Ion-Exchange Separation of Rare Earth Elements and Aluminium during Recycling the Spent Fluid Cracking Catalysts
A. O. PUZHEL1, V. A. BORISOV2, M. V. TRENIKHIN2
1Dostoevsky Omsk State University, Оmsk, Russia
2Omsk State Technical University, Оmsk, Russia
Keywords: sorption extraction of rare earth elements, chelating cation exchange resin, sorption mechanism, metal separation, spent fluid cracking catalysts
Abstract
The possibility of selective ion-exchange separation of rare earth elements (REE), in particular La3+, from weakly acidic solutions containing an excess of Al3+ and Fe3+ ions has been demonstrated. The sorption of REEs and Al3+ was conducted under static and dynamic conditions using the chelating ampholytic resin Purolite S-930 in the Na-form. Selective REE desorption was performed by washing the column with the aqueous solution of EDTA, while Al3+ ions were retained in the column. The conditions for La3+ ion extraction were optimized, and the mechanism of their sorption was investigated. Experiments confirmed effective lanthanum extraction at the optimal pH 4.0 and a temperature of 25 °C. An increase in temperature to 65 °C reduces the sorption equilibrium time from 5 to 3 hours at an initial lanthanum concentration of 2.4 mg/L. The effective activation energy of the process was calculated to be 36.9 kJ/mol, and the maximum sorption capacity was determined as 322 mg/g. The influence of EDTA concentration on the efficiency of La3+ ion desorption in the presence of Al3+ was demonstrated. The developed methodology was applied for the sorption purification of REE-containing technological solution obtained during complex fluoride processing of the spent oil-cracking catalysts. Laboratory-scale sorption purification of this solution yielded a sufficiently pure concentrate (with the total REE oxide content at 85 wt%). Selective desorption from the iminodiacetate ampholyte allows a 30-fold REE concentrating from the technological solution, with losses not higher than 20 %.
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