Mineralogical variations and geochemical distribution of rare earths and Yttrium (REY) in coal and overburden rocks of some Indian coal mines of Gondwana coalfield.

Conventional sources of rare earth elements including Yttrium (REY) are not sufficient to meet the global demand. This article targets to delineate alternative resources such as coal and overburden rocks (OB) associated with the respective coal mines. The authors have reported the occurrence and distribution pattern of REY, and seamwise mineralogical variations in some coal mines of Jharia and Rajmahal Basins. In addition to REY, occurrences of some other trace and critical elements like Sc, Ga, Sr, Rb, Nb, etc., in coal and OB have also been reported. The mineralogical transformation and REY partitioning from coal to high-temperature ash (HTA) have also been determined. The highest composition of REY in coal, HTA and OB has reached up to 239.2, 1012.4 and 1051.0 ppm, respectively. Thus, the REY content in all coal and HTA is higher than the global cut-off grade. The enrichment of REY from parent coal to HTA can be understood by the enrichment coefficient (Δe), thus, Δe of each HTA is estimated to reach up to a maximum of 7.01. Outlook coefficient (Cout) is used in demarcating REY ore body as promising, highly promising and unpromising. The Cout of the present study ranges from 0.57 to 2.16. The highest Cout of coal, HTA and OB are 1.09, 0.88 and 2.16, respectively. The findings of the present study are encouraging for some promising secondary resources of REY. Research highlights: Coal, coal ash and OB rocks as alternative sources of rare earths and Yttrium Seamwise mineralogical variations in coal, HTA and OB rocks Occurrence and distribution of REY in Jharia and Rajmahal mines of Gondwana coalfield Use of outlook coefficient to determine potential secondary source of REY [ABSTRACT FROM AUTHOR]