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1.
Degradation of coke in the blast furnace is influenced by its inherent mineral matter, the formation of which is itself dependent upon the nature of the coal mineral matter. To date few studies have been made of coke mineralogy and its relationship to the mineralogy of the parent coal. In this study the effect of carbonisation on coal mineral matter has been investigated by a detailed quantitative mineralogical examination of nine cokes and their parent coals. The quantitative analysis was performed on X-ray diffraction patterns of the mineral matter of cokes and coals, using SIROQUANT™. Coke mineralogy and its composition varied strongly between cokes, more strongly than variations in elemental composition of the ash. The mineral matter in the studied cokes consisted of crystalline mineral phases and also significant levels of amorphous phase (ranging between 44 and 75%). Decomposition of clays such as kaolinite, montmorillonite, illite and chamosite produced the amorphous phase and some of the crystalline mineral phases such as mullite, γ-alumina, spinel, cristobalite and leucite. The type of association of mineral matter in coals had an important role in how the clays decomposed. For example, association of kaolinite with silica-bearing minerals in intimate intermixture favoured formation of mullite over γ-alumina. Akermanite and diopside result from reaction of kaolinite with associated calcium bearing minerals (calcite, dolomite or ankerite). Quartz, fluorapatite and the three polymorphs of TiO2 (anatase, brookite and rutile) were the coal minerals that were least affected during carbonisation, as they were also found in the cokes, yet even they were affected in some cases.  相似文献   

2.
Any and all proposed theories regarding the origin of sapphires are still very much open to debate. Critical inconsistency arises on the magmatic petrogenesis mechanism of sapphire crystal formation. The Nezametnoye Deposit is one of the most prospective placer deposits of jewelry grade corundum (sapphire) and zircon (jacinth) in Russia, and is known for its native and alluvial gold–wolframite–tin deposits. We present new data obtained from mineral and primary melt inclusions that are syngenetic to corundum. Electron microprobe analysis indicates that rutile, zircon, albite, zinc-bearing hercynite, columbite, and fluorite represent syngenetic mineral inclusions. Silicate melt inclusions are almost always associated with carbon dioxide inclusions; this correlation suggests that a heterogeneous fluid–melt system was present during corundum crystallization. Distinctive features of chemical composition of the inclusions, along with their agpaitic coefficients, indicate that corundum crystallization occurred from granosyenite melts. Primary carbon dioxide-rich inclusions form random groups, or are associated with melt inclusions. P–T conditions for corundum crystallization have been calculated as 780–820 °C and 1.7–3 kbar, based on data from primary carbon dioxide and melt inclusions.  相似文献   

3.
The objective of the study was to characterize changes of reflectance, reflectance anisotropy and reflectance indicating surface (RIS) shape of vitrinite, sporinite and semifusinite subjected to thermal treatment under inert conditions. Examination was performed on vitrinite, liptinite and inertinite concentrates prepared from channel samples of steam coal (Rr = 0.70%) and coking coal (Rr = 1.25%), collected from seam 405 of the Upper Silesian Coal Basin. The concentrates were heated at temperatures of 400–1200 °C for 1 h time in an argon atmosphere.All components examined in this study: vitrinite, sporinite and semifusinite as well as matrix of vitrinite and liptinite cokes, despite of rank of their parent coal, show, in general, the most important changes of reflectance value and optical anisotropy when heated at 500 °C, 800 °C (with the exception of bireflectance value of sporinite) and 1200 °C.After heating the steam coal at 1200 °C, the vitrinite and the semifusinite reveal similar reflectances, whereas the latter a slightly stronger anisotropy. Sporinite and matrix of liptinite coke have lower reflectances but anisotropy (Rbi and Ram values) similar to those observed for vitrinite and semifusinite. However, at 1000 °C sporinite and matrix of liptinite coke have the highest reflectivity of the studied components. The RIS at 1200 °C is the same for all components.The optical properties of the three macerals in the coking coal become similar after heating at 1000 °C. Coke obtained at 1200 °C did not contain distinguishable vitrinite grains. At 1200 °C semifusinite and vitrinite coke matrix have highest Rr values among the examined components. Maximum reflectance (Rmax) reach similar values for vitrinite and sporinite, slightly lower for semifusinite. Matrix of liptinite coke and matrix of vitrinite coke have considerably stronger anisotropy (Rbi and Ram values) than other components. RIS at 1200 °C is also similar for all components.  相似文献   

4.
We have used a recently developed quantitative pyrolysis-Fourier transform infrared spectroscopy method to measure the production of water and carbon dioxide during 250 °C desorption and 1000 °C gasification steps for a range of carbonaceous chondrites. Greater yields of water and carbon dioxide during gasification are associated with meteorites believed to have experienced more aqueous alteration on their asteroid parent body (i.e. gas yields for petrographic type 1 > type 2 > type 3). Volatile yields most likely reflect quantities of hydrated mineral phases and partially oxidised organic matter. Methane was not detected in the gasification products of the meteorites, allowing an upper limit on its production of around 100 ppm to be calculated based on the sensitivity of the pyrolysis-Fourier transform infrared spectroscopy technique employed. When considered alongside rates of infall of cosmic dust throughout Earth history, the data can be used to evaluate the production of volatiles during the thermal ablation of dust upon atmospheric entry, and to estimate their contribution to a terrestrial planet’s atmosphere and hydrosphere. Over the long term, it appears that contributions of this nature to the Earth’s volatile inventory are small, although production rates are calculated to have been substantially higher before and during the Late Heavy Bombardment of 3.8-4.0 Ga. Moreover, ablation of carbonaceous chondritic material does not appear to be a plausible source of the atmospheric methane budget of Mars.  相似文献   

5.
Two sets of cooling experiments were run at atmospheric conditions for two anhydrous starting latitic and trachytic melts: 1) five cooling rates (25, 12.5, 3, 0.5, and 0.125 °C/min) between 1300° and 800 °C, and 2) a 0.5 °C/min cooling rate from 1300 °C with quench temperatures at 1200°, 1100°, 1000° and 900 °C. Trachytic run-products are invariably glassy. Nucleation is also suppressed in the latitic run-products at the three highest cooling rates. Conversely, in the 0.5 and 0.125 °C/min runs, latites have a crystal content of  90 vol.%. The phases are: plagioclase, clinopyroxene, glass and iron-bearing oxide (in order of abundance). The variable quench temperatures, investigated by coupling experiments with Pt wire and Pt capsule sample containers in set 2, again did not produce crystallization of trachyte, whereas latitic samples are characterized by  10 vol.% of oxides, pyroxenes and plagioclase (in order of appearance), at temperature < 1000 °C. Effects of (preferential) heterogeneous nucleation on sample holders, of superheating degree, and chemical species loss during cooling are absent for both melt compositions. The difference of solidification paths between these two silicate melts can be ascribed only to their small chemical differences. In comparison with calculated equilibrium conditions all the experimental latitic and trachytic run-products revealed strong kinetic effects, interpretable in the light of the nucleation theory. The glass-forming ability (GFA) of trachyte is higher, whereas their critical cooling rate (Rc) is lower (< 0.125 °C/min), in comparison to latitic melts (Rc > 0.5 °C/min). The experimental results carried out in this study can be applied to lava flows and domes; trachytic lavas are able to flow for longer period with respect to latitic ones in a metastable condition. Glass-rich terrestrial lavas, i.e. obsidians, can be the result of sluggish nucleation kinetics due to the relative high polymerisation of evolved silicate melts.  相似文献   

6.
A high-resolution multi-proxy study including the elemental and isotopic composition of bulk organic matter, land plant-derived biomarkers, and alkenone-based sea-surface temperature (SST) from a marine sedimentary record obtained from the Jacaf Fjord in northern Chilean Patagonia (44°20′S) provided a detailed reconstruction of continental runoff, precipitation, and summer SST spanning the last 1750 yr. We observed two different regimes of climate variability in our record: a relatively dry/warm period before 900 cal yr BP (lower runoff and average SST 1°C warmer than present day) and a wet/cold period after 750 cal yr BP (higher runoff and average SST 1°C colder than present day). Relatively colder SSTs were found during 750–600 and 450–250 cal yr BP, where the latter period roughly corresponds to the interval defined for the Little Ice Age (LIA). Similar climatic swings have been observed previously in continental and marine archives of the last two millennia from central and southern Chile, suggesting a strong latitudinal sensitivity to changes in the Southern Westerly Winds, the main source of precipitation in southern Chile, and validating the regional nature of the LIA. Our results reveal the importance of the Chilean fjord system for recording climate changes of regional and global significance.  相似文献   

7.
The particulate organic matter in < 63 µm surface sediments from the Mackenzie River and its main tributaries was studied using Rock-Eval pyrolysis and organic petrology. The organic matter in the sediments is dominated by refractory residual organic carbon (RC) of mainly terrigenous nature, as indicated by abundant inertinite, vitrinite, and type III kerogen. Sediments from the tributaries contained significantly more algal-derived organic matter than from the main channel of the river, highlighting the importance of low-energy system dynamics in the tributaries, which allows modest algal production, more accumulation, and better preservation of autochthonous organic matter. This is particularly true for tributaries fed by lacustrine systems, which showed the highest S1 and S2 fractions, and consequently higher total particulate organic carbon (POC) in the basin. Organic petrology of the sediment samples confirms abundant liptinitic materials (i.e., fat-rich structured algae, spores and pollen, cuticles, and resins). Forest fire and coal deposits are also confirmed to contribute to the basin. Assuming that suspended and fine surfacial sediments have a similar OC composition, the Mackenzie River is estimated to deliver a total POC flux of 1.1 Mt C/yr to its delta, of which 85% is residual carbon with liptinitic OC (S1 + S2) and S3 accounting for another 9% and 6%, respectively.  相似文献   

8.
The Higo Complex of west-central Kyushu, western Japan is a 25 km long body of metasedimentary and metabasic lithologies that increase in metamorphic grade from schist in the north to migmatitic granulite in the south, where granitoids are emplaced along the southern margin. The timing of granulite metamorphism has been extensively investigated and debated. Previously published Sm–Nd mineral isochrons for garnet-bearing metapelite yielded ca.220–280 Ma ages, suggesting high-grade equilibration older than the lower grade schist to the north, which yielded ca.180 Ma K–Ar muscovite ages. Ion and electron microprobe analyses on zircon have yielded detrital grains with rim ages of ca.250 Ma and ca.110 Ma. Electron microprobe ages from monazite and xenotime are consistently 110–130 Ma. Two models have been proposed: 1) high-grade metamorphism and tectonism at ca.115 Ma, with older ages attributed to inheritance; and 2) high-grade metamorphism at ca.250 Ma, with resetting of isotopic systems by contact metamorphism at ca.105 Ma during the intrusion of granodiorite. These models are evaluated through petrographic investigation and electron microprobe Th–U–total Pb dating of monazite in metapelitic migmatites and associated lithologies. In-situ investigation of monazite reveals growth and dissolution features associated with prograde and retrograde stages of progressive metamorphism and deformation. Monazite Th–U–Pb isochrons from metapelite, diatexite and late-deformational felsic dykes consistently yield ca.110–120 Ma ages. Earlier and later stages of monazite growth cannot be temporally resolved. The preservation of petrogenetic relationships, coupled with the low diffusion rate of Pb at < 900 °C in monazite, is strong evidence for timing high-temperature metamorphism and deformation at ca.115 Ma. Older ages from a variety of chronometers are attributed to isotopic disequilibrium between mineral phases and the preservation of inherited and detrital age components. Tentative support is given to tectonic models that correlate the Higo terrane with exotic terranes between the Inner and Outer tectonic Zones of southwest Japan, possibly derived from the active continental margin of the South China Block. These terranes were dismembered and translated northeastwards by transcurrent shearing and faulting from the beginning to the end of the Cretaceous Period.  相似文献   

9.
Mineralizing fluids at the San Martín skarn show an evolution characterized by prograde and retrograde associations. The prograde mineral associations consist of (1) a massive garnet zone, (2) a tremolite ± garnet zone, and (3) a late association of quartz, sphalerite, calcite and fluorite lining the vugs in the garnet zone. The fluids of the prograde associations exhibit decreasing temperatures of homogenization (Th) and variable salinities. The fluids of the massive garnet zone have salinities of 36 wt.% NaCl equiv. and Th of 645 to 570 °C, corresponding to pressures of 1055 bar. At the tremolite ± garnet zone, Th range from 438 to 354 °C. In the late association at the endoskarn, the following evolution can be drawn: (a) salinities of 50 to 42 wt.% NaCl equiv., and Th of 455 to 346 °C in quartz, (b) salinities of 46 wt.% NaCl equiv., and Th of 415 to 410 °C in sphalerite, (c) salinities of 50 to 37 wt.% NaCl equiv., and Th of 479 to 310 °C in calcite, (d) salinities of 33 to 28 wt.% NaCl equiv. and of 24 to 22 wt.% KCl in fluorite, and (e) two types of fluids with salinities of 2 and 39 wt.% NaCl equiv. and Th 344 and 300 °C, respectively, in later saccharoidal quartz segregations. The retrograde mineral associations comprise pervasive propylitic alteration to carbonization, and mantos with sulfides. Fluids in epidote have salinities of 7.6 wt.% NaCl equiv. and Th of 287 to 252 °C, and in calcite have salinities of 9.2 to 1 wt.% NaCl equiv. and Th of 188 to 112 °C. Fluids in the sulfide assemblages in the mantos have salinities of 8 to 3 wt.% NaCl equiv. and Th 300 °C, with corresponding pressures of 94 bar. Fluids in late epithermal veins close to the intrusive body have salinities of 10 to 5 wt.% NaCl equiv. and Th of 275 to 200 °C, and distal veins show salinities of 2 to 1 wt.% NaCl equiv. and Th of 160 °C.  相似文献   

10.
Heat flow and lithospheric thermal regime in the Northeast German Basin   总被引：3，自引：0，他引：3  
New values of surface heat flow are reported for 13 deep borehole locations in the Northeast German Basin (NEGB) ranging from 68 to 91 mW m− 2 with a mean of 77 ± 3 mW m− 2. The values are derived from continuous temperature logs, measured thermal conductivity, and log-derived radiogenic heat production. The heat-flow values are supposed free of effects from surface palaeoclimatic temperature variations, from regional as well as local fluid flow and from thermal refraction in the vicinity of salt structures and thus represent unperturbed crustal heat flow. Two-D numerical lithospheric thermal models are developed for a 500 km section along the DEKORP-BASIN 9601 deep seismic line across the basin with a north-eastward extension across the Tornquist Zone. A detailed conceptual model of crustal structure and composition, thermal conductivity, and heat production distribution is developed. Different boundary conditions for the thickness of thermal lithosphere were used to fit surface heat flow. The best fit is achieved with a thickness of thermal lithosphere of about 75 km beneath the NEGB. This estimate is corroborated by seismological studies and somewhat less than typical for stabilized Phanerozoic lithosphere. Modelled Moho temperatures in the basin are about 800 °C; heat flow from the mantle is about 35 to 40 mW m− 2. In the southernmost part of the section, beneath the Harz Mountains, higher Moho temperatures up to 900 to 1000 °C are shown. While the relatively high level of surface heat flow in the NEGB obviously is of longer wave length and related to lithosphere thickness, changes in crustal structure and composition are responsible for short-wave-length anomalies.  相似文献   

11.
Burial depth, cumulative displacement, and peak temperature of frictional heat of a fault system are estimated by thermal analysis in the fold–thrust belt of the Western Foothills complex, western Taiwan based on the vitrinite reflectance technique. The regional thermal structure across the complex reveals that the rocks were exposed to maximum temperatures ranging from 100 °C to 180 °C, which corresponds to a burial depth of 3.7–6.7 km. A large thermal difference of 90 °C were observed at the Shuilikeng fault which make the eastern boundary of the fold–thrust belt where it is in contact with metamorphic rock of Hsuehshan Range. The large thermal difference corresponds to cumulative displacements on the Shuilikeng fault estimated to be in the range of 5.2–6.9 km. However, thermal differences in across the Shuangtung and Chelungpu faults cannot be determined apparently due to small vertical offsets. The large displacement observed across the Shuilikeng fault is absent at the other faults which are interpreted to be younger faults within the piggyback thrust system. Localized high temperatures adjacent to fault zones were observed in core samples penetrating the Chelungpu fault. Three major fracture zones were observed at core lengths of 225 m, 330 m, and 405 m and the two lower zones which comprise dark gray narrow shear zones. A value of vitrinite reflectance of 1.8%, higher than the background value of 0.8%, is limited at a narrow shear zone of 1 cm thickness at the fracture zone at 330 m. The estimated peak temperature in the range of 550–680 °C in the shear zone is far higher than the background temperature of 130 °C, and it is interpreted as due to frictional heating during seismic faulting.  相似文献   

12.
The Jurassic Angren coal–kaolin deposit, Uzbekistan, is one of the largest producers of coal and kaolin suitable for refractories and industrial ceramics in central Asia. The Major coal seam, attaining a thickness between 4 and 24 m, is encased by kaolin-bearing bedsets which have been derived from supergene pre- and hypogene post coal kaolinization. Joint clay-mineralogical and coal petrographic analyses formed the basis of the environment analysis of this coal–kaolin series and constrained the physico-chemical conditions existing during the Triassic through Jurassic period of time. Massive kaolin I underneath the coal seam is a typical residual kaolin or underclay with arsenic Fe-disulfides and siderite indicative of a reducing swampy depositional environment developing under moderately hot climatic conditions. Towards the top, kaolin I became reworked fluvial by processes. The Major coal seam developed in swamps interfingering with a fluvial drainage system of suspended to mixed-load deposits. The maximum temperature for the post-depositional alteration of the carbonaceous material is 70 °C. Post-coal kaolinization (kaolin II) affecting trachyandesites and trachytes is of low-temperature origin and low-sulphidation-type. The temperature of formation was well below 200 °C, deduced from the absence of dickite in the clay mineral assemblage. Basaltic dykes intersected the coal–kaolin series and account for contact metamorphic reactions in the proximal parts of the aluminum-bearing wall rocks reaching sanidinite-facies conditions with temperatures around 1000 °C.  相似文献   

13.
This study presents an investigation of the purification of a raw diatomite by acid leaching conducted in hot solution (75 °C and 5 M HCl) for long periods up to 240 h, evaluates the use of these purified powders in the fabrication of porous materials, and examines their porosities. The treatment for 1 h increased the specific surface area of diatomite from 189 m2/g to 222 m2/g, but the SiO2 content of 78.66% was still low. Material leached for a relatively short time shows an amorphous phase with quartz and plagioclase phases and the plagioclase is removable at longer leaching times during which no disruptive effect on the fine microscopic pores of the particles was observed. Thus, the diatomite based powders have potential use in the fabrication of porous coating as a membrane-separating layer: sintering at a relatively high temperature (1300 °C) still showed a significantly high apparent porosity of 48%.  相似文献   

14.
Industrial plants that refine bauxite to alumina using the high temperature process have always held the belief that anatase was detrimental to the extraction of boehmite while rutile was not. This study shows that this effect is real and that it is observable at temperatures as low as 90 °C. The extraction of gibbsite is shown to be unaffected which leads us to believe that the kinetics of both the Ti-bearing mineral and the Al-bearing mineral is important in this phenomenon. In addition, it is shown that not only is the presence of anatase an issue in boehmite extraction but so too is the presence of sodium titanate. Rutile was found to have the least impact of the three mineral phases.  相似文献   

15.
A set of free-drift experiments was undertaken to synthesize carbonates of mixed cation content (Fe, Ca, Mg) from solution at 25 and 70 °C to better understand the relationship between the mineralogy and composition of these phases and the solutions from which they precipitate. Metastable solid solutions formed at 25 °C which are not predicted from the extrapolation of higher temperature equilibrium assemblages; instead, solids formed that were intermediary in chemical composition to known magnesite–siderite and dolomite solid solutions. A calcite–siderite solid solution precipitated at 25 °C, with the percentage of CaCO3 in the solid being proportional to the aqueous Ca/Fe ratio of the solution, while Mg was excluded from the crystal structure except at relatively high aqueous Mg/Ca and Mg/Fe ratios and a low Ca content. Alternatively, at 70 °C Mg was the predominant cation of the solid solutions. These results are compatible with the hypothesis that the relative dehydration energies of Fe, Ca and Mg play an important role in the formation of mixed cation carbonates in nature.  相似文献   

16.
High pressure deformation in two-phase aggregates   总被引：1，自引：0，他引：1  
We investigate the rheological behavior of multi-phase aggregates at high pressure and high temperature. Using synchrotron X-ray radiation as the probing tool, we are able to quantify the stress state of individual phases within the aggregates. This method provides fundamental information in interpreting the behavior of two phase/multi-phase mixtures, which contribute to our understanding of the deformation process at deep earth conditions. We choose MgAl2O4 spinel and MgO periclase as our model materials. Mixtures of various volume proportions were deformed in a multi-anvil high pressure deformation apparatus at pressure of 5 GPa and elevated temperatures. Stress is determined from X-ray diffraction, providing a measure of stress in each individual phase of the mixture in situ during the deformation. Macroscopic strain is determined from X-ray imaging. We compare the steady state strength of various mixtures at 1000 °C and 800 °C and at the strain rate in the range of 1.8 to 8.8 × 10− 5 s− 1. Our data indicate that the weak phase (MgO) is responsible for most of the accumulated strains while the strong phase (spinel) is supporting most of the stress when the volume proportion is 75% spinel and 25% MgO. The intermediate compositions (40/60) are much weaker than either of the end members, while the grain sizes for the intermediate compositions (submicrons) are much smaller than the end members (5–10 μm). We conclude that a change in flow mechanism resulting from these smaller grains is responsible for the low strength of the intermediate composition mixtures. This study demonstrates an approach of using synchrotron X-rays to study the deformation behaviors of multi-phase aggregates at high pressure and high temperature.  相似文献   

17.
L.I. Panina  L.M. Usoltseva 《Lithos》2008,103(3-4):431-444
To find out the reasons responsible for the diversity of igneous rocks forming the alkaline-ultrabasic carbonatite Krestovskiy massif (the Maimecha–Kotui province, Russia) we have studied melt inclusions in clinopyroxene of trachydolerites, porphyric melanephelinites, and tholeiites. It was established that the homogenization temperatures of inclusions in these rocks are rather close: 1140–1180 °C, 1190–1230 °C, and 1150–1210 °C, respectively. Compositions of melt inclusions in clinopyroxenes from different rocks are significantly different. The chemical composition of clinopyroxene of trachydolerites corresponds to that of trachybasalts and their derivatives. The inclusions are enriched in Sr, Ba, P, and S and their total sum of alkalies (at K ≥ Na) is never less than 5–6 wt.%. Inclusions from the rims of clinopyroxene phenocrysts in porphyric melanephelinites are similar in composition also to inclusions in trachydolerites. But in the cores of clinopyroxene phenocrysts the composition of inclusions corresponds to nephelinite melt. The composition of some melt inclusions in the intermediate and cores zones of clinopyroxene from porphyric melanephelinite has high SiO2 (53–55 wt.%), MgO (8–9 wt.%) and a low (1–2 wt.%) total sum of alkalies (at Na ≥ K) and is depleted in Al2O3 (6–7 wt.%), which is similar to the composition of basaltic komatiites. The composition of inclusions in tholeiites is also basic, highly magnesian, and low-alkaline, Sr and Ba are rare to absent. Compared to the inclusions of basaltic komatiite composition, the inclusions in tholeiites are enriched in Al and depleted in Ca, Ti, and P. The melts trapped in clinopyroxenes from different rocks contain low (0.014–0.018 wt.%) water but they are enriched in F: from 0.37 wt.% in nephelinite melts to 0.1–0.06 wt.% in tholeiite and basaltic komatiite melts. Inclusions in all the rocks under study, host clinopyroxene, and the rocks themselves are significantly enriched in incompatible elements (1–2 orders of magnitude relative to the mantle norm). In tholeiites, the partitioning of these elements is rather uniform, while in trachydolerites and especially in melanephelinites it is contrasting with a drastic depletion in HREE relative to LREE, MREE, and HFSE. A conclusion is made that the Krestovskiy massif was formed by no less than three mantle-derived magmas: melanephelinite, tholeiite and basaltic komatiite. Magmas were generated in different magma sources at different depths with various degrees of enrichment in incompatible elements. These magmas were, most likely, dominated by melanephelinite magma. In intermediate chambers this magma differentiated to form derivative melts of nephelinite, trachydolerite–trachyandesite–trachyte compositions. Komatiite-basalt melts were, most likely, derivatives of primitive meimechite magmas.  相似文献   

18.
V. Barberini  L. Burlini  A. Zappone   《Tectonophysics》2007,445(3-4):227-244
In this paper the elastic properties of amphibolites from the Serie dei Laghi and the Ivrea zone (Southern Alps, N-Italy) were investigated as a function of their mineralogical composition, microfabric and density.Three orthogonal cores were cut parallel and normal to foliation and lineation; from those, bulk and grain density were measured and the interconnected porosity was calculated. Bulk density varies from 2.75 to 3.07 g/cm3 and calculated porosity ranges from 0.02 to 0.88%.The same cores were also used to measure seismic velocity of ultrasonic waves at room temperature and at increasing confining pressure up to 300 MPa. At high pressure the matrix properties are separated from the crack-induced properties. P-wave velocity varies with respect to the direction of propagation: the slowest direction is always normal to foliation and the fastest parallel to the mineral lineation. The mineral lineation is typically defined by the elongation of amphibole crystals, in which the fastest Vp direction is parallel to the c axis, that is also the elongation axis. The Vp ranges between 6.76 and 7.54 km/s in the direction parallel to lineation and between 6.32 and 7.06 km/s in the direction normal to foliation. This defines a Vp anisotropy of up to 14%, whose shape varies from orthorhombic to axially symmetric (either prolate or flattened). It was observed that both Vp and Vp anisotropy increase with the amount of amphibole and decrease with the amount of plagioclase. Moreover, the c axis distribution of amphiboles is responsible of the Vp anisotropy intensity and shape, in agreement with observations from previous studies. The seismic properties calculated with the approach of Mainprice (1990), using the fabric data, the elastic constants and the modal composition, gave results in good agreement with the measurements.Exposed rocks in the Ivrea and Serie dei Laghi zones show that amphibolites are interlayered with metapelites on a scale from 1 to 100 m. Because of the very large acoustic impedance contrast (20.34 ± 1.75 for amphibolites, 17.16 ± 0.4 for metapelites), they represent a very reflective portion in the middle-lower crust.  相似文献   

19.
The demand for metallurgical coke for blast furnaces is forcing the coking industry to look for new sources of coking coals. The physical and chemical parameters of coals used in coking blends determine the quality (reactivity and strength) of the finished cokes. This study examines the technical properties of the cokes produced from various blends of three Polish coals with different coking. These coals were collected from three mines: Zofiówka, Szczygłowice, and Krupiński (Upper Silesian Coal Basin, Poland). The coal charges were coked in the laboratory scale, at temperatures of up to 1000 °C, in an inert atmosphere. The coke reactivity (index CRI) and the coke strength after reaction (CSR) were measured and correlated to the properties of parent coals using statistical analysis. The result of this study shows strong relationships between the concentration of the best coking coal (Zofiówka) in the blend and the CRI and CSR of the resulting coke. The CRI and CSR parameters for cokes obtained from single coals and from their blends show the additive character. This study also confirms the linear relationship between CRI and CSR parameters of the cokes.  相似文献   

20.
One hundred twenty-two samples of Jurassic and Paleogene brown coals and 1254 peat samples from the south-eastern region of the Western-Siberian platform were analyzed for gold by the neutron-activation method. Mean content of Au in Jurassic coals is 30 ± 8 ppb, in Paleogene coals is 10.6 ± 4.8 ppb, and in peat is 6 ± 1.4 ppb. Concentrations of gold as high as 4.4 ppm were found in coal ash and 0.48 ppm in the peat ash. Coal beds with anomalous gold contents were found at Western-Siberian platform for the first time.Negative correlation between gold and ash yield in coals and peat and highest gold concentrations were found in low-ash and ultra-low-ash coals and peat. Primarily this is due to gold's association with organic matter.For the investigation of mode of occurrence of Au in peat the bitumen, water-soluble and high-hydrolyzed substances, humic acids, cellulose and lignin were extracted from it. It was determined that in peat about 95% of gold is combined with organic matter. Forty to sixty percent of Au is contained in humic acids and the same content is in lignin. Bitumens, water-soluble and high-hydrolyzed substances contain no more than 1% of general gold quantity in peat.The conditions of accumulation of high gold concentrations were considered. The authors suggest that Au accumulation in peat and brown coals and the connection between anomalous gold concentrations and organic matter in low-ash coals and peat can explain a biogenic–sorption mechanism of Au accumulation. The sources of formation of Au high concentration were various Au–Sb, Au–Ag Au–As–Sb deposits that are abundant in the Southern and South-Eastern peripheries of the coal basin.  相似文献   

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