The extraction and recovery of rare earth elements from phosphate rock, phosphoric acid, and three phosphate fertilizer waste by-products, phosphogypsum, amine tailings, and waste clay, using a novel aqueous-based extraction solution and an adsorption polymer, poly 1-octadecene 2,5-furandione salt, are examined. Overall extraction and recovery yields were between 80% for gadolinium and 8% for praseodymium from amine tailings, between 70% for terbium and 7% for praseodymium from phosphogypsum, between 56% for scandium and 15% for praseodymium from phosphate rock, and between 77% for samarium and 31% for praseodymium from waste clay. Poly 1-octadecene 2,5-furandione salt effectively bound 100% of the rare earth elements extracted from the solids. Treatment of phosphoric acid with poly 1-octadecene 2,5-furandione salt did not effectively recover appreciable amounts of REEs. These results suggest that this process may be an efficient means of recovering rare earth elements from phosphate mining waste products, and that treatment of phosphogypsum stack water and leachate with poly 1-octadecene 2,5-furandione salt may effectively reduce metal contamination of both surface and groundwater.
Joseph P. Laurino and Jack Mustacato. Periodic Products, Inc. October 2015.