Method for leaching platinum group metals from spent catalyst by UV-vis

Patent metadata

Field	Value
Publication number	US-11952642-B2
Application number	US-202318512770-A
Country	US
Kind code	B2
Filing date	Nov 17, 2023
Priority date	Nov 18, 2022
Publication date	Apr 9, 2024
Grant date	Apr 9, 2024

Abstract

The present invention belongs to the field of recovery of secondary resources of noble metals, and discloses a method for leaching platinum group metals from spent catalyst by UV-vis, which uses ferric oxalate complex/hydrogen peroxide-chloride salt solution as a solvent for extracting platinum group metals under the condition of UV-vis, converts the platinum group metals from metallic state to platinum group metal complex, and obtains platinum group metal lixivium to realize the leaching of the platinum group metals. The platinum leaching rate of the method of the present invention can reach more than 97%. The present invention has mild reaction conditions, realizes the green recovery of platinum group metals from spent catalyst, avoids the use of strong acids and bases and toxic substances and avoids the production of toxic gases in the leaching process, so as to reduce the environmental hazards of the spent catalyst.

First claim

The invention claimed is:

1. A method for leaching platinum group metals from spent catalyst by UV-vis, which uses a platinum group metal lixiviant for extracting platinum group metals from spent catalyst under the condition of UV-vis to obtain platinum group metal lixivium, so as to recover platinum group metals from spent catalyst, comprising the following steps:
(1) shearing spent catalyst, crushing to 80-200 meshes, and sieving;
(2) preparing the platinum group metal lixiviant: uniformly mixing ferric oxalate complex with chloride salt solution at a liquid-to-solid ratio of 40:1 to 10:1, adding 30 wt % aqueous hydrogen peroxide solution with a volume fraction of 0.1-4 vol. % of the system, and mixing uniformly; wherein the chloride salt is at least one of sodium chloride, potassium chloride and ammonium chloride;
(3) leaching platinum group metals: adding the spent catalyst sieved in step (1) to the platinum group metal lixiviant obtained in step (2) at a liquid-to-solid ratio of 20:1 to 5:1, and stirring under the condition of UV-vis for 10-120 min at a speed of 200-600 r/min to obtain a mixture, wherein the wavelength range of the UV-vis is 200-760 nm;
(4) carrying out solid-liquid separation: carrying out solid-liquid separation of the mixture obtained in step (3), the liquid phase obtained is a mixture of platinum group metal lixivium and ferric oxalate complex, and the solid phase is solid catalyst;
(5) separating the platinum group metals: placing the liquid phase obtained in step (4) under UV-vis for 2-24 h to obtain a solid-liquid mixture, the solid phase is ferrous oxalate solid, and the liquid phase is platinum group metal lixivium;
(6) stirring the platinum group metal lixivium obtained in step (5) at 40-80° C. for 2-8 h at a speed of 200-600 r/min to obtain a solid substance enriched with platinum group metals;
(7) recycling iron: collecting the ferrous oxalate solid obtained in step (5), washing with deionized water, drying at 40-80° C. for 12-24 h, and roasting at 300-700° C. for 4-8 h to obtain ferric oxide;
(8) the ferric oxide obtained in step (7) can be recycled as a reactant for preparing ferric oxalate complex.

2. The method according to claim 1 , wherein the spent catalyst is derived from spent catalyst for industrial treatment of VOCs with platinum group metals as the active component, and the platinum group metals include at least one of platinum (Pt), palladium (Pd) and rhodium (Rh).

3. The method according to claim 1 , wherein the ferric oxalate complex is obtained from oxalic acid and ferric oxide under the condition of oil bath, wherein water is used as a solvent, a mass ratio of the oxalic acid to the ferric oxide is 5:1 to 1:1, a liquid-to-solid ratio is 10:1 to 2:1, stirring is carried out at 60-98° C. for 0.5-10 h at a speed of 400-800 r/min, and a concentration of the ferric oxalate complex obtained is 50-370 g/L.

Assignees

• Univ Dalian Tech

Inventors

• Qu Zhenping
• Zhao Xinna
• Wang Hui

Classifications

• C22B11/048 Primary

  from spent catalysts · CPC title

• C22B1/248 Primary

  of metal scrap or alloys · CPC title

• Y02P10/20

  Recycling · CPC title

• C22B7/007

  by acid leaching · CPC title

• C22B7/009

  General processes for recovering metals or metallic compounds from spent catalysts (for recovering specific metals C22B11/00 - C22B61/00) · CPC title