RECOVERY OF RARE EARTH ELEMENTS FROM COAL COMBUSTION FLY ASHES

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7105-98-8 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 11, 995-1002 pp, DOI: 10.5593/sgem2017/11/S04.127

ABSTRACT

According to data reported in the EU report, critical raw materials include 20 raw materials, including rare earth heavy metals (Gd-Lu and Y) and rare earth light metals (La-Eu). Thus, rare earth metals include lanthanides of atomic number 58-71 and scandiums with atomic numbers Sc -21, Y -39 and La -57, respectively.
Rare earth metals are used in many modern, innovative techniques such as optics, nuclear technology, production of permanent magnets that are part of discs for computers and automotive hybrid motors, thermal coatings for jet engines, catalysts, etc. The paper analyzes the process of recovery of rare earth metals from fly ash from Polish power plants with coal combustion in pulverized coal boilers. It has been confirmed that the total rare earth content in fly ashes from Polish power plants is between 250-450 ppm and rarely reaches 500 ppm. It has been found that elements with odd atomic numbers are less common in the test material than with even atomic numbers. Research on the hydrometallurgical recovery of rare earth metals from fly ash using sulfuric acid as a leaching agent was conducted. The effect of sulfuric acid concentration and some kinetic parameters on the leaching rate of individual rare earths was determined. The possibility of obtaining rare earth metals from ashes in Polish conditions was assessed.

Keywords: fly ash, recovery of rare earth metals, hydrometallurgy