The effect of the agitation time on the behaviour of a dispersion during separation in a batch mixer-settler was studied. The studies were carried out on the four stages of copper transfer from hydrochloric acid to sulphuric acid medium using the bifunctional extractant Kelex 100(R). The organic phase was a 20% (v/v) solution of Kelex 100(R); the aqueous phase had different salt compositions and acidities in the different stages. The measurements were performed after completion of the mass transfer process. Four periods were distinguished in the behaviour of the dispersion. There were three cases of interfacial movement during the free motion of the droplets.