Development of an engineering model for nickel loading onto an iminodiacetic resin for resin-in-pulp applications: Part II — Evaluation of existing models and their extension into a hybrid correlation

This paper examines the applicability of several engineering models to the case of nickel loading onto an iminodiacetic chelating resin, under infinite solution volume conditions. Results showed that the Vermeulen model for intraparticle diffusion and the second order reaction model were best able to predict the shape of individual test runs. However, none of the models examined was able to fit data over the entire test range of 50–5000 ppm nickel, using a single fit parameter. A two-parameter hybrid correlation was developed which was able to provide a good fit to the data over this concentration range at two different resin bead size fractions. This hybrid correlation was fit to nickel loading onto a second iminodiacetic resin, as well as to copper and cobalt loading onto the first resin tested. The correlation showed versatility in being able to provide adequate fits to all data sets, and the order of magnitude of the empirical diffusivities is similar to self-diffusion coefficients reported in the literature. Preliminary results suggest that the second fit parameter, α, is an indicator of how sharp a boundary exists between the reacted and unreacted portions of the ion exchange bead.