Phase transformations during the oxidation of fayalite in iron-rich nickel slag

2020 ◽  
Vol 111 (4) ◽  
pp. 290-296
Author(s):  
Xueyan Du ◽  
Yongbo Ma
Keyword(s):  
Phase Transformations ◽  
Magnetic Separation ◽  
Peritectic Reaction ◽  
Isothermal Oxidation ◽  
Oxidation Time ◽  
Mossbauer Spectrum ◽  
Magnetic Minerals ◽  
Heating Stage ◽  
Air Atmosphere ◽  
Xrd Patterns

Abstract Phase transformations during the oxidation of fayalite (Fe2SiO4) are investigated for the recovery of iron from iron-rich nickel slag by oxidation-magnetic separation. The proportions of various phases calculated by FactSage 7.1 show that augite and spinel are the major phases in the FeO-SiO2-MgO-CaO-O2 system in air atmosphere. The decreased content of Fe2+shows that Fe2SiO4 is gradually oxidized into Fe3O4 with increasing oxidation time. XRD patterns demonstrate that Fe3O4and Ca(Mg,Fe)Si2O6 are the dominant phases after the oxidation. The Mössbauer spectrum indicates that 93.1 wt.% of iron in oxidized nickel slag is in magnetic minerals, while a limited amount of iron is contained in non-magnetic minerals. Ca(Mg,Fe)Si2O6 was formed during the heating stage in Ar atmosphere through the polymerization of SiO4 4-and also via peritectic reaction after the isothermal oxidation.

Behavior of the Nano Alumina Powder Conformed by Slip Casting under Microwave Sintering

2014 ◽  
Vol 793 ◽  
pp. 105-111
Author(s):  
A. Arellano ◽  
J. Lemus-Ruiz ◽  
D. Bouvard ◽  
L. Olmos
Keyword(s):  
Heating Rate ◽  
Microwave Sintering ◽  
Slip Casting ◽  
Alumina Powder ◽  
Secondary Phases ◽  
Transition Alumina ◽  
Air Atmosphere ◽  
Sample Characterization ◽  
Phase Quantification ◽  
Xrd Patterns

The effect of the transformation of phase in nanopowders of transition alumina has showed to be detrimental for the final characteristics of the consolidated materials. It was found that the complete transformation from gamma (γ-Al2O3) to alpha (α-Al2O3) alumina generated larger grain sizes and lower relative densities. This work studies the effect of slip casting preformed on the transformation phase of alumina during microwave sintering of α-alumina nanopowders. The sintering of the samples was carried out in a typical unimodal microwave furnace with a 2.5 GHz frequency. Sintering was carried out under air atmosphere at temperatures vary between 1100 and 1500 °C with heating rate of 100 and 200 °C/min and with a sintering plateau of 5 minutes. Sample characterization was performed by XRD, SEM, and TEM. The phase quantification was calculated using the Rietveld software from the XRD patterns. To have a good heating control in the microwave system it is possible by using slip casting to preform compact. It was observed that the heating rate has a strong effect on the phase transformations. Secondary phases like θ, θ’(x, y) appeared in samples sintered with a heating rate of 200 °C/min no matter the sintering temperature. Meanwhile the complete alumina transformation was found when sample were heating at 100 °C/min.

scholarly journals Magnetic Separation of Weakly Magnatic Copper Minerals

1989 ◽  
Vol 2 (4) ◽  
pp. 191-195
Author(s):  
J. N.M. Agricola ◽  
J. L. Top ◽  
A. F. Fort
Keyword(s):  
Magnetic Separation ◽  
Background Field ◽  
Magnetic Fraction ◽  
Magnetic Minerals ◽  
High Gradient Magnetic Separation ◽  
High Gradient ◽  
Copper Mineral ◽  
Copper Concentrate ◽  
Mineral Particles ◽  
Weakly Magnetic

High Gradient Magnetic Separation of small (5-38 µm) weakly magnetic copper mineral particles from a copper concentrate and ore has been performed. In previous work coarser fractions of these minerals, bornite and chalcopyrite, were separated successfully. The recovery of the smaller particles in the magnetic fraction decreases but their grade increases compared to the results obtained on the larger particles. At a magnetic background field of 1.3 T the concentrate was upgraded from 72% bornite and chalcopyrite to 86% with a recovery of 82% and the ore from 16% magnetic minerals to 44% with a recovery of 72%.

The Role of MgCl2 in Preparation of SnO2, MgSnO3 and Mg2SnO4 Nanopowders

2011 ◽  
Vol 403-408 ◽  
pp. 640-645
Author(s):  
Ali Taherkhani ◽  
A.Taheri Asghari
Keyword(s):  
Annealing Temperature ◽  
Weight Ratio ◽  
Growth Inhibitor ◽  
Solid State Reactions ◽  
High Yield ◽  
Grain Sizes ◽  
Air Atmosphere ◽  
One Step ◽  
Xrd Patterns

Tin oxide (SnO2) ,MgSnO3and Mg2SnO4nanocrystals have been synthesized by one-step solid-state reactions. in the first step, The powder of SnCl4.5H2O was mixed with MgCl2and Mg(OH)2with weight ratio of Sn to Mg (1:1), (2:1) And (1:2) in an air atmosphere at room, and annealing temperature in this work were 200°C, 400°C ,600°C , 800°C and 1000°C . XRD patterns show the SnO2, MgSnO3and Mg2SnO4particle size of synthesized powders by MgCl2were 3 nm, 4nm and 27 nm respectively. In fact the excess amount of Mg role of crystallite growth inhibitor in SnO2. this method is a simple ,inexpensive ,efficient and economic preparation for SnO2, MgSnO3and Mg2SnO4nanoparticles with adjustable grain sizes in the range of 3-44nm in high yield. This article shows the role of mass MgCl2in producing of SnO2nanoparticles.

scholarly journals Recovery of Catapleiite and Eudialyte from Non-Magnetic Fraction of Eudialyte ore Processing of Norra Kärr Deposit

Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 19
Author(s):  
Ivan Silin ◽  
Devrim Gürsel ◽  
Christian Büchter ◽  
Lars Weitkämper ◽  
Hermann Wotruba
Keyword(s):  
Magnetic Separation ◽  
Froth Flotation ◽  
Magnetic Fraction ◽  
Low Grade ◽  
Magnetic Minerals ◽  
Potential Source ◽  
Ore Processing ◽  
Eudialyte Concentrate ◽  
Acid Esters ◽  
Alkali Feldspars

Eudialyte ores from Norra Kärr (Sweden) and Kringlerne (Greenland) are considered a potential source of rare-earth elements (REE) for the development of a sustainable REE industry outside China. Magnetic separation is successfully applicated to recover eudialyte as a magnetic fraction. In the case of the Norra Kärr deposit, up to 20% of the REE and up to 40% of the Zr are lost during mineral processing in the non-magnetic fraction. Zr and REE are associated with non-magnetic minerals such as catapleiite, low- or non-magnetic eudialyte species, and both their intergrowths. Besides zirconosilicates such as catapleiite and eudialyte, the non-magnetic fraction has valuable and already-liberated minerals such as alkali feldspars and nepheline, which should not be considered as tailings. In this investigation, a possible way to recover REE bearing zirconosilicates from the non-magnetic fraction using flotation is presented. First, a low-grade eudialyte concentrate (1.8% Zr, 0.94% REE) from ground ore was obtained using magnetic separation. The non-magnetic fraction was then treated using froth flotation, and a Zr-REE bearing product (9% Zr, 1.5% REE) was obtained as froth product. For this purpose, phosphoric acid esters were used as selective collectors for zirconosilicates at a pH between 3.5 and 4.5. The reagent regime could be proposed not only to recover Zr- and REE-bearing minerals, but also simultaneously to remove Fe, Ti, and other colored impurities from the nepheline-feldspar product and to minimize the tailings volume.

Influence of Annealing Temperature on the Properties of Sol-Gel Deposited Nb-Doped TiO2 Thin Films

2020 ◽  
Vol 845 ◽  
pp. 59-64
Author(s):  
Wen Cheng Tzou ◽  
Hon Kuan ◽  
You Cheng Chang
Keyword(s):  
Thin Films ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Optical Transmittance ◽  
Crystalline Phases ◽  
Air Atmosphere ◽  
Coating Method ◽  
Nb Content ◽  
Xrd Patterns ◽  
Surface Morphologies

Nb-doped TiO2 (TNO) thin films were prepared by a sol-gel spin coating method with Nb content of 5 at.%, and then annealed in the temperature range of 500-900 °C. The surface morphologies and the crystalline phases of the TNO thin films were investigated by using SEM and XRD patterns. The grain sizes increased with rising annealing temperature, and the crystalline phases were completely transformed from anatase into rutile when the annealing temperature was above 900 °C in air atmosphere. In addition, the optical band gap decreased and the average optical transmittance was between 75 and 70 % in the range of visible light. Furthermore, the better electrical properties were obtained at the annealing temperature of 600 °C.

Analysis on High Temperature Oxidation of U71Mn Steel under CO2

2012 ◽  
Vol 496 ◽  
pp. 359-362 ◽  
Author(s):  
Zeng Wu Zhao ◽  
Yong Zhi Li ◽  
Bao Wei Li ◽  
Shuo Li ◽  
Wen Fei Wu
Keyword(s):  
High Temperature Oxidation ◽  
Unit Area ◽  
Oxidation Kinetic ◽  
Isothermal Oxidation ◽  
Oxidation Time ◽  
Temperature Oxidation ◽  
Exponential Law ◽  
Long Time ◽  
Mass Increase ◽  
Kinetics Of

Isothermal oxidation kinetics of U71Mn steels under pure CO2 at 1073--1473K are experimentally studied in this paper. The oxidation kinetic results are similar: mass increase per unit area as function of oxidation time nearly follows linear role for long time, with a more rapid increase at the begin. Oxidation rate constants of the steel under pure CO2, from 1073K to 1473K, keep exponential law as function of oxidation time.

scholarly journals Effects of CaO Addition on the Iron Recycling from Nickel Slags by Oxidation-Magnetic Separation

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 956 ◽  
Author(s):  
Yongbo Ma ◽  
Xueyan Du
Keyword(s):  
Phase Diagrams ◽  
Magnetic Separation ◽  
Thermodynamic Analysis ◽  
Crystallization Temperature ◽  
Total Iron ◽  
Iron Recovery ◽  
Characteristic Temperatures ◽  
Air Atmosphere

To recover iron from water-quenched nickel slags, CaO was added. Thermodynamic analysis showed that CaO promotes the reaction between fayalite (Fe2SiO4) and O2. Phase diagrams of the FeO-SiO2-MgO-CaO slag with various CaO contents in an air atmosphere drawn by FactSage 7.1 showed that the phase components can be significantly affected by the CaO contents. With increasing CaO content, the fusion characteristic temperatures decreased rapidly to a minimum and subsequently increased slightly. The oxidization of Fe2SiO4 in nickel slags was accelerated significantly by the addition of CaO, which led to an increase of FeO activity and decrease of Fe2O3 activity to promote the formation of MgFe2O4. Excess addition of CaO led to the formation of more silicates. In addition, the crystallization temperature was also reduced with increasing CaO content, causing less spinel to crystalize. With increasing CaO content, the iron recovery and yield of concentrate first increased and subsequently decreased, while the total iron (TFe) content was almost not influenced and maintained a relatively stable value.

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