Effect of internal recycle on mixer-settler performance

A diffusion with interfacial reaction model was applied to simulate the transfer mechanism for copper extraction with LIX64N in a mixer-settler. The simulations of the experimental data of both batchwise and continuous operations indicate that the reaction at the interface is the rate-limiting step. With a simplified interfacial reaction model, the performance of the mixer-settler under continuous operation with either phase recycling was predicted with the model parameters obtained from the previous simulation. The agreement between the predicted values and the experimental data was reasonably good. The effect of internal recycle can be accounted for by the change of the phase ratio in the mixer. In both continuous and continuous with recycle operations, optimum performance was obtained at an organic-to-aqueous phase ratio, ( O/ A) mixer , equal to two. Improvement in the performance of a mixer-settler for the copper-LIX64N system can be obtained when recycle gives ( O/ A) mmixer=2.0, otherwise the effect is detrimental no matter which phase is recycled.