Abstract: Recently, there has been considerable interest in the use of microchannel reactors for hydrometallurgy of rare earths (REs). Here, a novel integrated microchannel reactor based on the hollow-strut SiC foam material is presented and demonstrated to extract Ce³⁺ and Pr³⁺ using 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (P507) as the extractant. The typical three-dimensional reticulated structure of the hollow-strut SiC foam was characterized by scanning electron microscopy and X-ray micro computed tomography. Since the reactor’s structure plays a key role in fluid mixing and mass diffusion during the extraction process, the structure-performance relationship of the foam was studied by extraction experiments combined with numerical simulations. Using the foam with the optimal structure, the influence of the flow rate Q₀ of the two liquid phases on the extraction efficiency η and overall volume mass transfer coefficient K_La was discussed. For both RE ions, with increasing Q₀, η decreases while K_La increases. For the total flow rate of the two phases of 4 ml·min^-1, the η values of Pr³⁺ and Ce³⁺ reached 98.7% and 97.0%, respectively. For the total flow rate of 36 ml·min^-1 which was much higher than that of many other microchannel reactors reported in the literatures, the η values of Pr³⁺ and Ce³⁺ still reached 92.2% and 86.9%, respectively, and the K_La values of Pr³⁺ and Ce³⁺ were 0.198 and 0.161 s^-1, respectively, similar to the high values reported for other microchannel reactors studied in previous work. These findings indicate that the hollow-strut SiC foam microchannel reactor is suitable for use in REs extraction.

Key words: Extraction, Hollow, Foam, Microchannels, Numerical simulation

摘要： Recently, there has been considerable interest in the use of microchannel reactors for hydrometallurgy of rare earths (REs). Here, a novel integrated microchannel reactor based on the hollow-strut SiC foam material is presented and demonstrated to extract Ce³⁺ and Pr³⁺ using 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (P507) as the extractant. The typical three-dimensional reticulated structure of the hollow-strut SiC foam was characterized by scanning electron microscopy and X-ray micro computed tomography. Since the reactor’s structure plays a key role in fluid mixing and mass diffusion during the extraction process, the structure-performance relationship of the foam was studied by extraction experiments combined with numerical simulations. Using the foam with the optimal structure, the influence of the flow rate Q₀ of the two liquid phases on the extraction efficiency η and overall volume mass transfer coefficient K_La was discussed. For both RE ions, with increasing Q₀, η decreases while K_La increases. For the total flow rate of the two phases of 4 ml·min^-1, the η values of Pr³⁺ and Ce³⁺ reached 98.7% and 97.0%, respectively. For the total flow rate of 36 ml·min^-1 which was much higher than that of many other microchannel reactors reported in the literatures, the η values of Pr³⁺ and Ce³⁺ still reached 92.2% and 86.9%, respectively, and the K_La values of Pr³⁺ and Ce³⁺ were 0.198 and 0.161 s^-1, respectively, similar to the high values reported for other microchannel reactors studied in previous work. These findings indicate that the hollow-strut SiC foam microchannel reactor is suitable for use in REs extraction.

关键词: Extraction, Hollow, Foam, Microchannels, Numerical simulation