scholarly journals Uranium Mineralogical and Chemical Features of the Na-Metasomatic Type Uranium Deposit in the Longshoushan Metallogenic Belt, Northwestern China

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 335 ◽  
Author(s):  
Chi-Da Yu ◽  
Kai-Xing Wang ◽  
Xiao-Dong Liu ◽  
Michel Cuney ◽  
Jia-Yong Pan ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Hydrothermal Fluid ◽  
Uranium Deposit ◽  
Northwestern China ◽  
Compositional Variation ◽  
Chemical Compositions ◽  
Metallogenic Belt ◽  
Uranium Minerals ◽  
Chemical Dating

The Longshoushan Metallogenic Belt (northwestern China) is known for its word-class Jinchuan Ni-Cu sulfide (Pt) deposit and is also an important uranium metallogenic belt. The Jiling uranium deposit in this belt is a typical Na-metasomatic uranium deposit, which rarely occurs in China. Mineralization in the Jiling uranium deposit is hosted in granitoids that have suffered a Na-metasomatic alteration. There are three kinds of uranium minerals, including uraninite, pitchblende, and coffinite in the Jiling uranium deposit. Pitchblende is the predominant uranium mineral. Integrating the mineralogy and geochemistry of uranium minerals, and in situ electron microprobe analyzer (EMPA) U-Th-Pb chemical dating, we aimed to unravel the age and nature of the mineralization, to decipher the characteristics of the hydrothermal alteration and the U mineralization process. Based on the microtextural features and compositional variations, primary uraninite was altered to uraninite A and B, and fresh pitchblende was altered to pitchblende A and B. The best-preserved uraninite crystals displayed a euhedral-shape with high Pb and low SiO2, CaO, FeO, and Al2O3 contents, and was interpreted as primary uraninite. The EMPA U-Th-Pb chemical ages revealed that uraninite may have formed at 435.9 ± 3.3 Ma. High ThO2 + ΣREE2O3 + Y2O3 contents illustrated that the best preserved uraninite crystallized at a high temperature. Altered pitchblende A showed a relatively brighter gray color in backscattered electron (BSE) images and with a lower SiO2 content than B. Three analysis spots of the fresh pitchblende showed low contents of ΣSiO2 + CaO, indicating no obvious alteration. EMPA U-Th-Pb chemical dating gave a mean chemical age of 361 Ma. The low Th + ΣREE2O3 contents indicated that this pitchblende formed at a relatively low temperature. According to the different characteristics of occurrence and chemical composition, the coffinite in the Jiling uranium deposit can be divided into coffinite A and B, respectively. The compositional variation of the fresh and altered uraninite and pitchblende indicated that both uraninite and pitchblende underwent at least two discrete hydrothermal fluid alterations. The U mineralization was divided into two stages; uraninite was formed at a high temperature and possibly from a magmatic-hydrothermal fluid during ore stage I. Then, pitchblende was formed at a low temperature, during ore stage II. According to the petrographic observations and their chemical compositions, coffinite A and B resulted from the alterations of uraninite and pitchblende, respectively.

scholarly journals The effect of platinum-aluminide coating features on high-temperature fatigue life of nickel-based superalloy Rene®80

2019 ◽  
Vol 55 (2) ◽  
pp. 235-251
Author(s):  
M.M. Barjesteh ◽  
K. Zangeneh-Madar ◽  
S.M. Abbasi ◽  
K. Shirvani
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
High Activity ◽  
Layer Thickness ◽  
Low Cycle Fatigue ◽  
Aluminide Coating ◽  
Chemical Compositions ◽  
Cycle Fatigue ◽  
Platinum Layer ◽  
Low Activity

Low cycle fatigue is the most important failure mode in Aviation/Industrial engine rotary turbine parts. In this paper, the influence of Pt-aluminide coating parameters on high temperature low cycle fatigue behavior of superalloy Rene?80 which is used to manufacture turbine blades, has been investigated. For this purpose, initial platinum layers of different thicknesses (2?m and 8?m) were coated on fatigue specimens. Then the aluminizing process was performed with two conditions of low temperature-high activity and high temperature-low activity. The results of microstructure investigations performed by scanning electron microscope and X-ray diffraction phase analysis indicated a three-layer structure for the coating (bi-phase (Ni,Pt)Al+PtAl2, single-phase (Ni,Pt)Al and interdiffusion zone) with different chemical compositions at both thicknesses of the platinum layer and using both aluminizing methods. Also, the results of low cycle fatigue tests at 871?C, R=0 and strain rate of 2?10 -3 s-1 showed a decline in fatigue properties in coated specimens as compared to uncoated sample, at total strains of 0.4, 0.8, and 1.2%. This reduction was lower in the low temperature-high activity with platinum layer thickness of 2?m, while it was more significant in the high temperature-low activity with the platinum layer thickness of 8?m. The fractography studies on coated and uncoated specimens indicated a mixed mode of ductile and brittle fracture.

scholarly journals Compositional Variation of Amphiboles During Magma Mixing: A Case Study of Huangyangshan A-Type Granite in Kalamaili Metallogenic Belt, East Junggar, China

2021 ◽  
Vol 9 ◽  
Author(s):  
Chenyang Ye ◽  
Yonggang Feng ◽  
Ruxiong Lei ◽  
Gaoxue Yang
Keyword(s):  
Trace Element ◽  
Magma Mixing ◽  
Compositional Variation ◽  
Chemical Compositions ◽  
Magma Evolution ◽  
Metallogenic Belt ◽  
Trace Element Contents ◽  
Type Granite ◽  
Textural Evidence

The Huangyangshan A-type granitic pluton, distributed along the thrust fault in the Kalamaili region of East Junggar, Xinjiang, China, consists of alkaline granite containing abundant dioritic enclaves that formed via magma mixing. Both the host granite and the enclaves contain sodic amphiboles. The textural evidence indicates that amphiboles crystallized as a magmatic phase in both units. We determined major and trace element contents of amphiboles from both units to investigate the compositional variation of the amphiboles during the magma mixing process. The results show that cations of W- and C-site are influenced by chemical compositions of the magma whereas cations of A-, B- and T-site and Al3+ are controlled by crystal structure. Therefore, the variations of W- and C-site cations can reflect magma evolution. The core and rim of the amphiboles show similar trace element patterns, which also suggests that the amphiboles are late-stage phases. Furthermore, the amphibole-only thermometers yield reasonable estimates that are consistent with petrographic evidence. However, thermometers based on partition coefficients and all the currently available amphibole-based barometers that rely on Al contents or DAl cannot be applied to Fe-rich and Al-poor amphiboles.

Low- and high-temperature granites

2004 ◽  
Vol 95 (1-2) ◽  
pp. 125-140 ◽  
Author(s):  
B. W. Chappell ◽  
A. J. R. White ◽  
I. S. Williams ◽  
D. Wyborn
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Partial Melting ◽  
Fractional Crystallisation ◽  
Source Rocks ◽  
Compositional Variation ◽  
Mafic Rocks ◽  
Temperature Group ◽  
Source Materials ◽  
Felsic Rocks

ABSTRACTI-type granites can be assigned to low- and high-temperature groups. The distinction between those groups is formally based on the presence or absence of inherited zircon in relatively mafic rocks of a suite containing less than about 68% SiO2, and shown in many cases by distinctive patterns of compositional variation. Granites of the low-temperature group formed at relatively low magmatic temperatures by the partial melting dominantly of the haplogranite components Qz, Ab and Or in H2O-bearing crustal source rocks. More mafic granites of this type have that character because they contain restite minerals, often including inherited zircon, which were entrained in a more felsic melt. In common with other elements, Zr contents correlate linearly with SiO2, except sometimes in very felsic rocks, and Zr generally decreases as the rocks become more felsic. All S-type granites are apparently low-temperature in origin. After most or all of the restite has been removed from the magma, these granites may evolve further by fractional crystallisation. High-temperature granites formed from a magma that was completely or largely molten, in which zircon crystals were not initially present because the melt was not saturated in that mineral. High-temperature suites commonly evolved compositionally through fractional crystallisation and they may extend to much more mafic compositions through the production of cumulate rocks. However, it is probable that, in some cases, the compositional differences within high-temperature suites arose from varying degrees of partial melting of similar source rocks. Volcanic equivalents of both groups exist and show analogous differences. There are petrographic differences between the two groups and significant mineralisation is much more likely to be associated with the high-temperature granites. The different features of the two groups relate to distinctive source rock compositions. Low-temperature granites were derived from source rocks in which the haplogranite components were present throughout partial melting, whereas the source materials of the high-temperature granites were deficient in one of those components, which therefore, became depleted during the melting, causing the temperatures of melting to rise.

Petrology of forearc peridotite from the Hahajima Seamount, the Izu-Bonin arc, with special reference to chemical characteristics of chromian spinel

2006 ◽  
Vol 70 (1) ◽  
pp. 15-26 ◽  
Author(s):  
H. Okamura ◽  
S. Arai ◽  
Y.-U. Kim
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Equilibrium Temperature ◽  
Atomic Ratio ◽  
Chromian Spinel ◽  
Compositional Variation ◽  
Chemical Characteristics ◽  
Abyssal Peridotite ◽  
Size Dependent ◽  
Modal Abundance

AbstractForearc peridotite is generally characterized by low Mg# (= Mg/[Mg + Fe2+] atomic ratio) at a given Cr# (= Cr/[Cr + Al] atomic ratio) of chromian spinel compared to common abyssal peridotite. This may be due to (1) smaller modal abundance of spinel and/or (2) lower equilibrium temperature, for the forearc peridotite. Forearc peridotite has the same amount of spinel as abyssal peridotite, eliminating the first possibility. Spinel in harzburgite and dunite from the Hahajima Seamount at the Izu-Bonin forearc, has a large Cr#, >0.57, and the Mg# is slightly variable towards low values at a given Cr#. The Mg# of spinel cores decreases strongly with a decrease in size. This is due to cooling along with hydration, which gave rise to a compositional variation of Ca-amphibole, from edenitic hornblende (high-temperature) to tremolite (low-temperature) in the Hahajima peridotite. The average two- pyroxene temperature of the Hahajima peridotite, 921°C, is less than that of the abyssal peridotite (1138°C), which is not consistent with a size-dependent Mg# of spinel for the latter. Forearc peridotite has been cooled effectively by H2O released from the subducted slab, causing a small Mg# of their spinels.

Primary zoning in pyrochlore group minerals from carbonatites

2000 ◽  
Vol 64 (4) ◽  
pp. 683-697 ◽  
Author(s):  
D. D. Hogarth ◽  
C. T. Williams ◽  
P. Jones
Keyword(s):  
Crystal Growth ◽  
High Temperature ◽  
Low Temperature ◽  
General Formula ◽  
Temperature Effects ◽  
Compositional Variation ◽  
Pyrochlore Group ◽  
High Temperature Metamorphism

AbstractPyrochlore group minerals have the general formula A16–xB16O48Z8–y·nH2O, with A mainly Na, Ca, Sr, REE, Th, U; B mainly Nb, Ta, Ti and Z being O, F, OH. In this study, pyrochlore specimens were examined from carbonatites at Argor, Carillon Dam, Chilwa Island, Fen, Lueshe, Oka, Mbeya, Meech Lake and Verity. Primary features include a background with little compositional variation, from core to rim, upon which are commonly superimposed narrow oscillatory zones, parallel to {111}. These zones are usually characterized by high Ta, in many cases coupled with U (here Argor, Meech Lake and Verity specimens), but Chilwa Island and Fen pyrochlores have little Ta and zonation is mainly by enrichment in Ce and Nb. Primary zonation may persist through high-temperature metamorphism (Meech Lake and Verity) and metamictization (Meech Lake). Oscillatory zones were generated by a disequilibrium system that cooled under tranquil conditions, signalling absence of magma turbulence and, in many cases, the end of crystal growth. Some fresh crystals (Oka, Fen) have no oscillatory zones, possibly the product of magma turbulence in space or time. Low-temperature effects may mimic those of primary high temperature and are especially characterized by replacement rims, pyrochlore-inpyrochlore veinlets and low A-ion totals (Carillon Dam, Lueshe, Myeba).

Design and Integrity Evaluation of a Finned-Tube Sodium-to-Air Heat Exchanger in a Sodium Test Facility

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Hyeong-Yeon Lee ◽  
Hyungmo Kim ◽  
Jong-Bum Kim ◽  
Ji-Young Jeong
Keyword(s):  
High Temperature ◽  
Heat Exchanger ◽  
Low Temperature ◽  
Finned Tube ◽  
Test Facility ◽  
Chemical Compositions ◽  
Design Codes ◽  
Creep Fatigue ◽  
Section Viii ◽  
Elevated Temperature Design

A high-temperature design and an integrity evaluation for a finned-tube sodium-to-air heat exchanger (FHX) in a sodium test facility were conducted based on full 3D finite-element analyses, and comparisons of the design codes were made. A model FHX has been installed in a sodium test facility of sodium thermal-hydraulic experiment loop for finned-tube sodium-to-air heat exchanger (SELFA) for simulating the thermal hydraulic behavior of the FHX unit in the prototype Gen IV sodium-cooled fast reactor (PGSFR). For the design evaluations, ASME Section VIII Div. 2 has been applied for the FHX as a whole. For parts of the FHX operating in the creep regime, nuclear grade elevated temperature design (ETD) codes of ASME Section III Subsection NH and RCC-MRx were additionally applied to evaluate the integrity against creep-fatigue damage. For parts of the FHX operating at low temperature, ASME Section III Subsection NB was applied additionally to evaluate the integrity upon load-controlled stresses and fatigue. The integrity of the FHX was confirmed based on the design evaluations as per the design codes. Code comparisons were made in terms of the chemical compositions, material properties, and conservatism. The conservatism was quantified and compared at the critical low temperature location between ASME Section VIII Div. 2 and ASME-NB, and at the critical high-temperature location between ASME-NH and RCC-MRx.

Influence of VOC Emission on Asphalt Components

2014 ◽  
Vol 599 ◽  
pp. 178-181 ◽  
Author(s):  
Hong Hua Zhang ◽  
Pei Qiang Cui ◽  
Liu Jing Zi Qiu ◽  
Shao Peng Wu
Keyword(s):  
Surface Layer ◽  
High Temperature ◽  
Volatile Organic Compounds ◽  
Low Temperature ◽  
Organic Compounds ◽  
Chemical Components ◽  
Chemical Compositions ◽  
Voc Emission ◽  
Volatile Organic ◽  
Different Temperatures

Volatile organic compounds (VOC) emission from different asphalts not only causes the change in the performances of the bitumen, but also its chemical compositions. This paper carried out four-component analysis to study the influence of VOC emission from different asphalts on bitumens chemical compositions under different conditions. Results show that four-component of asphalts from different places is different. Also as the time of VOC emission increases, the total contents of resins and asphaltenes increase, but the total contents of saturates and aromatics decrease. VOC emission under different temperatures also has a great impact on the asphalt chemical components; Saturates and aromatics decrease in high temperature is larger than in low temperature, and there exists big differences in the asphalt surface layer and the internal of chemical components.

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Superconducting Wind Generators with Capacities of 10 MW and Larger

2020 ◽  
Vol 10 (10) ◽  
pp. 59-67
Author(s):  
Victor N. ANTIPOV ◽  
◽  
Andrey D. GROZOV ◽  
Anna V. IVANOVA ◽  
◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Wind Power ◽  
State Of The Art ◽  
Superconducting Materials ◽  
Commercial Application ◽  
Synchronous Generators ◽  
High Temperature Superconducting ◽  
Wind Generators ◽  
Main Factor

The overall dimensions and mass of wind power units with capacities larger than 10 MW can be improved and their cost can be decreased by developing and constructing superconducting synchronous generators. The article analyzes foreign conceptual designs of superconducting synchronous generators based on different principles: with the use of high- and low-temperature superconductivity, fully superconducting or only with a superconducting excitation system, and with the use of different materials (MgB2, Bi2223, YBCO). A high cost of superconducting materials is the main factor impeding commercial application of superconducting generators. In view of the state of the art in the technology for manufacturing superconductors and their cost, a conclusion is drawn, according to which a synchronous gearless superconducting wind generator with a capacity of 10 MW with the field winding made of a high-temperature superconducting material (MgB2, Bi-2223 or YBCO) with the «ferromagnetic stator — ferromagnetic rotor» topology, with the stator diameter equal to 7—9 m, and with the number of poles equal to 32—40 has prospects for its practical use in the nearest future.

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