Flow characteristics and mass transfer performance of phosphoric acid extraction in a T-type central plug-in microreactor

In recent years, the demand for phosphoric acid, a key raw material for lithium iron phosphate batteries, has surged. However, current phosphoric acid extraction equipment faces challenges such as low mass transfer efficiency and difficulty in phase separation, leading to reduced production efficiency, bulky equipment, and scaling issues. To address these problems, this study introduces a T-type central plug-in microreactor (TCPM) designed to enhance mass transfer efficiency and facilitate rapid phase separation. The extraction of phosphoric acid from the water phase to the organic phase (volume ratio of tributyl phosphate to kerosene is 4:1) was chosen as the experimental system. We investigated the effects of various parameters on liquid-liquid flow and mass transfer characteristics in the TCPM. Visualization techniques identified slug and parallel flow as the primary liquid-liquid flow patterns within the TCPM. Notably, the central plug-in promotes the formation of parallel flow, improving phase separation compared to conventional T-type microreactors. The volume mass transfer coefficient of the TCPM ranges from 0.023 to 0.074 s^-1, and the optimal phosphoric acid extraction efficiency and volume mass transfer coefficient can reach up to 90.5% and 0.074 s^-1, respectively, outperforming conventional T-type microreactors. Predictive model for extraction efficiency was developed, showing deviations within 10%. These findings demonstrate the TCPM's potential as an efficient phosphoric acid extraction device with rapid phase separation, holding significant promise for liquid-liquid extraction applications.