KR100440469B1 - Recycling method of waste sulfuric acid etching solution, waste chloric acid etching solution and waste nitric acid etching solution - Google Patents

Abstract

The present invention relates to a method for regenerating waste sulfuric acid etching liquid, waste hydrochloric acid etching liquid and waste nitric acid etching liquid, and more particularly, (a) hydrochloric acid by vacuum evaporation of a mixed solution of waste sulfuric acid etching liquid containing aluminum and waste acid hydrochloric acid etching liquid containing aluminum. Recovering; (b) further adding aluminum to the spent sulfuric acid etching solution containing aluminum after vacuum evaporation; (c) adding a waste nitric acid etchant to the waste sulfuric acid etchant added with aluminum to prepare a mixed solution; And (d) substituting, rectifying and vacuum evaporating the mixed solution to separate the nitric acid and aluminum sulfate water treatment coagulants.

The waste sulfuric acid etchant, waste hydrochloric acid etchant and waste nitric acid etchant solution of the present invention are environmentally friendly and can recycle aluminum sulfate water treatment coagulant, hydrochloric acid and nitric acid from waste sulfuric acid etchant, waste hydrochloric acid etchant and waste nitric acid etchant.

Description

Recycling method of waste sulfuric acid etching solution, waste hydrochloric acid etching liquid and waste nitric acid etching liquid {RECYCLING METHOD OF WASTE SULFURIC ACID ETCHING SOLUTION, WASTE CHLORIC ACID ETCHING SOLUTION AND WASTE NITRIC ACID ETCHING SOLUTION}

[Industrial use]

The present invention relates to a method for regenerating waste sulfuric acid etching solution, waste hydrochloric acid etching liquid and waste nitric acid etching liquid, and more particularly, is environmentally friendly and regenerates aluminum sulfate water treatment coagulant, hydrochloric acid and nitric acid from waste sulfuric acid etching liquid, waste hydrochloric acid etching liquid and waste nitric acid etching liquid. The waste sulfuric acid etching liquid, the waste hydrochloric acid etching liquid, and the waste nitric acid etching liquid which can regenerate this method are related.

[Prior art]

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

In order to remove the hazardous waste sulfuric acid etchant and waste nitric acid etchant, a method of neutralizing and disposing with caustic soda, calcium carbonate or calcium hydroxide has been generally used. However, large amounts of new secondary wastes such as arsenic, copper, iron, zinc, lead, and cadmium are generated in the waste sulfuric acid etchant and waste nitric acid etchant removal process. Among them, arsenic, lead, etc. A very harmful substance that causes serious environmental pollution.

Therefore, instead of the method 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 for completely evaporating a spent sulfuric acid etch solution, pyrolysing to form sulfurous acid gas, replacing it with a catalyst, absorbing it in water and regenerating it with 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 is a problem that sulfuric acid cannot be recovered from the waste sulfuric acid etching solution efficiently during the recovery of the waste sulfuric acid etching solution.

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

division HNO ₃ (g / ℓ) Al (g / ℓ) Mg (ppm) Fe (ppm) Ca (ppm) P (ppm) Mn (ppm) Nitrate Waste Etching Solution 120-160 15-25 0.1-4 0.5-5 0.8-7 1-5 2-9

As shown in Table 1, the waste nitric acid etchant contains a large amount of aluminum components, in order to use the waste nitric acid etchant as an etching solution, aluminum ions must be removed and the aluminum concentration in the waste nitric acid etchant is 15-25 g / l. The concentration is very low compared to 30-50 g / L, which is a preferable aluminum concentration as an aluminum nitrate water treatment coagulant, and cannot be used as an etchant or water treatment coagulant or for any use. In addition, the aluminum nitrate waste etching solution is environmentally regulated in terms of biochemical oxygen demand (COD) and total nitrogen content in the water treatment process, there is a problem that the aluminum nitrate waste etching solution is not suitable for use as a water treatment coagulant.

Table 2 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 2, since the waste sulfuric acid etching solution contains a large amount of hydrochloric acid and aluminum components, in order to reuse the waste sulfuric acid etching solution as an etching solution, it is necessary to remove impurities such as hydrochloric acid and aluminum to increase the purity of sulfuric acid to be regenerated.

In addition, Table 3 below shows the contents of the aluminum sulfate water treatment coagulant generally used.

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 Sulfate Water Treatment Coagulant 7-8 (4-5) 5-7.5 3.5-8.5 190 122 65.3

In Table 3, 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 3, when the aluminum sulfate water treatment coagulant is used, the optimum pH range is 3.5-8.5, which is almost neutral, but the amount of sulfuric acid contained in the spent sulfuric acid etchant is too high and the nitric acid contained in the waste nitric acid etchant is used. In order to use the waste sulfuric acid etchant and the waste nitric acid etchant as an aluminum sulfate water treatment coagulant because the content is too high, there is a problem in that the waste sulfuric acid etchant and the waste nitric acid etchant are 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.

The present invention is to solve the above-mentioned problems, an object of the present invention is an environmentally friendly waste sulfuric acid etching solution, waste hydrochloric acid which can recover aluminum sulfate water treatment coagulant, hydrochloric acid and nitric acid from waste sulfuric acid etching solution, waste hydrochloric acid etching solution and waste nitric acid etching solution. An etching solution and a waste nitric acid etching solution are provided.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing a method for regenerating waste sulfuric acid etching liquid, waste hydrochloric acid etching liquid and waste nitric acid etching liquid.

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) further adding aluminum to the spent sulfuric acid etching solution containing aluminum after vacuum evaporation; (c) adding a waste nitric acid etchant to the waste sulfuric acid etchant added with aluminum to prepare a mixed solution; And (d) provides a method for regeneration of the waste sulfuric acid etching solution, waste hydrochloric acid etching solution and waste nitric acid etching solution comprising the step of separating, rectifying and vacuum evaporation of the mixed solution to the nitric acid and aluminum sulfate water treatment coagulant.

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

The method for regenerating waste sulfuric acid etchant, waste hydrochloric acid etchant and waste nitric acid etchant comprises: (a) recovering hydrochloric acid by vacuum evaporation of a mixed solution of waste sulfuric acid etchant including aluminum and waste hydrochloric acid etchant containing aluminum; (b) further adding aluminum to the spent sulfuric acid etching solution containing aluminum after vacuum evaporation; (c) adding a waste nitric acid etchant to the waste sulfuric acid etchant added with aluminum to prepare a mixed solution; And (d) separating the mixed solution into a nitric acid and aluminum sulfate water treatment coagulant by substitution, rectification, and vacuum evaporation.

In the method for regenerating the waste sulfuric acid etchant and waste nitric acid etchant of the present invention, (a) hydrochloric acid is recovered by vacuum evaporation of a mixed solution of the waste sulfuric acid etchant containing aluminum and the waste hydrochloric acid etching solution containing aluminum. The aqueous hydrochloric acid solution can be recovered by heating the spent sulfuric acid etchant and the spent nitric acid etchant in vacuo. This is because sulfuric acid is nonvolatile but hydrochloric acid is highly volatile. When the spent sulfuric acid etching solution is heated to evaporate the hydrochloric acid contained in the spent sulfuric acid etching solution in advance, the remaining waste sulfuric acid etching solution becomes a higher concentration of waste sulfuric acid etching solution as much as the amount of evaporated hydrochloric acid.

After evaporating the waste sulfuric acid etching solution (b), the aluminum is further added to the waste sulfuric acid etching solution containing aluminum after vacuum evaporation. That is, to evaporate hydrochloric acid from the residual spent sulfuric acid etching solution and to add aluminum to be used as an aluminum sulfate 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 raised to the aluminum sulfate concentration required for use as the aluminum sulfate water treatment coagulant, and the residual solids are filtered.

In general, the concentration of aluminum in waste sulfuric acid etchant is only about 9-11 g / l, so that aluminum is added to the waste sulfuric acid etchant before diffusion dialysis so that the concentration of aluminum is 30-50g / l, which can be used as aluminum sulfate water treatment coagulant. It is preferable to heat and melt | dissolve and to raise the density | concentration of aluminum in waste sulfuric acid etching liquid.

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 by completely degreasing with alkaline degreasing solution to remove impurities.

After adding aluminum to the residual waste sulfuric acid etching solution, (c) the waste nitric acid etching solution is added to the waste sulfuric acid etching solution to which the aluminum is added to prepare a mixed solution.

(D) Subsequently, the mixed solution is substituted, rectified and vacuum evaporated to separate the nitric acid and aluminum sulfate water treatment coagulants.

The waste nitric acid etching solution is added to the residual waste sulfuric acid etching solution to which the aluminum is added and heated. That is, when the waste nitric acid etching solution is added to the aluminum sulfate solution and heated, the aluminum nitrate contained in the waste nitric acid etching solution is replaced with aluminum sulfate.

Since aluminum is easier to form a complex with sulfuric acid than with nitric acid, aluminum contained in the spent nitric acid etchant easily forms a complex with sulfuric acid contained in the spent sulfuric acid etchant. Therefore, the waste nitric acid etchant is mixed with the waste sulfuric acid etchant and the aluminum nitrate contained in the waste nitric acid etchant is separated into nitric acid and aluminum. You can do it.

In addition, in order to increase the purity of the regenerated nitric acid and aluminum sulfate can be further carried out a rectification process.

Further, the mixed solution of the waste nitric acid etchant is evaporated in the waste sulfuric acid etchant. This is because sulfuric acid is non-volatile, but nitric acid is highly volatile, and nitric acid can be separated by heating in vacuum. The nitric acid separated by vacuum evaporation can be reused as a metal etchant.

In the substituted and rectified waste sulfuric acid etching solution, the aluminum concentration contained in the aluminum sulfate solution is most preferably about 4% (42 g / L).

After measuring the concentration of the substituted and rectified waste sulfuric acid etching solution, it was adjusted to 35-45 g / l, which is suitable for use as a water treatment coagulant, and reused as a water treatment coagulant. The nitric acid recovered in the substitution and rectification process can be used as an etching solution. The nitric acid concentration is adjusted to 130-150 g / l and reused as an etchant.

As described above, the recycling method of waste sulfuric acid etching solution, waste hydrochloric acid etching solution and waste nitric acid etching solution of the present invention is environmentally friendly and can recover aluminum sulfate water treatment coagulant, hydrochloric acid and nitric acid from waste sulfuric acid etching solution, waste hydrochloric acid etching solution and waste nitric acid etching solution. have.

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 1-3 and Comparative Example]

The waste sulfuric acid etching solution was heated in vacuo to separate and recover hydrochloric acid, thereby preparing a high concentration of waste sulfuric acid etching solution of 500 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.

The waste nitric acid etchant was slowly added to the waste sulfuric acid etchant in which aluminum was dissolved, and heated in vacuo to recover nitric acid and replace aluminum nitrate with aluminum sulfate.

Moreover, the water treatment coagulant generally used was made into the comparative example. Table 4 shows the results of analyzing the components of the water treatment coagulant prepared through the above examples.

division pH importance Al (g / ℓ) Fe (mg / L) NO ₃ ^- (g / ℓ) Cl ^- (g / ℓ) SO ₄ ^2- (g / ℓ) Example 1 1.1 One. 48.2 26.3 - 0.2 331.7 Example 2 1.9 1.3 43.9 16.5 - 0.4 235.6 Example 3 2.0 1.3 47.3 59.1 - 0.2 228.7 Comparative Example 1 3.0 1.3 46.4 9.7 - 278.4

As shown in Table 4, the water treatment coagulant recycled according to the embodiment of the present invention includes a component similar to the water treatment coagulant generally used.

The waste sulfuric acid etching solution, waste hydrochloric acid etching solution and waste nitric acid etching solution recycling method of the present invention is environmentally friendly and can recover aluminum sulfate water treatment coagulant, hydrochloric acid and nitric acid from waste sulfuric acid etching liquid, waste hydrochloric acid etching liquid and waste nitric acid etching liquid.

Claims (2)

(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) further adding aluminum to the spent sulfuric acid etching solution containing aluminum after vacuum evaporation; (c) adding a waste nitric acid etchant to the waste sulfuric acid etchant added with aluminum to prepare a mixed solution; And (d) separating the mixed solution into a nitric acid and aluminum sulfate water treatment coagulant by substitution, rectification and vacuum evaporation; Waste sulfuric acid etchant, waste hydrochloric acid etchant and waste nitric acid etchant solution comprising a. The method of regenerating waste sulfuric acid etchant, waste hydrochloric acid etchant and waste nitric acid etchant according to claim 1, wherein the aluminum of step (b) is waste aluminum chip.