Pyrometallurgical processing of spent automotive catalysts by collector metal smelting

This review consolidates current knowledge on the influence of flux addition on the structural and rheological properties of the slag phase during the pyrometallurgical smelting of spent automotive catalysts using a collector metal. The analysis draws on Russian and international studies that examine the processing of automotive catalysts containing platinum-group metals. The study evaluates the mechanisms by which flux additives, including calcium, sodium, and boron oxides, as well as calcium fluoride, modify the melt microstructure. It focuses on the degree of polymerization in silicate and aluminosilicate networks resulting from variations in the distribution of chemically bound oxygen. The findings show that effective control of the pyrometallurgical smelting process depends on maintaining an appropriate balance between polymerized and depolymerized structural units in the slag. Basic oxides reduce melt viscosity by breaking bridging bonds; however, they also increase oxygen activity, which promotes oxidation and loss of platinum, palladium, and rhodium. These results underscore the need for composite flux formulations that adjust melt properties while minimizing the oxidation potential of the slag. A central challenge in improving the recovery of platinum-group metals from this secondary raw material is the development of quantitative models that link flux composition, slag structure, and oxidation potential. These conclusions support predictive evaluation of multicomponent systems and provide a basis for optimizing smelting parameters to increase metal recovery to the collector while reducing energy use and operating costs. The development of predictive models using modern thermodynamic software packages represents a key direction for further research.

1. Liu Chuan, Sun Shuchen, Zhu Xiaoping, Tu Ganfeng. Metals smelting-collection method for recycling of platinum group metals from waste catalysts: a mini review. Waste Management and Research. 2020;39(1):43-52. https://doi.org/10.1177/0734242X20969795. EDN: HYTLPJ.

2. Hughes A.E., Haque N., Northey S.A., Giddey S. Platinum group metals: a review of resources, production and usage with a focus on catalysts. Resources. 2021;10(9):93. https://doi.org/10.3390/resources10090093. EDN: ZYVXZN.

3. Tang Huimin, Peng Zhiwei, Tian Ran, Ye Lei, Zhang Jian, Rao Mingjun, et al. Platinum-group metals: demand, supply, applications and their recycling from spent automotive catalysts. Journal of Environmental Chemical Engineering. 2023;11(5):110237. https://doi.org/10.1016/j.jece.2023.110237. EDN: DGJXTS.

4. Chvileva T., Golovina E. Publication of reporting of metallurgical companies in context of the concept of corporate sustainable development. Journal of Industrial Pollution Control. 2017;33(1):926-930. EDN: XNFPGF.

5. Litvinenko V.S., Petrov E.I., Vasilevskaya D.V., Yakovenko A.V., Naumov I.A., Ratnikov M.A. Assessment of the role of the state in the management of mineral resources. Journal of Mining Institute. 2023;259:95-111. (In Russ.). https://doi.org/10.31897/PMI.2022.100. EDN: APFXQN.

6. Grilli M.L., Slobozeanu A.E., Larosa C., Paneva D., Yakoumis I., Cherkezova-Zheleva Z. Platinum group metals: Green recovery from spent auto-catalysts and reuse in new catalysts – a review. Crystals. 2023;13(4):550. https://doi.org/10.3390/cryst13040550. EDN: QQZMFU.

7. Murata T., Yamaguchi K. Recovery of palladium and platinum particles suspended in the Al₂O₃–CaO– SiO₂ slag using copper-based extractants at 1723 K. Materials Transactions. 2021;62(10):1495-1501. https://doi.org/10.2320/matertrans.M-M2021844. EDN: TDVHTX.

8. Aleksandrova T.N., О’Connor C. Processing of platinum group metal ores in Russia and South Africa: current state and prospects. Journal of Mining Institute. 2020;244:462-473. (In Russ.). https://doi.org/10.31897/PMI.2020.4.9. EDN: UKMJUX.

9. Canhimbue L., Talovina I. Geochemical distribution of platinum metals, gold and silver in intrusive rocks of the Norilsk Region. Minerals. 2023;13(6):719. https://doi.org/10.3390/min13060719. EDN: EZRTOC.

10. Sun Shiqiang, Jin Chenxi, He Wenzhi, Li Guangming, Zhu Haochen, Huang Juwen. A review on management of waste three-way catalysts and strategies for recovery of platinum group metals from them. Journal of Environmental Management. 2022;305:114383. https://doi.org/10.1016/j.jenvman.2021.114383. EDN: PKNNBD.

11. Trinh Ha Bich, Lee Jae-Chun, Suh Yong-Jae, Lee Jaeryeong. A review on the recycling processes of spent auto-catalysts: towards the development of sustainable metallurgy. Waste Management. 2020;114:148-165. https://doi.org/10.1016/j.wasman.2020.06.030. EDN: EGIIZK.

12. Cherepovitsyn A., Mekerova I., Nevolin A. Analysis of the palladium market: a strategic aspect of sustainable development. Mining. 2025;5(3):39. https://doi.org/10.3390/mining5030039. EDN: VIRTOC.

13. Karim S., Ting Yen-Peng. Recycling pathways for platinum group metals from spent automotive catalyst: a review on conventional approaches and bio-processes. Resources, Conservation and Recycling. 2021;170:105588. https://doi.org/10.1016/j.resconrec.2021.105588. EDN: QONNPE.

14. Xia Jinsong, Ghahreman A. Platinum group metals recycling from spent automotive catalysts: metallurgical extraction and recovery technologies. Separation and Purification Technology. 2023;311:123357. https://doi.org/10.1016/j.seppur.2023.123357. EDN: OPCTAY.

15. Tang Huimin, Peng Zhiwei, Tian Ran, Ye Lei, Zhang Jian, Rao Mingjun, et al. Recycling of platinum-group metals from spent automotive catalysts by smelting. Journal of Environmental Chemical Engineering. 2022;10(6):108709. https://doi.org/10.1016/j.jece.2022.108709. EDN: NJSYDH.

16. Litvinova T.E., Suchkov D.V. Comprehensive approach to the utilisation of technogenic waste from the mineral resource complex. Mining informational and analytical bulletin. 2022;6-1:331-348. (In Russ.). https://doi.org/10.25018/0236_1493_2022_61_0_331. EDN: VWGWFK.

17. Pashkevich M.А., Evdokimova M.E. Finely-dispersed wastes of titanium production as an additive for manufacturing of building materials. Ecology and Industry of Russia. 2025;29(2):19-23. (In Russ.). https://doi.org/10.18412/1816-0395-2025-2-19-23. EDN: KMWLNS.

18. Yan Jisen, Wei Jia, Zhang Fan, Zhang Xin, He Zhenkun, Xie Fang, et al. Comprehensive review on recovery of platinum group metals from spent automotive catalysts by metal capture technology: present progress and outlook. Journal of Environmental Chemical Engineering. 2024;12(5):114017. https://doi.org/10.1016/j.jece.2024.114017. EDN: FHJVUN.

19. Sapunov A.V., Litvintsev I.Yu., Sapunov V.N. Phosphorus poisoning of a cerium-containing catalyst. Khimicheskaya promyshlennost segodnya. 2005;(8):40-44. (In Russ.). EDN: LNKDTO.

20. Pakhomov R.A., Fokina S.B., Mushikhin E.A., Shcherbakov S.V. Use of multicomponent phase diagrams of slag systems for recycling of spent automotive catalysts. Tsvetnye Metally. 2023;2:49-59. (In Russ.). https://doi.org/10.17580/tsm.2023.02.07. EDN: YSKUZZ.

21. Zheng Huandong, Ding Yunji, Wen Quan, Zhao Shizhen, He Xuefeng, et al. Slag design and iron capture mechanism for recovering low-grade Pt, Pd, and Rh from leaching residue of spent auto-exhaust catalysts. Science of the Total Environment. 2022;802:149830. https://doi.org/10.1016/j.scitotenv.2021.149830. EDN: NDGTSM.

22. Peng Zhiwei, Li Zhizhong, Lin Xiaolong, Tang Huimin, Ye Lei, Ma Yutian, et al. Pyrometallurgical recovery of platinum group metals from spent catalysts. JOM. 2017;69(9):1553-1562. https://doi.org/10.1007/s11837-017-2450-3. EDN: YHZIZN.

23. Zheng Huandong, Ding Yunji, Wen Quan, Liu Bo, Zhang Shengen. Separation and purification of platinum group metals from aqueous solution: recent developments and industrial applications. Resources, Conservation and Recycling. 2021;167:105417. https://doi.org/10.1016/j.resconrec.2021.105417. EDN: TBUDQF.

24. Ilyas S., Kim Hyunjung. Recovery of platinum-group metals from an unconventional source of catalytic converter using pressure cyanide leaching and ionic liquid extraction. JOM. 2022;74(3):1020-1026. https://doi.org/10.1007/s11837-021-05119-6. EDN: KCFVQJ.

25. Boduen A.Ya., Fokina S.B., Fedorov A.T., Petrov G.V. Technological improvement of adsorptive concentration of platinum metals from chloride solutions after hydrometallurgical processing of low-sulfide flotation concentrates. Gornyi Zhurnal. 2023;10:34-40. (In Russ.). https://doi.org/10.17580/gzh.2023.10.04. EDN: MVEQZQ.

26. Karim S., Saw Han Mei, Ting Yen-Peng. Evaluation of green chemistry metrics for sustainable recycling of platinum group metals from spent automotive catalysts via bioleaching. Green Chemistry. 2024;26(7):4112-4126. https://doi.org/10.1039/d3gc03918h. EDN: NWBEQS.

27. Shi Bingyin, Qian Guoyu, Pang Sheng, Sun Yiwei, Peng Hongbing, Fu Wenlong, et al. Synchronous extraction of Pt, Zr and Ce from spent catalysts via SoG-Si scraps melting collection by regulating Si reduction based on a new fluorine-containing slag. Separation and Purification Technology. 2024;351:128086. https://doi.org/10.1016/j.seppur.2024.128086. EDN: WVEHOJ.

28. Yang Dongfang, Yang Qingyuan, Ma Wenhui, Wang Shiding, Lei Yun. Co-treatment of diamond-wire-saw silicon kerf and spent automotive catalysts for simultaneous recovery of PGMs, REEs, Zr, and high-purity Si. Waste Management. 2023;171:237-247. https://doi.org/10.1016/j.wasman.2023.08.035. EDN: AWPKFJ.

29. Litvinova T.E., Gerasev S.A. Behaviour of cerium (III) phosphate in a carbonate-alkaline medium. Journal of Mining Institute. 2025;271:181-188. EDN: BJJVKD.

30. Wang Zhe, Wei Qi-long, Shi Cheng-bin, Guo Zhan-cheng. Effect of Al2O3/SiO2 mass ratio and CaO content on viscosity and structure of slag for pyrometallurgical processing of spent automotive catalysts. Journal of Iron and Steel Research International. 2024;31(3):608-621. https://doi.org/10.1007/s42243-024-01181-x. EDN: YDBVOQ.

31. Sasaki H., Maeda M. Zn-vapor pretreatment for acid leaching of platinum group metals from automotive catalytic converters. Hydrometallurgy. 2014;147:59-67. https://doi.org/10.1016/j.hydromet.2014.04.019. EDN: SOFKVB.

32. Liu Chuan, Sun Shuchen, Tu Ganfeng, Xiao Faxin. An integrated capture of red mud and one-step heat-treatment process to recover platinum group metals and prepare glass-ceramics from spent auto-catalysts. Minerals. 2022;12(3):360. https://doi.org/10.3390/min12030360. EDN: FQFKRJ.

33. Liu Chuan, Sun Shuchen, Tu Ganfeng, Xiao Faxin. Co-treatment of spent automotive catalyst and cyanide tailing via vitrification and smelting-collection process for platinum group metals recovery. Journal of Environmental Chemical Engineering. 2021;9(5):105823. https://doi.org/10.1016/j.jece.2021.105823. EDN: LOCYYQ.

34. Bazhin V.Yu., Masko O.N., Nikitina L.N. Decarbonization of exhaust gases of industrial metallurgical furnaces. Metallurgist. 2024;67(9-10):1407-1417. https://doi.org/10.1007/s11015-024-01632-6. EDN: GHZZGE.

35. Fedorova E., Morgunov V., Lobko K., Pupysheva E. Review: axial motion of material in rotary kilns. Eng. 2025;6(6):106. https://doi.org/10.3390/eng6060106. EDN: TIGGRJ.

36. Chen Shuyu, Song Qingming, Xu Zhenming. Mechanism of PGMs capture from spent automobile catalyst by copper from waste printed circuit boards with simultaneous pollutants transformation. Waste Management. 2024;186:130-140. https://doi.org/10.1016/j.wasman.2024.06.001. EDN: LLCIGP.

37. Ding Yunji, Zheng Huandong, Zhang Shengen, Liu Bo, Wu Boyu, Jian Zhuming. Highly efficient recovery of platinum, palladium, and rhodium from spent automotive catalysts via iron melting collection. Resources, Conservation and Recycling. 2020;155:104644. https://doi.org/10.1016/j.resconrec.2019.104644. EDN: YUEHQU.

38. Liang Guangbing, Qu Zhenping. Insight into pyrometallurgical recovery of platinum group metals from spent industrial catalyst: co-disposal of industrial wastes. ACS ES and T Engineering. 2023;3:1532-1546. https://doi.org/10.1021/acsestengg.3c00129. EDN: BCLXMH.

39. Liu Chuan, Sun Shuchen, Zhu Xiaoping, Tu Ganfeng. Feasibility of platinum recovery from waste automotive catalyst with different carriers via cooperative smelting-collection process. Journal of Material Cycles and Waste Management. 2021;23:581-590. https://doi.org/10.1007/s10163-020-01143-x. EDN: ZQIYJW.

40. Sun Shuchen, Liu Chuan, Xiao Faxin, Tu Ganfeng. Recovery of platinum and synthesis of glass–ceramic from spent automotive catalyst via co-treatment process with coal fly ash. Journal of Material Cycles and Waste Management. 2022;24:1971-1981. https://doi.org/10.1007/s10163-022-01451-4. EDN: BRUEAY.

41. Liu Chuan, Sun Shuchen, Tu Ganfeng, Xiao Faxin. A novel method for extraction of platinum from spent automotive catalyst: utilization of spent fluid catalytic cracking catalyst as flux. Environmental Technology. 2021;44(2):139-149. https://doi.org/10.1080/09593330.2021.1965662. EDN: DOEOWJ.

42. Kirichenko A.S., Nekhamin S.M., Samotaev N.N., Antonov A.A. New mechanism for depositing platinum, palladium and rhodium on iron metal collector. Metallurg. 2020;5:65-68. (In Russ.). EDN: HPEAML.

43. He Xue-Feng, Yin Xi-Ping, Ding Yun-Ji, Shi Zhi-Sheng, Zhao Bao-Huai, Zheng Huan-Dong, et al. Slag design and optimization for iron capturing platinum group metals from alumina-based spent catalysts. Rare Metals. 2023;42(6):2093-2103. https://doi.org/10.1007/s12598-023-02262-8. EDN: FVEFAQ.

44. Petrov G.V., Fokina S.B., Nikitina T.Y. Aspects of iridium extraction from chloride solutions. Non-ferrous Metals. 2021;50(1):10-14. https://doi.org/10.17580/nfm.2021.01.02. EDN: JTCCOQ.

45. Kirichenko A.S., Seregin A.N. Efficiency rise of pyrometallurgical processing of wasted automotive catalysts using Fe-based metal collector. Chernye Metally. 2017;11:59-62. (In Russ.). EDN: ZXPYBV.

46. Bodrov S.G., Dorokhov S.N., Kalmykov A.V., Nosov A.N. Method of separating multicomponent material containing metallic components. Patent RF, no 2248406; 2005. (In Russ.). EDN: GWUSMP.

47. Kirichenko A.S., Seregin A.N. Method of processing of catalysts containing platinum metals on aluminium oxide carriers. Patent RF, no 2553117; 2015. (In Russ.). EDN: FCYVWG.

48. Nemchinova N.V., Ilin А.A., Tyutrin А.А., Galachieva S.V., Yakovleva А.А. Structure and dynamic viscosity of CaO–SiO2 and CaO–SiO2–B2O3 model slag systems. iPolytech Journal. 2024;28(3):562-575. (In Russ.). https://doi.org/10.21285/1814-3520-2024-3-562-575. EDN: IXGBEL.

49. Ilin A.A., Zobnin N.N., Pikalova I.A., Nemchinova N.V. Distribution of iron and boron between silicon metal smelting products in industrial saf using borate fluxes. Silicon. 2024;16:3085-3092. https://doi.org/10.1007/s12633-024-02895-z. EDN: TWOJLD.

50. Vasyutinsky N.A. Metallurgical slags. Kiev: Tekhnika; 1990, 152 p. (In Russ.).

51. Onaev I.A. Physico-chemical properties of non-ferrous metallurgy slags. Alma-Ata: Nauka; 1972, 120 p. (In Russ.).

52. Sizyakov V.M., Brichkin V.N., Kurtenkov R.V., Maksimova R.I. Synthesis, properties and applications of complex calcium aluminates and hydroaluminates. Non-ferrous Metals. 2025;1:10-17. https://doi.org/10.17580/nfm.2025.01.02. EDN: TGASFO.

53. Murata T., Yamaguchi K. Effects of SiO₂ and CaO on distributions of platinum group metals between Cu–CuO₀.₅ and Pb–PbO-based slags at 1523 K. Metallurgical and Materials Transactions B. 2023;54(5):2360-2369. https://doi.org/10.1007/s11663-023-02837-x. EDN: PQVCZQ.

54. Tang Huimin, Peng Zhiwei, Li Zhizhong, Ma Yutian, Zhang Jian, Ye Lei, et al. Recovery of platinum-group metals from spent catalysts by microwave smelting. Journal of Cleaner Production. 2021;318:128266. https://doi.org/10.1016/j.jclepro.2021.128266. EDN: TFTLSD.

55. Telyakov A.N., Rubis S.A. Processing wastes containing nonferrous and platinum metals. Patent RF, no 2484154; 2013. (In Russ.). EDN: FGISVF.

56. Bi Zhisheng, Li Kejiang, Chunhe Jiang, Zhang Jianliang, Ma Shufang. Effects of amphoteric oxide (Al₂O₃ and B₂O₃) on the structure and properties of SiO₂-CaO melts by molecular dynamics simulation. Journal of Non-Crystalline Solids. 2021;559:120687. https://doi.org/10.1016/j.jnoncrysol.2021.120687. EDN: PBKYCV.