Results Of Thermodynamic Modeling Research Articles

Comparative analysis and multi-criteria optimization of a supercritical recompression CO2 Brayton cycle integrated with thermoelectric modules

Regarding the high expense of the exploiting energy from energy resources, each innovation or modification on the energy systems with the aim of enhancing the efficiency and affordability is so valuable. Along with this fact, in the present work, the effects of employing thermoelectric (TEG) unit in a recompression Brayton cycle ( $${\text{sCO}}_{2}$$ -reB/TEG) are examined. The results of thermodynamic modeling represents that adding the thermoelectric to the system in the s $${\text{CO}}_{2}$$ -reB can improve the net output power about 2.41 kW and increase the first and second law efficiency of s $${\text{CO}}_{2}$$ -reB/TEG system about 1.09% and 1.12% in comparison with s $${\text{CO}}_{2}$$ -reB system. Additionally the exergo-economic analysis for s $${\text{CO}}_{2}$$ -reB/TEG revealed that the reactor and turbine II should be considered more than other elements from exergo-economic point of view since the highest values of $$\dot{Z}_{\rm k} + \dot{C}_{\rm D,k}$$ belong to these components. After identifying the important parameters as well as evaluating system from thermodynamic and economic aspects, a multi-objective optimization is implemented on the $${\text{sCO}}_{2}$$ -reB-TEG system for determining the optimum conditions. Two optimization scenarios are defined using the results of parametric analysis. Multi-objective optimization with first scenario results in total cost rate of 1.6 $ h−1 and total exergy efficiency of 0.5 in minimum temperature, maximum temperature and compression ratio of 36.17 °C, 577.15 °C and 1.6. Furthermore, for optimization based on second scenario results in total exergy destruction cost and exergy destruction rate of 3.04 $ h−1 and 435.85 kW in 48.75 °C, 569.77 °C and 3.44 for minimum temperature, maximum temperature and compression ratio.

Waste heat recovery in an intercooled gas turbine system: Exergo-economic analysis, triple objective optimization, and optimum state selection

The development of heat and power generation systems has a major step towards sustainable development, reducing fossil energy consumption and reducing environmental pollution. Integrated energy systems are considered widely due to their high efficiency. In the present paper, an intercooled gas turbine system is developed to achieve a system with high thermal efficiency as well as better economic performance and cleaner production. The main goals of the suggested system is improvement of thermodynamic and exergo-economic performance beside multi-criteria optimization, which lead to improve the system sustainability. The intercooled gas turbine in the current work integrated with hot water system and thermoelectric generator unit to develop an advanced combined heat and power system. A comprehensive energy, exergy, and exergo-economic analyses are employed to price assessment of the new introduced system. A comparative analysis with conventional intercooled gas turbine system is presented. The results of thermodynamic modeling indicate that an improvement about 613.3 kW, 8.21 kW, and 12.3 kW can be obtained in the gas turbine, Kalina cycle, and regenerative organic Rankine cycle subsystems. The results of energy and exergy analysis show that the values of both energy and exergy efficiencies for all subsystems experience increment in the new introduced. Parametric analysis based on thermodynamic and exergo-economic criteria is done and a triple objective optimization conducted to determine the best system configurations. The Technique for Order of Preference by Similarity to Ideal Solution is employed to choose the final optimal state of the system. The result of optimum selection among non-dominant solutions suggested by Pareto points indicates that the energy efficiency, total exergy destruction rate and electricity cost rate are 53.91%, 2392.01 kW, and 52.29 $/h.

Analysis of the Causes of Cracks in the Production of Ingots and Forgings from Austenitic Stainless Steel 08Х18Н10Т (AISI 321)

Austenitic stainless steels are widely used in industry. Increased requirements for the quality of products from these steel grades, the difficulties associated with the implementation of technological processes, as well as the high cost of steel, determine the necessity to assess probable causes of defects. This article presents an analysis of the influence of main process parameters on the quality of products from the grade 08X18H10T steel. Based on the results of statistical analysis and thermodynamic modeling, it was concluded that the increased content of titanium and nitrogen affects the quality of products, which is caused by the formation of titanium carbonitrides in the process of steel solidification.

Effect of Liquid Water Content of Particles and Acidity of Particulate Matter on the Formation of Secondary Inorganic Components in Xinjiang Petrochemical Industrial Area

Secondary species are dominant components of PM2.5 in Dushanzi, Xinjiang. It is crucial to investigate the conversion process of secondary components in the atmosphere for regional air pollution control. The water-soluble components were analyzed for samples collected from Dushanzi District of Xinjiang from September 2015 to July 2016. The results showed that the total water-soluble ions (TWSIs) showed a seasonal variation consistent with PM2.5, and the seasonal variation of the ions was in the order-winter (67.86 μg·m-3) > autumn (13.77 μg·m-3) > spring (10.09 μg·m-3) > summer (4.85 μg·m-3); secondary ions (NH4+, SO42-, and NO3-)-accounting for 98% of TWSIs in winter. The results of the aerosol thermodynamic model (E-AIM) that explores the particle liquid water and acidity in Dushanzi District showed that the particles in Dushanzi are acidic with an annual in-situ pH of 0.81, and the pH value of the winter samples was the highest (2.93). The seasonal variation of particles in water was of the order: winter (331.32 μg·m-3) > autumn (5.91 μg·m-3) > spring (5.46 μg·m-3) > summer (1.62 μg·m-3). The annual average nitrogen oxidation rate and sulfur oxidation rate were 0.13 and 0.47, respectively, indicating a secondary conversion of regional pollutants. Further analysis showed that the concentration of sulfate in the particle phase was significantly affected by liquid water content of particles and in-situ pH. The formation of nitrate was mainly caused by heterogeneous reactions under high water content of particle.

About the Role of Fluorine-Bearing Apatite in the Formation of Oxalate Kidney Stones

Using electron microprobe analysis, 17 kidney stones containing apatite were studied. According to the results of the research, it was found that the apatite of all the oxalate kidney stones contained fluorine, while in the apatite of the phosphate kidney stones, fluorine was present in trace amounts or absent. Direct correlation between the amount of oxalate mineral phases and the fluorine content was observed. Ionic substitutions in the apatite of kidney stones have a multidirectional effect on the unit cell parameters. The fluorine content increases with the increase of a unit cell parameter, which is probably associated with a simultaneous increase in the amount of H2O in the structure of apatite. The results of thermodynamic modeling show that fluorapatite is stable at lower pH values than hydroxylapatite, and therefore can be a precursor of calcium oxalates crystallization.

Thermodynamic calculations on system «Portland cement – water – carbon nanomodifier»

The article presents the results of thermodynamic modelling in a cement-water-carbon nanomodifier system. A carbon nanomodifier contains fullerenes C60 and C70. Thermodynamic calculations make it possible to evaluate the contribution of a carbon nanomodifier to the hydration process of Portland cement. Using thermodynamic calculations, changes in the phase composition and general properties of the system (total enthalpy, entropy) with the introduction of a carbon nanomodifier were determined.

Zircon formation in mafic and felsic rocks of the Bushveld Complex, South Africa: Constraints from composition, zoning, Th/U ratios, morphology, and modelling

Zircon is a potential petrogenetic indicator that can be used to derive physicochemical conditions during magma crystallization. In this study, such conditions are obtained from zircon of both felsic and mafic rocks of the Bushveld Complex (BC), which are characterized by a wide range in bulk-rock Zr contents (4–552 ppm). For that, information from bulk-rock compositions, petrography, zircon trace element data and morphologies are combined with results of thermodynamic modelling using the software packages rhyolite-MELTS and Perple_X. In felsic rocks (Lebowa Granite, Rashoop Granophyre), zircon is formed in rutile-free assemblages together with olivine-clinopyroxene-amphibole-biotite-ilmenite-titanite-apatite after ≥20% fractional crystallization at 761–935 °C (mean: 860 °C), based on Ti-in-zircon thermometry using aTiO2 = 0.3, in agreement with independent geothermometers and modelling results. The resulting zircon populations show {100}- and {101}-dominated morphologies as well as high ƩREE (mean: 651 ppm) and low Ti contents (mean: 9.5 ppm), and only minor zoning in Th/U (0.3–0.8) and Nb/Ta (1.2–4.4). Identical zircon characteristics in gabbros and diorites of the Upper Zone within the Rustenburg Layered Suite (RLS) suggest admixing of felsic melts during ingression of mafic parental magmas. In contrast, zircons in mafic rocks of the lower RLS (Basal Ultramafic Sequence to lower Main Zone) show significantly lower ƩREE (mean: 324 ppm), commonly higher Ti contents (8–60 ppm), as well as large variations in Ti, U, Th contents, Th/U (0.2–24) and Nb/Ta ratios (0.15–18) as well as in zircon morphology. These zircons mostly occur in rutile-bearing intercumulus domains associated with orthopyroxene-biotite-amphibole-plagioclase-quartz-rutile and are formed at 690–962 °C (mean: 835 °C; aTiO2 = 1.0) based on Ti-in-zircon thermometry. These temperatures are in good agreement with zircon morphologies, but mostly higher than those obtained by rhyolite-MELTS modelling, suggesting zircon growth at <810 °C after >75% fractional crystallization of high Mg andesitic (B1) and tholeiitic parental magma (B2). These lower temperatures perhaps result from oversimplified modelling parameters or may reflect variable mixing of parental magma with evolved resident magma. Zircon populations in rutile-bearing mafic rocks of the lower RLS reveal two distinct zoning trends: an early trend at high Ti (>20 ppm), characterized by increasing Th/U (0.5 to 18) at decreasing U (175 to 10 ppm) from core to rim and a reverse trend at lower Ti contents. Both trends require zircon formation in intercumulus melt pockets at high zircon/melt ratios. The high-Ti trend can be explained by Rayleigh-like fractionation due to zircon growth together with rutile, both having highly different partition coefficients for U ≫ Th. The low-Ti trend results from zircon growth after onset of the biotite-in reaction, causing breakdown of previously formed rutile, thereby releasing U but no Th. The absence of pronounced Th/U zoning of zircon in felsic rocks reflects zircon growth in less fractionated melts, resulting in ThU fractionation compensated by coeval crystallization of abundant rock-forming minerals, all being highly incompatible for Th and U.

Thermodynamic Functions of the Anodic Oxidation Reactions of Niobium and Tantalum

In this paper, we develop the thermodynamic models of electrochemical oxidation of niobium and tantalum that allow predicting the composition of their anodic oxides depending on the electrolyte composition. The reactivity of metals with respect to electrolyte anions was evaluated. It was revealed that doping additives can be included in the composition of anodic oxide films of Nb and Ta depending on the nature of the anions supplied by the electrolyte components. The thermodynamic modeling results will allow predicting the component compositions of anodizing solutions to obtain anodic oxide films of these elements with a specified composition.

Morphology, Mineralogy, and Composition of Sulfide Droplets in Picrodolerite from a Near-Bottom Apophysis of the Yoko-Dovyren Layered Intrusion

The paper presents data on sulfide globules in picrodolerites from a bottom apophysis of the Yoko-Dovyren massif, northern Transbaikalia. Textural features of the rocks indicate that they crystallized at rapid magma cooling. Their composition is similar to that of chilled olivine gabbronorites from the lower contact of the massif. Many droplet-shaped sulfides, which range from 2 to 15 mm, were identified in one of the samples using X-ray computed tomography. The largest of these globules was drilled out and studied in detail to clarify its inner structure, which consists of the main spheroid and a surrounding halo of disseminated sulfides. The main globule and surrounding halo significantly differ in composition (the halo is richer in Cu), as was calculated using the average compositions of the dominant sulfide phases and their relative proportions. The weighted mean (with regard for halo) composition can be assumed as an approximation of the composition of the initial sulfide liquid that was formed near the chill zone of the gabbronorite apophysis from the main intrusive chamber. The Cu content in the initial sulfide corresponds to the results of thermodynamic modeling (with the COMAGMAT-5 program package) of the geochemistry of primitive sulfides in ultramafite rocks from the basal zone of the massif. The differences in the composition of the halo and the main globule indicate the possibility of local migration (within a few millimeters) of the residual sulfide liquids enriched in Cu when the protosulfide melt differentiated. As a physical mechanism that produced the halo, we assumed that the latest sulfide fraction was pressed off into the pore space of rapidly crystallizing olivine orthocumulates.

Моделирование восстановления металлов из расплавов B2O3-CaO-Fe2O3-ZnO смесями CO-CO2

Thermodynamic modeling technique has been developed to predict the conditions of metals reduction from oxide melt by gas during bubbling processes. The technique provides approximation to real systems with periodic removal of metal phase and gases from the working body. The given work presents thermodynamic modeling results of Zinc and Iron reduction processes from B2O3-CaO-Fe2O3-ZnО melts by СО-СО2 different composition mixtures in the 1273-1673 K temperature range. Approximation to real processes is used. Zinc and Iron oxides content in the melt and its reducing degree have been estimated during the calculations. Three stages of the process have been obtained by the calculations. Reducing of Fe2O3 to Fe3O4 and FeO is realized in the first stage. Concentration of Fe2O3 (СFe2O3) decreases almost to zero while СFe3O4 и СFeO have been increased simultaneously. Concentration of СFe3O4 reaches its maximum to the end of process. Transition of Fe3O4 → FeO takes place in second stage when СFeO reaches its maximum, and Zinc and Fe begin its reducing. Temperature increase promotes metallization by Zinc, but decreases by Iron. An increase of input gas CO/CO2 ratio leads to Fe reducing degree. It thereby ensures required indicators of the Zinc selective reduction achievement but requires more gas consumption. The relationships between CZnO and φZn depending on temperature and amount of reducing input gas consumption have been obtained. Given work results may be useful for precut estimation of the probable parameters of Zinc distillation process from the melt. Besides, these results may be useful as the basis for the experimental results analysis.

Thermodynamic simulation of silicothermic chromium reduction process

Thermodynamic modeling of chromium reduction from the oxide system of the following composition was carried out, (wt %): 25.0 – 37.5 CaO, 25.0 – 12.5 SiO 2 , 25 CrO 3 , 5 FeO; 14 MgO, 3 MnO, 3 Al 2 O 3 . Silicon of ferrosilicon of FeSi20, FeSi45, FeSi65 grades was used as a reducing agent in amount of 110 % of stoichiometrically needed for iron, manganese and chromium reduction. Modeling was performed on HSC Chemistry 6.12 software package developed by Outokumpu (Finland). Calculations were performed using “Equilibrium Compositions” module in the initial nitrogen medium at total pressure of 0.1 MPa and in temperature range of 1500 – 1700 °С with step of 50 °С. The thermodynamic characteristics of chemical compound CrO (II) was introduced into the database. Thermodynamic constants of CaCr 2 O 4 compound presented in a database have been adjusted. Calculation results were presented in form of graphic dependences of change in degree of chromium reduction η Cr on temperature t, slag basicity (CaO)/(SiO 2 ), and silicon concentration in ferrosilicon [Si] FeSi . It was shown that increase in the process temperature from 1500 to 1700 °C at (CaO)/(SiO 2 ) = 2 reduces η Cr by 1.87, 6.04 and 7.38 % when using FeSi20, FeSi45 and FeSi65 reducing agents respectively. It was found that increase in (CaO)/(SiO 2 ) from 1 to 3 at temperature of 1600 °C leads to an increase of η Cr 2 by 17.3, 14.2 and 12.5 % using FeSi20, FeSi45, and FeSi65 respectively. Increase in silicon concentration from 20 to 65 % in [Si] FeSi ferrosilicon facilitates an increase of η Cr by 9.5, 5.9 and 4.2 % at slag basicity of 1, 2 and 3 respectively and at temperature of 1600 °C. Chemical composition of metal was determined. Results of thermodynamic modeling can be used to calculate degree of chromium reduction from recovery period slags of the argon-oxygen refining process in stainless steel production.

Metasedimentary Metatexites with Trondhjemitic Leucosomes from NE Sicily: Another Example of Prograde Water-fluxed Melting in Collisional Belts

Trondhjemitic leucosomes, hosted in late Variscan metasedimentary migmatites from the upper amphibolite-facies basement of the north-eastern Peloritani Mountains (southern Italy), have petrographic and geochemical features consistent with their origin as near-pure melts derived from in situ water-fluxed melting of their paragneiss host-rocks. Comparison with results of experimental melting and thermodynamic modelling of metasedimentary rocks suggests a dominant derivation of the leucosomes by melting, at c. 1.0 GPa and 700 °C, metagreywackes with a high pelitic content. Migmatization likely began at the thickening-related baric peak, or during the early post-collisional exhumation stages. A subsequent heating stage following the decompression and solidification of the leucosomes triggered a second melting stage, involving muscovite and biotite incongruent breakdown, with an associated production of peritectic sillimanite and garnet, and small leucogranitic patches within the trondhjemitic leucosomes. These melting events can be framed in the typical clockwise P-T-(t) evolution of the Variscan Belt in western and southern Europe, depicting collision-related thickening followed by widespread migmatization, starting close to the baric peak at c. 345 Ma and continuing during exhumation, with a duration of c. 25 Ma, up to c. 320 Ma.

Late Eocene magmatism of the eastern Qiangtang block (eastern Tibetan Plateau) and its geodynamic implications

Post-collisional magmatism offers significant clues to reveal the deep dynamic process and surface uplift of plateaus. New zircon U-Pb ages, biotite Ar-Ar ages, zircon trace elements, and whole-rock geochemistry, integrated with published data of igneous rocks from the eastern Qiangtang block (eastern Tibetan Plateau) were determined to unravel the geodynamics and constrain the uplift history. These igneous rocks consist of few mafic and many intermediate-felsic series. Geochronological studies reveal that the magmatism mainly occurred in ~43–33 Ma. The late Eocene igneous rocks are characterized by high potassium, enrichment in large ion lithophile elements (LILE, e.g., Rb, Ba, Th, U), depleted in high field strength elements (HFSE, e.g., Nb, Ta, Ti), negligible Eu anomalies, with a wide range of highly incompatible element ratios. The parental magmas of these rocks were most probably generated by different degrees of partial melting of the lithospheric mantle, which were heterogeneously metasomatized by subduction related multiphase fluids/melts. Whole-rock geochemistry, zircon trace elements, and thermodynamic modeling results suggest that the parental magmas experienced complicated and different differentiation processes. Mantle metasomatism, fractional crystallization, and magmatic recharge made contributions to the enrichment of incompatible elements and the wide range ratios between highly incompatible elements. In combination with the estimated Eocene crustal thickness, we suggest that the southward continental subduction of the Songpan-Ganzi block triggered the magmatism, thickened the crust, and induced the surface uplift to no more than ~3 km in the late Eocene.

Incorporation of trace metals Cu, Zn, and Cd into gypsum: Implication on their mobility and fate in natural and anthropogenic environments

The coexistence of calcium (Ca2+), sulfate (SO42−) with trace metal cations (M(II)) can possibly lead to M(II)-gypsum coprecipitation and solid solution formation. However, gypsum's role in the fixation of M(II) is still largely unknown. This study investigated the precipitation of Ca2+ and SO42− in the presence of M(II) (i.e., Cu2+, Zn2+, or Cd2+) and the incorporation of the metal cations into the gypsum structure at different environmental conditions. Trace metals in two natural gypsum samples (Yunnan and Neimeng, China) and one hydrometallurgical byproduct gypsum sample from a Cu refinery were also assessed. X-ray diffraction, scanning electron microscopy-energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy were employed to characterize the solid samples. The lab-scale results showed that the M(II) content in the coprecipitates increased with pH and the initial M(II) concentration. At lower pH, Zn2+ and Cd2+ were dominantly fixed through isomorphic substitution for Ca2+ in the gypsum structure, while Cu2+ was likely incorporated into the channel structure of the gypsum where the water molecules reside. In contrast, at higher pH, thermodynamic modeling results indicated that M(II)-hydroxides and base metal sulfates (Mx(OH)y(SO4)z) were formed and constituted an appreciable fraction of M(II)-bearing species in the host solids. Our study further showed that trace amounts of Cu, Zn, and Cd were also substitutianly incorporated in the two natural and one hydrometallurgical gypsum samples. The present study may have important implications for understanding the geochemical cycle of trace metals in Ca2+ and SO42− coexisting systems, as well as possible attenuation mechanisms that may occur along their supersaturation and coprecipitation.

Theoretical Bases and Technology of Steel Exhaustive Metal Desulfurization and Direct Microalloying with Boron Beneath Basic Boron-Containing Slags

Results of theoretical and experimental studies of the physicochemical properties of slags of the CaO–SiO2–B2O3 system containing 15% Al2O3 and 8% MgO lie at the basis for the development of technology for exhaustive desulfurization of metal beneath basic boron-containing slags formed in a steelpouring ladle in a ladle-furnace unit (LFU), and steel direct microalloying with boron. Methods of simplex lattice planning of an experiment, a software complex HSC 6.1 Chemistry (Outokumpu), and the method of electro-vibration viscosimetry are used. Results of thermodynamic modeling of the effect of slag basicity and B2O3 content on sulfur and boron equilibrium distribution coefficient between slag of the oxide system under study and low-carbon metal are presented. The quantitative effect of basicity and B2O3 content on slag viscosity containing 15% Al2O3 and 8% MgO at a temperature of 1600°C and the influence of the slag chemical composition of the oxide system under study on the degree of wear of periclase-carbon refractory material are shown. Results of studying physicochemical properties of slags of the CaO–SiO2–B2O3 system containing 15% Al2O3 and 8% MgO are a basis for developing a ladle slag composition with low viscosity and providing exhaustive metal desulfurization, and direct microalloying of boron steel with low corrosive effect on periclase-carbon refractories. Development of this technology provides, depending on the steel grade, a boron content of 0.001–0.008%, low metal sulfur concentration at 0.004–0.014%, a reduction in manganese ferroalloy consumption from 0.5 kg/ton of steel 08KP to 1.4 kg/ton of steel 09G2S, exclusion of ferroboron and fluorspar additives in the ladle, and achievement of good finished metal product mechanical properties.

Physicochemical Conditions of the Formation of Elevated Indium Contents in the Ores of Tin–Sulfide and Base-Metal Deposits in Siberia and Far East: Evidence from Thermodynamic Modeling

Abstract—The base-metal (70–75 wt %) and tin–sulfide (10–15 wt %) deposits are the main indium suppliers in the world. However, the causes and conditions of In accumulation in the ores of these deposits are still unclear. To shed light on this problem, we simulated the physicochemical conditions of formation of base metal and tin–sulfide ores with elevated indium content. For this purpose, the average composition of ore–bearing hydrothermal solutions and parameters of ore precipitation at these deposits were determined using available literature data. Based on these data, obtained standard thermodynamic characteristics $$\Delta G_{{\text{f}}}^{0},$$$$\Delta H_{f}^{0},$$$$S_{f}^{0},$$$$V_{f}^{0},$$$$C_{p}^{0}$$ of chloride indium species ($${\text{InCl}}_{2}^{ + },$$ InCl3, InClOH+), coefficients required for calculations at elevated temperature and pressure, the formation of elevated indium contents in these ores was numerically simulated using “Gem–Selektor-3” and “Chiller” softwares. The results of thermodynamic modeling of the formation of quartz–cassiterite and tin–sulfide ores show that the higher In contents in tin–sulfide ores are related to their formation from acid (pH 4.3), high–chloride (6.6 m) solutions, which contain In (0.002 m) in form of (InCl3aq). The quartz–cassiterite ores were formed from near–neutral (pH 5.3), low–chloride (1.02 m) solution, in which In occurred as hydroxocomplexes InO2H and $${\text{InO}}_{2}^{ - }$$ in concentrations no more than 0.00004 m, which, respectively, determined its low contents in these ores. Computer modeling of the formation of indium–bearing sulfide-base metal and barite-base metal deposits shows that they were formed form high–temperature chloride (1.3–4.3 m) hydrothermal solutions of near–neutral composition (pH 5.8–6). The main In speciations are hydroxocomplexes InO2H and $${\text{InO}}_{2}^{ - }$$, which provide In concentrations of 5–9 × 10–5 m). However, due to the low indium concentrations in hydrothermal solutions, the forming sulfide minerals (sphalerite, pyrite, and chalcopyrite) differ in the lower indium contents compared to the minerals of tin–sulfide ores.

Термодинамическое моделирование восстановления металлов из расплавов B2O3-СaO-Ni(Zn, Pb, Cu)O водородом

Thermodynamic modeling is used to describe the metal reduction processes by hydrogen from oxide melt in the B2O3-CaO- MeO (Me – Ni, Zn, Pb, Cu) system. Open systems approximation with periodic removal of metal particles and gases from the working melt composition is used in the method. By this work we present the thermodynamic modeling results of metal reduction processes (Ni, Cu, Pb, Zn) by Hydrogen. The reducible metals oxides content in the all melts was 3 mass %, and the mass ratio of B2O3/CaO was taken as 3 to be close to eutectic composition. The calculations made it possible to determine such parameters as oxide melt compositions and elements reduction degree depending on the induced gas quantity. of the Nickel, Copper, Lead and Zinc reduction process simulation from B2O3-CaO-MeO melts proved the reduction process by Hydrogen is similar to that which was earlier established when Carbon monoxide was used as the reducing agent. When Copper is reduced from CuO, the process occurs with intermediate Cu2O oxide formation (CuO → Cu2O → Cu). The Nickel (NiO → Ni), Lead (PbO → Pbs + Pbg) and Zinc (ZnO → Zng) recovery have been realized by one stage. The non-ferrous metals change content in the oxide melt and the degrees of its reduction depending on temperature and reducing agent quantity introduced are described by the second-order polynomial functional equations. Comparison of the Carbon monoxide and Hydrogen used for Nickel, Copper, Lead, and Zinc reducing to 90% metallization degree proved much less Hydrogen consumption.

Tracing Highly Siderophile Elements through Subduction: Insights from High-pressure Serpentinites and ‘Hybrid’ Rocks from Alpine Corsica

Abstract The highly siderophile elements (HSE) include the economically critical platinum group elements (PGE; Os, Ir, Ru, Rh, Pt, Pd, Au and Re), gold and rhenium. The HSE are redox sensitive in mantle and seafloor environments and have a strong affinity to iron and sulphur, therefore their distribution within the subducted mantle lithosphere record changes to oxidation state and sulphidation. The mobility of the HSE during subduction has important implications for Re–Os isotopic signatures in the mantle, and the formation of Cu–Au arc-related ore deposits. In this study, subducted rock samples from Alpine Corsica are used to track the HSE in serpentinites and hybrid ultramafic–mafic rocks through the subduction cycle. A comparison of bulk-rock HSE concentrations with those in pre-subduction analogues provides insights into the transfer of the HSE throughout the subduction cycle. Serpentinites subducted to blueschist–eclogite-facies conditions have similar HSE concentrations to primitive upper mantle (PUM) concentrations, therefore it is concluded that the HSE are not mobilized from serpentinites on the scale of the whole-rock or greater. Therefore, as suggested in previous studies, crustal lithologies may be more important contributors of the HSE to the sub-arc mantle, particularly Pt, Pd and Re. In contrast, HSE concentrations in hybrid rocks (talc schist and chlorite schist) deviate from protolith concentrations. Rhenium is higher in the talc schist, and Ir and Ru are lower in the chlorite schist than in the PUM, or possible mafic protoliths. Mineral parageneses place temporal constraints on the growth of hosts to the HSE (sulphides, oxides and metal alloys), and record changes to the activities of oxygen and sulphur (aO2–aS2), and hence redox conditions, from pre-subduction to exhumation. Laser ablation inductively coupled plasma mass spectrometry was used to determine the HSE concentrations in sulphides and oxides, and the detection of small (∼2–25 µm2) platinum group minerals utilized high-resolution SEM mapping techniques. The prograde and retrograde sulphides have lower HSE concentrations compared with sulphides from pre-subduction settings. Therefore, the redistribution of the HSE on a mineral scale from sulphides to alloys and/or other sulphides has occurred within the serpentinites, which may reflect more reducing conditions during serpentinization or subduction, consistent with the results of thermodynamic modelling. In contrast, the mineral assemblages in the hybrid rocks imply an increase in the extent of sulphidation and oxidation, and higher fluid:rock ratios during exhumation, coincident with Re enrichment in the talc schist, and a decrease in the concentrations of Ir and Ru in the chlorite schist, at length scales greater than those of the rock samples. Therefore, hybridization of lithologies at the slab–mantle interface may enhance the transfer of the HSE to the sub-arc mantle. If Re transfer from the slab to the sub-arc mantle is possible, this questions the robustness of Re–Os isotope signatures as tracers of crustal recycling.

Crystal structure and cation ordering in novel perovskite type oxides PrBaCoTa(Nb)O6–δ

Novel complex oxides PrBaCoNbO6–δ (PBCN) and PrBaCoTaO6–δ (PBCT) are obtained via solid state reactions. X-ray and electron diffraction data for PBCN and PBCT demonstrate cubic space symmetry (S.G. Fm–3m) of the double perovskite crystalline lattice characterized by the rock salt type ordered arrangement of Co/Nb and Co/Ta and random distribution of Pr/Ba atoms. The ab initio electronic structure calculations reveal that the disordered elementary cell is distinguished with the minimum energy. The optical measurements show that PBCN and PBCT compounds are semiconducting materials having maximum light absorption in ultraviolet (UV) region which is consistent with the computer simulations of electronic structure. The thermodynamic modeling results suggest that the structural robustness of PBCN and PBCT phases at heating may be related with large absolute values of oxygen partial enthalpies.

Structure and mechanical properties of an in situ refractory Al20Cr10Nb15Ti20V25Zr10 high entropy alloy composite

Structure, deformation behavior, and mechanical properties of a refractory Al20Cr10Nb15Ti20V25Zr10 high entropy alloy are reported. In the as-cast state, the alloy had a composite-like hypoeutectic microstructure comprised of a softer primary B2 phase and a harder eutectic mixture consisting of a C14 Laves and the B2 phases. Annealing at 1200 °C retained the composite-like constitution and led to the formation of a small amount of a Zr5Al3-type phase. The annealing also had a positive effect on strength and ductility of the alloy at 22 and 800 °C; compatibility of plastic deformation at 800 °C can be ascribed to the relative softness of the B2 phase. Reasonable agreement was found between the experimental structures and the results of thermodynamic modeling.