Removal of REE's concentrate from spent catalysts of FCC by sulfuric-fluorine method.

This paper presents a method for extracting rare earth element (REE) concentrate from spent catalysts of fluid catalytic cracking (SFCC) using the method of sulfuric acid leaching of a mixture of SFCC and NH4F. The optimal conditions for obtaining the concentrate are an excess of H2SO4 (1.3 times), the experiment duration of 40 minutes, and an excess of NH4F (1.3 times). The XRD, IR spectroscopy, scanning electron microscopy with EDX analysis, and atomic absorption spectroscopy were used. The resulting concentrate contains REE in the form of fluorides, their content increases by 3–9 times. Physicochemical methods of analysis detect REE fluorides, Topaz, and SiO in the concentrate. The ratio of cerium:lanthanum in thr concentrate is higher than in SFCC because lanthanum is extracted into solution as a sulfate. [ABSTRACT FROM AUTHOR]