Correlation between optical, chemical and micro-structural parameters of high-rank coals and graphite

• Type: Article in International Scientific Journal
• Date: 2009

Authors

Marques, M (Author) Other; Suarez Ruiz, I (Author) Other; Flores, D (Author) FCUP; Guedes, A (Author) FCUP; Rodrigues, S (Author) Other

Journal

Title: International Journal of Coal Geology

Vol. 77

Pages: 377-382

ISSN: 0166-5162

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 112 Citations

Scopus - 132 Citations

Scientific classification

FOS: Engineering and technology > Environmental engineering

Other information

Authenticus ID: P-003-NPZ

DOI: 10.1016/j.coal.2008.06.002

Abstract (EN): In order to identify the parameters that best characterize the chemical and structural evolution of organic matter during coalification, the relationships between optical, chemical and micro-structural parameters in high-rank coals and natural graphite were studied. The samples include anthracites from Pefiarroya-Belmez-Espiel Basin (Spain), Douro Basin (Portugal), and Alto Chicama Basin (Peru); and natural graphite from Canada, Mozambique, and Austria. Correlations between the following optical parameters were assessed: vitrinite random reflectance (R(r)), Reflectance Indicating Surfaces (RIS) axis (R(MAX), R(INT) and R(MIN)), and RIS parameters (R(am), R(ev) and R(st)), as well as B(w) and Al anisotropy parameters. Furthermore, the chemical parameters used were chosen according to their significant variation in coals, namely volatile matter, carbon, and hydrogen contents calculated in dry ash free basis (VM(daf), C(daf), H(daf)), as well as the H/C atomic ratio. Structural organization was characterized by micro-Raman spectroscopy and XRD. Raman parameters used were the full width at half maximum (FWHM) and position of G and D1 bands on the first-order Raman spectrum, and the ID1/IG intensity area ratio. The selected XRD parameters were interlayer spacing d(002), and crystallite sizes L(a) and L(c) . Results show that: (i) R(MAX) RIS axis seems to correlate best with chemical and micro-structural parameters; (ii) for the majority of studied samples, H(daf) and H/C atomic ratio are the only chemical parameters with significant correlations with R(MAX); (iii) the FWHM of the G band of Raman spectrum shows good linear correlation with the XRD parameter d(002); and, (iv) structural organization of carbon materials, as measured by trends in their optical and crystalline parameters, is influenced by their hydrogen content (daf basis) and therefore by the H/C atomic ratio.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 6