Comparison of dysprosium production from different resources by life cycle assessment

Abstract

Rare earth elements (REEs) are essential for low carbon technologies. Production of dysprosium (Dy) is mostly induced by rare earth magnets demand (approximately (approx.) 95% of total demand). It is almost exclusively supplied by ion adsorption clays (IACs) of Southern China. Other sources, such as bastnaesite/monazite or eudialyte ores, are also conceivable. Bastnaesite/monazite ores usually show low dysprosium contents. So far, hardly any REEs from eudialyte ores have been processed. The Norra Kärr deposit (Sweden) is one of the largest, highest grade, non-Chinese heavy REE deposits in Europe. Almost all studies on environmental effects of REEs production investigate the bastnaesite/monazite route. Recently, a first life cycle assessment (LCA) of IAC in-situ leaching was published. The present study broadens the scope firstly by including additional beneficiation and separation processes and subsequent production of the single metal dysprosium. Secondly, a comparison of the environmental performance of three production routes from different resources, IAC, bastnaesite/monazite and eudialyte is investigated. The results show that the environmental performance based on eudialyte is the best. The results of IAC and bastnaesite/monazite routes are comparable, but only for low amounts of leaching agent for IACs. For all three minerals freshwater ecotoxicity, human toxicity as well as eutrophication marine and freshwater are important environmental effects. In case of IAC marine eutrophication has the largest share due to in-situ leaching. This paper allows for the first time a straight comparison of Dy production based on three different minerals due to a consistent methodological frame, basic assumptions and parameters.