This work presents an approach to describe the liquid-liquid equilibrium in metal ion extraction processes in industrial conditions with high metal ion loadings. At these conditions, the concentration of unbonded extractant is depleted, and extraction curves deviate significantly from those obtained for single ion extraction. As case study, the extraction of Co2+, Mg2+ and Mn2+ with Cyanex 272 was considered. Preliminarily, the equilibrium of single metal ion extraction and total loadings below 2% was modeled. The extraction of each metal ion was described by considering the extraction mechanism as a function of pH (coupling the chemical and the phase equilibria) and adjusting the overall equilibrium constant. Finally, the extension of the previous equations to account for the presence of multiple extractable ions was developed. The extraction of cobalt from multicomponent solutions at total metal ion loadings of approximately 45%, typical of industrial production and separation operations, was experimentally studied and successfully predicted. Whereas simple, the proposed extension provided an adequate description of the extraction ratio at these conditions, allowing the simulation of industrial process scenarios using only single-ion extraction data, without adding any adjustable parameter.