Research article


Hugo Javier Sánchez Moreno, Mishell Moreno Samaniego, Raúl Dávalos-Monteiro, Lenin Javier Ramirez Cando

Online First: April 14, 2023

This work presents an acid leaching process to establish the best leaching agent, for the recovery of lanthanum from the depleted catalyst of the FFC unit at the Esmeraldas Refinery using the following leaching reactants; hydrochloric acid, nitric acid and sulfuric acid. The laboratory work included the physical, chemical and mineralogical characterization of the depleted catalyst sample. From the physical characterization, the granulometry, the real density, and its bulk density were established. The mineralogical analysis was performed by X-ray diffraction, while the chemical analysis was performed by acid digestion and atomic absorption. Subsequently, the best leaching agent was evaluated, for which some conditions were modified, such as: concentration of the leaching agent (0.5; 1.0; 2.0; 3.0; 4.0; and 6.0; M), the incidence of the percentage of solids (10, 20, 30, 40 and 50%) and the leaching time of the process (2, 6, 9, 15, 18 and 24 hours). The maximum recovery of lanthanum achieved was 93.7 % when leaching with hydrochloric acid at a concentration of 2 M for a time of 24 hours and with a solids content of 10 %. Lanthanum recovery analyses in the depleted catalyst were investigated by inductively coupled plasma: ELMER OPTIMA 8000 PLASMA OPTICAL SPECTROMETRY (IPP). Therefore, the intensive research in this field is not only expanding the possibilities of recovery and recycling but also is leading to new and interesting cost-effective and sustainable approaches, as well as providing a reliable industrial perspective to recover and purify rare earths within the framework of a sustainable recycling strategy.


lanthanum, leaching, acid, depleted catalyst, plasma optical spectrometry.