Fariborz Goodarzi

Reconnaissance study of mineral matter and trace elements in Greek lignites

Abstract Mineral matter in low-temperature ashes, major oxides and trace elements were determined for twenty-eight selected lignite samples and their respective 1000°C ashes from various locations in Greece using X-ray diffraction, X-ray fluorescence spectroscopy and INAA. Lignites ashed at lower temperature (150°C) reveal the presence of quartz, feldspars, layer silicates, pyrite, gypsum, bassanite and anhydrite in all samples. In northwestern Greece (Epirus, Kozani, Florina and Ptolemais) calcite, siderite, magnesite, epsomite, hexahydrite, jarosite and meta-aluminite coexist with the common occurring minerals. Large variation in the concentration of major constituents in the 1000°C ashes is observed. SiO 2 varies from 11.98% to 87.72%, Al 2 O 3 from 4.53% to 23.36%, Fe 2 O 3 from 3.01% to 39.72%, CaO from 0.55% to 43.05%, MgO from 0.18% to 9.17% and SO 3 from 0.02% to 32.72%. Smaller variations are exhibited by TiO 2 , Na 2 O, K 2 O and P 2 O 5 . These variations are attributed to the depositional environment. High concentrations of Pb (548 ppm), Zn (2991 ppm), Ba (1520 ppm), As (1131 and 1675 ppm), Mo (565 and 712 ppm), W (191–420 ppm) and Sb (69 ppm) are reported in the 1000°C ashes of the selected lignites from Serres and Drama, northern Greece. Samples from another location in northern Greece, Serres, yield >5000 ppm U while in Drama (Dipotama) U concentration reaches as high as 17,600 ppm. The U enrichment of lignites in these locations is attributed to the leaching of this element from the superimposed U-bearing volcanic rhyodacitic rocks of Oligocene age. In southern Greece, Peloponnesus, lignite samples from Megalopolis, Xidias, Drossato and Vounargo show high F ranging from 154 to 218 ppm. Present results indicate that not only the wide variety and combination of elements that can be used to fingerprint lignitic basins but also the possibility of extracting such valuable elements from lignites and their ashes whenever the concentration and economics warrants such an undertaking.

Concentration of elements in lacustrine coals from zone A Hat Creek deposit no 1, British Columbia, Canada

Abstract Coal samples from the 170-m-thick A zone of the Hat Creek coal deposit No. 1 in central British Columbia were examined for major-, minor- and trace-element distribution. The coal is lignite/ subbituminous in rank and of Eocene age. This study shows: (1) As, B, Br, Cl and S are the only elements organically associated in these samples; (2) Concentration of certain elements such as Fe, Mn and Co can be related to the presence or absence of carbonate and/or sulphide minerals; (3) Distribution of certain elements, (i.e. Al, B, Br, Cl, Cr, Fe, Th, U and Zn) follow similar patterns of concentration or depletion across the vertical thickness of Zone A and suggest three depositional cycles; (4) Concentration of boron versus chromium, sodium, sulphur and uranium for these coals clearly placed them in a freshwater environment; (5) Rates of sedimentation using the Na/K ratio also suggest three depositional cycles; (6) In resinite samples, hand-picked from these coals, the concentrations of all elements except As and Se were lower than their concentrations in the whole coals.

Monitoring the species of arsenic, chromiumand nickel in milled coal, bottom ash and fly ash from a pulverized coal-firedpower plant in western Canada

The concentration of As, Cr and Ni and their speciation (As3+;5+, Cr3+;6+ and Ni0;2+) in milled coal, bottom ash and ash collected by electrostatic precipitator (ESP) from a coal fired-power plant in western Canada were determined using HGAAS, ICP-AES and XANES. The chemical fractionation of these elements was also determined by a sequential leaching procedure, using deionized water, NH4OAC and HCI as extracting agents. The leachate was analyzed by ICP-AES. Arsenic in the milled coal is mostly associated with organic matter, and 67% of this arsenic is removed by ammonium acetate. This element is totally removed from milled coal after extraction with HCI. Arsenic occurs in both the As3+ and the As5+ oxidation states in the milled coal, while virtually all (>90%) of the arsenic in bottom ash and fly ash appears to be in the less toxic arsenate (As5+) form. Both Ni and Cr in the milled coal are extracted by HCI, indicating that water can mobilize Ni and Cr in an acidic environment. The chromium is leached by water from fly ash as a result of the high pH of the water, which is induced during the leaching. Ammonium acetate removes Ni from bottom ash through an ion exchange process. Chromium in milled coal is present entirely as Cr3+, which is an essential human trace nutrient. The Cr speciation in bottom ash is a more accentuated version of the milled coal and consists mostly of the Cr3+ species. Chromium in fly ash is mostly Cr3+, with significant contamination by stainless-steel from the installation itself.

Graptolites as indicators of the temperature histories of rocks

A pilot study of the optical properties of graptolite skeletal materials shows progressive changes of reflectance, bireflectance, refractive index and absorptive index, produced by temperature changes related to depth of burial. Samples of Lower Ordovician to Upper Silurian graptolites were selected from across Canada, from locations where the conodont alteration indices of adjacent conodont collections provide a control index of temperature. The reaction to temperature of graptolite skeletal material appears to be similar to that of bitumen, but somewhat different to that of the vitrinite and liptinite maceral components of coal. Maximum reflectance in oil and bireflectance appear to be the characteristics most diagnostic of maximum temperature, and both show progressively higher rates of increase at higher temperatures. These factors show potential for more sensitive discrimination of temperatures at high levels of conodont alteration indices. The optical properties of graptolites may perhaps provide a useful tool for unravelling the post-depositional histories of Lower Palaeozoic rocks in deformed belts.

Organic petrography of graptolite fragments from Turkey

Abstract The reflectance and bireflectance of graptolite fragments (Silurian-Ordovician) from southeast Turkey were examined and the morphology was described using reflected light microscopy. The dispersion of maximum and minimum reflectance of graptolites sectioned parallel and perpendicular to the bedding was also determined. The graptolites were anisotropic and the anisotropy was stronger for sections perpendicular to the bedding. The graptolite fragments show two types of surface morphology: granular and non-granular. The granular type had a rough surface and granular anisotropy, the non-granular fragments showed a smooth surface and basic anisotropy. The fine internal structure of graptolite was evident under crossed-polars. The reflectance of graptolite increased with depth and was higher than other organic material, e.g. bitumen, found in the same sediment. The present study indicates that the reflectance of graptolite in sediment can be used to determine the maturity of the dediment.

Elemental concentrations in Canadian coals: 2. Byron creek collieries, British Columbia

Abstract The concentration of 58 elements in Byron Creek coals ( % Ro = 0.942 1 .05 ), and their 1000 °C ashes were determined using intense neutron activation and plasma emission spectrometry. The organic-inorganic affinities of elements were detected by the trend of element concentration versus ash content of the samples. Antimony, boron, bromine and selenium are the only elements that are enriched in these coals. The higher concentration of boron in one coal seam is considered to indicate that this seam was deposited in a more marine environment than the other seams. Coal seams can be identified by the concentration or depletion of certain trace elements, such as boron, sodium, thorium and uranium. Similarity indices of coal samples are also a useful tool in seam identification. Certain elements, for example gallium, thorium and uranium, are more concentrated in carbominerite from the roof or floor than within the coal. Regular variation of boron, sodium, thorium and uranium may indicate the repetition of certain units in tectonically thickened coal seams.

Organic petrology of Hat Creek coal deposit no 1, British Columbia

Abstract The upper Eocene Hat Creek coal deposits of British Columbia, Canada, are one of the thickest lignite to subbituminous coal deposits of the world, and comprise 350–550 m of coal. Samples of sedimentary organic material were taken from a 560-m interval of interbedded shale, siltstone and carbonate that was penetrated by corehole 75–106 in the centre of the coal basin, and the reflectances of huminite (eu-ulminite) from coal and kerogen from the organic material were determined and petrographical analyses were made. The coal deposit contains many leaf- and resinite-rich horizons, and the reflectance of huminite in these horizons in lower than in corresponding horizons containing less liptinite. When compared with huminite in adjacent coal beds, the reflectance of huminite in shale is lower, that in siltstone is similar, and huminite associated with carbonate rocks has slightly higher reflectance values. The petrological variation in the coal is mainly within the huminite group of macerals. The coal at the top of the deposits is lignite (% R o = 0.38) and becomes subbituminous C (% R o = 0.50) at the base. The inertinite content is very low, indicating a low level of peat fire or oxidation. The early stages of transformation of gelinite to macrinite are described. The paleoenvironment appeared to be lacustrine, as determined by organic petrological analysis of coals and interbedded sediments. Four major zones, each containing many subzones, were found. Paleoenvironments were similar for the A and C zones and also for the B and D zones.

The influence of geological factors on the concentration of boron in Australian and Canadian coals

Abstract The concentration of boron in Australian and Canadian coals determined using atomic emission spectrometry (AES), inductively coupled plasma spectrometry (ICP-AES) and prompt gamma-ray spectrometry is summarized in order to assess the variation of B content in coal with respect to rank, age, geological setting (in-seam and stratigraphic) and the degree of paleosalinity of the coal-forming environment. This study indicates that no/or very complex relations exist between boron and rank (subbituminous to anthracite). Variations of B with ash content for Canadian coals of different age (Devonian to Oligocene-Eocene) indicate that the B content of coals is not governed by the age of the coal. There is some evidence of variation of B with maceral content in Canadian coals, particularly as related to the inertinite and vitrinite content of coals. The B content of coal seams is sensitive to the environment of deposition, with B contents remaining relatively stable and within the range of values designated for each depositional setting. However, B values may show variation in the same seam laterally due to changes of the environment of deposition and/or the enrichment of B by a secondary source. The vertical variation of B in a coal-bearing section or strata is related to depositional environment and lithology of rock. There is often little variation in B content for coal layers as compared to the partings (dirt bands). The B content of partings in a coal-bearing strata may vary greatly as compared to the coal seams. After reappraising earlier work, and on the basis of more recent studies on Australian and Canadian coals, it is proposed that the following ranges of values for B in coal indicate the degree of marine influence during the early stages of coalification: • up to 50 ppm B: freshwater-influenced coals • 50–110 ppm B: mildly brackish water-influenced coals • >110 ppm B: brackish water-influenced coals. Using these criteria, assessments are given for the degree of marine influence on Canadian and Australian coals.

Regional maturity as determined by organic petrography and geochemistry of the Schei Point Group (Triassic) in the western Sverdrup Basin, Canadian Arctic Archipelago

Abstract Maturity and source rock potential of organic rich beds in the Triassic Schei Point Group in the Sverdrup Basin, Arctic Canada have been investigated using reflected light microscopy and the results are compared with other maturity parameters determined geochemically (i.e. Rock Eval, and biomarker maturation parameters). The samples evaluated belong to the Eden Bay Member of the Hoyle Bay Formation and contain a predominance of marine algal material, in the form of Tasmanales , and dinoflagellates, along with mixed terrestrial organics. The rock matrix is dominantly carbonate with some shaly input, indicating that the rocks were deposited in an iron-poor highly euxinic environment. With few exceptions there is good agreement between parameters,determined using microscopy; namely % R o , λ max and R GQ and geochemical parameters, T max , HI , Dia C 27 Dia C 27 + reg C 27 steranes, S (S+R) C 29 steranes. The ternary diagram showing the abundance of normalized C 27 , C 28 and C 29 regular steranes indicates a mostly marine depositional environment for the Schei Point source rock. This is confirmed by the abundance of marine fauna and flora in these samples. Analytical results from several different techniques indicate that the source rocks become more mature from the margin towards the axis of the Sverdrup Basin. This is due, in part, to the increase in overburden of sediments in the axis of the basin. Also the high thermal conductivity of salt has strongly influenced the maturity of Schei Point source rocks over the crest of the salt cored structures, i.e. Well Hazen F-54, and the proximity of salt has enhanced maturation levels at Well Rock Point J-43. The sections investigated were also considered to have an excellent gas potential due to their higher than average TOC content.

Organic petrology and RockEval analysis of the Lower Carboniferous Emma Fiord Formation in Sverdrup Basin, Canadian Arctic Archipelago

Abstract Samples of the Lower Carboniferous Emma Fiord Formation from two localities in the Sverdrup Basin of Arctic Canada were examined using reflected white and fluorescent light. The samples from Kleybolte Peninsula on Ellesmere Island show a relatively high level of thermal maturity. In contrast, those from Grinnell Peninsula on Devon Island are immature to marginally mature and include subbituminous coals and oil shales. Two types of oil shales are distinguished on the basis of liptinite content, mineral matrix, RockEval pyrolysis analysis, and concentration of boron. One is characterized by a liptinite-rich, clay-carbonate matrix with a relatively high hydrogen index and boron content, and the other by a liptinite-poor carbonate matrix with a relatively low hydrogen index and boron content. Hydrogen-rich components of these shales consist of alginite, matrix bituminite and minor amounts of exsudatinite and sporinite. Kerogen Types III and IV comprise only minor components of the organic matter. Thermal maturity of the Grinnell Peninsula oil shales increases with depth. Matrix bituminite in these oil shales has seeped into cavities and microfractures in the kerogen Types III and IV, forming exsudatinite. The distribution and character of the organic constituents and also the concentration of boron in these samples indicate a fresh to brackish water environment.