JPH028961B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for recovering hydrochloric acid from a hydrochloric acid solution containing copper ions and other metal ions, such as a waste hydrochloric acid solution after metal pickling, by a specific two-stage process. Pickling has traditionally been carried out as a pretreatment for surface finishing of various metals such as mild steel and stainless steel. Hydrochloric acid is generally used as the pickling solution, and the hydrochloric acid contains a large amount of metal ions due to metal cleaning. Once the effectiveness of hydrochloric acid has decreased, it is disposed of as a waste acid solution through neutralization. However, because the waste acid solution to be disposed of still contains a high concentration of hydrochloric acid, or because the amount of solution typically handled in the pickling process is large, it is necessary to dispose of it through neutralization treatment, etc. This is not economical as it requires a large amount of neutralizing agent and sludge treatment equipment, and is also a great loss in terms of resource conservation. Therefore, recently, it has been considered to remove the metal ions contained in the waste acid solution and recover the hydrochloric acid, and then circulate the hydrochloric acid again to the pickling process to supply only the missing amount of acid. For this purpose, it is necessary to efficiently remove metal ions from the waste acid solution. It is known that it is theoretically possible to remove metal ions from a waste acid solution by using an ion exchange resin method or an electrolytic deposition method. However, if hydrochloric acid is directly recovered from a solution with a very high concentration of metal ions, such as a waste acid solution after pickling, using the above method, a large amount of ion exchange resin or a large amount of electricity is required. For this reason, it is completely impractical. On the other hand, the method of recovering hydrochloric acid from waste acid solution by diffusion dialysis is extremely practical. According to this method, it is relatively easy to remove iron, chromium, nickel, etc. from the waste acid solution, and even if trace amounts of these metal ions are mixed into the recovered hydrochloric acid, there will be no problem when cleaning the metal. However, since copper ions exist as complex ions in the waste acid solution and exhibit the same behavior as hydrochloric acid, a large amount leaks into the recovered hydrochloric acid by diffusion dialysis. When hydrochloric acid mixed with such copper ions is circulated and used again as a pickling solution to pickle steel materials, the copper ions adhere to the surface of the steel, giving it a reddish tinge and significantly reducing the effectiveness of pickling. This leads to the negative effect of lowering the quality of the product. The present inventors have conducted intensive research on a method for recovering hydrochloric acid from a hydrochloric acid solution containing copper ions and other metal ions, and have found that by combining two known methods and processing under specific conditions, Discovered that highly pure hydrochloric acid could be efficiently recovered,
The present invention has now been provided. That is, in the present invention, the concentration of other metal ions in the diffusion solution is reduced by diffusion dialysis using an anion exchange membrane on a hydrochloric acid solution containing copper ions and other metal ions at least 10 times the amount of copper ions. This method for recovering hydrochloric acid is characterized by reducing the ion concentration to 10 times or less, and then substantially removing copper ions using an anion exchange resin or electrolytic deposition. The method of the present invention generally uses a waste hydrochloric acid solution after pickling metals with hydrochloric acid, and various eluted metal ions such as Ni, Ni,
Contains Cr, Mo, etc., especially copper ions and
Applied to hydrochloric acid solutions containing 10 times more other metal ions. Among these, it is particularly applied to hydrochloric acid solutions containing copper ions and iron ions. In the first stage treatment of the present invention, from a waste hydrochloric acid solution containing copper ions and other metal ions,
First, diffusion dialysis is performed to recover the hydrochloric acid solution from which other metal ions have been removed. The diffusion dialysis method is
An anion exchange membrane is used as a diaphragm, and water is brought into contact with an aqueous hydrochloric acid solution containing metal ions. Note that water to which a small amount of acid or alkali is added is also used for recovering hydrochloric acid. In addition, water becomes an aqueous solution of hydrochloric acid due to the diffusion of hydrochloric acid in the diffusion chamber, and in the present invention, these solutions are referred to as a diffusion liquid. As the anion exchange membrane used in the present invention, any known anion exchange membrane can be used without particular limitation. Further, any diffusion dialysis device having a known structure may be used without any restriction, but a filter press type is usually preferably used. What is particularly important in the present invention is to control the concentration of other metal ions in the diffusion liquid obtained by the first stage diffusion dialysis method. That is,
The concentration of other metal ions in the hydrochloric acid solution recovered by diffusion dialysis should be 10 times or less, preferably 5 times or less, relative to the copper ion concentration. If the concentration of the other metal ions is 10 times or more that of copper ions, it becomes difficult to remove copper ions in the next second stage treatment. For example, when using an anion exchange resin method as the second stage treatment, if the iron ion concentration increases with respect to the same concentration of copper ions, the adsorption ratio of iron ions to the anion exchange resin will increase.
The adsorption amount of copper ions decreases, and this becomes noticeable when the concentration of iron ions is more than 10 times that of copper ions. In addition, when electrolytic deposition is used as the second stage treatment, the iron concentration in the pickling waste liquid generally varies between divalent and trivalent.
Valid iron ions are mixed, and as the iron ion concentration increases for the same copper ion concentration, the power efficiency and current efficiency decrease. The concentration of metal ions and copper ions in the diffusion solution by diffusion dialysis treatment can be adjusted by adjusting the supply rate of a hydrochloric acid solution containing copper ions and metal ions to the diffusion dialysis apparatus, or by supplying water. Known methods such as speed adjustment may be used. The anion exchange resin used in the present invention is not particularly limited as long as it is basic, but preferably strongly basic ion exchange resins, such as Dowex 2×8 (manufactured by Dow Chemical Co., USA), Diaion SA11A, SA10A (manufactured by Mitsubishi Chemical Industries),
Duolite A-42, A-40 (manufactured by Diamond Siam Rock Company, USA), IRA-410, 900, 400 (ROHM
and Haas Inc.) are preferably used. The amount of strongly basic anion exchange resin used in the present invention depends not only on the amount of metal ions, but also on the properties of the resin, such as resin quality, type of functional group, morphology, degree of crosslinking, particle size, and the amount of metal ions. Generally, an amount of resin is used that has a total exchange capacity of 1 to 20 equivalents of the metal ions to be adsorbed, although this will vary depending on the concentration, contact method, etc. Further, the size of the anion exchange resin is preferably 20 to 50 mesh, which is generally used industrially, but the smaller the particle size, the better the removal effect. Batch and column methods are used as the contact method, but generally the column method can remove metal ions more effectively. Furthermore, the electrolytic deposition method used in the present invention is a method in which a current is passed through an ionic conductor such as an ordinary electrolyte solution or a molten electrolyte to cause a chemical change, and metal is deposited on the cathode surface. Those having the following structure can be used without particular restriction.
As for the electrode, any of the monopolar type, bipolar type, or fluidized bed electrode can be applied, but the anode has good electrical conductivity, is not attacked by the hydrochloric acid solution used as the electrolyte, has low oxygen overvoltage, and is durable. Magnetite, lead dioxide, alloy coated platinum, etc. are preferably used. In addition, since the cathode does not corrode,
Almost any metal material can be used, such as aluminum, iron, copper, etc. EXAMPLES Hereinafter, Examples will be shown to further specifically explain the present invention, but the present invention is not limited to these Examples. Incidentally, the concentration of copper ions or other metal ions in the present invention was measured by atomic absorption spectrometry. Example 1 Hydrochloric acid 140g/, iron ion 35g/, copper ion 1.0
The hydrochloric acid pickling waste solution containing g/
Diffusion dialysis was performed using The diffusion dialysis tank was equipped with 20 anion exchange membranes (trade name: NeoSepta AFN, manufactured by Tokuyama Soda Co., Ltd.) with an effective membrane area of 2 dm ² .
Water at 20°C was supplied to the diffusion chamber from the upper part of the diffusion dialysis tank at a rate of 360 ml/Hr, and the pickling waste liquid was supplied from the lower part of the diffusion dialysis tank. As a result, a diffusion solution containing 144 g of hydrochloric acid, 5.1 g of iron ions, and 0.8 g of copper ions was recovered from the bottom of the dialysis tank. Next, when this diffused liquid was passed through a glass tube with an inner diameter of 20 mm filled with 40 ml of strong basic anion exchange resin Amberlite IRA-410 (manufactured by Rohm and Haas) at a flow rate of 30 ml/Hr, up to 400 ml of the effluent hydrochloric acid
An aqueous solution with an iron ion concentration of 4.5 g/or less and a copper ion concentration of 0.1 g/or less was obtained. Example 2 200ml of the diffusion liquid obtained in Example 1 was poured into a cup.
It was placed in an acrylic resin container measuring 12 cm by 7 cm in width, using a platinized titanium plate for the anode and an iron plate for the cathode.
Use a potentiostat to set the potential of the cathode to -
The voltage was set from 0.3V to -0.5V, and the power was turned on for 6 hours. As a result, 0.17 g of copper was electrodeposited, and the concentration of the solution was 110 g of hydrochloric acid, 5 g of iron ions, and 0.1 g of copper ions.
It became. Comparative example 1 Hydrochloric acid 128g/, iron ion 140g/, copper ion
Diffusion dialysis treatment was performed on the hydrochloric acid pickling waste solution containing 1.0 g/in the same conditions as in Example 1, and a diffusion solution containing 155 g/in hydrochloric acid, 16.8 g/in iron ions, and 0.84 g/in copper ions was recovered. This diffusion liquid was then passed through an anion exchange resin under the same conditions as in Example 1. As a result, the effluent
Up to 100ml, the copper ion concentration was less than 0.1g/, but when the effluent was 200ml, the copper ion concentration was 0.6.
It became g/. Comparative Example 2 A diffusion liquid collected under the same conditions as in Comparative Example 1 was energized for 10 hours under the same conditions as in Example 2. As a result, 0.1 g of copper was electrodeposited, and the concentration of the solution was 110 g of hydrochloric acid/
, iron ion 5g/, copper ion 0.9g/. Example 3 A waste acid solution containing 140 g of hydrochloric acid, 1.0 g of copper ions, and a concentration of 140 g of iron ions was prepared using the same diffusion dialysis tank as in Example 1, and by changing the supply rates of water and waste acid. A diffusion recovery solution having the iron ion/copper ion concentration shown in Table 1 was obtained. Next, each of these recovered liquids was passed through the same resin column as in Example 2 at a flow rate of 30 ml/Hr. The results are shown in Table 1.

[Table] Example 4 Diffusion dialysis was performed on four types of waste hydrochloric acid with different iron ion concentrations under the same conditions as in Example 1.
Diffusion liquids having iron ion concentrations, copper ion concentrations, and hydrochloric acid concentrations of 120 g/1 as shown in Nos. 1 to 4 of the table were collected. Next, 200 ml of the above recovered liquid was subjected to energization treatment for 6 hours under the same conditions as in Example 2.
A hydrochloric acid solution containing copper ion concentrations shown in Table 2 was obtained. In Table 2, No. 3 to No. 4 correspond to Examples,
No. 1 to No. 2 correspond to comparative examples.

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Claims (1)

[Claims] 1. A hydrochloric acid solution containing copper ions and other metal ions at least 10 times the amount of copper ions is subjected to diffusion dialysis treatment using an anion exchange membrane to reduce the concentration of other metal ions in the diffusion solution. 10 for copper ion concentration
1. A method for recovering hydrochloric acid, which comprises reducing the amount of hydrochloric acid to less than 100%, and then substantially removing copper ions using an anion exchange resin or electrolytic deposition. 2. The method for recovering hydrochloric acid according to claim 1, wherein the other metal ion is iron. 3. The method for recovering hydrochloric acid according to claim 1, which processes waste hydrochloric acid after pickling metals.