JPH0622659B2 - Treatment method for surface treatment waste liquid of A1 material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for treating a surface treatment waste liquid of an Al material.

Conventional technology and its problems Conventionally, a single acid such as HCl and HNO ₃ is generally used for the surface treatment of Al material, and the waste liquid generated by this treatment is obtained by dissolving Al in a single acid such as HCl and NHO ₃ . Since all of these acids are volatile acids, it is possible to separate and recover the Al salt and the free acid by simply evaporating and concentrating to distill the free acid with water. Is.

Taking the case of an HCl-based waste liquid as an example, the Al ₂ O ₃ concentration is 11
%, That is, AlCl ₃ is concentrated to 29%, so that the relative volatility of HCl becomes large and HCl in the raw waste liquid is increased.
Since almost all of the HCl is distilled off, not only is the HCl recovery rate as high as 98% or more, but also the HCl content remaining in the concentrated AlCl ₃ solution becomes only 0.5% or less. It can be used as it is as a flocculant, etc. Therefore, waste liquid can be treated without pollution.

However, recently, in order to improve the surface treatment effect, H ₂ SO ₄ or a mixed acid of H ₂ SO ₄ and HCl or HNO ₃ has been used, and treatment of the waste liquid has become very difficult. If _what, H 2 SO ₄ or this and HCl
Alternatively, in the case of the surface treatment waste liquid by the mixed acid with NHO ₃ , H
For volatile acids such as Cl and NHO ₃ , HCl and HNO ₃ can be distilled and recovered by the same evaporation and concentration as in the conventional method, but H ₂ SO ₄ which is a non-volatile acid is separated. Is very difficult.

Taking HCl-H ₂ SO ₄ system waste liquid as an example, free H ₂ SO 4
_{If the 4} concentration is about 0.1%, the treatment can be performed in the same manner as in the case of a single acid containing only HCl. However, when the free H ₂ SO ₄ concentration is 1% or more, Al ₂ O is used. _When concentrated to ₃ concentration of 9.5%, Al ₂ (SO ₄ ) ₃ is precipitated,
This not only causes clogging and scaling in various parts of the processing equipment, but when the concentrated liquid is left to cool to room temperature, the whole solidifies into a gel, so the Al ₂ O ₃ concentration is at most 7%.
Can only be concentrated up to. Therefore, since the relative volatility of HCl in the concentrated solution does not become so large as in the conventional method, the amount of HCl distilling is small and the recovery rate is at most 70-8.
The remaining free acid concentration is too high, and not only the concentration of HCl remaining in the concentrated solution becomes high, but also the concentration of H ₂ SO ₄ increases due to concentration, so that the total free acid concentration becomes too high to be used as a coagulant or the like. Due to such drawbacks, at present, the Al material treatment waste liquid with the mixed acid containing H ₂ SO ₄ is disposed of after being neutralized with an alkaline agent.

Further, as a treatment method other than the evaporative concentration, a recovery treatment method in which diffusion dialysis is performed by using an anion exchange membrane that selectively permeates free acid and hardly permeates metal ions can be considered. In this case, most of the free acid can be recovered, but if the recovery rate is raised too much, the leak amount of Al ³⁺ increases and the amount of A mixed in the recovered acid increases.
Since the concentration of l ³⁺ becomes large, the limit is usually 80%.
Therefore, about 20% of the remaining free acid remains on the dialysis waste liquid side. Moreover, the concentration of neutral salts such as Al ₂ (SO ₄ ) ₃ and AlCl ₃ remains almost unchanged from the original waste liquid, so that it is not useful. Even if this is concentrated in the waste liquid, the concentration of free acid will be remarkably high, so that it must be neutralized with an alkali and discarded.

Means for Solving the Problems As a result of intensive studies to solve the problems of the above-mentioned conventional techniques, the present inventor has found a method capable of treating a surface treatment waste liquid of an Al material containing free H ₂ SO ₄ without pollution. The development was successful and the present invention was completed.

That is, the present invention relates to H ₂ SO ₄ or H ₂ SO ₄ and HCl.
Alternatively, a waste solution of surface treatment of Al material by mixed acid with HNO ₃ containing 1% or more of free H ₂ SO ₄ as residual acid is subjected to diffusion dialysis using an anion exchange membrane to recover most of the free acid. Then, it is electrodialyzed using an anion exchange membrane and a cation exchange membrane to recover and remove almost all of the residual free acid, and the resulting deoxidized solution is concentrated by evaporation to obtain an Al ₂ O ₃ concentration of 8% or more. A characterized by recovering a neutral salt solution
The present invention relates to a method for treating the surface treatment waste liquid of L material.

According to the invention, H ₂ SO ₄ or this and HCl or HN
The surface treatment waste liquid of the Al material by the mixed acid with O ₃ was subjected to diffusion dialysis using an anion exchange membrane and then electrodialysis using an anion and cation exchange membrane to obtain 98% or more of the free acid in the raw waste liquid. It can be recovered and removed, and the recovered free acid can be reused as it is. On the other hand, on the deoxidized liquid side, a liquid mainly composed of a neutral salt from which the free acid has been removed is obtained. By evaporating and concentrating this liquid to evaporate water, HCl, HNO _3, etc., the Al ₂ O ₃ concentration can be increased. Since it can be recovered as a neutral salt solution of 8% or more, and the solution can be directly used as a coagulant or the like, the raw waste liquid can be treated without pollution.

The waste liquid to which the method of the present invention can be applied is H ₂ SO ₄ or H ₂ S.
A surface treatment waste liquid of an Al material by a mixed acid of O ₄ and HCl or HNO ₃ , which is 1% or more of free H ₂ S as a residual acid.
There is no particular limitation as long as it contains O ₄ . Specifically, for example, a waste liquid obtained by surface-treating an Al material such as an aluminum foil or an aluminum sash by a usual method such as etching or anodic oxidation can be used.

Hereinafter, the method of the present invention will be described by taking an example of a surface treatment waste liquid (referred to as a raw waste liquid) of an Al material with a mixed acid of H ₂ SO ₄ and HCl.

First, the raw waste liquid is subjected to diffusion dialysis using an anion exchange membrane. The anion exchange membrane used here is not particularly limited, but a membrane that selectively passes a free acid and hardly permeates metal ions is preferable. For example, an anion exchange membrane having a dense crosslinked condensed thin layer formed on the surface (Japanese Patent Publication No. 36-1).
5258), an anion exchange membrane in which only the surface layer portion is oxidatively decomposed (JP-B-45-30693), and an anion exchange membrane in which the surface is inactivated (JP-B-48-34999, JP-B-SHO-5).
3-1071), an anion exchange membrane in which a compound having a plurality of reactive groups on the surface or the surface layer is reacted (Japanese Patent Publication No. 54-17587), and only the surface layer is treated with a haloalkyl group by treatment with a Lewis acid. A crosslinked anion exchange membrane (Japanese Examined Patent Publication No. 56-8049) or an anion exchange membrane obtained by irradiating the surface of the exchange membrane matrix having a haloalkyl group with ionizing radiation is effective. Specifically, the product name is “Neoceptor AFN” [Tokuyama Soda Co., Ltd.
The anion exchange membrane having a quaternized pyridine ring as an ion exchange group, which is commercially available in the market, is used.

Diffusion dialysis is performed according to a conventional method. For example, by using a dialysis diffusion tank having a plurality of anion exchange membranes that are diaphragms and configured in a filter press type, the raw waste liquid and water are supplied in countercurrent through the anion exchange membranes. . The supply rate of the raw waste liquid and water is not particularly limited, but usually the raw waste liquid is about 0.6 to 1.6 / Hr · m ² while the water is about 0.6 to 1.6 / Hr · m ^2. Just supply it.

Anion exchange membranes are difficult to dialyze salts, but free acids are easily dialyzed, so SO ₄ ions, Cl ions and H ions in the raw waste liquid pass through the anion exchange membranes to the water side to recover acid solution (recovery). Acid), while the raw effluent becomes a dialysis effluent from which most of the free acid has been removed.

Next, the dialysis waste liquid obtained by the above diffusion dialysis is electrodialyzed using an anion exchange membrane and a cation exchange membrane.

The anion exchange membrane used here is not particularly limited, but one having a low H ⁺ diffusivity is preferable. For example, an anion exchange membrane (JP-A-51-103039) in which a resin component is attached to a porous membrane having specific characteristics, a weak basicity having a specific ion exchange capacity and a glass transition temperature of 70 ° C or lower. Alternatively, a strongly basic anion exchange membrane (Japanese Patent Laid-Open No. 52-
No. 52189, JP-A-52-103389), an anion exchange membrane having a long-chain alkyl group introduced (JP-A-55-78).
No. 021), and an anion exchange membrane (Japanese Patent Publication No. 54-10938) having a thin layer of opposite load formed on the surface layer are effective. Specifically, an ultra-low diffusive acid-concentrating anion exchange membrane or the like, which is commercially available under the trade name "Neoceptor ACM" [manufactured by Tokuyama Soda Co., Ltd.], is used.

The cation exchange membrane is also not particularly limited, but a cation exchange membrane that allows easy passage of monovalent cations is preferable. Examples of such a cation exchange membrane selectively permeable to monovalent ions include, for example, cation exchange membranes in which a thin cationic layer is formed on the surface layer (Japanese Patent Publication Nos. 46-23607 and 47-3081).
Issue, Japanese Examined Patent Publication No. 47-3801, Japanese Examined Patent Publication No. 47-3802
Issue, Japanese Examined Patent Publication No. 54-1272, Japanese Examined Patent Publication No. 54-17713
No.) is effective. Specifically, monovalent selective cation exchange membranes and the like, which are commercially available under the trade names “Neoceptor CMS” and “Neoceptor CSV” (manufactured by Tokuyama Soda Co., Ltd.) are used.

Electrodialysis is also performed according to a conventional method. For example, a filter press type electrodialysis tank configured such that a single or a plurality of anion exchange membranes and cation exchange membranes are alternately provided between a pair of anion and anode so that deoxidation chambers and concentration chambers are alternately formed. Is performed by supplying the dialysis waste liquid to the deoxidizing chamber and the recovered acid to the concentrating chamber and energizing. The supply rates of the dialysis waste liquid and the recovered acid are not particularly limited and can be appropriately selected, but both are usually supplied at a rate of about 1 to 10 cm / sec. The amount of direct current during energization is not particularly limited and may be appropriately selected, but is usually 3.0 to 5.0 A / dm ² .

As a result, SO ₄ ions and Cl ions in the dialysis waste liquid in the deoxidation chamber move to the concentration chamber through the anion exchange membrane, and H ions move to the concentration chamber through the cation exchange membrane. Almost all of the residual free acid in the dialysis waste liquid is usually removed in an amount of about 98% or more to obtain a deoxidized liquid mainly composed of a neutral salt of Al, while the acid concentration of the recovered acid in the concentration chamber side is increased.

The deoxidation liquid mainly composed of the neutral salt of Al can be evaporated to concentrate excess water to obtain a concentrated liquid having an Al ₂ O ₃ concentration of 8% or more and usually about 8 to 9%. Moreover, Al ₂ (SO ₄ ) ₃ does not precipitate during concentration.

Or _H 2 has been described surface treatment effluent Al material by mixed acid of SO ₄ and _HCl, H 2 SO ₄ alone and this and H
The same effect can be obtained with the completely same treatment method even in the case of the Al material surface treatment waste liquid by the mixed acid with NO ₃ .

According to the present invention, H ₂ SO ₄ or H ₂ SO ₄ and HCl or HN
The surface treatment waste liquid of the Al material by the mixed acid with O ₃ was subjected to diffusion dialysis using an anion exchange membrane and then electrodialysis using an anion and cation exchange membrane to obtain 98% or more of the free acid in the raw waste liquid. It can be recovered and removed, and the recovered free acid can be reused as it is. On the other hand, on the deoxidized side, a liquid mainly composed of a neutral salt from which free acid has been removed is obtained. By evaporating and concentrating this liquid to evaporate the water content, the Al ₂ O ₃ concentration is 8% or more neutral. Since it can be recovered as a salt solution and the solution can be used as it is as a coagulant, the raw waste liquid can be treated without pollution.

Examples The following examples are given to further clarify the present invention.

Example 1 A treatment waste liquid with sulfuric acid or a mixed acid of sulfuric acid or a mixture thereof with hydrochloric acid or nitric acid shown in Table 1 discharged after etching or anodizing an aluminum material was first subjected to diffusion dialysis. Diffusion dialysis is an anion exchange membrane having a quaternized pyridine ring as an ion exchange group [trade name: Neoceptor AFN, Tokuyama Soda Co., Ltd.
Manufactured by using a filter press type diffusion dialysate having 1700 sheets as a diaphragm [effective area 50 dm ² ] and supplying the waste liquid and water in a countercurrent, the waste liquid supply rate is 1000 kg / Hr, and the water supply rate is 800- The dialysis waste liquid and the recovered acid were obtained by setting the pressure to 870 kg / Hr.

Next, the dialysis waste liquid obtained by diffusion dialysis was electrodialyzed. Electrodialysis uses a monovalent selective cation exchange membrane between a pair of anion and anode [trade name: Neoceptor CMS, manufactured by Tokuyama Soda Co., Ltd.]
And anion exchange membranes for ultra-low diffusivity for acid concentration (trade name: Neocepta ACM, manufactured by Tokuyama Soda Co., Ltd.) are alternately used for a total of 500 pieces (the effective area of each exchange membrane is 25 dm ² and the total area is 1).
25m ² ), using a filter press type electrodialysis tank in which deoxidizing chambers and concentrating chambers are alternately formed, dialysis waste liquid is supplied to the deoxidizing chambers and recovered acid is supplied to the concentrating chambers at a speed of 6 cm / sec. Then, a current density of 3 to 5 A / dm ² was applied to obtain a deoxidized liquid and a recovered acid.

The obtained deoxidized solution was concentrated by evaporation to produce a concentrate having an Al ₂ O ₃ concentration of 8%, but Al ₂ (SO ₄ ) ₃ did not precipitate. The obtained concentrated liquid contained sulfuric acid at a concentration of 20 to 25% in total, but almost all of it was present as a salt,
Since free sulfuric acid was present in a very small amount, it could be used as a flocculant as it was.

Table 1 shows waste water, dialysis waste liquid by diffusion dialysis and recovered acid,
The total acid concentration (% by weight) and Al ₂ O ₃ concentration (% by weight) of the deoxidized liquid and the recovered acid by electrodialysis and the concentrated liquid are shown.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasio Morimoto 3-3 Suehiro-cho, Kita-ku, Osaka City, Osaka Prefecture Daido Chemical Engineering Co., Ltd. (72) Inventor Yoshiaki Noma 7-3, Hanawatake Town, Tokuyama City, Yamaguchi Prefecture (72) Inventor, Ryuji Takeshita 7-3, Hanawatake Town, Tokuyama City, Yamaguchi Prefecture

Claims (1)

[Claims] 1. H ₂ SO ₄ or H ₂ SO ₄ and HCl or H
Alkali surface treatment waste solution with mixed acid with NO ₃ and containing 1% or more of free H ₂ SO ₄ as residual acid is subjected to diffusion dialysis using an anion exchange membrane to recover and remove most of free acid. Then, electrodialysis is performed using an anion exchange membrane and a cation exchange membrane to recover and remove almost all of the residual free acid, and the resulting deoxidized solution is evaporated and concentrated to obtain an Al ₂ O ₃ concentration of 8%.
A method for treating a surface treatment waste liquid of an Al material, which comprises recovering the above neutral salt solution.