| Abstract Scope |
The increasing importance of rare earth elements (REEs) in modern electronics and green energy applications, coupled with rising geopolitical supply risks, has generated interest for developing secondary REE supply chains. Phosphogypsum (PG), a waste from fertilizer production containing 0.03 – 0.4 wt% REEs, is identified as a secondary resource for REEs. Here, a novel process utilizing microwave pretreatment was developed to increase PG porosity by heating and releasing water therein, improving lixiviant diffusion into the PG particles. Optimal microwave conditions were found at low power and short duration (600 W, 5 min), which increases PG porosity with minimal conversion of gypsum to less soluble phases, and at high power and long duration (1200 W, 15 min), in which thermal PG degradation and REE release occur at the expense of gypsum conversion to less soluble phases. The highest REE extractions (80% Nd, 99% Y, 99% Dy) were achieved with the latter. |