A thermodynamic approach to ion flotation. II. Metal ion selectivity in the SDS–Cu–Ca and SDS–Cu–Pb systems

Two thermodynamically based, theoretical models are developed to predict the selectivity coefficients for Ca2+/Cu2+ and Pb2+/Cu2+ in ion flotation with sodium dodecylsulfate (SDS) as the collector. Pseudo selectivity coefficients predicted from surface tension measurements are 1.12 and 1.69 for Ca2+/Cu2+ and Pb2+/Cu2+. This agrees rather poorly with experimentally measured selectivity coefficients of 1.44 and 2.14, but does predict the order of selectivity Cu2+<Ca2+<Pb2+. The selectivity coefficients estimated by the dehydration model are 1.55 and 2.07 for Ca2+/Cu2+ and Pb2+/Cu2+, respectively, which agrees well with the experimentally measured values.