For the effective modelling of in-pulp sorption processes the effect of competitive adsorption and fouling must be included. A multicomponent Freundlich isotherm was incorporated in the branched pore adsorption model and applied to the batch adsorption of different metal cyanides onto activated carbon. A leached ore was also used in the verification of the modelling strategy. As a result of the complexity of a leached pulp it is impossible or impractical to consider the competitive or fouling effect of each individual species. Hence, competitive adsorption and fouling were effectively accounted for by the lumping of these effects as a combined competition coefficient. The decreased gold adsorption in a complex multicomponent system compared with a solution of gold on its own can be ascribed conceptually to competition by an imaginary component in a simplified two component system. Pseudo equilibrium isotherms can be used, but carbon/solution contacting times of less than 72 hours could lead to ineffective modelling.