KR100613257B1 - Recycling method of waste acid etching solution - Google Patents

Abstract

The present invention relates to a method for regenerating waste sulfuric acid etchant and waste hydrochloric acid etchant, and more particularly, (a) recovering hydrochloric acid by vacuum evaporation of a mixed solution of waste sulfuric acid etchant containing aluminum and waste hydrochloric acid etchant containing aluminum. ; (b) adding aluminum to the spent sulfuric acid etchant containing aluminum after vacuum evaporation; And (c) diffusing dialysis of the waste sulfuric acid etching solution to which the aluminum is added to separate the sulfuric acid and aluminum sulfate water treatment coagulant.

The waste sulfuric acid etchant and waste hydrochloric acid etching solution recycling method of the present invention is environmentally friendly and can recycle aluminum sulfate, sulfuric acid and hydrochloric acid with high purity from the waste sulfuric acid etching solution and the waste hydrochloric acid etching solution.

Waste sulfuric acid etching solution, waste hydrochloric acid etching solution, vacuum evaporation, diffusion dialysis, ion exchange membrane, water treatment coagulant

Description

Recycling method of waste acid etching liquid {RECYCLING METHOD OF WASTE ACID ETCHING SOLUTION}

1 is a view showing a method of separating a waste sulfuric acid etching solution added with aluminum by diffusing dialysis into an aluminum sulfate water treatment coagulant and sulfuric acid.

2 is a view showing a regeneration method of the spent acid etching liquid of the present invention.

[Industrial use]

The present invention relates to a method for regenerating waste sulfuric acid etching solution and waste hydrochloric acid etching solution, and more particularly, to recycling waste acid etching liquid which is environmentally friendly and can recycle aluminum sulfate water treatment coagulant, sulfuric acid and hydrochloric acid with high purity from waste sulfuric acid etching liquid and waste hydrochloric acid etching solution. It is about a method.

[Prior art]

Sulfuric acid and hydrochloric acid have been widely used as industrial metal etching solutions. However, since the sulfuric acid and hydrochloric acid are strong acid having a very low pH, the waste sulfuric acid etching solution and the hydrochloric acid etching solution remaining after etching are very harmful to the environment.

In order to remove the hazardous waste sulfuric acid etchant, neutralizing with caustic soda, calcium carbonate or calcium hydroxide and the like has been generally used. However, a large amount of new secondary wastes such as arsenic, copper, iron, zinc, lead, and cadmium are generated in the waste sulfuric acid etching solution removal process, among which arsenic and lead are very harmful to humans as well as to all living organisms in nature. .

Instead of neutralizing and removing the waste sulfuric acid etching solution, a method of regenerating the waste sulfuric acid etching solution with sulfuric acid has been proposed. U.S. Patent No. 4,547,353 describes a method of completely evaporating a waste sulfuric acid etch solution, pyrolysing it into sulfurous acid gas, replacing it with a catalyst, absorbing it in water, and regenerating it with high purity sulfuric acid. However, the regeneration method of sulfuric acid requires a large amount of energy to decompose sulfuric acid, high temperature corrosion resistance facilities due to the metal corrosion of sulfuric acid, and a large-scale device is required. Therefore, there was a problem in that sulfuric acid can not be efficiently recovered from the waste sulfuric acid etching solution during the recovery of the waste sulfuric acid etching solution.

Table 1 below shows the types and contents of various impurities in the waste sulfuric acid etching solution generated after the etching process of aluminum foil.

 division H ₂ SO ₄ (g / ℓ)  HCl (g / ℓ)  Al (g / ℓ)  Na (ppm)  Fe (ppm)  Ca (ppm)  Mg (ppm)  Mn (ppm) Waste sulfuric acid etching solution  380-395  12-34  9-11  0.2-1.0  3-10  2-11  1-6  2-7

As shown in Table 1, since the waste sulfuric acid etching solution contains a large amount of aluminum components, there is a problem in that the purity of sulfuric acid to be recovered by removing impurity components such as aluminum must be increased in order to reuse the waste sulfuric acid etching solution as an etching solution.

In addition, Table 2 below shows the contents of the commonly used aluminum sulfate water treatment coagulant.

  division Al ₂ O ₃ (Al concentration) (%) Effective pH Neutralization of NaOH (g / kg) Metal hydroxide generation amount (g / kg)  Solubility (g / 100ml)  Proper area  Area of use Aluminum Sulphate Water Treatment Flocculant  7-8 (4-5)   5-7.5   3.5-8.5   190   122   65.3

In Table 2, the amount of NaOH used for neutralization (g / kg) is the amount of NaOH used to neutralize 1 kg of aluminum sulfate water treatment coagulant, and the amount of metal hydroxide generated (g / kg) is the amount of metal hydroxide sludge generated in 1 kg of aluminum sulfate water treatment coagulant. Solubility (g / 100 mL) refers to the amount of aluminum sulfate water treatment coagulant dissolved in 100 mL of water.

As shown in Table 2, when the aluminum sulfate water treatment coagulant is used, the optimum pH range is 3.5-8.5, which is almost neutral. However, the amount of sulfuric acid contained in the waste sulfuric acid etching solution is too high, so the waste sulfuric acid etching solution is used as the aluminum sulfate water treatment coagulant. There is a problem in that the waste sulfuric acid etching solution must be neutralized with a large amount of neutralizing agent.

In addition, the aluminum concentration in the general waste sulfuric acid etching solution is 9-11 g / l, it can be seen that the concentration is very low compared to 30-50 g / l, which is a preferable aluminum sulfate water treatment coagulant. Therefore, there is a problem that the waste sulfuric acid etching solution is not suitable for use as the aluminum sulfate water treatment coagulant.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for regenerating waste acid etching liquid which is environmentally friendly and can regenerate aluminum sulfate water treatment coagulant, sulfuric acid and hydrochloric acid with high purity from waste sulfuric acid etching solution and waste hydrochloric acid etching solution. It is for.

In order to achieve the above object, the present invention comprises the steps of (a) recovering hydrochloric acid by vacuum evaporation of a mixed solution of waste sulfuric acid etching solution containing aluminum and waste hydrochloric acid etching solution containing aluminum; (b) adding aluminum to the spent sulfuric acid etchant containing aluminum after vacuum evaporation; And (c) diffusing dialysis of the waste sulfuric acid etching solution to which the aluminum is added, and separating the sulfuric acid etching solution into a sulfuric acid and aluminum sulfate water treatment coagulant.

Hereinafter, the present invention will be described in more detail.

The regeneration method of the sulfated etching solution of the present invention

(a) recovering hydrochloric acid by vacuum evaporating a mixed solution of waste sulfuric acid etching solution containing aluminum and waste hydrochloric acid etching solution containing aluminum;

(b) adding aluminum to the spent sulfuric acid etching solution containing aluminum after the vacuum evaporation; And

(c) separating the aluminum sulfate-added waste sulfuric acid etching solution into sulfuric acid and aluminum sulfate water treatment coagulant.

It includes.

In the present invention, the sulfuric acid and aluminum ions contained in the waste sulfuric acid etching solution are separated into a waste metal solution containing sulfuric acid solution and aluminum by using diffusion dialysis, and the sulfuric acid solution is reused as an etching solution, and the waste metal solution containing aluminum ions. The reuse of silver as an aluminum sulfate water treatment coagulant is at the heart of the present invention. In addition, it is the core of the present invention that hydrochloric acid recovered by vacuum evaporation of waste hydrochloric acid etching solution can be usefully reused as an etching liquid.

In order to regenerate the spent sulfuric acid etchant and the spent hydrochloric acid etchant, (a) a mixed solution of the spent sulfuric acid etchant containing aluminum and the spent hydrochloric acid etchant containing aluminum is vacuum-evaporated to recover hydrochloric acid.

Sulfuric acid and hydrochloric acid are widely used as etching solutions. However, since sulfuric acid and hydrochloric acid are strong acids, metal components such as aluminum may be dissolved during the etching process. Therefore, the waste etching solution remaining after the etching process contains metal components such as aluminum.

At this time, when the mixed solution of the waste sulfuric acid etching liquid containing aluminum and the waste hydrochloric acid etching liquid containing aluminum is heated in vacuo, hydrochloric acid evaporates and it collect | recovers again to aqueous hydrochloric acid solution. This is because hydrochloric acid is volatile in comparison with sulfuric acid is nonvolatile, so that only hydrochloric acid is evaporated when the mixture of sulfuric acid and hydrochloric acid is heated. In addition, the aluminum contained in the mixed solution of the waste sulfuric acid etching liquid containing aluminum and the waste hydrochloric acid etching liquid containing aluminum is, of course, a metal and thus remains in the mixed liquid without evaporation.

Therefore, the mixed solution in which the hydrochloric acid is evaporated becomes a waste sulfuric acid etching solution containing a high concentration of aluminum.

After vacuum evaporation of the mixed solution of the spent sulfuric acid etchant and the spent hydrochloric acid etchant, (b) aluminum is added to the spent sulfuric acid etchant containing aluminum after the vacuum evaporation. That is, the aluminum sulfate is further added to the waste sulfuric acid etching solution containing the residual aluminum to regenerate the aluminum sulfate water treatment coagulant containing aluminum in the concentration desired as the water treatment coagulant.

The addition amount of the aluminum is preferably added so that the concentration of the final produced aluminum sulfate water treatment coagulant is 30-50 g / l. In addition, the concentration of aluminum in the spent sulfuric acid etching solution is increased to the aluminum sulfate concentration required for use as the aluminum sulfate water treatment coagulant, and the residual solids are filtered and diffused dialysis.

In general, the concentration of aluminum in the waste etching solution is only about 9-11 gℓ, and the sulfuric acid is separated and removed after diffusion dialysis, and thus, there is a problem in that the dissolution rate of the aluminum waste chip is slowed because the content of the sulfuric acid, a strong acid capable of dissolving aluminum, is small. . Therefore, it is preferable to increase the concentration of aluminum in the waste sulfuric acid etching solution by adding aluminum to the waste etching solution in advance before diffusion dialysis so that the concentration of aluminum is 30-50 g / l, which is the concentration usable as the aluminum sulfate water treatment coagulant.

At this time, it is preferable to use aluminum waste chips as waste resources in terms of environment friendliness and economics. Aluminum waste chips are preferably used after completely degreasing with alkaline degreasing liquid to remove impurities.

After the aluminum is added to the residual sulphate etching solution, (c) the waste sulfuric acid etch solution to which the aluminum is added is subjected to diffusion dialysis to separate the sulfuric acid and the aluminum sulfate water treatment coagulant.

1 is a view showing a method of separating a waste sulfuric acid etching solution added with aluminum by diffusing dialysis into an aluminum sulfate water treatment coagulant and sulfuric acid. In FIG. 1, the left side shows the waste metal liquid region and the right side shows the recovered sulfuric acid region based on the central ion exchange membrane.

As shown in FIG. 1, when one side flows water at the boundary of the central ion exchange membrane and the other side flows waste etchant in the opposite direction, the diffusion force is different due to the difference in concentration of the electrolyte at the interface of the ion exchange membrane. It moves in the direction of flowing water through the membrane and is discharged into the aqueous sulfuric acid solution, and residual waste etching solution containing no sulfuric acid is discharged into the metal waste liquid without passing through the ion exchange membrane. As described above, a method of dialysis of a substance through diffusion due to concentration difference is called diffusion dialysis.

The ion exchange membrane does not pass aluminum ions, only sulfuric acid passes. However, as the diffusion dialysis reaction proceeds, when the sulfuric acid concentrations on the left and right sides of the ion exchange membrane become almost the same, diffusion due to the difference in concentration does not occur from that time point. In FIG. 1, the water is introduced at the point where sulfuric acid concentration is 0 and the concentration of sulfuric acid at the point of exiting as recovered sulfuric acid is almost the same as the residual waste sulfuric acid etching solution.

On the contrary, the point where the waste metal liquid containing aluminum exits is pure water. Therefore, when the left and right sides of the ion exchange membrane reach an equilibrium concentration, the sulfuric acid concentration in the metal waste liquid containing aluminum is almost 0 and only aluminum ions are included. Waste fluid is discharged.

At this time, in order to increase the efficiency of diffusion dialysis and to ensure the stability of the equipment, and to use the recovered sulfuric acid aqueous solution and the aluminum-containing waste metal liquid as the etching solution and the aluminum sulfate water treatment coagulant, respectively, the flow rate of the recovered sulfuric acid region is the flow rate of the aluminum waste liquid region. It is desirable to be greater than or equal to.

Therefore, when the flow rate of the recovered sulfuric acid region in the diffusion dialysis machine is lower than the flow rate of the waste metal liquid region, a large amount of sulfuric acid is contained in the waste metal liquid, which is not suitable for use as an aluminum sulfate water treatment coagulant. This is because in order to use the waste metal liquid as the aluminum sulfate water-coagulant, the pH of the aluminum sulfate water-coagulant should be almost neutral.

It is preferable to control the flow rates of the recovered sulfuric acid region and the waste metal liquid region to 600-1200 ml / m ² hr based on the ion exchange membrane. If the flow rate exceeds 1200 ml / m ² hr, there is a problem that the ion exchange membrane slit occurs and the diffusion dialysis machine cannot be operated stably.

Controlling the flow rates of the recovered sulfuric acid region and the waste metal liquid region in excess of 1200 ml / m ² hr can prevent ion exchange membrane slit, but it is not preferable because there is a problem that the concentration of sulfuric acid to be recovered is lowered.

In addition, when the flow rate of the recovered sulfuric acid region and the flow rate of the waste metal liquid region are less than 600 ml / m ² hr, an ion exchange membrane contact phenomenon occurs, which makes it difficult to operate the diffusion dialysis machine.

After confirming the concentration of the recovered sulfuric acid obtained by the diffusion dialysis, if the sulfuric acid concentration in the recovered sulfuric acid is a high concentration of sulfuric acid which is inappropriate for use as an etching solution, water is added to lower the concentration. In addition, if the sulfuric acid concentration in the recovered sulfuric acid is a low concentration of sulfuric acid which is inappropriate for use as an etching solution, further sulfuric acid is added to increase the concentration to a high concentration of sulfuric acid solution suitable for use as an etching solution.

Also, after confirming the concentration of the waste metal liquid, the aluminum concentration in the waste metal liquid is adjusted to 35-45 g / L, and the aluminum-containing waste metal liquid is reused as an aluminum sulfate water treatment coagulant.

As described above, the waste sulfuric acid etchant and waste hydrochloric acid etching solution recycling method of the present invention is environmentally friendly, and can be recycled aluminum sulfate water treatment coagulant, sulfuric acid and hydrochloric acid from waste sulfuric acid etching solution and waste hydrochloric acid etching solution with high purity.

Hereinafter, preferred examples and comparative examples of the present invention are described. The following examples and comparative examples are intended to express the present invention more clearly, and the content of the present invention is not limited to the following examples.

[Example 1-9 and Comparative Example 1-11]

The waste sulfuric acid etching solution was heated in vacuo to separate and recover hydrochloric acid, thereby preparing a high concentration of sulfuric acid etching solution of 400 g / L. Then, a thin spiral aluminum waste chip having a thickness of 0.1 mm produced in an aluminum lathe processing process was finely chopped, soaked in ethyl alcohol, degreased by ultrasonic wave for 10 minutes, and then dissolved in the residual waste sulfuric acid etching solution.

A residual solid was then filtered from the aluminum spent sulfuric acid etchant using an experimental cartridge filter.

As a diffusion dialysis machine, the model name TDS-2 of Tokuyama Soda Co., Ltd., Japan, was used. In addition, the waste sulfuric acid etch solution was diffused dialysis with varying flow rates in the recovered sulfuric acid region and the waste metal liquid region using Neocepta AFX as an ion exchange membrane, and the results are shown in Table 3 below.

  division Flow rate inside diffusion dialyzer (ml / ㎡hr)  Concentration of regenerated sulfuric acid and waste metal liquid (g / ㎗)   Test result Recovery Sulfuric Acid Zone Waste Metal Liquid Area Recovered sulfuric acid Waste Metal Liquid aluminum Sulfuric acid aluminum Sulfuric acid Example 1 600 600 2.9 353 39.1 380     Good Example 2 800 600 2.5 329 39. 27 Example 3 800 800 2.5 348 39.5 45 Example 4 1000 600 1.9 302 40.3 21 Example 5 1000 800 2.1 330 39.6 36 Example 6 1000 1000 2.8 331 39.3 54 Example 7 1200 600 1.4 300 38.5 10 Example 8 1200 800 1.8 314 37.7 24 Example 9 1200 1000 2.2 298 38.8 46 Comparative Example 1 400 600 - - - - Ion Exchange Membrane Contact and Difficult Operation  Comparative Example 2  400  600  -  -  -  - Comparative Example 3 600 800 2.3 371 39.9 67 Large amount of neutralizer required due to excessive amount of sulfuric acid in waste metal liquid  Comparative Example 4  600  1000  1.9  379  40.1  86 Comparative Example 5 600 1200 1.7 385 40.2 105 Comparative Example 6 600 1400 - - - - Ion Exchange Membrane Slitting and Dialysis Operation  Comparative Example 7  1400  600  -  -  -  - Comparative Example 8 1400 800 1.7 247 38.2 16  Low recovery sulfuric acid concentration Comparative Example 9 1400 1000 1.9 234 38.7 38 Comparative Example 10  1600  1000  1.2  232  37.9  23 Comparative Example 11  1800  1000  -  -  -  - Ion exchange membrane slit

As shown in Table 3, the flow rate of the recovered sulfuric acid zone is equal to or greater than that of the metal waste zone, and the flow rates of the recovered sulfuric acid zone and the metal waste zone are both 600-1200 (ml / m 2 hr). In the case of Example 1-9, the concentration of the regenerated sulfuric acid and the waste metal liquid may be used as the etching liquid and the aluminum sulfate water treatment coagulant, corresponding to the preferred concentration ranges as the etching solution and the aluminum sulfate water treatment coagulant.

The regeneration method of the waste acid etching solution of the present invention is environmentally friendly and can regenerate the aluminum sulfate water treatment coagulant, sulfuric acid and hydrochloric acid from the waste sulfuric acid etching solution and the waste hydrochloric acid etching solution with high purity.

Claims (4)

(a) recovering hydrochloric acid by vacuum evaporation of the mixed waste acid etching solution of the spent sulfuric acid etching solution containing aluminum and the waste hydrochloric acid etching solution containing aluminum; (b) adding waste aluminum chips to the residual waste sulfuric acid etching solution containing aluminum after the vacuum evaporation; And (c) the residual waste sulfuric acid etching solution to which the waste aluminum chip is added Separating the diaphragm and the aluminum sulfate water treatment coagulant by diffusion dialysis under the condition that the flow rate of the recovered sulfuric acid region is equal to or greater than that of the metal waste region, and the flow rates of the recovered sulfuric acid region and the metal waste region are both 600-1200 ml / m 2 hr. Waste acid etching liquid regeneration method comprising a. delete delete The method of claim 1, The amount of waste aluminum chips added to the waste sulfuric acid etching solution is 30 ~ 50 g / l waste acid etching solution recycling method.

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