The segmented micro-flow extraction and separation of the adjacent elements of Co from Ni sulphate solution with Cyanex 272 was developed using a micro-scale coiled flow inverter (CFI). This was compared with the conventional batch extraction at comparable conditions. Continuous operation of a process involving liquid-liquid extraction and then two-phase separation was achieved. For the latter a micro-scale separator was used. Compared with batch extraction, the segmented micro-flow extraction process showed by order-of-magnitude faster extraction times, higher extraction ability for Co, lower extraction for Ni, and then a better selectivity between Co and Ni for industrial-matching sulfate solutions with high Co and Ni ions concentration. In addition, flow patterns were recorded in the CFI by a high speed camera. Regular columnar slug flow was formed at low flow rates, and the length of the inlet slug was found to be a Gaussian function of the flow rates. In-and outlet flows matched, i.e. there was no change in the flow pattern when passing the CFI. At higher flow rates, deviations from the ideal pattern were found and in-and outlet flow did not match. Finally, the mass transfer coefficient in the range of 0.014 to 0.24 mm•s -1 was obtained.

No abstract