Single-stage micro-scale extraction: Studies with single microbore tubes and scale-up

The study focuses on single-stage solvent extraction of HNO3 from 3 M HNO3 using 30% TBP in dodecane in microbore tubes. The objective of the study is to identify a configuration that ensures high stage efficiency (⩾90%), quick settling and low pressure drop (⩽2 bar) and to demonstrate this configuration at a total throughput of 1 LPH using parallel paths. To find out the right configuration, experiments with single microbore tubes are conducted to observe the effects of flow rate, diameter and length of microbore tube on stage efficiency, pressure drop and settling behavior. The experiments show that the configuration consisting of a Y-junction of 750 μm diameter having a single microbore tube of 800 μm diameter and 300 cm length on its downstream side is capable of handling total flow rate of 0.5 LPH with high stage efficiency, quick settling and low pressure drop. Two such configurations are used in parallel to achieve total flow rate of 1 LPH. Specific extraction rate achieved in the contactor based on microbore tubes is compared with the specific extraction rate estimated for a mixer-settler. The comparison shows that the use of microbore tube contactor leads to process intensification.