Quantitative Evaluation of Minerals in Lignites and Intraseam Sediments from the Achlada Basin, Northern Greece

Abstract

Seven core samples (five lignite samples and two intraseam nonlignite rock samples) from the Achlada open-cut mine in northern Greece were characterized by X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques. Quantitative evaluation of the mineral phases in each sample was made from the powder X-ray diffractograms using Siroquant commercial interpretation software, which is based on Rietveld principles. The main minerals in the low-temperature ash (LTA) ash of the lignites are kaolinite and illite, with bassanite and quartz in minor proportions. The nonlignite rock samples mainly consist of illite, mica (2M1), and kaolinite (poorly ordered), along with quartz, chlorite (ferroan), feldspar (albite), rutile, and dolomite. Oriented-aggregate XRD study further shows the presence of smectite, and interstratified illite/smectite (I/S), in the clay fractions of the lignite and rock samples, with the mineral matter of the lignites being richer in kaolinite, smectite, and I/S than in mineral matter of the nonlignite materials. The differences in mineralogy between the lignite and the rock materials probably reflect selective concentration of minerals in the original peat during deposition, combined with authigenic precipitation of minerals such as kaolinte in the peat deposit. Inferred chemical analyses derived from the XRD data show reasonably good correlations with chemical data obtained by direct ash analysis, especially if the smectite and I/S are taken into account. This provides a link between mineralogical and chemical studies that may be valuable in evaluating the behavior of the lignite under different utilization conditions.

Determination of mineral matter and elemental composition of individual macerals in coals from Highveld mines

“…For example, the lowest percentage of SO 3 in Table III occurs in sample 2, which also has the lowest percentage of CaO, and the highest SO 3 percentage occurs in sample 6, which has the highest CaO percentage. Links between CaO and SO 3 in ashes prepared under similar conditions are discussed further by Koukouzas et al (2009).…”

Clay Mineralogy and Paleoclimatic Properties of the Neogene Deposits in Sinanpaşa Basin (Afyon-Western Anatolia)

“…However, the areas where Fe-rich chlorite in the coal levels are seen as pore fillings, may also be genetically linked to diagenetic origin (Bartier et al, 1998). Kaolinite, on the other hand, may have formed by the in situ / authigenic deposition of silicon and aluminum elements dominant in these environments as a result of the chemical decomposition of feldspars (mostly sodic plagioclases) in high water-active environments (Koukouzas et al, 2009) and also can be transported detritically to this environment (Keller, 1978). Non-clay minerals such as quartz, feldspar, cristobalite, opal-CT, amphibole, and zeolite (natrolite) were detected in the middle-late Miocene pyroclastic deposits.…”

“…The EDX analysis of these plates shows similarities to kaolinite (Table 4). The concentration of kaolinite, especially in the coalbearing levels, can be attributed to the autogenetic deposition of silicon and aluminum there (Koukouzas et al, 2009).…”

Clays from Neogene Achlada lignite deposits in Florina basin (Western Macedonia, N. Greece): A prospective resource for the ceramics industry

“…Pollen analysis and a microfaunal study (Ioakim, 1984;van de Weerd, 1979) have concluded in an early Ruscinian age (lower boundary: 5.3 Ma) for the lower members of the unit and a late Ruscinian one for the upper members (Koufos, 1982). Current studies (Koukouzas et al, 2009(Koukouzas et al, , 2010 have shown that the Achlada deposits belong to the Komnina lignite sequence, which is correlated to chron C3An.1n (6.01-6.28 Ma) (Weber et al, 2012). (iii) The upper unit (Lofi formation) presents alternations of clays, marls, marly breccias, and sandy conglomerates.…”