Rare Earth Elements Partition and Recovery During Electrodialytic Treatment of Coal Fly Ash

Abstract

Rare earth element (REE) recovery from waste (end-of-line, reusable, recyclable, etc.) should become an essential stream of REE for current demands, making methods to achieve this recovery paramount. This study uses the electrodialytic method (EDR) as an REE extraction method from coal fly ashes. We used different chemicals to assist REE extraction during EDR: distilled water, 0.01M NaNO3, 0.4M Sodium acetate in 1.0M Acetic acid, and 0.5M Citric acid. Citric acid achieved the highest REE extraction/recovery from the four studied solutions: up to 40%. This represents a total recovery of 148 g REE from 1 ton of coal ashes. The citric acid experiment also proved to be energy efficient, using 70Wh per 100g of treated coal ash. The acidic environment provided by the citric acid supplies higher REE migration rates toward the cathode. Once at the cathode compartment, REEs then precipitate at the cathode complexed as Ca- and P-bearing minerals.