Special Section on 2018 Clean Energy

Simultaneous Extraction of Clean Coal and Rare Earth Elements From Coal Tailings Using Alkali-Acid Leaching Process

[+] Author and Article Information
Vinoth Kumar Kuppusamy

Norman B. Keevil Institute of
Mining Engineering,
University of British Columbia,
517-6350 Stores Road,
Vancouver BC V6T 1Z4, Canada
e-mail: vinothkumar@alumni.ubc.ca

Amit Kumar

Norman B. Keevil Institute of
Mining Engineering,
University of British Columbia,
517-6350 Stores Road,
Vancouver BC V6T 1Z4, Canada
e-mail: Amit.kumar.ism@gmail.com

Maria Holuszko

Norman B. Keevil Institute of
Mining Engineering,
University of British Columbia,
517-6350 Stores Road,
Vancouver BC V6T 1Z4, Canada
e-mail: meh@mining.ubc.ca

1Corresponding author.

Contributed by the Advanced Energy Systems Division of ASME for publication in the JOURNAL OF ENERGY RESOURCES TECHNOLOGY. Manuscript received June 27, 2018; final manuscript received March 13, 2019; published online April 19, 2019. Assoc. Editor: Ashwani K. Gupta.

J. Energy Resour. Technol 141(7), 070708 (Apr 19, 2019) (7 pages) Paper No: JERT-18-1469; doi: 10.1115/1.4043328 History: Received June 27, 2018; Revised March 13, 2019

With the supply restriction from traditional rare earth deposits, alternative sources of rare earth elements (REEs) such as coal are being studied. The United States National Energy Technology Laboratory has identified US coal deposits as a potential source of rare earth elements. Several techniques such as physical separation, flotation, ion-exchange, agglomeration, and leaching are being evaluated for the successful exploitation of these elements from coal and its by-products. A previous study published in the Geoscience BC 2018 mineral report on the characterization of REE in the British Columbian coal samples have shown that a major portion of the rare earth in the run of mine coal reports to the middling and tailing streams. Hence, this study is focused on the extraction of the rare earth from coal tailings. Several studies have shown the use of an alkali-acid leaching process to successfully demineralize various high ash coals to produce a clean coal concentrate since the ash-bearing components such as clay and quartz were removed from the coal during this process. In this study, the alkali-acid leach process was adopted to chemically clean coal tailings as well as to extract rare earth elements. Different process parameters such as sodium hydroxide (NaOH) concentration, temperature, and time were studied. Results showed that it is possible to extract more than 85% of REE with this process and simultaneously produce clean coal from coal tailing.

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Grahic Jump Location
Fig. 1

Alkali-acid leach test procedure

Grahic Jump Location
Fig. 2

Particle size distribution of tailings coal sample

Grahic Jump Location
Fig. 3

Effect of sodium hydroxide concentration on product ash (%) for various temperatures

Grahic Jump Location
Fig. 4

Quantitative XRD result of feed coal sample used for the alkali-acid leach test

Grahic Jump Location
Fig. 5

FTIR spectra of coal tailings and residue after leaching

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Fig. 6

REE recovery in selected clean coal residue with varying ash content (low to high) obtained after alkali-acid leach test. Results are displayed in increasing order of REE recovery.



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