Researcher: MSc. Santeri Kurkinen, LUT University, Department of Separation Science, Yliopistonkatu 34, 53850 Lappeenranta
Supervisors: Prof. Tuomo Sainio, Dr. Sami Virolainen, both from LUT University
Rare earth elements (REE) are a set of 17 elements with extraordinary properties. Their numerous applications include electronics, LEDs, high strength magnets, automotive catalytic converters, and high temperature superconductors. REE are not particularly rare in Earth’s crust, but they are difficult to extract and purify cost-effectively.
Besides ores, REE are found in by-products of minerals processing. Phosphogypsum waste (PG), which is formed in phosphate fertilizer production, may contain 0.2 wt-% of REE. PG is available in huge quantities. In Finland alone, more than 1.5 million tons of PG is produced and piled annually.
REE can be leached from PG with, e.g., sulphuric acid. Interestingly, leaching can be done under very mild conditions if functionalized polymeric particles, called ion exchange resins, are added to the leaching reactor. The polymer particles quickly bind the liberated REE ions from the solution, increasing leaching yield.
PuREE project aims at further developing such a “resin-in-leach” process. Significant improvements in leaching efficiency and selectivity are achieved by optimizing the chemistry of the functionalized polymer. Once the REEs are bound to the polymer, they must be recovered to reuse the polymer. The sustainability of this step is improved by using biodegradable chemicals for REE recovery. Further purification of the REEs is done in a separation column using another type of polymeric separation material.
PuREE project produces new data and process options for sustainable production of REEs from a secondary source in Finland.