Cradle-to-gate life cycle assessment of the production of separated mix of rare earth oxides based on Australian production route
Paul Koltun, Vasyl Klymenko
Abstract
Purpose. Life cycle assessment (LCA) to investigate environmental impact resulting from the production of separated mixture of rare earth oxides (REO) mined in Australia. Methods. Analytical study of the literature reviews data, measurements and manufacturers' reports, life cycle inventory databases and reasonable estimates of the processes involved in the production of a separated mixture of different REO was performed. To refine the data, was used an approach based on the basis of the matrix and Monte Carlo simulation. To estimate environmental impact from the production of each REO, the method of distributing the environmental impact between different REO was also used. Findings. The obtained results show that the production process of separated REO has a different environmental impact depending upon type of REO: for light REO global warming potential (GWP) is 1.7-3.9 t of CO 2 eq./t of produced REO; a substantially higher impact for medium and heavy REO (GWP is about 90 t of CO 2 eq. per tonne of REO). The major impact comes from production of praseodymium/neodymium (Pr/Nd) oxides (it's about 80% for GWP). The environmental impact from the radioactivity exposure (if waste from the production process is properly managed) shows a relatively low contribution to overall impact on human health (about 0.2%). Originality. The paper pioneered the method of environmental impact distribution, developed by the authors considering the economic value associated with the removal of several co-products from the production processes. The Monte Carlo simulation was used to determine uncertainty of the obtained results during the LCA study. Such approach was allowed more accurately assess different components of the environmental impact resulting from REO production in Australia for the technology described in this paper. Practical implications. The results obtained in the study on the basis of the proposed methodology allows to identify environmental "hot spots" in the production of separated REO and take practical steps to reduce the negative environmental impact of such production.