WO-2026095244-A1 - METAL RECOVERY METHOD USING NITRIC ACID LEACHING AND ELECTROLYSIS

Abstract

The present invention relates to a metal recovery method using nitric acid leaching and electrolysis, and has the effect of providing a metal recovery method that is environmentally friendly by diluting high-concentration nitric acid (HNO 3 ) used in a metal recovery process to a predetermined concentration for use, and that is economical and has improved process efficiency by recycling the nitric acid (HNO 3 ) to enable resource circulation. In addition, the present invention has the effect of providing a metal recovery method using nitric acid leaching and electrolysis, in which electrolysis is performed while stirring at an appropriate speed, thereby increasing the recovery speed and significantly reducing the recovery time, and improving the recovery rate to 99.0% or more.

Inventors

• PARK, JONGSUNG
• KIM, SU HWAN
• CHO, Seyeon

Assignees

• 경상국립대학교산학협력단

Dates

Publication Date

20260507

Application Date

20250612

Priority Date

20241101

Claims (11)

1. A step of preparing a leaching solution containing the metal by leaching a metal-containing substance into an aqueous nitric acid ( HNO₃ ) solution; A step of diluting the above-mentioned leachate; A step of recovering the metal by electrolyzing the above diluted leachate; and A method for recovering metal using nitric acid leaching and electrolysis, characterized by including the step of filtering and drying the leaching solution from which the metal has been recovered.
2. In Article 1, The concentration of the above nitric acid ( HNO₃ ) aqueous solution is, A method for recovering metal using nitric acid leaching and electrolysis, characterized by being 40 to 70 weight%
3. In Article 1, The above metal-containing material is, It is silver powder, waste solar cells, waste silver oxide batteries, waste lithium-ion batteries, or waste display panels, and A method for recovering metal using nitric acid leaching and electrolysis, characterized by being in powder form
4. In Article 1, The above leaching solution is, A method for recovering metal using nitric acid leaching and electrolysis, characterized by including an aqueous solution of silver nitrate ( AgNO₃ ).
5. In Article 1, The step of preparing the above leaching solution is, A method for recovering metal using nitric acid leaching and electrolysis, characterized by magnetic stirring at 400 to 800 rpm for 20 to 28 hours at 15 to 35°C.
6. In Article 1, In the step of recovering the above metal, A method for recovering metal using nitric acid leaching and electrolysis, characterized in that the concentration of silver dissolved in the above-described diluted leaching solution is 1.0 to 7.0 mg/mL.
7. In Article 1, The step of diluting the above-mentioned leachate is, A method for recovering metal using nitric acid leaching and electrolysis, characterized by diluting the above-prepared leaching solution with distilled water 5 to 15 times.
8. In Article 1, As a device for the above-mentioned electrolysis, A method for recovering metal using nitric acid leaching and electrolysis, characterized by comprising: an electrode portion including a cathode and an anode; and a power supply portion electrically connected to the electrode portion to apply voltage.
9. In Article 8, The above cathode electrode is, A method for recovering metal using nitric acid leaching and electrolysis, characterized by using an insoluble electrode coated with at least one component selected from titanium (Ti), palladium (Pd), iridium (Ir), ruthenium (Ru), and tantalum (Ta); a silver electrode; or an electrode made of stainless steel.
10. In Paragraph 8, The above cathode electrode is, A method for recovering metal using nitric acid leaching and electrolysis, characterized by having a plate shape, rod shape, wire structure, foil, plate, cylinder, or bowl shape.
11. In Article 1, The above electrolysis is, A method for recovering metal using nitric acid leaching and electrolysis, characterized by applying a variable voltage of 0.8 to 5.0 V for 30 to 80 minutes.

Description

Metal recovery method using nitric acid leaching and electrolysis The present invention relates to a method for recovering metal using nitric acid leaching and electrolysis, and more specifically, to a method for recovering metal using nitric acid leaching and electrolysis characterized by not only being able to recover metal with high purity and recovery rate, but also enabling resource recycling by recycling nitric acid ( HNO₃ ) generated during the metal recovery process and improving process efficiency. According to the Ministry of Environment, the volume of discarded solar panels is projected to reach 988 tons in 2023, 1,223 tons in 2025, and 2,645 tons in 2027, and is expected to approach 28,153 tons in 2033. The global recycling market for discarded solar panels is also expected to grow from $205 million (260 billion won) in 2022 to $478 million (600 billion won) in 2026, according to the Korea Institute of Science and Technology Information, with an average annual growth rate of 20.2%, leading to the anticipated release of large amounts of waste solar cells. As mentioned above, waste solar cells released in large quantities not only cause serious environmental pollution, but also, since expensive materials are used to increase photoelectric conversion efficiency, if these materials are discarded without recovery, it can cause serious environmental pollution in addition to the problem of resource waste. However, conventional methods of extracting and recovering valuable metals such as silver from waste that have been studied so far have problems in terms of recycling costs and energy consumption, as they require high-temperature conditions and long extraction processes. Accordingly, as seen in the prior art, various research and development efforts are underway to recover valuable metals from spent solar cells. Conventional methods for leaching valuable metals from spent cells include acid leaching and alkaline leaching. In the case of acid leaching, valuable metals are recovered by electrolytic extraction after leaching using sulfuric acid ( H₂SO₄ ). However, there are disadvantages, such as the difficulty in selectively recovering high-purity metals because large amounts of other components, such as zinc, iron, and manganese, are leached out in addition to the metal to be selectively recovered, and the subsequent process is complex or requires multiple types of processes. Furthermore, since solutions mixed with hydrochloric acid, NaOH, hydroxide, and hydrofluoric acid react quickly and violently, there is a high rate of metal loss and the release of harmful gases, which still poses environmental problems during the recovery process. Accordingly, the inventor has completed the present invention by developing a technology capable of recovering high-purity valuable metals using only nitric acid and electrolytic extraction methods. FIG. 1 is a process block diagram illustrating a method for recovering metal using nitric acid leaching and electrolysis according to a preferred embodiment of the present invention. Figure 2 is a photograph showing a copper electrode reacted with nitric acid ( HNO₃ ). Figure 3 is a photograph showing the results of metal precipitation. Figure 4 is a photograph showing the metal recovery process according to Example 1 of the present invention. Figure 5 shows the XRD analysis results according to Example 1 of the present invention. Figure 6 is a photograph showing the metal recovery process according to Example 5 of the present invention. Figure 7 shows the SEM-EDS analysis results according to Example 4 of the present invention. Figure 8 shows the SEM-EDS analysis results according to Example 4 of the present invention. Figure 9 shows the SEM-EDS analysis results according to Example 5 of the present invention. The present invention will be described in detail below according to preferred embodiments with reference to the attached drawings, but specific descriptions of configurations and operations that are readily known to those skilled in the art will be omitted. Furthermore, it should be noted that the present invention is not necessarily limited by the following embodiments, and that those skilled in the art can make various modifications to the invention within the scope of the technical concept of the invention without departing from it. The terms used in this specification have been selected based on currently widely used general terms whenever possible, taking into account their functions in the present invention; however, these terms may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Additionally, in specific cases, terms have been arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the relevant description of the invention. Therefore, the terms used in this invention should be defined not merely by their names, but based on their meanings and the overall