Reduction Kinetics of Bayan Obo Associated Iron Niobium Ore

2011 ◽  
Vol 230-232 ◽  
pp. 1389-1395
Author(s):  
Fu Shun Zhang ◽  
Zeng Wu Zhao ◽  
Fang Zhang ◽  
Nai Xiang Feng
Keyword(s):  
Loss Rate ◽  
Influence Factor ◽  
Mass Loss Rate ◽  
Reduction Process ◽  
Reduction Kinetics ◽  
Carbon Gasification ◽  
Second Stage ◽  
Bayan Obo ◽  
Two Stages ◽  
Kinetics Of

The mass loss rate of carbon-bearing pellet during reduction process was investigated at the temperature from 900 to 1050 °C. The results show that temperature is the significant influence factor to the reduction of carbon-bearing pellet. In addition, the reduction process includes two stages and the first stage is faster than second stage. Both of steps are controlled by carbon gasification, and that is confirmed by means of the activation energy.

Reduction Kinetics of Bayan Obo Coexisted Iron and Niobium Ore by Carbon-Bearing Pellet

2011 ◽  
Vol 418-420 ◽  
pp. 346-352 ◽  
Author(s):  
Fu Shun Zhang ◽  
Zeng Wu Zhao ◽  
Yan Li ◽  
Nai Xiang Feng
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Reaction Rate ◽  
Mass Loss Rate ◽  
Reduction Process ◽  
Inert Atmosphere ◽  
Reaction Rate Constant ◽  
Carbon Gasification ◽  
Reaction Rate Constants ◽  
Two Stages

The mass loss rate of carbon-bearing pellet of coexisted iron and niobium ore during reduction process was investigated between 900 and 1050°C in inert atmosphere. The reduction mechanism was studied by analyzing reaction rate constant, apparent activation energy，and the controlling step. The results show that temperature has the significant effect on the reduction of carbon-bearing pellet. The reduction processes include the faster reaction stage and the slower reduction stage, and respective reaction rate constants in two stages are k1=exp (21.025-40484/(RT)) and k2= exp (21.060-42516/(RT))，while respective apparent activation energy are 337 and 353 KJ/mol. Both steps are controlled by carbon gasification.

BF Charge Reduction with Gases of Different H2 Ratio in High Temperature Zone

2011 ◽  
Vol 284-286 ◽  
pp. 1152-1157
Author(s):  
Guo Zhang Tang ◽  
Zhen Gao ◽  
Yan Chang Kong ◽  
Kun Ouyang ◽  
Fu Min Li
Keyword(s):  
Loss Rate ◽  
Direct Reduction ◽  
Mass Loss Rate ◽  
Reduction Rate ◽  
Reduction Kinetics ◽  
Reduction Degree ◽  
Charge Reduction ◽  
Temperature Zone ◽  
Metallization Rate ◽  
Direct Reduction Degree

The reduction of different basicity BF charge with gases of different H2 ratio has been determined to simulate different BF technology. The results reveal: reduction rate (R & r) and metallization rate of charge increase with the H2 ratio increasing, and the temperature increasing while the reducing time becomes longer simultaneously. The direct reduction degree of charge in Hydrogen-enrichment BF is very low, thus the energy consumption of Ironmaking could be reduced. There is certain difference between metallization rate and reduction degree due to reduction kinetics. The mass loss rate of coke increases sharply with the H2 ratio increasing, the H2 ratio of gas should be selected an appropriate value.

Kinetics of Mixed Low-Level Waste Incapsulation Using Iron Phosphate Chemically Bonded Cement

2006 ◽  
Vol 932 ◽  
Author(s):  
A.S. Aloy ◽  
T.I. Koltsova ◽  
E.N. Kovarskaya ◽  
M.Yu. Silin
Keyword(s):  
Formation Process ◽  
Iron Phosphate ◽  
Structural Formation ◽  
Low Level ◽  
Second Stage ◽  
Bivalent Iron ◽  
Acid Reaction ◽  
The Moment ◽  
Two Stages ◽  
Kinetics Of

ABSTRACTThe iron phosphate cement (IPC) structure formation process has been studied by Mossbauer spectroscopy. The IPC is formed as a result of interaction of iron oxides with orthophosphoric acid and could be used as a matrix for immobilization of low-level radioactive waste.The structural formation process has been shown may be considered to consist of two stages. The first stage lasts to the moment of setting, when the diffusion process goes on in the liquid phase. At this stage the main fragments of the structural polymeric frame of the IPC are developed consisting of iron (+2) and (+3) phosphates. The rate of the oxides-with-phosphoric-acid reaction as well as the time of hardening depends on the bivalent iron content.The second stage begins from the moment of setting when the diffusion becomes slower. At this stage the process is characterized by the negligible increase in the iron phosphates (+2), (+3) content and transformation of the previously formed phosphates.The nuclear gamma-resonance (NGR) parameters have been determined of FeH3(PO4)2·2.5H2O, forming in the hematite (Fe2O3) based IPC: isomeric shift (IS) = 0.46 mm/s, quadrupole splitting (QS) = 0.197 mm/s, FWHM =0.282 mm/s.

Oxidation Kinetics of the Sintered Iron Parts Steam Treated in an Industrial Continuous Furnace

2010 ◽  
Vol 660-661 ◽  
pp. 243-248
Author(s):  
Eduardo Nunes ◽  
Ivan Gilberto Sandoval Falleiros
Keyword(s):  
Oxidation Kinetics ◽  
Continuous Furnace ◽  
Steam Treatment ◽  
Sintered Iron ◽  
Second Stage ◽  
Parabolic Law ◽  
Controlling Mechanism ◽  
Iron Diffusion ◽  
Two Stages ◽  
Kinetics Of

It has been studied a steam treatment process in an industrial continuous furnace for sintered iron parts in a temperature range varying from 490 to 570 °C and sample´s sintered densities of 6,52 and 6,77 g / cm3 . The tests have showed oxidation kinetics with two stages, each of them obeying a parabolic law. The first stage was faster than the second. The oxidation time when the oxidation kinetics of the first stage has changed for the second stage showed off very sensitive to the process temperature and sintered densities of the parts which are in agreement with the process rate controlling mechanism that was found to be the iron diffusion through the oxide layer.

Rubberised fabric for fuel soft storage tanks*

2018 ◽  
Vol 45 (7) ◽  
pp. 322-324
Author(s):  
Yu.N. Rybakov ◽  
A.V. Dedov ◽  
D.S. Plokhoi ◽  
D.V. Kolotilin
Keyword(s):  
Diffusion Processes ◽  
Motor Fuel ◽  
Residual Monomer ◽  
Experimental Conditions ◽  
Second Stage ◽  
Before And After ◽  
Nitrile Rubbers ◽  
Two Stages ◽  
Kinetics Of

The kinetics of extraction of dibutyl sebacinate by different grades of motor fuel from rubberised fabric based on a blend of nitrile rubbers SKN-26M and SKN-40M was investigated. The kinetics was determined according to the GOST 9.030-74 standard from the change in weight of the specimen after holding in fuel at 50°C and drying. The change in quality of the fuel after contact with the fabric was recorded from the change in the content of existent gum in fuel according to GOST 1567-97 (ISO 6246-95) and its acidity according to GOST 5985-79 before and after contact with the rubberised fabric. It was shown that the process of extraction proceeds in two stages, the time of the first of which under experimental conditions is not dependent on the type of fuel. The rate of the first stage is much higher than the rate of the second stage. The relation of rates and proportion of extracted fuel at the first and second stages depends on the type of fuel. It can be asserted that the surplus amount of extracted substances is made up of impurities, which include residual monomer or its derivatives and substances used in the synthesis of the rubber. The mechanism of extraction with extractant counterflow into the vulcanisate and its dependence on the grade of petrol is proposed, based on allowance for the diffusion processes in the system.

Kinetics of Mg2Sn Synthesis Reaction under Isothermal Condition

2010 ◽  
Vol 146-147 ◽  
pp. 1712-1716
Author(s):  
Yu Feng Wu ◽  
Wen Bo Du ◽  
Zhao Hui Wang ◽  
Tie Yong Zuo
Keyword(s):  
Isothermal Condition ◽  
Growth Control ◽  
Nucleation And Growth ◽  
Synthesis Process ◽  
Synthesis Reaction ◽  
Isothermal Reaction ◽  
Second Stage ◽  
Two Stages ◽  
Kinetics Of ◽  
Good Agreement

The kinetics of Mg2Sn synthesis reaction was studied under isothermal condition in the present paper. Results indicated that the isothermal reaction of Mg2Sn was controlled by two reactive mechanisms: the nucleation and growth control in the first stage corresponding to the Avrami exponent, m≈3, and the phase boundary control in the second stage corresponding to m≈1.1. The reactive activation energy (Ea ) for the two stages was 293.6 kJ·mol-1 and 358.1 kJ·mol-1, respectively. The microstructural evolution in Mg2Sn synthesis process was in good agreement with the two reactive mechanisms.

Kinetics of B2 and D03 Ordering: Theory

1990 ◽  
Vol 186 ◽  
Author(s):  
L. Anthony ◽  
B. Fultz
Keyword(s):  
Range Order ◽  
Rate Theory ◽  
Probability Method ◽  
Interatomic Potentials ◽  
Second Stage ◽  
Activated State ◽  
State Rate ◽  
Two Stages ◽  
Kinetics Of ◽  
Path Probability Method

AbstractMonte-Carlo simulations (MCS) and the path probability method (PPM) were used to study disorder→order transformations in bcc alloys having the AB3 stoichiometry. Both methods used an explicit vacancy mechanism of ordering and an activated-state rate theory for the vacancy jumps. We studied the evolution of short-range order (SRO) as well as B2 and D03 long-range order (LRO) in alloys that began as random solid solutions. The growth rates of SRO and LRO were significantly higher for the PPM than for the MCS. We attribute this difference to improper handling of correlated vacancy motions in the PPM. The PPM also suffered from an artificial incubation time for the initiation of LRO. Both the MCS and the PPM showed that SRO has a tendency to develop in two stages. In the first stage there is a quick relaxation of the SRO by itself. In the second stage, which occurs with a longer time constant, the SRO and LRO grow simultaneously. Parametric plots of one order parameter against another, here termed “kinetic paths”, are discussed. A variety of different kinetic paths through the B2 and D03 order parameters can be predicted theoretically, depending on the choice of interatomic potentials. This range of calculated kinetic paths is broad enough to encompass our experimental results of SRO and LRO evolution in Fe3Al.

Kinetics of Carbothermic Reduction of Ilmenite

2016 ◽  
Vol 852 ◽  
pp. 315-322 ◽  
Author(s):  
Min Chen ◽  
Xuan Xiao ◽  
Xue Feng Zhang
Keyword(s):  
Activation Energy ◽  
Kinetic Parameters ◽  
Carbothermic Reduction ◽  
Reduction Process ◽  
Phase Evolution ◽  
Reduction Kinetics ◽  
Isokinetic Relationship ◽  
Exponential Factor ◽  
Morphology Change ◽  
Kinetics Of

The reduction kinetics of ilmenite was investigated. Phase evolution during the reduction process was identified by XRD and morphology change was observed using SEM. Kinetic parameters of the activation energy and pre-exponential factor were determined by Kissinger-Akahira-Sunose (KAS) method and Coast-Redfern method&artificial isokinetic relationship (IKP) respectively. Results showed that when the reaction of titanium suboxides makes a growing contribution, the conversion dependence of activation energy has an ascending trend. When the conversion exceeded 0.7, the reactants almost consumed, and the process was controlled by diffusion.

Metal Dusting Corrosion of 9Cr-1Mo Steel in Propane-Butane Gas Mixture

2009 ◽  
Vol 289-292 ◽  
pp. 477-483
Author(s):  
Zbigniew Grzesik ◽  
Marek Danielewski ◽  
Stanisław Mrowec
Keyword(s):  
Total Pressure ◽  
Petrochemical Industry ◽  
Diffusion Processes ◽  
Metal Dusting ◽  
Second Stage ◽  
Reaction Proceeds ◽  
Two Stages ◽  
Kinetics Of ◽  
Low Rate ◽  
Propane Butane

The kinetics and mechanism of metal dusting corrosion of 9Cr-1Mo steel, commonly used in CCR platforming units, have been studied as a function of temperature (773 – 1173 K) in propane-butane atmosphere, being the mixture of 70 vol. % of propane and 30 vol. % of butane with the total pressure equal 105 Pa. The kinetics of corrosion have been studied thermogravimetrically in the apparatus enabling the mass changes of corroded sample to be followed continuously with the accuracy of the order of 10-6 g. It has been found that metal dusting corrosion in this atmosphere, modeling in some way industrial environments in petrochemical industry, is complex and two-stages of linear kinetics may be distinguished. In the first stage, which may be considered as an incubation period, the reaction proceeds with rather low rate, which increases dramatically in the second stage, the beginning of which depends strongly on temperature. Linear course of reaction indicates that chemical reactions and not diffusion processes determine the rate of corrosion. This conclusion is confirmed by the fact, that the layer of corrosion products is not compact but considerably porous.

Growth of block copolymer stabilized metal nanoparticles probed simultaneously byin situXAS and UV–Vis spectroscopy

2016 ◽  
Vol 23 (1) ◽  
pp. 293-303 ◽  
Author(s):  
C. Nayak ◽  
D. Bhattacharyya ◽  
S. N. Jha ◽  
N. K. Sahoo
Keyword(s):  
Block Copolymer ◽  
Reduction Process ◽  
Pt Nanoparticles ◽  
Vis Spectroscopy ◽  
The Difference ◽  
Two Stages ◽  
Real Time Information ◽  
Kinetics Of ◽  
Time Information

The growth of Au and Pt nanoparticles from their respective chloride precursors using block copolymer-based reducers has been studied by simultaneousin situmeasurement of XAS and UV–Vis spectroscopy at the energy-dispersive EXAFS beamline (BL-08) at INDUS-2 SRS at RRCAT, Indore, India. While the XANES spectra of the precursor give real-time information on the reduction process, the EXAFS spectra reveal the structure of the clusters formed at the intermediate stages of growth. The growth kinetics of both types of nanoparticles are found to be almost similar and are found to follow three stages, though the first stage of nucleation takes place earlier in the case of Au than in the case of Pt nanoparticles due to the difference in the reduction potential of the respective precursors. The first two stages of the growth of Au and Pt nanoparticles as obtained byin situXAS measurements could be corroborated by simultaneousin situmeasurement of UV–Vis spectroscopy also.

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