scholarly journals Authigenic and Detrital Minerals in Peat Environment of Vasyugan Swamp, Western Siberia

Minerals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 500 ◽  
Author(s):  
Maxim Rudmin ◽  
Aleksey Ruban ◽  
Oleg Savichev ◽  
Aleksey Mazurov ◽  
Aigerim Dauletova ◽  
...  
Keyword(s):  
Western Siberia ◽  
Geochemical Evolution ◽  
Peat Bogs ◽  
Anaerobic Oxidation Of Methane ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mineral Inclusions ◽  
Oxidation Of Methane ◽  
Mineral Associations ◽  
Shed Light

Studies of mineral-forming processes in modern peat bogs can shed light on metal concentrations and their cycling in similar environments, especially in geological paleoanalogs. In terms of the mineralogical and geochemical evolution of peat bog environments, the Vasyugan Swamp in Western Siberia is a unique scientific object. Twelve peat samples were collected from the Vasyugan Swamp up to the depth of 275 cm at 25 cm intervals. The studied peat deposit section is represented by oligotrophic (0–100 cm), mesotrophic (100–175 cm), and eutrophic (175–275 cm) peat, and this is underlain by basal sediments (from 275 cm). About 30 minerals were detected using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. The observed minerals are divided into detrital, clay, and authigenic phases. The detrital minerals found included quartz, feldspar, ilmenite, rutile, magnetite, zircon, and monazite. When passing from basal to oligotrophic bog sediments, the clay minerals changed from illite-smectite to kaolinite. Authigenic minerals are represented by carbonates (calcite and dolomite), iron (hydro-)oxides, galena, sphalerite, pyrite, chalcopyrite, Zn-Pb-S mineral, barite, baritocelestine, celestine, tetrahedrite, cassiterite, REE phosphate, etc. The regular distribution of mineral inclusions in peat is associated with the (bio)geochemical evolution of the environment. The formation of authigenic Zn, Pb and Sb sulfides is mainly confined to anaerobic conditions that exist in the eutrophic peat and basal sediments. The maximum amount of pyrite is associated with the interval of 225–250 cm, which is the zone of transition from basal sediments to eutrophic peat. The formation of carbonate minerals and the decreasing concentration of clay in the association with local sulfide formation (galena, sphalerite, chalcopyrite, stibnite) begins above this interval. The peak of specific carbonation appears in the 125–150 cm interval of the mesotrophic peat, which is characterized by pH 4.9–4.5 of pore water. Kaolinite is the dominant clay mineral in the oligotrophic peat. Gypsum, galena, chalcopyrite, sphalerite, and relicts of carbonate are noted in association with kaolinite. Changes in oxygen concentrations are reflected in newly formed mineral associations in corresponding intervals of the peat. This can be explained by the activity of microbiological processes such as the anaerobic oxidation of methane (AOM) and bacterial sulfate reduction (BSR), expressed in specific carbonatization (100–225 cm) and sulfidization (175–250 cm), respectively.

scholarly journals Extraction of Boron from Ludwigite Ore: Mechanism of Soda-Ash Roasting of Lizardite and Szaibelyite

Minerals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 533 ◽  
Author(s):  
Xin Zhang ◽  
Guanghui Li ◽  
Jinxiang You ◽  
Jian Wang ◽  
Jun Luo ◽  
...  
Keyword(s):  
Sodium Carbonate ◽  
Energy Dispersive Spectrometer ◽  
Low Grade ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Selective Activation ◽  
X Ray ◽  
Shed Light ◽  
Soda Ash ◽  
Scanning Electron

Ludwigite ore is a typical low-grade boron ore accounting for 58.5% boron resource of China, which is mainly composed of magnetite, lizardite and szaibelyite. During soda-ash roasting of ludwigite ore, the presence of lizardite hinders the selective activation of boron. In this work, lizardite and szaibelyite were prepared and their soda-ash roasting behaviors were investigated using thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microscope and energy dispersive spectrometer (SEM-EDS) analyses, in order to shed light on the soda-ash activation of boron within ludwigite ore. Thermodynamics of Na2CO3-MgSiO3-Mg2SiO4-Mg2B2O5 via FactSage show that the formation of Na2MgSiO4 was preferential for the reaction between Na2CO3 and MgSiO3/Mg2SiO4. While, regarding the reaction between Na2CO3 and Mg2B2O5, the formation of NaBO2 was foremost. Raising temperature was beneficial for the soda-ash roasting of lizardite and szaibelyite. At a temperature lower than the melting of sodium carbonate (851 °C), the soda-ash roasting of szaibelyite was faster than that of lizardite. Moreover, the melting of sodium carbonate accelerated the reaction between lizardite with sodium carbonate.

scholarly journals Liberation Characteristics of Ta–Sn Ores from Penouta, NW Spain

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 509
Author(s):  
Pura Alfonso ◽  
Sarbast Ahmad Hamid ◽  
Hernan Anticoi ◽  
Maite Garcia-Valles ◽  
Josep Oliva ◽  
...  
Keyword(s):  
White Mica ◽  
Low Grade ◽  
Economic Interest ◽  
X Ray Diffraction ◽  
Nw Spain ◽  
X Ray ◽  
Mineral Associations ◽  
Ore Minerals ◽  
Automated Mineralogy ◽  
Scanning Electron

The strategic importance of tantalum and its scarcity in Europe makes its recovery from low grade deposits and tailings interesting. In Penouta, the contents of Ta and Sn in old tailings from an Sn mine are of economic interest. Due to the relatively low grade of Ta of around 100 ppm, a detailed study of the mineralogy and liberation conditions is necessary. In this study, the mineralogy and the liberation characteristics of Sn and Ta ores of the Penouta tailings were investigated and compared with the current leucogranite outcropping ores. The characterization was conducted through X-ray diffraction, scanning electron microscopy, and electron microprobe. In addition, automated mineralogy techniques were used to determine the mineral associations and liberation characteristics of ore minerals. The grade of the leucogranite outcropping was found to be about 80 ppm for Ta and 400 ppm for Sn, and in the tailings used for the liberation study, the concentrations of Ta and Sn were about 100 ppm Ta and 500 ppm Sn, respectively. In both, the leucogranite outcropping and tailings, the major minerals found were quartz, albite, K-feldspar, and white mica. Ore minerals identified were columbite-group minerals (CGM), microlite, and cassiterite. The majority of CGM examined were associated with cassiterite, quartz, and muscovite particle compositions and cassiterite was mainly associated with CGM, quartz, and muscovite. The liberation size was 180 µm for CGM.

scholarly journals Lead-antimony sulfosalts from Tuscany (Italy). XVIII. New data on the crystal-chemistry of boscardinite

2017 ◽  
Vol 81 (1) ◽  
pp. 47-60 ◽  
Author(s):  
Cristian Biagioni ◽  
Yves Moëlo
Keyword(s):  
Single Crystal ◽  
Diffraction Study ◽  
Type Specimen ◽  
Structural Features ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Mineral Associations ◽  
Crystal Chemical Data ◽  
New Findings

AbstractBoscardinite, ideally TlPb4(Sb7As2)∑9S18, has been described recently as a new homeotypic derivative of baumhauerite, found at Monte Arsiccio mine, Apuan Alps, Tuscany, Italy. New findings of boscardinite in different mineral associations of this deposit have allowed the collection of new crystal-chemical data. Electron-microprobe analysis of the crystal used for the single-crystal X-ray diffraction study gave (in wt.%): Ag 1.81(5), Tl 12.60(21), Pb 17.99(12), Hg 0.14(5), As 9.36(12), Sb 33.60(27), S 23.41(30),Cl 0.06(1), total 98.97(100). On the basis of ∑Me= 14 apfu, it corresponds to Ag0.42Tl1.52Pb2.14Hg0.02(Sb6.82As3.08)∑9.90S18.04Cl0.04. With respect to the type specimen, these new findings are characterized by a strong Pb depletion, coupled with higher Tl contents, and a significant As enrichment. The single-crystal X-ray diffraction study of this (Tl,As)-enriched boscardinite confirms the structural features described for the type sample. The unit-cell parameters area= 8.1017(4),b= 8.6597(4),c= 22.5574(10) Å, α = 90.666(2), β = 97.242(2), γ = 90.850(2)°,V= 1569.63(12) Å3, space groupP̄1. The crystal structure was refined down toR1= 0.0285 on the basis of 6582 reflections withFo> 4σ(Fo). Arsenic is dominant in threeMeS3sites, compared to one in type boscardinite. The main As-enrichment is observed in the sartorite-type sub-layer. Owing to this chemical peculiarity, (Tl, As)-rich boscardinite shows alternation, alongb, of Sb-rich sites and As-rich sites; this feature represents the main factor controlling the 8 Å superstructure. The chemical variability of boscardinite is discussed; the Ag increase observed here gets closer to stoichiometric AgTl3Pb4(Sb14As6)∑20S36(Z= 1), against possible extension up to AgTl2Pb6(Sb15As4)∑19S36for type boscardinite.

scholarly journals Ab initio simulation and X-ray diffraction measurements of deviatoric stress in mineral inclusions

2019 ◽  
Vol 75 (a2) ◽  
pp. e261-e261
Author(s):  
Marta Morana ◽  
Mara Murri ◽  
Alice Girani ◽  
Ross J. Angel ◽  
Matteo Alvaro
Keyword(s):  
Ab Initio ◽  
Deviatoric Stress ◽  
X Ray Diffraction ◽  
Ab Initio Simulation ◽  
X Ray ◽  
Mineral Inclusions

scholarly journals Catalytic Performance of Calcium-Lanthanum co-doped Ceria (Ce0.85-xLa0.15CaxO2-δ) in Partial Oxidation of Methane

2021 ◽  
Vol 16 (3) ◽  
pp. 548-554
Author(s):  
Qassam Sarmad ◽  
U. M. Khan ◽  
Mustafa Anwar ◽  
A. H. Khoja ◽  
M. Ali ◽  
...  
Keyword(s):  
Partial Oxidation ◽  
Sol Gel ◽  
Performance Testing ◽  
Combustion Method ◽  
Catalytic Performance ◽  
Partial Oxidation Of Methane ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxidation Of Methane ◽  
Gel Combustion

In this study, Ce0.85-xLa0.15CaxO2-δ was synthesized using sol-gel combustion method and appliedfor partial oxidation of methane (POM). The physicochemical properties of catalyst were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and thermogravimetric analysis (TGA). Material shows a pure cubical structure and is highly stable up to 850 °C. The performance testing indicated the conversion of CH4 is 65% and selectivity of H2 and CO are 28% and 8%, respectively. The performance indicated the catalyst has a potential to be used for partial oxidation of methane on a larger scale. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

scholarly journals Effect of NaClO dosage on the structure of degummed hemp fibers by 2,2,6, 6-tetramethyl-1-piperidinyloxy-laccase degumming

2017 ◽  
Vol 89 (1) ◽  
pp. 76-86 ◽  
Author(s):  
Liu Liu ◽  
Yeping Xiang ◽  
Ruiyun Zhang ◽  
Bei Li ◽  
Jianyong Yu
Keyword(s):  
Composition Analysis ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Hemp Fibers ◽  
Cellulosic Materials ◽  
X Ray ◽  
Chemical Composition Analysis ◽  
Degumming Process ◽  
Fourier Transfer Infrared Spectroscopy ◽  
Shed Light

In this study, different dosages of NaClO were used in the 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)-laccase degumming system to remove non-cellulosic materials, and their effects on the structure of hemp fibers were analyzed and discussed. A scanning electron microscope was used to depict the surface morphology of fibers after oxidative degumming under various dosages of NaClO in the TEMPO-laccase degumming system. Chemical composition analysis was used to determine the content changes of the different components. Meanwhile, the content of functional groups was also discussed. Fourier transfer infrared spectroscopy, nuclear magnetic resonance spectroscopy, and X-ray diffraction were employed to evaluate the microstructural changes of degummed hemp fibers obtained from the degumming processes with different dosages of NaClO. The results showed that after the TEMPO-laccase system degumming process with a NaClO dosage of 16%, the cleanest and smoothest surface of degummed fibers could be observed and the non-cellulosic materials were significantly removed without any crystalline transformation or damage in the cellulose. This research could shed light on determining favorable operation parameters for hemp oxidation degumming and increasing the degumming efficiency, as well as in the oxidation control and quality assurance of hemp fibers for textile downstream end uses.

Mineralogical, micromorphological and geochemical evolution of the kaolin facies deposit from the Capim region (northern Brazil)

Clay Minerals ◽  
2007 ◽  
Vol 42 (1) ◽  
pp. 69-87 ◽  
Author(s):  
D. J. L. Sousa ◽  
A. F. D. C. Varajão ◽  
J. Yvon ◽  
G. M. Da Costa
Keyword(s):  
Electron Microscopy ◽  
Profile Analysis ◽  
Brazilian Amazon ◽  
Open Pit ◽  
Geochemical Evolution ◽  
Optical Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Northern Brazil

AbstractThe Capim Kaolin District (eastern Brazilian Amazon), is one of the largest kaolin deposits in the world; with the kaolin used mainly for paper coating. The kaolin developed at the expense of Cretaceous sandy-clayey sediments of the Ipixuna formation, through intense lateritization from the Mesozoic to Cenozoic times.This work describes the morphological, mineralogical, crystallochemical and geochemical evolution of the Capim kaolin facies. Based on the profile analysis in the open pit fronts, it encompasses X-ray diffraction, thin-section optical analysis, EDS-assisted scanning electron microscopy and transmission electron microscopy, chemical analysis, infrared and Mössbauer spectroscopies.Six facies were defined as different stages of the supergene process. Ferruginization led to a thick duricrust on the soft kaolin, which in turn evolved from sandy-clayey sediments of the Ipixuna Formation. A subsequent deferruginization event degraded the duricrust, resulting in the flint kaolin facies.

Study of temperature-dependent crystalline state evolution of β-SiC nanorods by X-ray diffraction

2013 ◽  
Vol 28 (S1) ◽  
pp. S37-S40 ◽  
Author(s):  
M. Zhang ◽  
Z.J. Li ◽  
A.L. Meng
Keyword(s):  
Electron Microscope ◽  
Structural Information ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Transmission Electron ◽  
State Evolution ◽  
Specific Temperature ◽  
Temperature Scanning ◽  
Shed Light

Investigations into the morphology and structural evolvement of nanomaterials are essential for understanding the growth process. Herein, we present meaningful results on crystallinity transformation of β-SiC nanorods at different preparation temperatures using X-ray diffraction. Results of the characterization indicated that both crystallinity and yield of the as-prepared β-SiC nanostructures were enhanced with increasing reaction temperature. Scanning electron microscope and high-resolution transmission electron microscope were further employed to understand detailed structural information of the SiC nanorods obtained at specific temperature. The results may shed light on structural evolvement for fabrication of nanomaterials.

scholarly journals A Decrease in NiO-MgO Phase Through Its Solid Solution Equilibrium with Tetragonal(La1−zSrz)2Ni1−yMgyO4−δ: Effect on Catalytic Partial Oxidation of Methane

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Xiong Yin ◽  
Liang Hong ◽  
Zhengliang Gong
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Partial Oxidation ◽  
Methane Conversion ◽  
Partial Oxidation Of Methane ◽  
Catalytic Partial Oxidation ◽  
X Ray Diffraction ◽  
Oxide Mixture ◽  
X Ray ◽  
Oxidation Of Methane

Calcination of an oxide mixture consisting of 0.4 La2O3, 0.2 SrCO3,(1−x)NiO, andxMgO at800∘Cresults in an equilibrium between tetragonal(La1−zSrz)2Ni1−yMgyO4−δphase and NiO-MgO phase. Forming rock-salt NiO-MgO facilitates the NiO to join the tetragonal phase. The size of the NiO-MgO phase in the resulting composite is reduced with the increase in MgO (thexvalue). The composite thus obtained is used to catalyze partial oxidation of methane, and the maximum methane conversion of ca. 93% is achieved whenx=0.2. A further rise inxvalue results in a monotonic decrease in the methane conversion. X-ray diffraction, electron microscopy, and chemosorption all confirm a decrease in both size and amount of the supportedNi0clusters with the increase in MgO dosage. The reduction in size promotes the dispersion ofNi0sites and gives rise to both high activity and strong coking resistance.

scholarly journals Multi-length scale 5D diffraction imaging of Ni–Pd/CeO2–ZrO2/Al2O3 catalyst during partial oxidation of methane

2021 ◽  
Author(s):  
Dorota Matras ◽  
Antonis Vamvakeros ◽  
Simon D. M. Jacques ◽  
Marco di Michiel ◽  
Vesna Middelkoop ◽  
...  
Keyword(s):  
Partial Oxidation ◽  
Partial Oxidation Of Methane ◽  
Length Scale ◽  
Catalytic Reactor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxidation Of Methane ◽  
Multiple Length Scales ◽  
Diffraction Imaging ◽  
Al2o3 Catalyst

Operando 5D X-ray diffraction imaging reveals complex heterogeneities across multiple length scales in a catalytic reactor for the partial oxidation of methane reaction.

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