Petrographic and reflectance analysis of solvent-swelled and solvent-extracted South African vitrinite-rich and inertinite-rich coals

Daniel Van Niekerk, Gareth D. Mitchell, Jonathan P. Mathews

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Maceral transitions during solvent swelling and extraction of two South African coals similar in rank and age, but different in maceral composition, were evaluated. Inertinite-rich Highveld coal (dominated by semifusinite) and vitrinite-rich Waterberg coal were used. Maceral-group analysis of solvent-extracted and solvent-swelled residues showed no changes in the maceral composition for both coals. Solvent-extracted residues exhibited significant observable changes of some particles: particle fracturing, decrease in reflectance and rounding of particle edges. Inertinite-rich coal exhibited extensive fracturing during solvent treatment. Random reflectance analyses of both coals showed that solvent treatment reduces reflectance values of both vitrinite and inertinite. Vitrinite reflectograms showed a shift from the dominant reflecting V-types to lower-reflecting V-types. The inertinite reflectograms exhibited an increase in the number of reflecting inertinite-types (I-types) with solvent treatment, resulting in a broadening of the reflectograms. The changes in reflectance between the original and solvent-treated coal may be attributed to a combination of structural, elemental or surface changes. Current data for these South African coals suggests a relationship between solvent extraction and mean random reflectance: the higher the extraction yields the lower the mean random reflectance.

Original languageEnglish (US)
Pages (from-to)45-52
Number of pages8
JournalInternational Journal of Coal Geology
Volume81
Issue number1
DOIs
StatePublished - Jan 7 2010

All Science Journal Classification (ASJC) codes

  • Fuel Technology
  • Geology
  • Economic Geology
  • Stratigraphy

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