Targeting ash generated from coal combustion as secondary source of rare earth elements

ABSTRACT

The demand of Rare Earth Elements (REEs) has increased for the development of clean and green technologies. Conventional geological sources of REE are insufficient to overcome the high demand of REE; hence, the secondary resources are being actively explored. Coal ashes (CAs), a potentially hazardous material, is one of the best secondary sources containing high concentration of REE. The present study aims to explore the abundance of REE in coal and coal ash from different Thermal Power Stations (TPS). The mineralogy and surface morphology of all samples have been determined. The coals mostly consist of quartz and kaolinite, whereas CAs predominantly contain quartz and mullite. Both coal and CAs are dominated by LREE elements, followed by MREE and HREE. The outlook coefficient (C_out) is close to “1” and the critical percentage (C_p) is more than 30%. Coal ash from some of the TPS is identified as secondary source for REE. Fractionation study of REE from coal to CA is carried out to understand the feasibility of CA. A Pearson correlation has been plotted for individual REE elements with other parameters to understand the affinity of REE to different phases of CA.

KEYWORDS:

• Rare Earth Elements (REEs)
• secondary resources
• coal ash (CA)
• fractionation
• mineralogy

Acknowledgements

SM likes to thank the Science and Engineering Research Board, Govt. of India for Research Grant (No. EMR/2017/000856). We thankfully acknowledge all the Power Plants for allowing us to collect the samples. Authors thank SAIF, IIT, Bombay for providing the ESEM-EDS analyses, RQA Research Group, CSIR –CIMFR, Dhanbad for providing the proximate analyses of coals and Environment, Emissions and CRM Section, CSIR–CIMFR, Dhanbad for providing ultimate analyses of coal samples. We are also thankful to the Director, CSIR–Central Institute of Mining and Fuel Research, Dhanbad for allowing publishing this manuscript.

Disclosure Statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Supplementary Data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/19392699.2023.2194640.

Additional information

Funding

The work was supported by the Science and Engineering Research Board [EMR/2017/000856]