Method for selectively dissolving precious metal by utilizing ionizing radiation

Abstract

The invention relates to a method for selectively dissolving precious metal by ionizing radiation, which comprises the following steps: immersing a precious metal-containing material to be dissolved into a cyanogen compound solution, and selectively dissolving and recycling the precious metal in a metal material by high-energy ray irradiation (such as gamma ray, X ray and the like). Compared with the prior art, the method for selectively dissolving the precious metal through ionizing radiation does not need to use highly corrosive aqua regia or highly toxic cyanide, has the advantages of mildness, energy conservation, high efficiency, environmental protection, no need of adding any catalyst or oxidant, low cost and the like, and breaks through the existing understanding of the precious metal selective dissolving process; the high-energy radiation penetrability is high, and the device is suitable for recovering a large amount of precious metal in large volume and has great application value in the aspect of recovery treatment of waste containing precious metal.

Description

Technical Field

[0001] The present invention relates to the fields of ionizing radiation technology and precious metal recovery, and particularly to a method for selectively dissolving precious metals by using ionizing radiation. Background Art

[0002] Gold and silver in precious metals were used as legal tender in history and have the functions of financial reserve and international payment. Nowadays, they are widely used in traditional industries and modern high-tech fields, such as electronics, communication, aerospace, chemical industry, medical treatment, and automobile exhaust purification. Although the usage amount is small, precious metals play an irreplaceable key role in fields such as electronics, new energy, and environmental protection, and are known as "industrial vitamins". However, with the surge in the demand for precious metals (such as gold, silver, platinum, palladium, rhodium, osmium, ruthenium, iridium (Au, Ag, Pt, Pd, Rh, Os, Ru, Ir), etc.) in modern industry, the problems of their scarcity and resource sustainability have become increasingly prominent. The global reserves of precious metals are limited and unevenly distributed. Traditional mining and smelting processes not only consume a large amount of energy, but also are accompanied by serious ecological damage and pollution. Therefore, the development of efficient, environmentally friendly, and highly selective precious metal recovery technologies has become a key challenge in resource recycling.

[0003] Currently, the mainstream precious metal recovery processes such as the aqua regia method and the cyanidation method can extract precious metals, especially gold, but the obtained metal ion solution has no selectivity, and the aqua regia and highly toxic cyanides used are extremely harmful to the environment and human health, with high recovery costs and serious pollution.

[0004] Patent CN114293018A discloses a method for recovering various rare precious metals from waste printed circuit boards. In this method, Sn is first separated and leached, followed by the leaching of Cu in the circuit board, and then the leaching and recovery of Al, Ni, and Zn are carried out respectively. Finally, the leaching and recovery of Au and Ag are carried out. It has the advantages of mature process and resource recycling, but it involves the use of aqua regia in the process and has obvious deficiencies in terms of environmental friendliness, selectivity, energy consumption, and precious metal recovery rate.

[0005] Patent CN112553465A discloses a photocatalytic selective metal solvent and a dissolution method. In this method, a metal material is dispersed into the photocatalytic selective metal solvent, and each metal in the metal material can be selectively dissolved by irradiating with light for a certain time. This method has the advantages of environmental protection and high selectivity, but the light sources used are ultraviolet light and infrared light, with poor penetrability, making it difficult to directly process waste materials in complex forms and requiring mechanical crushing or pretreatment.

[0006] Therefore, in this context, there is an urgent need to develop a green, highly selective, and large-scale usable noble metal dissolution technology. Ionizing radiation (such as γ-rays, X-rays, high-energy electron beams) provides new ideas for the selective dissolution of noble metals due to its unique physical and chemical effects. This method can not only replace the traditional strong acid process but also significantly reduce the reagent dosage and the risk of secondary pollution, opening up a new path for the precision and low-carbon of noble metal recycling. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for selectively dissolving noble metals using ionizing radiation to overcome the defects of the existing technologies described above.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A method for selectively dissolving noble metals using ionizing radiation, wherein the noble metal-containing material to be dissolved is immersed in a solution of a cyanide compound, and high-energy rays are irradiated for a certain period of time to selectively dissolve the noble metals in the metal material.

[0010] Further, the noble metals include one or several of osmium, ruthenium, rhodium, iridium, gold, silver, platinum, or palladium.

[0011] Further, the content of the cyanide compound in the solution of the cyanide compound is 0.1-100% (volume fraction), the pH of the solution of the cyanide compound is 1-14, and the pH adjustment reagent for the solution of the cyanide compound includes acids, bases, and buffer solutions; the acids include organic acids and inorganic acids such as hydrochloric acid, sulfuric acid, acetic acid, phosphoric acid, tartaric acid, citric acid, maleic acid, etc.; the bases include inorganic bases and organic bases such as sodium hydroxide, potassium hydroxide, sodium bicarbonate, lithium hydroxide, calcium hydroxide, composite bases, amine compounds, etc.; the buffer solutions include phosphate buffer solution, boric acid buffer solution, borate buffer solution, citrate buffer solution, carbonate buffer solution, acetate buffer solution, glycine buffer solution, etc.

[0012] Further, the metal materials include all pure gold products, all types of noble metal-containing ores, all noble metal-containing waste products, including but not limited to central processing units (CPUs), printed circuit boards (PCBs), connectors, memory chips, optical product coatings, sensors, noble metal ornaments, noble metal-containing aerospace devices, supercapacitor electrode materials, diodes, anode slime, catalysts, fuel cell catalysts, automotive exhaust purification catalysts, chemical industry catalysts, metal nanoparticles, metal microparticles, supported catalysts, gold and silver minerals, mixed concentrates, smelting slag, etc.

[0013] Furthermore, the energy of the high-energy rays ranges from a few electron volts (eV) to millions of electron volts (MeV), including X-rays, gamma rays (γ rays), α rays, β rays, proton rays, neutron rays or a combination of several rays, etc. The irradiation dose is 1Gy-400kGy, and the irradiation time is 0.001-240h.

[0014] Furthermore, the reaction of selectively dissolving the precious metal using ionizing radiation is carried out in an environment with a temperature of 0-100°C.

[0015] Furthermore, the cyanide compounds include all organic cyanides and inorganic cyanides, but are not limited to acetonitrile, benzyl cyanide, cyanoacetic acid, ethylsulfonylacetonitrile, propionitrile, acrylonitrile, malononitrile, benzonitrile, butyronitrile, isobutyronitrile, valeronitrile, benzyl cyanide, melamine and mixtures of the above cyanide compounds.

[0016] Furthermore, the solvent used for the cyanide compound solution includes all organic solvents and water that are miscible with organic nitrile compounds, including but not limited to various types of water, dichloromethane, methanol, ethanol, isopropanol, N,N-dimethylformamide, dimethyl sulfoxide, acetone, acetic acid, ethyl acetate or a combination of several solvents.

[0017] Furthermore, the method for selectively dissolving precious metals by ionizing radiation includes adding various metal particles containing high atomic number elements, various metal elemental particles, various metal semiconductor particles, and various metal composite materials into the reaction system, including but not limited to nanoparticles containing gold elements, micron particles containing gold elements, nanoparticles containing gadolinium elements, micron particles containing gadolinium elements, nanoparticles containing bismuth elements, micron particles containing bismuth elements, nanoparticles containing tungsten elements, micron particles containing tungsten elements, titanium dioxide, iron oxide particles, etc.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The present invention provides a new method for selective dissolution and recovery of precious metals. The whole process has the advantages of being mild, energy-saving, green, efficient, environmentally friendly, and low-cost. It only requires the use of high-energy rays, does not require excessive energy consumption, does not require the use of highly corrosive aqua regia and highly toxic cyanide, and does not require other external catalysts and oxidants.

[0020] The common method of dissolving precious metals using aqua regia will emit toxic gases and produce a large amount of strong acidic waste liquid, which will cause great harm to the environment and human health; the strong corrosiveness of aqua regia will also damage reaction vessels, pipelines and other equipment, posing a safety hazard. The solvent used in the method of selectively dissolving precious metals using ionizing radiation is a solution of cyanide compounds, which does not involve the use of strong acids or corrosive solvents.

[0021] By adjusting the solution of different proportions of cyanide compounds and the pH value of the solution, the ability of ionizing radiation to selectively dissolve precious metals can be changed, enabling the large-scale dissolution of precious metals while base metals (such as iron, copper, zinc, nickel, etc.) remain undissolved.

[0022] 4. This method does not require stirring or high-temperature and high-pressure conditions during the irradiation dissolution of precious metals, saving energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 It is the physical diagram of the sample before and after the dissolution reaction in Example 1 and the column chart of the dissolution rate of each metal;

[0025] Figure 2 It is the physical diagram of the sample before and after the dissolution reaction in Example 2 and the column chart of the dissolution rate of each metal;

[0026] Figure 3 It is the physical diagram of the sample before and after the dissolution reaction in Example 3 and the column chart of the dissolution rate of each metal;

[0027] Figure 4 It is the physical diagram of the sample before and after the dissolution reaction in Example 4 and the column chart of the dissolution rate of each metal;

[0028] Figure 5 It is the physical diagram of the sample before and after the dissolution reaction in Example 5 and the column chart of the dissolution rate of each metal;

[0029] Figure 6 It is the physical diagram of the sample before and after the dissolution reaction in Example 6; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0031] Example 1

[0032] Immerse the waste CPU (containing only gold, copper, iron, zinc, nickel) in a cyanide compound solution with a certain pH value, irradiate it, and use ICP - AES to detect the content of each metal ion. The dissolution rate of gold is 91%, the dissolution rate of copper is 0%, the dissolution rate of iron is 0%, the dissolution rate of zinc is 4%, and the dissolution rate of nickel is 0%.

[0033] Figure 1The figure shows the physical pictures of the waste CPU samples before and after the reaction, as well as the bar charts of the dissolution rates of various metals. It can be clearly seen from the physical pictures that the gold plating layer on the surface of the CPU pins has faded. The test data of ICP can illustrate the high selectivity of this method for gold.

[0034] Example 2

[0035] Immerse the waste CPU (only containing gold, copper, iron, zinc, nickel) in a cyanide compound solution with a certain pH value, irradiate it, and use ICP-AES to detect the contents of various metal ions. The dissolution rate of gold is 6%, the dissolution rate of copper is 0%, the dissolution rate of iron is 0%, the dissolution rate of zinc is 5%, and the dissolution rate of nickel is 0%.

[0036] Figure 2 The figure shows the physical pictures of the waste CPU samples before and after the reaction, as well as the bar charts of the dissolution rates of various metals. It can be seen from the physical pictures that the gold plating layer on the surface of the CPU pins has not significantly faded. The test data of ICP can illustrate that this method has no special selectivity for gold.

[0037] Example 3

[0038] Immerse the waste CPU (only containing gold, copper, iron, zinc, nickel) in a cyanide compound solution with a certain pH value, irradiate it, and use ICP-AES to detect the contents of various metal ions. The dissolution rate of gold is 21%, the dissolution rate of copper is 0%, the dissolution rate of iron is 0%, the dissolution rate of zinc is 8%, and the dissolution rate of nickel is 0%.

[0039] Figure 3 The figure shows the physical pictures of the waste CPU samples before and after the reaction, as well as the bar charts of the dissolution rates of various metals. It can be seen from the physical pictures that part of the gold plating layer on the surface of the CPU pins has faded. The test data of ICP can illustrate that this method has a certain selectivity for gold.

[0040] Example 4

[0041] Immerse the waste CPU (only containing gold, copper, iron, zinc, nickel) in a cyanide compound solution with a certain pH value, irradiate it, and use ICP-AES to detect the contents of various metal ions. The dissolution rate of gold is 4%, the dissolution rate of copper is 0%, the dissolution rate of iron is 0%, the dissolution rate of zinc is 7%, and the dissolution rate of nickel is 0%.

[0042] Figure 4 The figure shows the physical pictures of the waste CPU samples before and after the reaction, as well as the bar charts of the dissolution rates of various metals. It can be seen from the physical pictures that the gold plating layer on the surface of the CPU pins has not significantly faded. The test data of ICP can illustrate that this method has no special selectivity for gold.

[0043] Example 5

[0044] Immerse the waste CPU (containing only gold, copper, iron, zinc, and nickel) in a cyanide compound solution with a certain pH value, irradiate it, and use ICP-AES to detect the content of each metal ion. The dissolution rate of gold is 20%, the dissolution rate of copper is 0%, the dissolution rate of iron is 0%, the dissolution rate of zinc is 6%, and the dissolution rate of nickel is 0%.

[0045] Figure 5 Figures 1 and 2 are the physical pictures of the samples before and after the reaction of the waste CPU and the bar charts of the dissolution rates of various metals. It can be seen from the physical pictures that the gold plating layer on the surface of the CPU pins has partially faded. The test data of ICP can illustrate that this method has a certain selectivity for gold.

[0046] Example 6

[0047] Immerse the gold foil in a cyanide compound solution with a certain pH value, irradiate it, and use ICP-AES to detect the content of gold ions. The dissolution rate of gold is 100%.

[0048] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for selectively dissolving precious metals using ionizing radiation, characterized in that, The method is as follows: Immerse the metal material in a solution of a cyanide compound, and irradiate it with high-energy rays for a certain period of time to selectively dissolve the precious metals in the metal material. In the solution of the cyanide compound, the content of the cyanide compound is 0.1 - 100% (volume fraction), the pH of the solution of the cyanide compound is 1 - 14, and the pH adjustment reagent for the solution of the cyanide compound includes acids, bases, and buffer solutions. The metal materials include all pure gold products, all kinds of precious metal-containing ores, and all waste products containing precious metals, including but not limited to central processing units (CPUs), printed circuit boards (PCBs), connectors, memory chips, optical product coatings, sensors, precious metal ornaments, aerospace devices containing precious metals, supercapacitor electrode materials, diodes, anode slime, catalysts, fuel cell catalysts, automotive exhaust purification catalysts, chemical industry catalysts, metal nanoparticles, metal microparticles, supported catalysts, gold and silver minerals, bulk concentrates, smelting slag, etc. The types of high-energy rays include but are not limited to X-rays, gamma rays (γ-rays), alpha rays, beta rays, proton rays, neutron rays, or a combination of several rays, etc. The energy range of the high-energy rays is from a few electron volts (eV) to several million electron volts (MeV), the irradiation dose is 1 Gy - 400 kGy, and the irradiation time is 0.01 - 240 h.

2. The method for selectively dissolving precious metals using ionizing radiation according to claim 1, characterized in that, The precious metals include one or several of osmium, ruthenium, rhodium, iridium, gold, silver, platinum, or palladium.

3. A method for selectively dissolving precious metals using ionizing radiation according to claim 2, characterized in that, The waste products containing precious metals include central processing units (CPUs), printed circuit boards (PCBs), connectors, memory chips, diodes, anode slime, catalysts, metal nanoparticles, metal microparticles, supported catalysts, gold and silver minerals, bulk concentrates, smelting slag, etc. of various models and forms.

4. A method for selectively dissolving precious metals using ionizing radiation according to claim 3, characterized in that, The energy range of the high-energy rays is from a few electron volts (eV) to several million electron volts (MeV), covering X-rays, gamma rays (γ-rays), alpha rays, beta rays, proton rays, neutron rays, or a combination of several rays, etc. The irradiation dose is 1 Gy - 400 kGy, and the irradiation time is 0.01 - 240 h. Preferably, the irradiation dose is 1 kGy - 100 kGy, and preferably the irradiation time is 0.5 - 72 h.

5. A method for selectively dissolving precious metals using ionizing radiation according to claim 4, characterized in that, The pH adjustment reagent for the solution of the cyanide compound includes acids, bases, and buffer solutions. The acids include organic acids and inorganic acids such as hydrochloric acid, sulfuric acid, acetic acid, phosphoric acid, tartaric acid, citric acid, maleic acid, etc. The bases include but are not limited to inorganic bases and organic bases such as sodium hydroxide, potassium hydroxide, sodium bicarbonate, lithium hydroxide, calcium hydroxide, compound bases, amine compounds, etc. The buffer solutions include but are not limited to phosphate buffer solution, boric acid buffer solution, borate buffer solution, citrate buffer solution, carbonate buffer solution, acetate buffer solution, glycine buffer solution, etc.

6. A method for selectively dissolving precious metals using ionizing radiation according to claim 5, characterized in that, The reaction of selectively dissolving precious metals by ionizing radiation is carried out in an environment with a temperature of 0 - 100 °C.

7. A method for selectively dissolving precious metals using ionizing radiation according to claim 6, characterized in that, The cyanide compounds described include all organic cyanides and inorganic cyanides, but are not limited to acetonitrile, phenylacetonitrile, cyanoacetic acid, ethylsulfonylacetonitrile, propionitrile, acrylonitrile, malononitrile, benzonitrile, butyronitrile, isobutyronitrile, valeronitrile, cyanobenzyl, melamine, and mixtures of the above cyanide compounds.

8. A method for selectively dissolving precious metals using ionizing radiation according to claim 7, characterized in that, The solvents used in the cyanide compound solution described include all organic solvents and water that can be miscible with organic nitrile compounds, including but not limited to various types of water, dichloromethane, methanol, ethanol, isopropanol, N,N-dimethylformamide, dimethyl sulfoxide, acetone, acetic acid, ethyl acetate, or combinations of several solvents, etc.

9. A method for selectively dissolving precious metals using ionizing radiation according to claim 8, characterized in that, The method for selectively dissolving precious metals by ionizing radiation described includes adding various metal particles containing high atomic number elements, various metal elemental particles, various metal semiconductor particles, various metal composite materials to the reaction system, including but not limited to nanoparticles containing gold elements, micron particles containing gold elements, nanoparticles containing gadolinium elements, micron particles containing gadolinium elements, nanoparticles containing bismuth elements, micron particles containing bismuth elements, nanoparticles containing tungsten elements, micron particles containing tungsten elements, titanium dioxide, iron oxide particles, etc.

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