Abstract
Indian coals have difficult to formidable washability characteristics. Presently, five Indian coals were subjected to solvent extraction under ambient pressure conditions using N-methylpyrrolidone (NMP) containing a small amount of Ethylenediammine (EDA) (termed as e, N solvent system). The coals and their solvent refined super clean coal (SCC) products obtained after solvent extraction have been extensively characterised for calorific value, ATR-FTIR spectral analysis, XRD measurements and ICP-MS analysis. The organo-refining of coals through the use of e, N extraction resulted in the production of Super clean coals (SCCs) having 0.2–1.5% ash. Studies have been carried out for the first time to analyse the concentration of minor elements in super clean coal. However, the ATR-FTIR analysis, XRD measurements and ICP-MS analysis also revealed the reduction of major elements such as Na, K, Al, Mg, Ca and Fe. The ATR-FTIR and XRD studies of SCC clearly demonstrated deashing of coals. As high as 94% improvement in calorific value in one of the high ash coals, Pandra coal could also be achieved on extraction with e, N solvent system.
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