Demineralization of Coal from Johilla Coalfield using Neutrophilic Native Bacteria: A Novel Technique to obtain REE from Coal

Abstract

Abstract Mineral matter in coal is the host of several environmentally sensitive elements and a potential source of Rare Earth Elements (REE). During combustion, some trace elements are liberated as gas, while others get concentrated in ash, contaminating soil and local water bodies. Minimizing the inorganic content makes the coal clean and eventually increases its calorific value. Bacteria serve as an eco-friendly remediation tool, particularly neutrophilic ones that facilitate the treatment at mild pH and ambient temperatures. Use of native bacteria accelerates the treatment process by readily adapting to substrates. We present the remediation potential of three native neutrophilic bacteria in this study. After six days of treatment, Bacillus sp. CpH06 has reduced ash yield by 15.96%, trace elements by 26% to 75%, and REE by 24% to 50%. Bacillus anthracis CpH08 has reduced ash yield by 22.6%, trace elements by 6.4% to 70.5%, and REE by 8.4% to 37%. Maximum ash yield reduction of 22.91% was attained by the Cronobacter sp. CpH10 including reduction of 8.1% to 73% of trace elements and 26% to 48% of REEs. The FTIR spectra reveal alterations in both peak intensity and position of inorganic functional groups resulting from the removal of elements, formation of new bonds, and the elimination of certain pre-existing functional groups. XRD spectra indicate bio-oxidation mechanism, exhibited by the removal of copper sulfate hydroxide and pyrite along with formation of Jarosite and metal-sulfide peaks. The findings encourage further research on the effectiveness and performance of these bacteria on diverse types of coals.