ΠΕΡΙΛΗΨΗΤα ανθρακικά πετρώματα της Θάσου είναι ολοκρυσταλλικά και παρουσιάζουν σπαριτικό ιστό. Οι δολομί τες έχουν μικρότερο μέγεθος κρυστάλλων (0,7-1,6 mm) από τα ασβεστιτικά μάρμαρα (0,8-2,2 mm). Στους δολομίτες εκτός του ομώνυμου ορυκτού, βρίσκονται ασβεστίτης (1-10%) και ίχνη χαλαζία, αστρίων και μαρμα ρυγιών. Στα ασβεστιτικά μάρμαρα εκτός του ασβεστίτη βρίσκονται δολομίτης (2-28%), χαλαζίας (1-28%), μαρ μαρυγίες (1-6%) και κατά περίπτωση, άστριοι, αργιλικά ορυκτά και γκαιτίτης. Οι δολομίτες παρουσιάζονται καθαρότεροι όλων των μαρμάρων του νησιού με κυριώτερη ξένη πρόσμιξη το Si0 2 (<0,88%). Εκτός των δια κοσμητικών εφαρμογών τα ασβεστιτικά μάρμαρα της Θάσου είναι κατάλληλα κυρίως για την παραγωγή αδρα νών υλικών οποιουδήποτε μεγέθους κόκκων, τσιμέντου και πιθανώς φιαλών, για περιβαλλοντικές χρήσεις και ως βελτιωτικά εδαφών. Τα δολομιτικά μάρμαρα είναι κατάλληλα για την παραγωγή λιπασμάτων και πιθανώς φιαλών, καθώς και ως πληρωτικά ή λευκαντικά υλικά στις βιομηχανίες χάρτου, χρωμάτων και ελαστικών. ABSTRACTThe carbonate rocks of Thassos Island are holocrystalline and present sparitic texture. The dolomites have smaller crystall size (0.7-1.6 mm) than the calcitic marbles (0.8-2.2 mm). In the dolomites except the synony mous mineral, calcite (1-10%) and traces of quartz, feldspars and micas are present. In the calcitic marbles except of the calcite, dolomite (2-28%), micas (1-6%) and occasionally feldspars, clay minerals and goethite occur. The results of chemical analysis agree with the mineralogical ones, as well as with the percentage of the isnoluble residue. The dolomites appear purer than all other marbles of the island. They most often contain Si0 2 (up to 0.88%). Beyond the decorative applications the calcitic marbles of Thassos are mainly suitable for the production of aggregates with any size requirement, cement and probably container glasses, for environmental uses and as soil conditioners. Respectively, the dolomitic marbles are suitable for the production of fertilizers and probably of container glasses and as fillers or whitenings in paper, paint and rubber industries.ΛΕΞΕΙΣ ΚΛΕΙΔΙΑ: ανθρακικά πετρώματα, βιομηχανικές χρήσεις, Θάσος.
In this paper the suitability of Kozani's broader area carbonate formations for certain applications is studied based on their mineralogical, chemical and technological characteristics. The studied formations geotectoniccally belong to the Pelagonian zone and are represented mainly by pure limestones with few occurences of dolomites and dolomitic limestones. The studied samples represent: a) the Vermion section (formations Be and Bd), b) the Kozani section (formations Be and Bd), c) the Siatista section (formations S1 and S2) and d) the Vouhnos section (formations Bo1, Bo2 and Bo3). The insoluble residue, the organic matter, the whiteness and the mineralogical and chemical composition are studied in order to investigate the suitability of the studied carbonates for specific industrial applications. The results showed that the dolomitic formation of Vermion (Bd) is suitable for the manufacture of flat glass, while the limestone formations of Siatista (S2) and Vourinos (Bo1) as well as the dolomitic formation of Vermion (Bd) are suitable for the manufacture of container glass. The limestone formations of Siatista (S1, S2) and the dolomitic formations of Vermion (Bd) and Kozani (Kd) can be used as fluxes in the metallurgical blast furnace to produce a slag with the acid components of the ore, while the limestone formations of Siatista (S1, S2), Kozani (Kc) and Vourinos (Bo1, Bo2, Bo3) as well as the dolomitic formations of Vermion (Bd) and Kozani (Kd) are suitable for the sinter blasts. Finally, only the S2 limestone formation of Siatista can be used in the desulphurising of flue gas, as it fulfills the chemical specifications and the restrictions in whiteness.
According to the microscopic examination of thin sections, the examined carbonate rocks are classified in two categories: a. Typical marbles and b. Recrystallised limestones. Category b is distinguished in two sub-categories: Micrites (b1) and sparites (b2). Calcite is the predominant mineral in almost all samples, whereas only in one sample there is a considerable quantity of dolomite. From the unessential minerals quartz, plagioclastes, talc, muscovite and chlorite were identified in traces. It's concluded that nine samples are very pure carbonate rocks and consist of >96% CaC03. The sum of the admixtures, that is all the oxides except for CaO and CO2, ranges from 1,6 to 8,7%, from which the most important is the S1O2 (0,5-6,7%), mainly in the form of quartz and the MgO (0,3-3,6%). The increased participation of Ni2+, Co2+, Rb+ and Zn2 + in relation to the worldwide average, could be attributed to the presence of foreign admixtures which occur in the examined carbonate rocks. The limited participation of Sr2* could be attributed to the absence of feldspars from these carbonate rocks. The mean value of the insoluble residue is 3,1%. The mean value of the included organic matter is 0,3%. Testing the degree of the whiteness it comes out that only one sample is almost absolutely white. Two samples are in the spectrum of the orange color, whereas the hues of six samples are in the spectrum of orange-yellow color. According to the chemical composition of the samples it is concluded that:• The samples from all the formations can be used for aggregates, because with the suitable breaking they can reach the requisite size for every use.• The samples from all the formations can be suitable feedstock for soil conditioners, after suitable grinding, in order to take grain sizes <5 mm, because their content in MgO is < 5%.• The samples from all the formations are considered to be ideal as feedstock in the cement industry, as long as the concentration of fluorine in them is < 0,1%.• The examined formations can be partly used into other industrial sections. However, supplementary specialized tests are needed.
In the present study the behavior of a lignite sample from Southern field, Ptolemais-Amynteon Lignite Center, is investigated during pyrolysis. Pyrolysis is a thermal depolymerization (cracking) of macromolecules in the absence of oxygen. The pyrolysis experiment was conducted three times and the pyrolysis temperatures were fixed at 600?C, 7007C and 800ΐ. A solid, black residue (carbonizate), no condensable gases and a liquid phase were produced. Course and product yields during pyrolysis are mainly influenced by such parameters as rank of the coal, final temperature, residence time, rate of heating, gas atmosphere and pressure. The weight of the solid phase is reduced during the process, depending on the quality and moisture content of the raw coal. At 800?C a weight loss of 52.95% is noted. The carbonizate contains more carbon and minerals than the starting material, but less volatile matter and moisture. The calorific value of the carbonizate is increased by the removal of low-energy components. Volatile compounds, such as C02 , CO, CH4, H2, CHm (tar), H20, H2S, NH3, are given off. A HP 6890 Gas Chromatograph was employed in this study. A thermal conductivity detector and a flame ionization detector were used to analyse the gases. Degasification began between 220 and 270?C. At the maximum temperature of 800?C, the volatile content is 4.39%. The total Gross Calorific Value of the pyrolysis gases is 42021 kJ m"3 (10036.5 kcal m3). The continuous degasification of this high-volatility lignite by pyrolysis can reduce the volatile content prior to burning, in other words, to produce a smokeless fuel (briquette). The carbonizate is briquetted with a binder in a press using a pressure of 11 bars. The briquette produced is a smokeless and odorless fuel. The energy required for the pyrolysis is obtained from combustion of the volatiles leading to a thermally autarkic process
Sixty-five marl samples were collected from the outcrops of six active and one abandoned mine of Ptolemais-Amynteon Lignite Center, Northern Greece. Core samples were also collected from the West Field, a Neogene lignite deposit located at the same area. The concentrations of 39 trace elements were determined using Instrumental Neutron Activation analysis (INAA) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Carbon and sulfur contents and the loss on ignition of the samples were also determined. The classification of the trace elements concentrations in each mine and their statistical processing allows determining the horizontal and vertical distribution in the coal deposits and in the entire basin. Regarding the vertical distribution of elements and geochemical groups, significant variations of the concentrations in both the different marl seams and the upper, intermediate and lower lignite seams were determined. The mining, processing, transportation, storage and utilization of marls release, among others, some amounts of trace elements into the environment. However, the low concentrations of all trace elements, except Pb in the South field, compared to the upper mean values of world rocks Crust (W.C-U.M.V) (enrichement factor <0.8) is of great environmental concern and prove the non hazardous role of the marl during mining, beneficiation and usage.
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