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Tytuł:
Electrokinetic and flotation behavior of rutile in the presence of lead ions and aluminium ions
Autorzy:
Cheng, Hongwei
Liu, Changmiao
Guo, Zhenxu
Feng, Ansheng
Wei, Min
Lv, Zihu
Wu, Dongyin
Zhao, Dengkui
Powiązania:
https://bibliotekanauki.pl/articles/110558.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
lead ions
aluminium ions
rutile
flotation
Opis:
The effects of Pb(II) ions and Al(III) ions on the electro kinetic and flotation behavior of rutile were investigated by micro-flotation tests, zeta potential measurements and solution chemistry analysis. Micro-flotation results indicate that the Pb(II) ions can effectively improve the flotation recovery of rutile while the Al(III) ions significantly inhibit the flotation of rutile. Zeta potential measurements reveal that a collector styrene phosphoric acid (SPA) can adsorb on the rutile surface after the addition of Pb(II) ions, but hardly adsorb on the rutile surface after the addition of Al(III) ions. Pb(II) ions adsorb on the rutile surface in the form of Pb(OH)+ and Pb(OH)2(s), and the latter one is the main reason that activates rutile flotation. Al(III) ions adsorb on the rutile surface mainly in the form of Al(OH)3(s), which prevent the direct interaction between the rutile and the collector, resulting in a decrease of rutile flotation recovery.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 2; 458-466
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Flotation separation of rutile from almandine using octadecyl amine polyoxyethylene ether as collector
Autorzy:
Li, Hongqiang
Zheng, Huifang
Chen, Qian
Kasomo, Richard M.
Leng, Jiahao
Weng, Xiaoqing
Song, Shaoxian
Xiao, Linbo
Tian, Chengtao
Powiązania:
https://bibliotekanauki.pl/articles/1449410.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
rutile
almandine
flotation separation
adsorption mechanism
Opis:
In this study, the flotation separation of rutile from almandine using cationic surfactant Octadecyl amine polyoxyethylene ether (AC1815) as a new collector was investigated. The adsorption mechanism of AC1815 on rutile was illustrated through zeta potential measurement, infrared spectrum and XPS analyses. The flotation experiments demonstrated that AC1815 exhibited an excellent collecting ability and selectivity for rutile. The results of zeta potential measurements and XPS analysis indicated that more AC1815 was adsorbed on rutile surface instead of almandine. The adsorption mechanism of AC1815on rutile was mainly attributed to the electrostatic interaction between the positively charged molecules of AC1815 and the negatively charged rutile surface, and the hydrogen bonding between the protonated $≡NH^+$, $≡N$ group of AC1815 and $Ti-OH$ on rutile surface.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 4; 653-664
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Insights into the interaction between octyl hydroxamic acid and the rutile surface activated by lead ion
Autorzy:
Cao, Qinbo
Chen, Xiumin
Zou, Heng
Yu, Xingcai
Powiązania:
https://bibliotekanauki.pl/articles/1845214.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
flotation
rutile
activation
density functional theory
adsorption
Opis:
The flotation of rutile can be enhanced using lead ion as an activator. However, the binding behavior of collector on the activated rutile surface is still not fully understood. In this work, flotation and theoretical calculation approaches were employed to evaluate the activation behavior of lead ion in the flotation of rutile with octyl hydroxamic acid (OHA). Flotation results indicated that the activation flotation with lead ion should be conducted at pH 6.5. The binding features of OHA molecule on the inactivated and Pb-activated rutile surfaces were both investigated by density functional theory (DFT) studies. The OHA molecule may dissociate into OHA− anion on the inactivated rutile surface, generating a new Ti–O bond. Differently, the chelate complex of Pb-OHA anion was generated on the activated rutile surface, producing two Pb–O bonds. The adsorption of OHA onto the activated rutile surface was more stable than that on the inactivated rutile surface, due to the formation of more chemical bonds on the activated rutile surface. The DFT calculation results delineated the role of Pb2+ in the rutile flotation with OHA.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 5; 928-938
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of the anatase to rutile transformation kinetics of the modified TiO2
Autorzy:
Grzmil, B.
Gleń, M.
Kic, B.
Lubkowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/779360.pdf
Data publikacji:
2013
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
TiO2
anatase
rutile
modification
phase transformation kinetics
Opis:
TiO2 attracts much interest because of its many potential applications. The use of titanium dioxide strongly depends on its polymorphic form: brookite, anatase, or rutile. Only rutile and anatase play an important role in industry. Anatase as a metastable form undergoes a non-reversible transformation into rutile. Understanding the kinetics of phase transformation and the processes of crystal growth of a material is essential for controlling its structure and, thus, its specific properties. The main purpose of this paper is to explain the anatase to rutile recrystallization kinetics in the modified TiO2 calcined from industrial hydrated titanium dioxide. The apparent activation energy of anatase to rutile transformation and the average size of titanium dioxide crystallites were determined for the unmodified TiO2 and TiO2 modified with P, K, Al, B, Zn, Zr, Ce, Sn, or Sb introduced in the amount of 0.5 mol% and 1.0 mol% when recalculated for their oxides. The growth of TiO2 crystallites during calcination was strongly inhibited by P, Ce and Zr, and inhibited to a lesser degree by Al, Sn and Sb. B and Zn did not affect the investigated process and K accelerated crystallites growth. The values of apparent activation energy depending on a modifier formed a relationship: Al
Źródło:
Polish Journal of Chemical Technology; 2013, 15, 2; 73-80
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Analysis of Titanium Dioxide Synthesis from Synthetic Rutile Waste using a Moderate Acid Concentration and Temperature
Autorzy:
Ahmad Mukifza, H.
Awang, H.
Yusof, S.
Farid, E.
Powiązania:
https://bibliotekanauki.pl/articles/1031724.pdf
Data publikacji:
2017-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
synthetic rutile
titanium dioxide
caustic hydrothermal
sodium titanate
Opis:
The present study is to clarify the present influences of acid concentration and temperature of caustic hydrothermal method on extracting the titanium dioxide (TiO₂) from synthetic rutile waste. In this experimental work, the caustic hydrothermal method comprises two processes: a decomposition and the sulphate process. The extracted titanium is characterized by using a electron dispersive X-ray spectroscopy to specify its chemical composition, field emission scanning electron microscope to determine the morphology and particle size, and lastly it is the X-ray diffraction to analyse the crystallinity of extracted titanium. In this study, we found that both acid concentration and temperature affected the TiO₂ growth while the calcination process could improve the crystallinity of extracted titanium.
Źródło:
Acta Physica Polonica A; 2017, 132, 3; 833-835
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The removal of Fe from the reduced ilmenite via aeration leaching assessing the effect of operating parameters
Autorzy:
Ibrahim, Siti Asmidar
Yunus, Farhana
Ariffin, Kamar Shah
Sheikh Abdul Hamid, Sheikh Abdul Rezan
Ismail, Suhaina
Jabit, Nurul Ain
Powiązania:
https://bibliotekanauki.pl/articles/2146865.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
ilmenite
reduced ilmenite
aeration leaching
synthetic rutile
titanium dioxide
Opis:
An upgrade of Malaysian ilmenite (FeTiO3) concentrate to synthetic rutile (TiO2) using aeration leaching was investigated in this study. Carbothermal reduction using Sarawak MukahBalingan coal and compressed National Gas (CNG) as a reductant was used to produce reduced ilmenite (RI) as an intermediate phase consisting of titanium oxide matrix with metallic iron prior to aeration leaching. Metallic iron was dissolved in ammonium chloride solution after the reduction process, separating synthetic rutile in the leaching residue. This study aims to evaluate the leaching parameters, such as concentration, temperature, and leaching time. The optimum conditions established by the design of the experiment (DOE) and the analysis of variance (ANOVA) has indicated that leaching temperature was the most significant parameter for iron dissolution. It was found that iron dissolution at a maximum value of 97.0% was achieved at an optimum condition of 0.5 M NH4Cl at 90°C for 7 hours. With an initial weight of 46 wt.%TiO2 and 37 wt.% Fe2O3, ilmenite was successfully upgraded to 80 wt.% and 8 wt.%, respectively. In conclusion, Malaysian ilmenite has a high potential value to be upgraded to synthetic rutile by aeration leaching with ammonium chloride via Becher process.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 6; 182--195
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adsorption of lead ion on the hydrated rutile (110) surface: a DFT calculation study
Autorzy:
Zou, Heng
Cao, Qinbo
Chen, Xiumin
Liu, Dianwen
Powiązania:
https://bibliotekanauki.pl/articles/109829.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
rutile
hydrated surface
lead ion
adsorption
density functional theory
Opis:
The adsorption behavior of lead species on the hydrated rutile surface was investigated with inductively coupled plasma mass spectrometry (ICP-MS) measurements and density functional theory (DFT) calculations. ICP-MS experiments suggested that lead species can be readily absorbed by the rutile powder in water at pH 6.5. From the ICP-MS results and the species distribution of Pb2+, it was concluded that Pb2+ was the major lead species adsorbing at the rutile/water interface at the pH of 6.5. DFT calculation results indicated that Pb2+ could adsorb at four different sites on the surface. At each site, water molecules or OH groups were involved in the reaction with Pb2+. The water molecules/OH groups on the rutile surface play an important role during the adsorption of Pb2+ on the hydrated rutile surface.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 4; 951-959
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Silesian Ridge in the light of petrological analyses and LA-ICP MS U-Pb analyses of the cohesive debrites from the Istebna Formation (Silesian Nappe, Outer Western Carpathians, Poland)
Autorzy:
Szczuka, Monika
Gawęda, Aleksandra
Waśkowska, Anna
Golonka, Jan
Szopa, Krzysztof
Chew, David
Drakou, Foteini
Powiązania:
https://bibliotekanauki.pl/articles/2187194.pdf
Data publikacji:
2022
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Outer Carpathians
Silesian Ridge
exotic clasts
U-Pb dating
zircon
rutile
Opis:
Exotic clasts present in flysch deposits of the Western Outer Carpathians enable investigation and reconstruction of the eroded crystalline basement of the Silesian Ridge. The flysch rocks of the Istebna Formation (Jasnowice Member: Paleocene) in the Silesian Nappe contain magmatic and metamorphic clasts derived from the Silesian Ridge basement. The crystalline rock fragments acquired from cohesive debrites were analyzed petrographically and geochemically, and zircon and rutile crystals were subject to LA-ICP-MS U-Pb dating. Granitoid clasts yielded Meso-Variscan U-Pb zircon ages (325.7 and 330.6 Ma), with older (Neoproterozoic to Paleoproterozoic) inherited cores and eNd330 = –12.0 (TDM age of 1.98 Ga). The orthogneiss clast yielded a protolith age of 1635 Ma and fingerprint of thermal reworking at ~288 Ma. Zircon crystals from the detrital clasts yielded similar U-Pb zircon ages to the granitoid clasts (311.5 to 391 and 331 Ma). The rutile crystals from sandstone yielded concordia age of 344.7 Ma. Zircon crystals from paragneiss, interpreted as a granitoid envelope, yielded 238U/206Pb ages between 557 and 686 Ma and include an inherited core of age ~1207.4 ±33.8 Ma. Age data from exotic clasts and the detrital zircon and rutile fraction suggest the core part of the Silesian Ridge was a Neoproterozoic to Mesoproterozoic envelope intruded by Meso-Variscan granitoid plutons.
Źródło:
Geological Quarterly; 2022, 66, 2; art. no. 20
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Crystal Structure And Optical Properties Of TiO2 Thin Films Prepared By Reactive RF Magnetron Sputtering
Charakterystyka cienkich warstw TiO2 otrzymanych metodą reaktywnego rozpylania magnetronowego RF
Autorzy:
Goto, S.
Adachi, Y.
Matsuda, K.
Nose, M.
Powiązania:
https://bibliotekanauki.pl/articles/352029.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
TiO2
rutile
anatase
sputtering
XRD
rutyl
anataz
rozpylanie
dyfrakcja promieniowania rentgenowskiego
Opis:
In sputtering deposition process of TiO2, metal Ti or sintered TiO2 target is used as deposition source. In this study, we have compared the characteristic of target materials. When TiO2 target was used, stoichiometric TiO2 films was deposited under the Ar atmosphere containing 1.0% of oxygen. The highest sputtering rate under this atmosphere was 3.9nm/min at 3.4W/cm2. But, sintered TiO2 target is fragile and cannot endure higher density of input power than 3.4W/cm2. On the other hand, Ti target needs higher oxygen concentration (8%) in sputtering gas atmosphere for obtaining rutile/anatase. Even though Ti target can be input twice power density of 7.9W/cm2, the highest deposition rate for Ti target was 1.4/nm, which was ~35% of the highest rate for TiO2 target. Then we have study out the composite target consisting of Ti plate and TiO2 chips. Using the composite target, stoichiometric TiO2 films were prepared in the rate of 9.6nm/min at 6.8 W/cm2 under the atmosphere of Ar/2.5%O2. Furthermore, we have found that the TiO2 films obtained from the composite target consisted of about 100% anatase, whereas TiO2 films obtained from other target have rutile dominant structure. The optical band gap energy of the film is determined by using the Tauc plot. The calculated band gap energies for the films deposited by Ti target and composite target were 2.95 and 3.24eV, which are equivalent to that of rutile and anatase structure, respectively.
W procesie nanoszenia TiO2 metodą rozpylania, jako tarczy używano metalicznego Ti lub spiekanego TiO2. W pracy dokonano porównania obu materiałów. W przypadku zastosowania jako tarczy TiO2 przy nanoszeniu w atmosferze Ar zawierającym 1,0% tlenu otrzymano stechiometryczną warstwę TiO2. Największa uzyskana szybkość rozpylania w tej atmosferze wyniosła 3,9 nm/min przy gęstości mocy wejściowej 3,4 W/cm2. Jednak spiekany TiO2 jest kruchy i nie wytrzymuje gęstości mocy wejściowej powyżej 3,4 W/cm2. Z drugiej strony, przy rozpylaniu z tarczy Ti konieczne jest zwiększone stężenie tlenu (8%) w atmosferze aby otrzymać fazę rutyl/anataz. Mimo że tarcza Ti wytrzymuje gęstość mocy dwa razy wyższą niż TiO2 (7,9 W/cm2), największa uzyskana szybkość rozpylania wynosiła 1,4 nm/min, co stanowi ~35% najwyższej szybkości uzyskanej dla tarczy TiO2. Zbadano także tarczę kompozytową składające się z płyty Ti oraz wiórów TiO2. W przypadku zastosowania tarczy kompozytowej, szybkość rozpylania wyniosła 9,6 nm/min przy mocy 6,8 W/cm2 w atmosferze Ar/2,5%O2. Dodatkowo, warstwy TiO2 otrzymane z tarczy kompozytowej zawierały około 100% anatazu, podczas gdy w przypadku warstw otrzymanych z pozostałych tarcz dominowała faza rutylu. Szerokość przerwy energetycznej wyznaczono na podstawie wykresu Tauca. Obliczone wartości przerwy energetycznej wynosiły 2,95 eV dla podłoża Ti i 3,24 eV dla podłoża kompozytowego, co odpowiada wartością przerw odpowiednio dla rutylu i anatazu.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2A; 965-967
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kinetics study and reaction mechanism for titanium dissolution from rutile ores and concentrates using sulfuric acid solutions
Autorzy:
Ismael, Mohamed H.
Mohammed, Hesham S.
El Hussaini, Omneya M.
El-Shahat, Mohamed F.
Powiązania:
https://bibliotekanauki.pl/articles/2146851.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
leaching kinetics
leaching mechanism
titanium
rutile concentrate
leaching design
shrinking
core model
Opis:
Recent developments of acid leaching of titanium concentrates and ores have produced renewed industrial and commercial interest. However, the leaching kinetics and mechanism of these concentrates and ores had received little attention. This work, therefore, addresses the leaching kinetics and mechanism of Ti from a rutile concentrate in sulfuric acid solution. The leaching reaction was controlled by diverse parameters like temperature, particle size, acid concentration, liquid/solid (L/S) ratio, and stirring speed. The leaching kinetics was investigated using the Shrinking Core Model in order to determine the optimum criteria which control the reaction. The kinetics analysis showed that the rate of dissolution of Ti increased by increasing reaction temperature, L/S ratio, and stirring speed, while it decreased upon increasing particle size. The kinetics analysis revealed that the dissolution reaction is controlled by the chemical reaction at the rutile particle surface. Applying the Arrhenius relation, the apparent energy of activation Ea for the leaching reaction was calculated to be 23.4kJ/mol. A semi-empirical overall rate equation was introduced to describe the combined effects of the process variables upon the rate of the dissolution reaction: 〖1-(1-x)〗^(1/3)=k_0 〖 C〗_([H2SO4])^0.803 〖 (dp)〗^(-0.518) 〖(L/S)〗^0.793 〖(w)〗^0.668 e^((-23400/RT)) t
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 1; 138--148
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of ethylene oxide groups in dodecylamine polyoxyethylene ether on rutile flotation
Autorzy:
Huang, Junwei
Chen, Qian
Mao, Yuxuan
Li, Hongqiang
Powiązania:
https://bibliotekanauki.pl/articles/1448539.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
rutile flotation
dodecylamine polyoxyethylene ether
ethylene oxide groups
steric hinder effect
adsorption mechanism
Opis:
To study the number of ethylene oxide (EO) groups effect on the flotation of rutile, three collectors with different EO number were evaluated: AC1203 (with three EO number), AC1210 (with ten EO number), AC1215 (with fifteen EO number). In addition to the flotation experiments, zeta potential measurements, collector adsorption experiments and XPS analysis were conducted to elucidate the adsorption mechanism. The results of flotation demonstrated that dodecylamine polyoxyethylene ether exhibited a profound collecting ability towards rutile mineral, it was worth mentioned that the recovery of rutile decreased with the increase of EO number. On the basis of zeta potential tests and XPS analysis, both protonated and neutral tertiary amine groups could act with rutile surface through electrostatic effect and hydrogen bond interaction. Furthermore, the results of collector adsorption experiments showed that with the increase of EO number, a lower adsorption density of collectors on rutile surface could be caused due to the steric hinder effects.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 1; 127-135
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of diffusible hydrogen content in the deposited metal of rutile electrodes by glycerin method
Oznaczanie ilości wodoru dyfundującego w stopiwie elektrod rutylowych metodą glicerynową
Autorzy:
Fydrych, D.
Tomków, J.
Świerczyńska, A.
Powiązania:
https://bibliotekanauki.pl/articles/263789.pdf
Data publikacji:
2013
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
diffusible hydrogen
rutile electrode
glycerin method
wodór dyfundujący
elektrody rutylowe
metoda glicerynowa
Opis:
The presence of diffusible hydrogen in welded joints is one of the causes of formation the welding imperfections. Improvement of weldability can be achieved by reducing the hydrogen amount in welded joints. This requires, among others, the finding of sources of hydrogen. For high hydrogen processes the commonly used method of determining the diffusible hydrogen amount is the glycerin method. This paper concerns issues related to the test procedure and the possibility to control the diffusible hydrogen amount in deposited metal.
Obecność wodoru dyfundującego w złączach spawanych jest jedną z przyczyn powstawania niezgodności spawalniczych. Poprawę spawalności stali można osiągnąć przez zmniejszenie nawodorowania złączy. Wymaga to m.in. wyznaczenia źródeł wodoru. W procesach wysokowodorowych często stosowaną metodą oznaczania ilości wodoru dyfundującego jest metoda glicerynowa. Praca dotyczy zagadnień związanych z procedurą badawczą i możliwością sterowania ilością wodoru dyfundującego w stopiwie.
Źródło:
Metallurgy and Foundry Engineering; 2013, 39, 1; 47-54
1230-2325
2300-8377
Pojawia się w:
Metallurgy and Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal metamorphic evolution of the Pułtusk H chondrite breccia – compositional and textural properties not included in petrological classification
Autorzy:
Krzesinska, A. M.
Powiązania:
https://bibliotekanauki.pl/articles/2060180.pdf
Data publikacji:
2016
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
meteorite
H chondrite
parent body metamorphism
petrologic classification
partial melting
spinel group minerals
rutile in chondrites
Opis:
The thermal history that chondrites experienced on their parent body is an aspect of their petrological classification. However, in the classification scheme, metamorphic conditions are generally limited to the peak metamorphic temperature attained, while it is known that reconstruction of the genuine thermal evolution of any rock requires identification of various metamorphic factors, definition of the temperature-time path during metamorphism and characterization of the processes responsible for heating. Study of the brecciated Pułtusk H chondrite shows that the meteorite comprises both low and high petrologic type material and should be classified as a H3.8–6 chondrite. Based on the textures and mineral and chemical composition, the thermal metamorphic history of the breccia is reconstructed and it is shown to be inconsistent with the petrologic classification; the textural maturation and degree of compositional equilibrium in the meteorite do not correspond to the temperatures attained. The metamorphic conditions are shown to be a function of the primary composition of the accreted minerals and of two metamorphic phases, progressive and retrogressive. First, a prograde phase led to textural maturation and equilibration of the chemical composition of silicates and oxides. The peak metamorphic temperatures were at least ~700ºC for the type 3.8. and 4 material, and up to ~1000ºC in H6 clasts i.e., sufficient to locally give rise to partial melting. The following retrograde metamorphism led to compositional re-equilibration of minerals and textural re-equilibration of minerals with partial melts. The cooling rate during retrograde metamorphism down to at least ~700ºC was low, which allowed potassium feldspar to form patches in Na-plagioclase and pseudobrookite-armalcolite breakdown to form an association of ilmenite and rutile. The two-phase metamorphic evolution of the Pułtusk breccia was the most likely the result of impact heating, which affected the parent body in its very early history.
Źródło:
Geological Quarterly; 2016, 60, 1; 211--224
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geology and genesis of vein-type corundum deposits in the Hafafit-Nugrus area, South Eastern Desert, Egypt
Autorzy:
Mahmoud, Soliman Abu Elatta A.
Ali, Hani H.
Powiązania:
https://bibliotekanauki.pl/articles/1841624.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
grossular
Cr-rich spinel
Nb-rich rutile
ultramafic rocks
secondary uranium minerals
spinel
rutyl
minerały
skały ultrazasadowe
uran
Opis:
Unusual deposits formed by corundum are described from two separate pegmatitic veins in the Hafafit-Nugrus area of the South Eastern Desert of Egypt. Other related minerals are described too. The vein-type of corundum at Locality 1 (Vein 1) crosscuts through exposed rocks of an ophiolitic mélange, whereas at Locality 2 (Vein 2), it crosscuts through exposed serpentinised ultramafic rocks. The main minerals in Vein 1 are plagioclase, corundum, grossular, phlogopite, muscovite and clinochlore, while almandine, xenotime-(Y), allanite-(Ce), zircon, Cr-rich spinel, apatite, titanite, fergusonite-(Y), meta-ankoleite, U-rich thorite (uranothorite), carbonate and illite are the accessories. In Vein 2, the main minerals are plagioclase, corundum, phlogopite and chlorite, while clinochlore, euxenite-(Y), Nb-rich rutile, almandine, xenotime-(Y), allanite-(Ce), zircon, spinel, apatite, titanite, kasolite, dickite, illite, carbonate, antigorite and talc are accessories. The two types of corundum veins differ in their concentrations of Th, U, Zr, Nb, Ta, REE, Y and Li in wholerock compositions. Field observations, mineralogy and chemical analyses of samples from the two veins of corundum deposits, as well as concentrations of chromophore elements in corundum crystals, suggest metasomatic origins. The present study suggests that the two types of corundum veins formed at different ages from different residual magmas that underwent in-situ hybridisation with the host rocks.
Źródło:
Geologos; 2020, 26, 3; 181-197
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of calcination temperature on photocatalytic activity of TiO2. Photodecomposition of mono- and polyazo dyes in water
Autorzy:
Mozia, S.
Powiązania:
https://bibliotekanauki.pl/articles/779014.pdf
Data publikacji:
2008
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
fotokataliza
dwutlenek tytanu
TiO2
anataz
wielkość krystalitów
barwnik azowy
photocatalysis
titanium dioxide
anatase
rutile
crystallite size
azo dye
Opis:
The presented studies have focused on the influence of TiO2 properties, such as crystalline phase, crystallite size and surface area, on the effectiveness of degradation of azo dyes in water under UV irradiation. Two monoazo dyes: Acid Red 18 (AR18, C20H11N2Na3O10S3) and Acid Yellow 36 (AY36, C18H14N3NaO3S), and one polyazo dye Direct Green 99 (DG99, C44H28N12Na4O14S4) were applied as model compounds. The photocatalysts were prepared from a crude titanium dioxide obtained directly from the production line (sulfate technology) at the Chemical Factory "Police" (Poland). The crude TiO2 was calcinated in air for 1-4h at the temperatures ranging from 600 to 800°C. The BET specific surface area of TiO2 decreased gradually with increasing the calcination temperature. The crude TiO2 exhibited specific surface area of 277 m2/g. In case of the catalysts heated at 600, 700 and 800°C the BET surface area amounted to 62.3-53.3, 33.4-26.8 and 8.9-8.3 m2/g, for the calcination time of 1-4h, respectively. The crystallite size of anatase increased with increasing heat treatment temperature and ranged from 19 to 53 nm, for the temperatures of 600-800°C, respectively. The catalysts annealed at 600 and 700°C contained primarily anatase phase (94-97%), whereas the photocatalysts heated at 800°C were composed mainly of rutile (97-99%). The highest effectiveness of azo dyes degradation was obtained in case of the photocatalyst calcinated for 1h at 700°C. The photocatalyst was composed mainly of anatase (97%) with crystallite size of 27 nm. The most effectively photodegraded was AR18, having the molecular weight of 640.4 g/mol. The most difficult to degrade was AY36 exhibiting the lowest molecular weight from all the dyes used (375.4 g/mol).
Źródło:
Polish Journal of Chemical Technology; 2008, 10, 3; 42-49
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 17

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