KR100742088B1 - A reusing method of copper nitrate waste water as etching solution and copper ingot by etching process - Google Patents

Abstract

A method for recycling copper nitrate wastewater generated in an etching process is provided to recycle nitric acid and copper by recovering nitric acid by evaporating copper nitrate wastewater and recovering copper by using electrowinning, thereby reducing the treatment cost. Solid sludge is filtered from copper nitrate wastewater. The copper nitrate wastewater is evaporated to recover nitric acid so that copper wastewater with increased copper ion concentration is obtained. The copper wastewater is electrowinned to recover electrolytic copper under conditions of current density 300-560 A/m^2, copper ion concentration over 20g/l, initial concentration of free acid below 50g/l, pH over -0.18, and thermal conductivity over 100mS/cm.

Description

A recycling method of copper nitrate waste water as etching solution and copper ingot by etching process

1 is a photograph of the electrolytic copper precipitated from the cathode in the electrowinning process,

Figure 2 is a photograph of the electrolytic copper precipitated on the cathode under appropriate electrolytic extraction conditions.

The present invention provides a method of vacuum-evaporating copper and nitric acid-containing etching waste liquid to reuse the etching liquid and electrolytic copper. The method includes filtering solid sludge from the copper nitrate waste liquid and recovering nitric acid by vacuum evaporating the copper nitrate waste liquid. Forming a waste liquid, adjusting the composition to control the electrolytic collection conditions of the waste liquid, and recovering the electrolytic copper by electrolytically collecting the waste liquid, thereby eliminating expensive chemicals. Environmentally friendly treatment and economic recovery of nitric acid and electrolytic copper.

Copper nitrate wastes from the etching process of copper circuit boards are super acidic and contain high concentrations of nitric acid of more than 300 g / l and copper ions of more than 80 g / l.

Conventionally, the super acidic copper nitrate waste solution is treated by neutralization precipitation method by precipitating by adding caustic soda as a neutralizing agent, or by adding an alkaline agent to raise the pH to precipitate copper hydroxide, and filtering the residual powder to produce copper oxide. To reuse.

Among these methods, the neutralization precipitation method uses a large amount of caustic soda, which is an expensive neutralizer, during the neutralization process, and the treatment cost is very high because the wastewater has to go through several stages of water treatment process or copper oxide recovery process after precipitation. Affects. In particular, total nitrogen regulation (30 ppm in clean area, 60 ppm in general area) should be preceded by the complete water treatment of the secondary wastewater containing nitrate nitrogen, but the known technique of total nitrogen removal method is the only biological method and Since the amount of methanol to be added three times the total nitrogen as food, there is a problem that it is not economical because the processing cost and initial investment cost is very high.

In addition, the copper nitrate waste contains high concentrations of nitric acid of more than 300 g / l and copper ions of concentrations of 80 g / l or more, which requires a large amount of caustic soda in proportion to the nitric acid content. The movement is thrown away as waste.

Therefore, it is required to develop an economical and environmentally friendly technique for recovering copper nitrate waste generated in the etching process of the copper circuit board without using expensive chemicals to add copper.

In accordance with these requirements, a diffusion dialysis method for recovering nitric acid and copper by applying a diffusion dialysis membrane to a copper nitrate waste solution was developed. However, since copper ions are strongly complexed and exist as copper nitride ions in the solution, the following Table 1 As shown in FIG. 2, copper ions are contained in the recovered copper nitrate solution, which is a barrier in recycling the recovered copper nitrate solution to the nitrate etching solution, and the recovery rate of the electrolytic copper is also reduced.

TABLE 1 Diffusion Dialysis Test Results for Copper Nitrate Wastes

division Acidity (HCl, g / l) Free acidity (HCl, g / l) Copper ion concentration density Total amount density Total amount Copper Nitrate Waste 392 392 373 373 91.7 Copper Nitrate Solution 68.5 65.2 1.70 0.96 72.4 Recovered nitric acid 354 336 368 365 19.3

In order to solve this problem, an object of the present invention is to recover the nitric acid by vacuum evaporation of copper and nitric acid-containing copper nitrate waste liquid, and to recover the electrolytic copper from the remaining copper waste liquid by using the electrolytic extraction method without using expensive chemicals To provide a way to recover and recycle nitric acid and copper.

Filtering solid sludge from the copper nitrate waste liquid of the present invention; and recovering nitric acid by vacuum evaporating the copper nitrate waste liquid to form a copper waste liquid having an increased copper ion concentration; and electrolytic extraction conditions of the copper waste liquid. Adjusting the composition so as to meet a phosphorus current density of 300 to 560 A / m ² , a copper ion concentration of 20 g / l or more, an initial concentration of free acid of 50 g / l or less, a pH of -0.18 or more, and a conductivity of 100 mS / cm or more; And recovering the electrolytic copper by electrolytically collecting the copper waste solution.

In addition, the copper nitrate waste liquid is evaporated in a vacuum such that the waste liquid has a free acid of 50 g / l or less and a copper ion concentration of 20 g / l or more.

In addition, the electrolytic extraction conditions of the waste liquid is a current density of 380 A / m ² , conductivity 640 mS / cm.

If the free acidity of the waste liquid is increased to 80 g / l or more when the electrolytic liquid is collected, the electrolytic extraction is stopped and the composition is re-adjusted by replenishing the waste liquid to meet the electrolytic collection conditions.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

In the present invention, an economical and eco-friendly recycling method for treating copper nitrate waste generated in the etching process of the copper circuit board by vacuum evaporation to recover the recovered silver nitrate with etching liquid, and recovering and recycling electrolytic copper by electrolytically collecting the remaining copper waste liquid. To provide.

The composition range of the composition of the copper nitrate waste liquid generated in the etching process of the copper circuit board is shown in Table 2 below.

TABLE 2 Composition range of composition of copper nitrate waste liquid generated in etching process of copper circuit board

ingredient Acidity (HCl, g / l) Free acidity (HCl, g / l) Cu (mg / l) Fe (mg / l) Al (mg / l) Sludge (mg / l) Concentration range 370-400 200-230 80-110 2 ~ 7 2 ~ 5 10-25 ingredient Si (mg / l) Ca (mg / l) Na (mg / l) Cl (mg / l) SO ₄ (mg / l) NO ₂ (mg / l) Concentration range 2 ~ 5 2 ~ 7 10-20 3,000-3,500 300-400 1,700-2,500

As shown in Table 2, the nitrate concentration is 370 g / l or more and the copper ion concentration is 80 g / l or more in the component composition of the copper nitrate waste liquid generated in the etching process of the copper circuit board. A small amount of other components is contained. Therefore, if nitric acid and copper ions are separated and recovered by an appropriate method, they can be efficiently recycled.

In the present invention, in treating the nitric acid and copper ion-containing copper nitrate waste liquid, first, by removing the solid sludge component contained in the copper nitrate waste liquid by using a micro-cartridge filter, the inside of the reactor in the vacuum evaporation and electrolytic extraction step of the next step Prevent contamination

Vacuum-evaporate the filtered copper nitrate waste solution as above to recover the nitric acid and recycle it as an etching solution, but the remaining copper solution has an initial free acidity of 50 g / l or less and a copper ion concentration of 20 g / l or more. .

If the initial concentration of free acid in the copper waste liquid remaining from the copper nitrate waste liquid is 50 g / l or more, workability is deteriorated, such as the need for a separate gas treatment device due to the generation of hydrogen in the electrolytic extraction process, which is the next step. This greatly occurs, and electrolytic copper is extremely difficult to collect. In addition, the copper ion concentration must be secured to 20 g / l or more to recover the whole turnover by electrolytic extraction. If the copper ion concentration decreases to 20 g / l or less during the electrolytic extraction, the waste liquid must be disposed of.

In the vacuum evaporation process, nitric acid is recovered and the composition is adjusted and electrolyzed to recover the electrolytic copper so that the current density of the remaining copper waste liquid is 300 to 560 A / m ² . Since the current density is the most important factor among various electrochemical factors related to electrolysis, the following describes a method of controlling the current density. If the current density of the copper waste fluid is less than 380 A / m ² , the electrodeposition state of the electrolytic copper at the cathode is not good even if various electrolytic conditions are applied. If the current density is higher than 560 A / m ² , the copper ion is not only However, the purity of the electrodeposited copper recovered by electrodeposition to other kinds of ions is lowered. Therefore, according to the overall analysis of the electrolytic conditions, the current density is 300 ~ 560 A / m ² , copper ion concentration 20 g / l or more, free acid initial concentration 50 g / l or less, pH -0.18 or more, conductivity 100 mS / cm or more It turns out that this should be.

In addition, when electrolytically collecting the waste liquid, if the concentration of the waste liquid is increased to 80 g / l or more, the electrolytic extraction is stopped and the component is re-adjusted by replenishing the waste liquid so as to meet the above-mentioned electrolytic collection conditions.

Hereinafter, the present invention will be described in detail with reference to Examples.

EXAMPLE

The pretreatment filtration device applies an apparatus including an acid resistant cartridge filter and an acid resistant magnet pump, and has a treatment capacity of 2,000 ml / min.

In order to prevent internal contamination of the reaction tank in the vacuum evaporation and electrolytic extraction process, which is a post-process, solid sludge is filtered from the copper nitrate waste liquid in the pretreatment filtration apparatus, and the filtered copper nitrate waste liquid is transferred to the vacuum evaporation apparatus.

The vacuum evaporation apparatus comprises a vacuum high pump capable of constituting the reaction vessel with a 1,000 ml Pyrex glass container, forming a heater in the lower portion of the reaction vessel, and maintaining a vacuum degree up to -750 mmHg. The experimental conditions were vacuum -720mmHg and a temperature of 60 ~ 90 ℃. In the experiment, vacuum was evaporated in the order of water, low concentration nitric acid solution, high concentration nitric acid solution, but in the analysis, the acid of the mixture of the water, low concentration nitric acid solution and high concentration nitric acid solution was The concentration was measured. The acid concentration analysis method was applied to the wet titration method using sodium hydroxide (NaOH).

The experimental results of the recovery of nitric acid from the copper nitrate waste liquid by vacuum evaporation method and the production of the waste liquid are shown in Table 3 below.

TABLE 3 Vacuum Evaporation Test Results for Copper Nitrate Wastes

division Acidity (HCl, g / l) Free acidity (HCl, g / l) Copper ion concentration (g / l) density Total amount density Total amount Copper Nitrate Waste 392 392 373 373 91.7 Copper waste 71.2 73.7 1.5 2.0 91.6 Recovered nitric acid 375 366 368 367 0.01

As described above, the concentration of copper ions in the nitric acid separated and recovered from the copper nitrate waste solution was 0.01 g / l, which was found to be almost 100% separated and recovered. The copper ion concentration of was almost the same as the copper ion concentration of copper nitrate waste. From these results, it can be seen that there is no problem in recycling the nitric acid recovered with high purity into the etching solution and the utilization is also increased. In addition, the high concentration of copper waste can be electrolytically collected, and the recovery rate can be further increased.

Electrolytic picking device is applied to the stainless steel plate STS 316 as a negative electrode, iridium oxide coated titanium plate as a positive electrode, and includes an acid-resistant pump, a thermostat, electrolyte circulating electrolytic device.

Using the copper waste liquid obtained in the vacuum evaporation process was carried out under various experimental conditions and the test results are shown in Table 4, Table 5 and Figures 1 and 2.

In the electrowinning experiment, various electrolytic conditions are applied so that copper ions in copper wastes are deposited on the cathode and precipitated as copper ions. Although various electrochemical factors exist here, the electrodeposition material on the surface of the cathode was investigated while changing the current density in that the reduction current density had the greatest effect. Electrolytic collection test conditions were applied to copper plate as a cathode, titanium plate coated with iridium anodized, current density 280 ~ 560A / m ² , pH -0.4 ~ 1.0, copper ion concentration 8 ~ 70 g / l, temperature 20 ~ 25 ℃ It was.

The results of the electrolytic extraction test are shown in Table 4 below, and photographs of the electrolytic copper electrodeposition state of the negative electrode according to the results of the various electrochemical sampling experiments set according to Table 4 above are shown.

2 is shown.

TABLE 4 Test results of electrolytic copper production from copper nitrate waste

As shown in Table 4, in the case where the current density is 280 A / m ² , the electrodeposition state of the electrolytic copper at the cathode is not good even when various other electrolytic conditions are applied, and the current density is 560 A / m ² . In this case, normal electrolytic copper could be obtained only when the initial free acid concentration was 50 g / l or less and the copper ion concentration was 20 g / l or more. In addition, in the photograph of FIG. 1, when the current density is 560 A / m ² , specimen numbers satisfying conditions of initial free acid concentration of 50 g / l or less and copper ion of 20 g / l or more, D, E, F , G showed good electrodeposition state of electrolytic copper.

According to the overall analysis of the electrolytic conditions based on Table 4 and Figure 1 according to the current density 300 ~ 560 A / m ² , copper ion concentration 20 g / l or more, free acid initial concentration 50 g / l or less, pH -0.18 or more It has been shown that the conductivity should be at least 100 mS / cm.

Also, FIG. 2 shows a photograph of the electrodeposited copper electrode electrodeposition state of the cathode according to the results of the electrochemical extraction experiment at the current density of 380 A / m ² and the conductivity of 640 mS / cm, which are appropriate conditions for the electrolytic extraction. As shown in FIG. 2, it was found that 622 g of electrolytic copper was obtained in a very good state by electrolytic extraction for 144 hours, and the results of purity analysis for the electrolytic copper are shown in Table 5.

TABLE 5 Purity analysis result of the electrolytic copper electrolyzed from the waste liquid

Table 5 shows that almost 99.99% of high purity electrolytic copper was recovered.

Since the method of the present invention recovers and recycles the nitrate and copper-containing copper nitrate wastes generated in the copper circuit board manufacturing process to nitric acid and electrolytic copper, the high processing cost required for the water treatment or recycling of the conventional copper nitrate wastes can be reduced. In addition, waste resources that have been disposed of in the past can be recycled as valuable resources.

In addition, the problem of sludge landfill caused in the conventional water treatment or recycling process can be solved, and secondary pollution by the heavy metal malignant waste liquid, which is difficult to treat, can be prevented.

As described above, the present invention has been described in detail with reference to the described embodiments, but it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention. It is also natural to fall within the scope.

Claims (4)

delete Filtering solid sludge from the copper nitrate waste liquor; The sludge filtered copper nitrate waste was vacuum evaporated to have a free acid of 50 g / l or less and a copper ion concentration of 20 g / l or more , and the reactor was composed of a 1,000 ml Pyrex glass container, and the inside of the reactor was Forming a heater in the lower portion , recovering nitric acid by vacuum evaporation using a vacuum evaporation apparatus including a vacuum high pump capable of maintaining a vacuum degree up to -750mmHg to form a copper waste liquid with increased copper ion concentration; The copper waste liquid from which the nitric acid has been recovered is delivered at a current density of 300 to 560 A / m ² , a copper ion concentration of 20 g / l or more, an initial concentration of free acid of 50 g / l or less, a pH of -0.18 or more, and a conductivity of 100 mS / cm or more. Collecting and recovering electrolytic copper; The recycling method of the copper nitrate waste liquid generate | occur | produced in the etching liquid and the etching process with electrolytic copper characterized by consisting of these. delete The method of claim 2, When electrolytically collecting the waste liquid, if the concentration of the waste liquid increases to 80 g / l or more, stopping the electrolytic extraction and re-adjusting the composition by replenishing the waste liquid so as to meet the above-described electrolytic collection conditions. The recycling method of the copper nitrate waste liquid generate | occur | produced in the etching liquid used and the etching process with electrolytic copper.

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