Magnetic Separation for Rare Earth Oxide Recovery at Sillamä, Estonia

Abstract

In summary, we have shown that magnetic separation can be used to concentrate rare earth oxides or actinides from extraneous materials yielding more efficient recovery and treatment operations. We have demonstrated that the extraction and concentration of paramagnetic actinides (PuO₂, UO₂, etc.) from soils is feasible, where our actinide separation results have shown that HGMS is effective for extracting >90% of small radioactive particles from soil slurries. In addition, recovery of rare earth oxides such as Pr₂O₃, Gd₂O₃, and Ce₂O₃ has successfully been demonstrated by HGMS and MRS. Analytical models were developed that describe both magnetic separation process. The model provides guidance in selecting the appropriate bench scale experiments to perform and assists in analyzing the resulting data. A validated analytical model also supports prototype design and process scaleup. We anticipate that with proper pretreatment, mainly consisting of size reduction, a permanent magnet roll separator will be the method of choice for recovery of rare-earth oxides. While magnetic separation cannot extract diamagnetic products (such as La₂O₃) from the soils, we expect that over 90% of paramagnetic rare earth oxide components can be extracted efficiently and economically.