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CN-122012939-A - Ultrasonic-assisted photocatalysis precious metal leaching method

CN122012939ACN 122012939 ACN122012939 ACN 122012939ACN-122012939-A

Abstract

The invention discloses an ultrasonic-assisted photocatalysis precious metal leaching method, and belongs to the technical field of precious metal recovery. The method comprises the following steps of (1) material pretreatment, namely, treating electronic waste powder containing gold, silver and copper into electronic waste powder capable of being leached by a proper method, (2) preparation of a reaction system, namely, adding the electronic waste powder containing gold, silver and copper into a leaching solvent, sequentially adding FeCl 3 and a photocatalyst, uniformly stirring, and (3) photocatalytic leaching, namely, placing a suspension reaction system under ultraviolet irradiation for ultrasonic-assisted leaching reaction, and (4) solid-liquid separation, namely, obtaining leaching liquid containing noble metals and leaching residues. The method combines the synergistic effect of FeCl 3 and the photocatalyst, realizes the efficient leaching of the noble metal under the irradiation of ultraviolet light, has the advantages of environmental protection, high efficiency, good circularity, mild condition, simple operation and the like, is suitable for large-scale recovery of the noble metal from the electronic waste containing gold, silver and copper, and has important economic and environmental significance.

Inventors

  • OU XING
  • ZHANG BOWEN
  • ZHONG QIFAN
  • SU ZIJIAN
  • AN CHANGSHENG
  • MING LEI

Assignees

  • 中南大学

Dates

Publication Date
20260512
Application Date
20260130

Claims (9)

  1. 1. An ultrasonic-assisted photocatalytic precious metal leaching method is characterized by comprising the following steps of: (1) The material pretreatment, namely, electronic waste powder containing gold, silver and copper is subjected to primary screening, roasting, ball milling and thermal reduction to obtain electronic waste powder for leaching; (2) Preparing a reaction system, namely adding the pretreated electronic waste powder into a leaching solvent, sequentially adding FeCl 3 and a photocatalyst, and performing ultrasonic dispersion to obtain a suspension reaction system; (3) Placing the suspension reaction system obtained in the step (1) in an ultraviolet irradiation environment for photocatalytic leaching reaction, and keeping stirring and ultrasound in the reaction process; (4) Solid-liquid separation, namely after leaching reaction is finished, carrying out solid-liquid separation on a reaction system to obtain leaching liquid containing noble metals and leaching residues; Wherein the leaching solvent is pure acetonitrile or acetonitrile-water mixed solvent, and the volume ratio of water in the acetonitrile-water mixed solvent is 0.1% -90%.
  2. 2. The method of claim 1, wherein in step (1), the air firing temperature of the electronic waste powder is 700-800 ℃.
  3. 3. The method of claim 1, wherein in step (1), the ball milling speed of the electronic waste powder is 400-800 r/min.
  4. 4. The method according to claim 1, wherein in the step (1), the thermal reduction atmosphere of the electronic waste powder is Ar/H2 atmosphere, and the thermal reduction temperature is 450-600 ℃.
  5. 5. The method of claim 1, wherein in the step (2), the particle size of the electronic waste powder is 100-500 mesh.
  6. 6. The method of claim 1, wherein in step (2), the solid-to-liquid ratio of the electronic waste powder to the leaching solvent is 1:1-1:5 mg/mL, and the photocatalyst is TiO 2 or a commercial miscible catalyst P25.
  7. 7. The method according to claim 1, wherein in the step (2), the FeCl 3 is added in an amount of 0.05 to 0.5 g/L, and the photocatalyst is added in an amount of 0.5 to 5 g/L.
  8. 8. The method according to claim 1, wherein in the step (3), the ultraviolet light has a wavelength of 200-400 nm, a power of 50-300W, an irradiation time of 1-36 h, a stirring rate of 300-800 r/min, a reaction temperature of 10-80 ℃, an ultrasonic power of 50-300W, and a volume ratio of water in the acetonitrile-water mixed solvent of 0.1% -90%.
  9. 9. The method according to claim 1, wherein in the step (4), the solid-liquid separation is centrifugal separation or filtration separation, the centrifugal rotation speed is 3000-8000 r/min, and a 0.22-0.45 μm filter membrane is used for filtration.

Description

Ultrasonic-assisted photocatalysis precious metal leaching method Technical Field The invention belongs to the technical field of precious metal recovery, and particularly relates to an ultrasonic-assisted photocatalysis precious metal leaching method which is particularly suitable for leaching and recovering precious metals from electronic wastes containing gold, silver and copper. Background With the rapid development of the electronic industry, the amount of electronic waste generated has increased dramatically. The electronic waste contains various noble metals such as gold, silver, copper and the like, and the noble metal content is far higher than that of natural ores, so that the electronic waste has extremely high recovery value. Therefore, the noble metal can be efficiently recovered from the electronic waste, so that the resource shortage problem can be relieved, the environmental pollution can be reduced, and the method has important economic and environmental significance. Currently, the methods for leaching noble metals from electronic waste mainly comprise two major categories, namely pyrometallurgy and hydrometallurgy. The pyrometallurgy has the defects of high energy consumption, toxic and harmful gas generation, low noble metal recovery rate and the like, and the hydrometallurgy is widely applied due to the advantages of low energy consumption, good selectivity and the like. The traditional hydrometallurgical leaching agent mainly comprises cyanide, thiourea, thiosulfate and the like, but the cyanide has extremely toxic effect and is extremely harmful to the environment and human bodies, and the leaching agent such as the thiourea, the thiosulfate and the like has the problems of low leaching efficiency, poor stability and the like. As an environment-friendly advanced oxidation technology, the photocatalysis technology has been attracting attention in the field of noble metal leaching in recent years. The photocatalyst can generate active species with strong redox performance under the illumination condition, and can promote the oxidative dissolution of noble metals. The existing photocatalysis leaching technology mostly adopts an aqueous solution system, and has the problems of poor leaching selectivity, high noble metal leaching rate and the like. Therefore, the development of the ultrasonic-assisted photocatalysis precious metal leaching method which is environment-friendly, efficient and good in selectivity has important practical significance. Patent CN114807613A discloses a method for recovering noble metals in solid waste by polar aprotic solvents, which realizes high-efficiency recovery of gold, but the system has certain defects that the leaching efficiency of noble metals is easy to be reduced to a large extent due to unavoidable introduction of water after multiple times of circulation. Benzyl (Nat. Sustin., 2021,14,618-626.) and the like propose a method for photo-catalytic recovery of noble metals by using MeCN/DCN as a solvent, which can selectively leach noble metals such as gold, silver and the like from electronic waste, waste automobile three-way catalysts and ores in a neutralizing way, and has high leaching rate. However, the system still has certain limitation that the conventional electronic waste material often contains a large amount of metallic copper, and the preferential leaching of copper during leaching leads to overlong reaction time required for recovering noble metals, and increases energy consumption; Aiming at the problems, the invention provides an ultrasonic-assisted photocatalysis precious metal leaching method, which adopts acetonitrile or acetonitrile-water mixed solvent as leaching solvent, combines the synergistic effect of FeCl 3 and a photocatalyst and is assisted by ultrasonic, and realizes high-efficiency precious metal leaching under ultraviolet irradiation. Disclosure of Invention In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: an ultrasonic-assisted photocatalytic precious metal leaching method comprises the following steps: (1) The material pretreatment, namely, electronic waste powder containing gold, silver and copper is subjected to primary screening, air roasting, ball milling and thermal reduction to obtain electronic waste powder for leaching; (2) Preparing a reaction system, namely adding the pretreated electronic waste powder into a leaching solvent, sequentially adding FeCl 3 and a photocatalyst, and performing ultrasonic dispersion to obtain a suspension reaction system; (3) Photocatalytic leaching, namely placing the suspension reaction system obtained in the step (1) in an ultraviolet irradiation environment to perform photocatalytic leaching reaction, and keeping stirring in the reaction process and adding ultrasound; (4) Solid-liquid separation, namely after leaching reaction is finished, carrying out solid-liquid separation on a reaction system to obtain leaching liquid contai