Simulation and optimizacion of the separation of rare earth elements

Abstract

Consulta en la Biblioteca ETSI Industriales

[ES] Rare earth elements (REE) are used nowadays in new technologies such as electronics devices and military applications. The world demand of these elements is increasing as well as the purity requirements. The subject of this work was to study the feasibility of the purification of REE via ionexchange chromatography from an industrial point of view. The decision variables were the loading, washing, elution and post-elution volumes as well as the gradient step and buffer concentrations. The value for these variables was optimized for each objective and the other design variables had beforehand fixed values. The study is based on a feed stock with mainly heavy REE, dominated by Erbium and Ytterbium. The final product consisted in separated fractions of REE with a purity requirement of 99% for the element to retrieve. The first conclusion was that the process is economically feasible. But the operation point for the highest annual benefits only retrieves Ytterbium and Thulium for the feed stock used in the present work. The production cost optimization showed eight different operation points which confirmed that the costs increased rapidly when the demand on yield increased. The option to retrieve only Ytterbium or Ytterbium and Thulium were still the most economical one, but retrieving Holmium and Erbium was still possible if the increase in production costs is affordable. In conclusion this study has showed that the ion exchange chromatography is a feasible separation operation on the industrial scale for the purification of REE which can be operated to retrieve a variable range of products.