Thermogravimetric and Raman spectroscopic investigations on different coals in comparison to dispersed anthracite found in permineralized tree fern Psaronius sp.

Simple procedure for an estimation of the coal rank using micro-Raman spectroscopy

“…1. It can be noted that, as the reflectance value of the grain increases, both D-and G-bands become narrower and the position of the D-band shifts to lower frequencies, as had been observed by other authors Nestler et al, 2003).…”

“…Few papers investigate large numbers of natural coal samples (Cuesta et al, 1994;Guedes et al, 2010;Kelemen and Fang, 2001;Nestler et al, 2003;Quirico et al, 2005;Zerda et al, 1981), or others have samples in a different R r range (Marques et al, 2009). While the reported data are consistent with our measurements, the plots found in the literature do not show the trend as clearly, as the data presented in this work.…”

“…The history of different approaches to coal analysis with Raman spectroscopy has been reviewed by Potgieter-Vermaak et al (2011). Raman spectroscopy has been used to estimate coal rank Kelemen and Fang, 2001;Liu et al, 2013;Marques et al, 2009;Nestler et al, 2003;Quirico et al, 2005;Ulyanova et al, 2014;Valentim et al, 2010;Zerda et al, 1981) and to track maturity changes in coals or kerogens after some additional thermal treatment (Bernard et al, 2010;Chabalala et al, 2011;Green et al, 1983;Johnson et al, 1986;Li et al, 2006a,b;Liu et al, 2014;Sheng, 2007;Zaida et al, 2007;Zhang et al, 2011;Zhou et al, 2014), high pressure application (Bustin et al, 1995), anisotropic stress (Urban et al, 2003), or metamorphic transformation (Bonal et al, 2006;Lahfid et al, 2010;Rahl et al, 2005;Wopenka and Pasteris, 1993).…”

“…Others use a third band between D-and G-bands (Johnson et al, 1986;Li et al, 1996), either on the high frequency side of the G-band (Rodrigues et al, 2013;Wopenka and Pasteris, 1993), or on the low frequency side of the D-band (Nestler et al, 2003;Zerda et al, 1981) in the fitting procedure. Angoni (1992) used three to four Lorentzian or Gaussian functions for coke and three for coals.…”

Raman spectroscopy for the analysis of coal: a review

“…A negative correlation between the FWHMof the G band and RoV% was also reported, namely that the graphitic character increased as the G band became narrower. Nestler et al [51] investigated 11 coals varying from low to high rank (VoR% from 1.5 to 60). The study was mainly to characterize a fossilized tissue by comparing it with the Raman spectra of various anthracitic and sub-bituminous coals and relate that to the degree of coalification.…”