scholarly journals Mineralogical characterization and beneficiation study of kaolin from Equador (RN) and Junco do Seridó (PB) to increase the brightness index

Cerâmica ◽  
2017 ◽  
Vol 63 (367) ◽  
pp. 369-375 ◽  
Author(s):  
V. M. J. S. Campos ◽  
L. C. Bertolino ◽  
O. C. Alves
Keyword(s):  
Magnetic Separation ◽  
Iron Oxides ◽  
Sodium Dithionite ◽  
Production Costs ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Mineralogical Characterization ◽  
X Ray ◽  
Three Samples ◽  
Two Samples

Abstract Kaolin is a rock composed mainly of kaolinite. It is used in many industrial segments, such as paper and ceramics. However, for these uses it is necessary to submit the ore to appropriate beneficiation, which generally involves magnetic separation and chemical bleaching, aiming to remove iron oxide and hydroxide, raising brightness index. This work reports the mineralogical characterization and analysis of the beneficiation of three samples of kaolin, two from Equador (Rio Grande do Norte - RN) and the third from Junco do Seridó (Paraíba - PB). The samples were submitted to granulometric classification in sieve of 44 μm, magnetic separation in a magnetic induction of 14000 gauss, and chemical bleaching with sodium dithionite during 240 min. The processes were divided into two beneficiation routes. X-ray diffraction, chemical analysis by X-ray fluorescence and scanning electron microscopy were used for mineralogical characterization of the ore and measurement of the brightness index, while electron paramagnetic resonance was applied to study the variation of iron oxides and hydroxides during beneficiation. The results indicate that just 30 min of chemical bleaching without magnetic separation was sufficient to increase the brightness index from 78.2 to 90.2% and from 91.3 to 95.7% in the two samples from Equador (RN) and from 86.9 to 90.4% in the sample from Junco do Seridó (PB). The magnetic separation, although causing a small increase in the brightness index, was inefficient for removal of iron oxides and hydroxides. The results indicated no need for using magnetic separation in plants for beneficiation of kaolin from these two locations, providing the reduction of production costs allowing better exploitation of the ore.

Mineralogy of the Residues from an Underground Coal Gasification Test

1988 ◽  
Vol 136 ◽  
Author(s):  
Gregory J. McCarthy ◽  
Robert J. Stevenson ◽  
Robert L. Oliver
Keyword(s):  
Coal Gasification ◽  
Metamorphic Rocks ◽  
Spinel Solid Solution ◽  
Underground Coal Gasification ◽  
X Ray Diffraction ◽  
Mineralogical Characterization ◽  
X Ray ◽  
Combustion Modeling ◽  
Three Samples ◽  
Melting Relations

ABSTRACTDetailed mineralogical characterization by X-ray diffraction, scanning electron microscopy and electron microprobe analysis has been performed on a suite of residues and on three samples of unaltered overburden excavated from a 1983 underground coal gasification (UCG) test conducted at a mine site near Centralia, Washington. The residues were classified into nine zones based on their appearance and location in the burn cavity. Because they were isochemical with the overburden, six of these zones could be identified as altered overburden and proved to be particularly useful for correlations of mineralogy with the temperature and redox atmosphere prevailing in these materials during the UCG process. A previously unrecognized, moderate temperature, reaction between reduced iron phases and clay minerals to form an Al-rich hercynite-spinel solid solution (Al-spinel), (Fe,Mg)Al2O4, was identified. This reaction is a precursor to the well-known formation of Fe-cordierite, (Mg,Fe)2 Al4Si5O18 from SiO2 and the Al-spinel at higher temperatures. The mineralogies of altered overburden were analogous to high-temperature, low pressure, metamorphic rocks of the sanidinite facies, and to thermally altered rocks from natural coal combustion. Modeling of the mineral phase assemblages was successfully performed using a phase diagram for the system (FeO+MgO)-Al2O3-SiO2 constructed from literature diagrams. Melting relations were also modeled with this diagram. Deviations from the assemblages predicted by this diagram were attributed to oxidizing conditions.

Mineralogy and technological characterization of two kaolin deposits from the Borborema Pegmatite Province, northeastern Brazil

Clay Minerals ◽  
2019 ◽  
Vol 54 (3) ◽  
pp. 283-291
Author(s):  
Victor Matheus Joaquim Salgado Campos ◽  
Luiz Carlos Bertolino ◽  
Luana Caroline Silveira Nascimento ◽  
José Yvan Pereira Leite ◽  
Vitor Schwenk Brandão ◽  
...  
Keyword(s):  
Optical Properties ◽  
Magnetic Separation ◽  
Chemical Characterization ◽  
Northeastern Brazil ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Structural Formulae

AbstractThis research presents the mineralogical and chemical characterization and beneficiation study of two kaolin deposits from the Borborema Pegmatite Province, Brazil. Seven samples were collected and treated in two different beneficiation routes involving magnetic separation and chemical bleaching. The fractions obtained were studied by X-ray diffraction, X-ray fluorescence spectrometry, scanning electron microscopy, particle-size analyses, electron paramagnetic resonance and determination of optical properties. The samples are composed mainly of subhedral kaolinite in the form of booklets, as well as muscovite, quartz, microcline and illite impurities. The kaolinite structural formulae indicated significant replacement of Si4+ by Al3+ in tetrahedral sites and low replacement of Fe3+ by Al3+ in the octahedral sites. The first 30 min of chemical bleaching improved significantly the optical properties of kaolin, indicating that the process is more efficient than magnetic separation.

scholarly journals Electrospun Nanosystems Based on PHBV and ZnO for Ecological Food Packaging

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2123
Author(s):  
Maria Râpă ◽  
Maria Stefan ◽  
Paula Popa ◽  
Dana Toloman ◽  
Cristian Leostean ◽  
...  
Keyword(s):  
Food Packaging ◽  
Spin Trapping ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Hno3 Solution ◽  
X Ray ◽  
Trapping Method ◽  
Ft Ir ◽  
Doped Zno ◽  
Electron Paramagnetic

The electrospun nanosystems containing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and 1 wt% Fe doped ZnO nanoparticles (NPs) (with the content of dopant in the range of 0–1 wt% Fe) deposited onto polylactic acid (PLA) film were prepared for food packaging application. They were investigated by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), antimicrobial analysis, and X-ray photoelectron spectrometry (XPS) techniques. Migration studies conducted in acetic acid 3% (wt/wt) and ethanol 10% (v/v) food simulants as well as by the use of treated ashes with 3% HNO3 solution reveal that the migration of Zn and Fe falls into the specific limits imposed by the legislation in force. Results indicated that the PLA/PHBV/ZnO:Fex electrospun nanosystems exhibit excellent antibacterial activity against the Pseudomonas aeruginosa (ATCC-27853) due to the generation of a larger amount of perhydroxyl (˙OOH) radicals as assessed using electron paramagnetic resonance (EPR) spectroscopy coupled with a spin trapping method.

Mixed Metal Oxide Interfaces: An Experimental and Theoretical Assessment of Secondary Metal Influences in Metal Impregnated Aluminas

1994 ◽  
Vol 368 ◽  
Author(s):  
M. Malaty ◽  
D. Singh ◽  
R. Schaeffer ◽  
S. Jansen ◽  
S. Lawrence
Keyword(s):  
Photoelectron Spectroscopy ◽  
Theoretical Calculations ◽  
Mixed Metal Oxide ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Mixed Metal ◽  
Metal Interactions ◽  
Metal Metal ◽  
Bimetallic System

ABSTRACTStudies of the mixed-metal interface in metal impregnated alumina have indicated the possibility of much metal-metal and metal-substrate interaction. Studies were carried out on NiCu/Al2O3 system which was evaluated to develop a better understanding of the forces that drive modification of the catalytic selectivity of Ni in the presence of Cu. Electron Paramagnetic Resonance (EPR), Powder X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD) and theoretical calculations were carried out on this bimetallic system, using Ni,Ag/Al2O3 as a reference as Ni shows negligible electron perturbation on co-adsorbance with Ag onto alumina. XRD results indicate that gross modification of the electronic fields of Ni and Cu are due to direct coupling and intercalation into the alumina matrix. As a result of this phenomena, these materials may form a good base for the development of novel ceramics based on mixed-metal interactions where the intermetallic perturbations are driven by the substrate effects.

scholarly journals Discovery of Fe7O9: a new iron oxide with a complex monoclinic structure

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Ryosuke Sinmyo ◽  
Elena Bykova ◽  
Sergey V. Ovsyannikov ◽  
Catherine McCammon ◽  
Ilya Kupenko ◽  
...  
Keyword(s):  
Applied Sciences ◽  
Crystal Structure ◽  
Iron Oxide ◽  
Iron Oxides ◽  
Industrial Applications ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Insight Into

Abstract Iron oxides are fundamentally important compounds for basic and applied sciences as well as in numerous industrial applications. In this work we report the synthesis and investigation of a new binary iron oxide with the hitherto unknown stoichiometry of Fe7O9. This new oxide was synthesized at high-pressure high-temperature (HP-HT) conditions, and its black single crystals were successfully recovered at ambient conditions. By means of single crystal X-ray diffraction we determined that Fe7O9 adopts a monoclinic C2/m lattice with the most distorted crystal structure among the binary iron oxides known to date. The synthesis of Fe7O9 opens a new portal to exotic iron-rich (M,Fe)7O9 oxides with unusual stoichiometry and distorted crystal structures. Moreover, the crystal structure and phase relations of such new iron oxide groups may provide new insight into the cycling of volatiles in the Earth’s interior.

Phase Formation in FeOx-SiO2-Cu2O-ZnO-FeS System during Melts Crystallization

2010 ◽  
Vol 297-301 ◽  
pp. 602-607
Author(s):  
Evgeny N. Selivanov ◽  
R.I. Gulyaeva ◽  
N.I. Selmenskich
Keyword(s):  
Cooling Rate ◽  
Phase Formation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Two Samples ◽  
And Calorimetry

The phase formation in oxide-sulphidic systems was studied with the use of X-ray diffraction, mineralography, combined thermogravimetry and calorimetry, in addition to Х-ray spectral microanalysis. The purpose of this work was to estimate the effect of cooling rate of melts in FeOx-SiO2-Cu2O-ZnO-FeS systems on structure and content of the resulting phases. Test subjects were two samples having following compositions (wt. %): I - 40.5 Fe, 2.41 S, 0.87 Cu, 3.87 Zn, 32.1 SiO2 and II - 40.7 Fe, 3.05 S, 8.55 Cu, 4.1 Zn and 19.5 SiO2. Cooling rate of the melts was changed from 0.3 up to 900оС/s.

Dependence of hydrogen embrittlement on annealing time in medium-Mn steels

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Juanping Xu ◽  
Jinxu Li ◽  
Zheng Wang ◽  
Hao Fu ◽  
Ming Wu
Keyword(s):  
Hydrogen Embrittlement ◽  
Annealing Time ◽  
Martensite Transformation ◽  
Design Methodology ◽  
Warm Rolling ◽  
X Ray Diffraction ◽  
Electron Backscattered Diffraction ◽  
Content Type ◽  
X Ray ◽  
Two Samples

Purpose The purpose of this paper is to investigate the effect of the soft annealing time on the microstructure and hydrogen embrittlement (HE) of Fe-0.22C-11.54Mn-2.05Al steels. Design/methodology/approach Steels A and B with different morphologies were prepared by cold rolling after warm rolling, long/short softening annealing and finally annealing at 700 °C for 30 min. Uncharged and charged samples were subjected to tensile, and HE behavior was studied by electron backscattered diffraction, scanning electron microscopy and X-ray diffraction. Findings The two samples exhibited similar tensile strengths. The homogeneous equiaxed microstructure of steel B was found to be more conducive to relieve its HE sensitivity. Steel A exhibited bimodal-grained microstructures – blocky and lath. The formation of crack in the blocky grains of steel A resulted in a significant reduction in its plasticity and tensile strength. Originality/value The high HE susceptibility of steel A is mainly connected with the inhomogeneity of martensite transformation.

scholarly journals Investigations of M3Al8O15:Eu3+,Dy3+ (M = Ba, Ca, Mg) phosphors

2016 ◽  
Vol 34 (2) ◽  
pp. 412-417
Author(s):  
Esra Öztürk
Keyword(s):  
Electron Microscopy ◽  
Solid State Reaction Method ◽  
Morphological Characterization ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray ◽  
Three Samples ◽  
Scanning Electron ◽  
The Eu

AbstractIn this work, aluminate type phosphorescence materials were synthesized via the solid state reaction method and the photoluminescence (PL) properties, including excitation and emission bands, were investigated considering the effect of trace amounts of activator (Eu3+) and co-activator (Dy3+). The estimated thermal behavior of the samples at certain temperatures (> 1000 °C) during heat treatment was characterized by differential thermal analysis (DTA) and thermogravimetry (TG). The possible phase formation was characterized by X-ray diffraction (XRD). The morphological characterization of the samples was performed by scanning electron microscopy (SEM). The PL analysis of three samples showed maximum emission bands at around 610 nm, and additionally near 589 nm, 648 nm and 695 nm. The bands were attributed to typical transitions of the Eu3+ ions.

scholarly journals Characteristics of Interlayer Materials in Non-Allophanic Volcanic Ash and Red Yellow Soils from Japan

2005 ◽  
Vol 5 (1) ◽  
pp. 1-23
Author(s):  
Anabella Tulin ◽  
Keyword(s):  
Iron Oxides ◽  
Volcanic Ash ◽  
Sodium Citrate ◽  
Citrate Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chemical Extractions ◽  
Oxalate Solution

The characteristics and properties of interlayer materials from 10 non-allophanic (Melanudand) and red yellow soils (Alfisols and Ultisols) from three locations in Japan were studied by chemical extractions and x-ray diffraction (XRD) analyses. Allophane was dissolved from clay samples using 0.15 M acid oxalate solution while silicon and aluminum were dissolved using both 0.15 M acid oxalate and 0.3 M sodium citrate solutions. XRD analyses were done for the treated and untreated samples. For the chemically extracted samples, the clay samples were treated with bicarbonate citrate solution for the removal of iron oxides after the dissolution treatments then saturated with K and Mg ions for XRD analyses. Results of the XRD patternd of the untreated and treated samples indicated the interlayer materials as a hydroxy-interlayered form for vermiculite (HIV). Between the two dissolution treatments, the 0.3 M sodium citrate treatment was found to be more effective in removing the interlayer materials than the 0.15 M acid oxalate treatment by allowing interlayer expansion and collapse.

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