Effects of dispersed phase flow rate and internals on the throughput of a mixer-settler extraction column with lifter-turbine impellers

Maximum throughput and pressure distribution within the mixer were measured for a mixer-settler extraction column of 100 mm diameter in which the inte rnals have been simplified in comparison with the column used in previous w ork. The effects of agitation speed, structure of riser and dispersed phase flow rate on the maximum flow rate of the continuous phase were examined, as well as the pressure distribution in the mixer. Throughput increases wit h agitation speed except for low agitation speed. The riser position which leads to the largest throughput is the point beneath the impeller. The flow resistance accompanied by the discharging dispersed phase and the effect o f shear flow at the upper end of the riser make it difficult to estimate th e effects of the riser diameter and the riser height on the maximum through put. It was confirmed that the throughput is substantially determined from the balance between the fluid flow pressure drop, the suction pressure indu ced by the lifter-turbine impeller, and the buoyant force. Though the estim ated value is somewhat larger than the experimental one for high agitation speed, the change ill maximum throughput with the organic flow rate for var ious diameters of the riser is reproduced by the calculation.