Solvent extraction with a three-dimensional reticulated hollow-strut SiC foam microchannel reactor

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• A novel 3-D reticulated microchannel reactor based on the hollow-strut SiC foam for rare earths extraction. • High extraction efficiency and excellent mass transfer performance at high flow rate. • The structure-performance relationship of the foam was studied by extraction experiments combined with numerical simulations. 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 Ce 3+ and Pr 3+ 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 Q 0 of the two liquid phases on the extraction efficiency η and overall volume mass transfer coefficient K L a was discussed. For both RE ions, with increasing Q 0 , η decreases while K L a increases. For the total flow rate of the two phases of 4 ml⋅min −1 , the η values of Pr 3+ and Ce 3+ 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 Pr 3+ and Ce 3+ still reached 92.2% and 86.9%, respectively, and the K L a values of Pr 3+ and Ce 3+ 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.