylene (PTFE).

In addition, the method of imparting acid resistance is not limited thereto, and may be, for example, a method of forming a portion which can be in contact with the mixed acid 100 with an acid-resistant plastic such as a vinyl chloride resin or an acrylic resin, or a metal material. A method in which a fluorine-based resin is applied to the surface of the body constitutes a portion that can be in contact with the mixed acid 100. Since the thermal conductivity of the mixed material of the metal and the acid-resistant resin is preferable, the liquid temperature can be adjusted by heating and cooling from the outside in a short time, which is suitable.

(supply unit 12)

The mixed acid 100 is accumulated in the supply unit 12. Such a supply unit 12 is provided above the distillation tank 11. A cock 181 is provided in the middle of the flow path connecting the supply unit 12 and the distillation tank 11, and the cock 181 can be operated to supply the mixed acid 100 accumulated in the supply unit 12 to the distillation tank 11, or vice versa. Stop the supply.

(distillation tank 11)

The distillation tank 11 is used to distill the tank in which the acid 100 is mixed. In the distillation tank 11, an induction line 111 for inducing the generated vapor to the cooling unit 15 is formed. Further, a thermometer 191 for measuring the temperature of the mixed acid 100 and a thermometer 192 for measuring the temperature of the vapor flowing in the induction line 111 are provided in the distillation tank 11.

(heating section 13)

The heating unit 13 has a function of heating the mixed acid 100 via the distillation tank 11 . As the heating unit 13, for example, as shown in the present embodiment, a heating jacket provided to cover the lower side portion of the distillation tank 11 may be included. The heating unit 13 can control the driving of the mixed acid 100 and the vapor to a specific temperature based on the sensing results of the thermometers 191 and 192.

Further, the heating unit 13 is not limited to the above configuration as long as the mixed acid 100 can be heated.

(mixing mechanism 14)

The separating device 1 preferably includes a stirring mechanism 14.

The stirring mechanism 14 has a function of agitating the mixed acid 100 in the distillation tank 11. By performing the distillation while stirring the mixed acid 100 by the stirring mechanism 14, the substance movement can be promoted in the mixed acid 100, and crystallization of solid (solid matter) or the like can be suppressed. In particular, it is possible to suppress crystallization or the like due to localization of concentration in the vicinity of the liquid surface or the inner wall of the container.

The stirring mechanism 14 is configured to include a stirring bar (141) disposed in the distillation tank 11, a hot stirrer (stirring device) 142 on which the distillation can 11 and the heating unit 13 are placed, and is configured by a hot agitator 142. The stirring bar 141 is rotated while stirring the mixed acid 100.

Further, instead of the agitator having the heating mechanism, a stirrer having no heating means may be used. Further, even if the stirrer is not provided, a physical method such as vibration can be applied to the wall surface of the container to stir the liquid in the distillation tank 11.

(cooling unit 15)

The cooling unit 15 has a function of cooling the vapor generated by heating the mixed acid 100 to obtain the distillate 200. As such a cooling portion 15, a commonly known cooling pipe can be used. That is, the cooling unit 15 is configured to include the inner tube 151 and the outer tube 152, and the vapor flows in the inner tube 151, and the cooling water flows between the inner tube 151 and the outer tube 152. Thereby, the vapor flowing in the inner tube 151 is cooled and liquefied by the cooling water to obtain the distillate 200.

In addition, as long as the distillate 200 is obtained, the length of the inner tube 151 or the temperature of the cooling water is not particularly limited.

(Recycling section 16)

The recovery unit 16 is connected to the cooling unit 15 and has a function of recovering the distillate 200. A cock 182 is disposed at the bottom of the recovery portion 16, and the distillate 200 accumulated in the recovery portion 16 can be discharged to the outside of the separation device 1 by operating the cock 182 (for example, as shown in FIG. 1 Recycled container 300).

(Exhaust treatment mechanism 17)

The exhaust gas treatment unit (gas cleaning unit) 17 has a function of neutralizing the exhaust gas that is not liquefied by the cooling unit 15 . The exhaust gas treatment mechanism 17 includes a container for storing water or an alkaline cleaning liquid 400, and performs exhaust gas neutralization treatment by inducing exhaust gas in the cleaning liquid 400.

The configuration of the separation device 1 will be described above.

2. Separation method of hydrofluoric acid

Next, a method of separating and recovering hydrofluoric acid from the mixed acid 100 (the separation method of the present invention) will be described.

The separation method of the present invention schematically illustrated in Fig. 2 includes a first distillation step and a second distillation step. The separation method described below is one in which the bottom residue 600 is extracted from the distillate 200 in the second distillation step after the distillate 200 is extracted from the mixed acid 100 in the first distillation step. The method may be a batch method in which the second distillation step is performed after the end of the first distillation step, and a distillation apparatus used in each of the first distillation step and the second distillation step, and the like. Any of the in-line methods in which an infusion tube is connected and processed by valve operation, pump operation, or the like.

(first distillation step)

For example, the mixed acid 100 is supplied from the supply unit 12 to the distillation pot 11, and the mixed acid 100 is heated to a specific temperature by the heating unit 13, whereby the acid 100 is distilled and distilled at atmospheric pressure. At this time, the mixed acid 100 in the distillation tank 11 may be stirred by the stirring mechanism 14. The heating temperature (specific temperature mentioned above) of the mixed acid 100 is not particularly limited, and is, for example, about 120 to 140 °C.

Thereby, water and hydrofluoric acid are mainly evaporated from the mixed acid 100, and these vapors reach the cooling unit 15 via the induction line 111, respectively. The vapor that has reached the cooling unit 15 is cooled by the cooling unit 15 to become a distillate (first liquid) 200, and is collected in the recovery unit 16. The distillate 200 recovered in the recovery unit 16 is a hydrofluoric acid (aqueous hydrofluoric acid solution) having a relatively low concentration of water and hydrofluoric acid as a main component.

Here, the hydrofluoric acid concentration of the distillate 200 is not particularly limited, and when the hydrofluoric acid concentration of the mixed acid 100 is A (wt%), it is preferably 0.75 A to 1.1 A (wt%). about.

Further, the yield (%) of hydrofluoric acid recovered as the distillate 200, that is, {(the amount of hydrofluoric acid contained in the distillate 200 / the amount of hydrofluoric acid contained in the mixed acid 100) ×100} is preferably about 55% or more. Thereby, the amount of hydrofluoric acid recovered as the distillate 200 can be made sufficient.

Further, the amount (%) of the distillate 200 to be distilled, that is, {(weight of the distillate 200 / weight of the mixed acid 100) × 100} is not particularly limited, but is preferably about 55 to 70%. Thereby, the safety of the device can be ensured, and a sufficient amount of the distillate 200 can be obtained.

Water and hydrofluoric acid can be separated from the mixed acid 100 by sufficiently performing such a first distillation step.

(Second distillation step)

After the completion of the first distillation step, the bottom residue (second liquid) 500 present in the distillation tank 11 is discharged from the distillation tank 11 and transferred to a recovery container (not shown). Further, the bottom residue 500 is supplied to other treatments as described below.

Then, in the empty distillation apparatus 1, the distillate 200 is supplied from the supply unit 12 to the distillation tank 11, and the distillate 200 is heated to a specific temperature by the heating unit 13, whereby the distillate 200 is distilled under atmospheric pressure. At this time, the distillate 200 in the distillation tank 11 may be stirred by the stirring mechanism 14. The heating temperature (the specific temperature mentioned above) of the distillate 200 is not particularly limited, and is, for example, about 100 to 120 °C.

Thereby, water and a small amount of hydrofluoric acid are evaporated from the distillate 200, and the vapor reaches the cooling unit 15 via the induction line 111. The vapor reaching the cooling unit 15 is cooled by the cooling unit 15, and the hydrogen fluoride at a relatively low concentration is recovered in the recovery unit 16.

Water more than hydrofluoric acid can be separated from the distillate 200 by sufficiently performing such a second distillation step. In other words, the distillate 200 can be concentrated, and after the second distillation step is completed, the bottom residue (third liquid) 600 remaining in the distillation tank 11 is made to have a hydrofluoric acid having a hydrofluoric acid concentration higher than that of the distillate 200 ( Hydrofluoric acid aqueous solution).

In particular, when the heating temperature of the distillate 200 in the second distillation step is set lower than the heating temperature of the mixed acid 100 in the first distillation step, when the water is removed from the distillate 200, the mixing is reduced. The amount of hydrofluoric acid removed by the removal of the distillate together with the water. Therefore, the yield of hydrofluoric acid can be increased.

Here, the hydrofluoric acid concentration of the bottom residue 600 is not particularly limited, and when the hydrofluoric acid concentration of the mixed acid 100 is A (wt%), it is preferably 2.0 A to 3.0 A (wt%). about.

Further, the yield (%) of hydrofluoric acid recovered as the bottom residue 600, that is, {(the amount of hydrofluoric acid contained in the bottom residue 600 / the amount of hydrofluoric acid contained in the mixed acid 100) ×100} is preferably about 30% or more. Thereby, the amount of hydrofluoric acid recovered as the bottom residue 600 can be made sufficient.

The bottom residue 600 (hydrogen fluoride) obtained in this manner can be used again as an etchant. When used as an etching solution, for example, it can also be mixed with a new etching liquid. Alternatively, the bottom residue 600 can be used in applications for adjusting the concentration of hydrofluoric acid in a new etching solution.

The method for separating hydrofluoric acid from the mixed acid 100 will be described above.

According to this method, it is possible to easily and efficiently separate and recover a relatively high-concentration hydrofluoric acid having a relatively high concentration from the mixed acid. Further, since a new etching liquid can be formed by mixing chemicals separated and recovered from the etching waste liquid, reuse of the etching waste liquid can be achieved, and the etching process can be reduced in cost. Moreover, since the amount of etching waste liquid which is disposed of without being reused can be reduced, excellent environmental protection can be exhibited.

3. Method for separating ammonium hydrogen fluoride

Ammonium hydrogen fluoride can be separated and recovered from the bottom residue 500 obtained in the middle of the above-described separation method of hydrofluoric acid. Hereinafter, the separation method will be described based on Fig. 2 .

The bottom residue 500 obtained in the above first distillation step is crystallized by cooling or the like to precipitate a solid containing ammonium hydrogen fluoride and ammonium fluoroantimonate. Further, depending on the amount of evaporation of water from the mixed acid 100, a solid 900 containing ammonium hydrogen fluoride and ammonium fluoroantimonate may be precipitated even if the above cooling is not carried out.

Therefore, first, the solid 900 is separated from the bottom residue 500. The separation method is not particularly limited, and for example, a usual precipitation method can be used. That is, the solid 900 can be separated from the bottom residue 500 by precipitating the solid 900 in the bottom residue 500.

Here, in the liquid (fourth liquid) 700 from which the solid 900 is separated from the bottom residue 500, hydrofluoric acid which is not completely separated in the first distillation step remains. Therefore, the liquid 700 can be returned to the supply unit 12 and treated again with the mixed acid 100 by the first distillation step. Thereby, more hydrofluoric acid can be separated and recovered from the mixed acid 100. Further, since the processing is preferable and unnecessary, the arrows in Fig. 2 are indicated by dotted lines.

Then, after the solid 900 is dried, the solid 900 is completely dissolved in a solvent such as water (about 50 to 70 ° C) to obtain a solution (fifth liquid) 801. Hereinafter, the solution 801 is cooled in two stages, and a solid having a different weight ratio of ammonium hydrogen fluoride and ammonium fluoroantimonate is precipitated in each stage by the difference in solubility.

First, the solution 801 is cooled to about 35 to 60 ° C (first crystallization step). Thereby, the solid 810 is precipitated in the solution 801. Then, after the solid 810 is removed from the solution 801 (the solution in which the solid 810 is removed from the solution 801 is referred to as "solution 802"), the solution 802 is cooled to about 5 to 20 ° C (second crystallization step). Thereby, solid 820 is precipitated in solution 802.

The dried solid 810 contains, for example, about 70 to 80% by weight of ammonium hydrogen fluoride, and contains about 20 to 30% by weight of ammonium fluoroantimonate. Further, the dried solid 820 contains about 95 to 99 wt% of ammonium hydrogen fluoride and contains about 1 to 5 wt% of ammonium fluoroantimonate.

Thus, ammonium fluoride ammonium is separated and recovered from the mixed acid 100 at a high concentration (high purity) by precipitating the solid 820.

Further, depending on the concentration of the ammonium hydrogen fluoride obtained, when the first crystallization step is sufficient, the second crystallization step may not be performed, and the obtained solid 810 may be used as a raw material of a new etching liquid.

Here, in the solution 803 in which the solid 820 is removed from the solution 802, ammonium hydrogen fluoride which is not completely separated in this step remains. Therefore, the solution 803 can be returned to the supply unit 12 and treated again with the mixed acid 100 by the first distillation step. Thereby, more ammonium hydrogen fluoride can be separated and recovered.

Although the separation method and the separation device of the present invention have been described based on the embodiments shown in the drawings, the separation method and the separation device of the present invention are not limited thereto, and any other constituents or steps may be added. Further, a combination of a plurality of distillation steps and a crystallization step has been described. However, even if only a separation method in which hydrofluoric acid is separated by a plurality of distillation steps is carried out, a regeneration technique excellent in environmental protection can be provided.

[Examples]

Hereinafter, specific embodiments of the present invention will be described.

(Example 1)

Prepare a mixed acid as an etching waste. Further, the concentration of the hydrofluoric acid before the separation of the mixed acid was 12.6% by weight, the concentration before the separation of ammonium hydrogen fluoride was 27.6 wt%, and the concentration before the separation of the ruthenium was 0.4 wt%, and the balance was approximately water. The measurement of these concentrations was carried out using the above apparatus and method (the concentrations are also the same as described below).

[First distillation step]

500 g of the mixed acid was placed in a distillation tank, and the mixed acid was heated to 120 ° C under atmospheric pressure to carry out distillation. Thereby, hydrogen fluoride acid (aqueous solution of hydrofluoric acid) as the distillate A was obtained. This step was carried out until the amount of distillation reached 60%, thereby obtaining 297 g of distillate A.

The concentration of each component in the distillate A was measured, and as a result, the concentration of hydrofluoric acid was 10.5 wt%, the concentration of ammonium hydrogen fluoride was 0.01 wt%, and the concentration of rhodium was 0.02 wt%. The yield of hydrofluoric acid relative to the mixed acid was 49.6%.

[Second distillation step]

Then, the distillate A obtained in the first distillation step was placed in a distillation tank, and the distillate A was heated to 120 ° C under atmospheric pressure to carry out distillation. Thereby, a relatively low concentration of hydrogen fluoride as distillate B is obtained. This step was carried out until the amount of distillation reached 80%, thereby obtaining 223 g of distillate B. Further, the concentration of each component in the distillate B was measured, and as a result, the concentration of hydrofluoric acid was 4.8 wt%, the concentration of ammonium hydrogen fluoride was 0 wt%, and the concentration of rhodium was 0.008 wt%.

On the other hand, 53 g of bottom residue C was obtained from the distillation tank. The concentration of each component in the bottom residue C was measured, and as a result, the concentration of hydrofluoric acid was 32.1 wt%, the concentration of ammonium hydrogen fluoride was 0.08 wt%, and the concentration of rhodium was 0.08 wt%. Further, the yield of hydrofluoric acid relative to the mixed acid was 27.0%.

Thus, the high concentration and high purity hydrofluoric acid as the bottom residue C can be recovered.

[Separation step]

Using the first distillation step, 193 g of bottom residue D was obtained from the distillation tank. In the bottom residue D, a solid (solid content) is precipitated, and the solid is separated from the bottom residue D by a precipitation method and dried. Thereby 97 g of solid E was obtained. The component of the solid E was measured, and as a result, solid ammonium E contained 85.1 wt% of ammonium hydrogen fluoride and 11.0 wt% of ammonium fluoroantimonate.

Then, 80 g of a solid (solid E before drying) precipitated from the bottom residue was mixed in 50 g of distilled water, and completely dissolved at 50 ° C to obtain 130 g of a solution F. Then, the solution F was cooled to 35 ° C, and a solid G was precipitated in the solution F. Then, the solid G was separated from the solution F by a precipitation method, and the solid G was dried. Thereby 13 g of solid G was obtained. The component of the solid G was measured, and as a result, solid ammonium G contained 77.7 wt% of ammonium hydrogen fluoride and 21.3 wt% of ammonium fluoroantimonate.

Then, 108 g of the solution F of the separated solid G was cooled to 20 ° C, and solid H was precipitated in the solution F. Then, solid H was separated from solution F by a precipitation method, and solid H was dried. Thereby 14 g of solid H was obtained. The component of the solid H was measured, and as a solid H, 96.6 wt% of ammonium hydrogen fluoride and 3.4 wt% of ammonium fluoroantimonate were contained. The yield of ammonium hydrogen fluoride relative to the mixed acid was 29.1%.

Thus, high-purity ammonium hydrogen fluoride as a solid H can be recovered.

Furthermore, the above results are shown in FIGS. 3 and 4.

(Example 2)

Prepare a mixed acid as an etching waste. Further, the mixed acid had a hydrofluoric acid concentration of 16.8 wt%, the ammonium hydrogen fluoride concentration was 31.2 wt%, the rhodium concentration was 0.11 wt%, and the balance was approximately water.

[First distillation step]

Then, 500 g of the mixed acid was placed in a distillation tank, and the mixed acid was heated to 120 ° C under atmospheric pressure to carry out distillation. Thereby, hydrogen fluoride acid (aqueous solution of hydrofluoric acid) as the distillate A' was obtained. This step was carried out until the amount of distillation reached 65%, thereby obtaining 322 g of distillate A'.

The concentration of each component in the distillate A' was measured, and as a result, the concentration of hydrofluoric acid was 18.2 wt%, the concentration of ammonium hydrogen fluoride was 0.01 wt%, and the concentration of rhodium was 0.01 wt%. The yield of hydrofluoric acid relative to the mixed acid was 69.8%.

[Second distillation step]

Then, the distillate A' obtained in the first distillation step was placed in a distillation tank, and the distillate A' was heated to 120 ° C under atmospheric pressure to carry out distillation. Thereby, a relatively low concentration of hydrogen fluoride as the distillate B' is obtained. This step was carried out until the amount of distillation reached 69%, thereby obtaining 222 g of distillate B'. Further, the concentration of each component in the distillate B' was measured, and as a result, the concentration of hydrofluoric acid was 12.4 wt%, the concentration of ammonium hydrogen fluoride was 0 wt%, and the concentration of rhodium was 0.004 wt%.

On the other hand, 80 g of bottom residue C' was obtained from the distillation tank. The concentration of each component in the bottom residue C' was measured, and as a result, the concentration of hydrofluoric acid was 34.5 wt%, the concentration of ammonium hydrogen fluoride was 0.23 wt%, and the concentration of rhodium was 0.01 wt%. Further, the yield of hydrofluoric acid relative to the mixed acid was 32.8%.

Thus, the high concentration and high purity hydrofluoric acid as the bottom residue C' can be recovered.

[Separation step]

Using the first distillation step, 171 g of bottom residue D' was obtained from the distillation tank. In the bottom residue D', a solid (solid content) is precipitated, and the solid is separated from the bottom residue D' and dried. Thereby 76 g of solid E' was obtained. The component of the solid E' was measured, and as a result, the solid E' contained 96.6 wt% of ammonium hydrogen fluoride and 3.0 wt% of ammonium fluoroantimonate.

The same operation as in Example 1 was carried out to recover high-purity ammonium hydrogen fluoride.

Furthermore, the above results are shown in Fig. 5.

1. . . Separation device

11. . . Distillation tank

12. . . Supply department

13. . . Heating department

14. . . Mixing mechanism

15. . . Cooling section

16. . . Recycling department

17. . . Exhaust treatment mechanism

100. . . Mixed acid

111. . . Induction line

141. . . Stir bar

142. . . Hot agitator

151. . . Inner tube

152. . . Outer tube

181. . . Plug

182. . . Plug

191. . . thermometer

192. . . thermometer

200. . . Distillate

300. . . Recycling container

400. . . Cleaning fluid

500. . . Bottom residue

600. . . Bottom residue

700. . . liquid

801. . . Solution

802. . . Solution

803. . . Solution

810. . . solid

820. . . solid

900. . . solid

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing a separation apparatus according to a preferred embodiment of the present invention.

Fig. 2 is a schematic view for explaining a separation method of a preferred embodiment of the present invention.

Figure 3 is a table for explaining the embodiment.

Figure 4 is a table for explaining the embodiment.

Figure 5 is a table for explaining the embodiment.

100. . . Mixed acid

200. . . Distillate

500, 600. . . Bottom residue

700. . . liquid

801, 802, 803. . . Solution

810, 820, 900. . . solid

Claims (9)

A separation method for separating the hydrofluoric acid from a mixed acid containing at least hydrofluoric acid, ammonium hydrogen fluoride, an antimony compound, and water, the separation method comprising: a first distillation step of distilling the mixed acid And recovering the first liquid containing the hydrofluoric acid and water as the distillate, recovering the second liquid containing the ammonium hydrogen fluoride and the ruthenium compound as a bottom residue; and the second distillation step, by distilling the above In the first liquid, the water is mainly separated from the first liquid, and the third liquid having a higher concentration of the hydrofluoric acid as the bottom residue than the first liquid is recovered. The separation method of claim 1, wherein the heating temperature of the first liquid in the second distillation step is lower than a set temperature of a heating temperature of the mixed acid in the first distillation step. The separation method of claim 1 or 2, wherein the solid containing the ammonium hydrogen fluoride and the ruthenium compound is crystallized from the second liquid, and the solid is separated from the second liquid by the first step. The fourth liquid is treated together with the mixed acid. The separation method according to claim 1 or 2, wherein the first distillation step is carried out while stirring the mixed acid. The separation method according to claim 1, comprising a separation step of separating the ammonium hydrogen fluoride from the solid containing the ammonium hydrogen fluoride and the ruthenium compound and crystallizing from the second liquid. The separation method of claim 5, wherein in the separating step, utilizing The above crystallization method separates the above ammonium hydrogen fluoride from the above solid. The separation method of claim 5, wherein the separating step comprises the steps of: preparing a solution in which the solid is dissolved, and cooling the solution to a specific temperature to perform a first crystallization step; and lower than the above A second crystallization step performed at a temperature of 1 crystallization temperature. The separation method of claim 1 or 2, wherein the mixed acid is an etching waste liquid which is produced by etching a material containing ruthenium. A separating apparatus comprising: a distillation tank; a supply unit that supplies a mixed acid containing at least hydrofluoric acid, ammonium hydrogen fluoride, a hydrazine compound, and water to the distillation tank; a heating unit that heats the distillation tank; and a stirring mechanism that stirs the distillation tank The mixed acid; a cooling unit that cools the vapor generated by the distillation tank to obtain a distillate of hydrofluoric acid and water; a recovery unit that recovers the distillate; and an exhaust gas treatment mechanism that cannot liquefy the cooling unit The exhaust gas is neutralized.