Interlaboratory comparisons of petrography of liquefaction residues from three Argonne Premium coals

摘要

Three Argonne Premium coal samples, the Beulah-Zap lignite (North Dakota), the high volatileA bituminous Stockton (West Virginia), and the low volatile Pocahontas No. 3 (Virginia), were groundto three initial sizes: -20 mesh, -100 mesh, and "micronized". The samples were each subjected toliquefaction at 673 K for 30 min at a 2:1 tetralin :coal ratio and in an H 2 atmosphere at 13.79 MPa(~ 2000 psi). Polished pellets of the unconverted residues were circulated to three laboratories for a studydesigned to determine, albeit on a limited scale, the interlaboratory consistency in constituent identificationand the problem areas in maceral/neo-maceral/mineral recognition. Within broad categories, theagreement for the Beulah-Zap and Pocahontas No. 3 residues is good. The high volatile A bituminousStockton coal was the most plastic and most altered, resulting in a residue lending itself to more subjectiveinterpretations. The biggest discrepancy between the laboratories is in the distinction of granular residueand mineral matter and in the transitions between "partially reacted macerals" and "vitroplast" andbetween "vitroplast" and "granular residue". The initial size of the feed coal appears to influence therecognition of material in the residue.