scholarly journals Kinetics of extracting magnesium from prefabricated pellets by silicothermic process under flowing argon atmosphere

2020 ◽  
pp. 31-31
Author(s):  
J.-H. Guo ◽  
D.-X. Fu ◽  
J.-B. Han ◽  
Z.-H. Ji ◽  
Z.-H. Dou ◽  
...  
Keyword(s):  
Diffusion Process ◽  
Atmospheric Pressure ◽  
Gas Flow ◽  
Continuous Production ◽  
Reduction Rate ◽  
Reduction Process ◽  
Control Step ◽  
Isothermal Kinetic ◽  
Carrier Gas Flow ◽  
Kinetics Of

The Pidgeon process is the main extraction method of magnesium, but its continuous production cannot be achieved due to the switch between vacuum and atmospheric pressure. Therefore, it is vital to realize continuous extraction of magnesium under atmospheric pressure. In this paper, the process of extracting magnesium from prefabricated pellets in flowing argon was proposed. The isothermal kinetic analysis of the reduction process was carried out, the results showed that the reduction process was controlled by diffusion process in 1 h, and the apparent activation energy of extracting magnesium from prefabricated pellets in flowing argon was 218.75 kJ/mol. Then the influence of experimental factors on the reduction rate was explored, including briquetting pressure, carrier gas flow rate, ferrosilicon content, reaction temperature and time. Through analysis and calculation, it was concluded that the main control step of diffusion process was silicon diffusion.

scholarly journals Reduction Mechanism of Fine Hematite Ore Particles in Suspension

2021 ◽  
Author(s):  
Zhiyuan Chen ◽  
Christiaan Zeilstra ◽  
Jan van der Stel ◽  
Jilt Sietsma ◽  
Yongxiang Yang
Keyword(s):  
Particle Size ◽  
Temperature Drop ◽  
Reduction Rate ◽  
Reduction Process ◽  
Reciprocal Relationship ◽  
Drop Tube ◽  
Surface Nucleation ◽  
Order Of Magnitude ◽  
Relationship Of ◽  
Kinetics Of

AbstractIn order to understand the pre-reduction behaviour of fine hematite particles in the HIsarna process, change of morphology, phase and crystallography during the reduction were investigated in the high temperature drop tube furnace. Polycrystalline magnetite shell formed within 200 ms during the reduction. The grain size of the magnetite is in the order of magnitude of 10 µm. Lath magnetite was observed in the partly reduced samples. The grain boundary of magnetite was reduced to molten FeO firstly, and then the particle turned to be a droplet. The Johnson-Mehl-Avrami-Kolmogorov model is proposed to describe the kinetics of the reduction process. Both bulk and surface nucleation occurred during the reduction, which leads to the effect of size on the reduction rate in the nucleation and growth process. As a result, the reduction rate constant of hematite particles increases with the increasing particle size until 85 µm. It then decreases with a reciprocal relationship of the particle size above 85 µm.

Approximate kinetics of a desorption into a carrier-gas flow for systems with a strongly convex langmuir isotherm

1977 ◽  
Vol 12 (4) ◽  
pp. 429-432
Author(s):  
V. I. Nazarok ◽  
V. G. Koval'chuk ◽  
D. I. Evseeva ◽  
P. N. Galich
Keyword(s):  
Langmuir Isotherm ◽  
Gas Flow ◽  
Carrier Gas ◽  
Strongly Convex ◽  
Carrier Gas Flow ◽  
Kinetics Of

Investigation of the Mechanism and Growth Kinetics of Homoepitaxial 4H-SiC Growth Using CH3Cl Carbon Precursor

2006 ◽  
Vol 527-529 ◽  
pp. 171-174 ◽  
Author(s):  
Huang De Lin ◽  
Jeffery L. Wyatt ◽  
Yaroslav Koshka
Keyword(s):  
Growth Rate ◽  
Gas Flow ◽  
Linear Trend ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Gas Flow Rate ◽  
Flow Conditions ◽  
Precursor Decomposition ◽  
Carrier Gas Flow ◽  
Kinetics Of

In this work, the mechanism of the epitaxial growth of 4H SiC using CH3Cl as the carbon source gas was investigated. The experiments were conducted with a H2 carrier gas flow rate reduced in comparison to the standard conditions used for device-quality, full-wafer C3H8 growth. Low-H2 conditions have been found favorable for investigating the differences between the two gas systems. A non-linear trend of the growth rate dependence on CH3Cl flow was observed. This dependence was quantitatively different for C3H8 growth, which serves as an indication of different kinetics of CH3Cl and C3H8 precursor decomposition, as well as differences in Si droplet formation and dissociation. The maximum growth rate that we were able to achieve was by a factor of two higher for the CH3Cl precursor than for the C3H8 precursor at the same temperature and flow conditions. The growth on lower off-axis angle substrates produced surface morphology degradation similar for both CH3Cl and C3H8 precursor systems.

Potential for an Atmospheric-Pressure Low-Power Microwave-Induced Plasma Ionization Source for Mass Spectrometry

1997 ◽  
Vol 51 (10) ◽  
pp. 1500-1503 ◽  
Author(s):  
Nohora P. Vela ◽  
Joseph A. Caruso ◽  
R. Duane Satzger
Keyword(s):  
Atmospheric Pressure ◽  
Gas Flow ◽  
Direct Injection ◽  
Sample Introduction ◽  
Ionization Source ◽  
Plasma Ionization ◽  
Microwave Induced Plasma ◽  
Flow Adjustment ◽  
Liquid Sample Introduction ◽  
Carrier Gas Flow

The potential for using the microwave-induced plasma (MIP) as an ionization source is further explored. This source operates at atmospheric pressure, minimizing pumping problems and, through power and gas-flow adjustment, offers the possibility of selecting from elemental spectra to fragmentation spectra resembling those from electron impact sources. The effect of microwave power, carrier gas-flow rate, and injector-prob e configuration in the production of fragment ions is demonstrated with the use of perfluorotributylamine and tetramethyltin. Initial potential for liquid-sample introduction to the MIP is accomplished by using a direct-injection nebulizer (DIN) at higher reproducibility levels than in earlier studies.

scholarly journals A STUDY ON THE KINETICS OF OXYGEN REDUCTION FOCOAR

2018 ◽  
Vol 55 (5B) ◽  
pp. 111
Author(s):  
Le Quoc Khanh
Keyword(s):  
Oxygen Reduction ◽  
Oxygen Concentration ◽  
Reduction Rate ◽  
Reduction Process ◽  
Oxygen Depletion ◽  
Reducing Agent ◽  
Time Interval ◽  
Low Oxygen ◽  
Living Organisms ◽  
Kinetics Of

          In poor oxygenated environments the oxidation and growth of the living organisms are slowed or stopped, so that food is better preserved. The most appropriate method for oxygen depletion in the air-tight minienvironment is oxygen reduction with iron-based reducing agent, which can reduce the air oxygen concentration to about 0 %, and maintain this low oxygen concentration long during storage. This paper studies the kinetics of oxygen reduction by reducing agent FOCOAR in an airtight minienvironment under isobaric conditions. The kinetics of the reduction process calculated according to the relation vav = [21 % - (end) ] / tend, in which vav is average reduction rate, (end) is oxygen concentration at the end of the experiment, tend is total time needed for the oxygen reduction experiment. Instantaneous reduction rate vred was calculated according to equation vred = ∆/△t, in which ∆is oxygen concentration reduced in time △t, and △t = ti+1 - ti is time interval for oxygen reduction. It is found that vav depends on the quantity of reducing agent FOCOAR, and in certain time interval varies as linear function of reduction time, corresponding to constant vred.  The kinetic result allows an estimating the amount of the reducing agent FOCOAR needed for a preserve minienvironment.

The Kinetics of the Reduction of Lead Monoxide by Hydrogen

1962 ◽  
Vol 15 (1) ◽  
pp. 40 ◽  
Author(s):  
RV Culver ◽  
IG Matthew ◽  
ECR Spooner
Keyword(s):  
Gas Flow ◽  
Reduction Rate ◽  
Gas Flow Rate ◽  
Initial Value ◽  
Lead Monoxide ◽  
Partial Pressures ◽  
Steady Rate ◽  
Rate Period ◽  
Kinetics Of ◽  
Rate Controlling Step

The rate of reduction of fused lead monoxide particles in a differential reactor with H2-N2 and H2-H2O mixtures has been measured by absorbing the H2O of reaction or chemically analysing the product, Pb-PbO. After falling from a high initial value, the reduction rate remains virtually constant until 40-50% of the PbO has been reduced, and then slowly declines. The rate of reduction is independent of the gas flow rate from 5-151. S.T.P./min and not markedly influenced by variations in particle size from -36+52 to -7+10 mesh B.S.S. With H2-N2 mixtures the rate of reduction of PbO at 575 and 675 �C is proportional to pH2, and with H2-H2O mixtures at 575 �C it is proportional to pH2/(1+0.5pH2O), where pH2, and pH2O are the partial pressures of H2 and H2O, respectively. The activation energy for reduction with H2-N2 and H2-H2O mixtures over the temperature range 475-775 �C is 39 kcal/g-mole. Chemisorption of H2 on the PbO appears the most likely rate controlling step at the Pb-PbO interface. Rates of reduction over the steady rate period, k0, are correlated by the expression k0=f(R)[pH2/(1+0 5 pH2O)] exp(-39 000/RT), where f(R) is a parameter related to particle shape and size.

scholarly journals Statistical Optimisation and Kinetic Studies of Molybdenum Reduction Using a Psychrotolerant Marine Bacteria Isolated from Antarctica

2021 ◽  
Vol 9 (6) ◽  
pp. 648
Author(s):  
Syazani Darham ◽  
Khadijah Nabilah Mohd Zahri ◽  
Azham Zulkharnain ◽  
Suriana Sabri ◽  
Claudio Gomez-Fuentes ◽  
...  
Keyword(s):  
Marine Bacteria ◽  
Culture Media ◽  
Reduction Rate ◽  
Reduction Process ◽  
Kinetic Studies ◽  
Best Fitting ◽  
Industrial Use ◽  
Kinetics Of ◽  
Fitting Model ◽  
Potential Use

The extensive industrial use of the heavy metal molybdenum (Mo) has led to an emerging global pollution with its traces that can even be found in Antarctica. In response, a reduction process that transforms hexamolybdate (Mo6+) to a less toxic compound, Mo-blue, using microorganisms provides a sustainable remediation approach. The aim of this study was to investigate the reduction of Mo by a psychrotolerant Antarctic marine bacterium, Marinomonas sp. strain AQ5-A9. Mo reduction was optimised using One-Factor-At-a-Time (OFAT) and Response Surface Methodology (RSM). Subsequently, Mo reduction kinetics were further studied. OFAT results showed that maximum Mo reduction occurred in culture media conditions of pH 6.0 and 50 ppt salinity at 15 °C, with initial sucrose, nitrogen and molybdate concentrations of 2.0%, 3.0 g/L and 10 mM, respectively. Further optimization using RSM identified improved optimum conditions of pH 6.0 and 47 ppt salinity at 16 °C, with initial sucrose, nitrogen and molybdate concentrations of 1.8%, 2.25 g/L and 16 mM, respectively. Investigation of the kinetics of Mo reduction revealed Aiba as the best-fitting model. The calculated Aiba coefficient of maximum Mo reduction rate (µmax) was 0.067 h−1. The data obtained support the potential use of marine bacteria in the bioremediation of Mo.

Kinetics of the catalytic hydrodesulphurization reaction system; hydrogenolysis of thiophene

1980 ◽  
Vol 45 (10) ◽  
pp. 2728-2741 ◽  
Author(s):  
Pavel Fott ◽  
Petr Schneider
Keyword(s):  
Atmospheric Pressure ◽  
Active Sites ◽  
Flow Reactor ◽  
Kinetic Equations ◽  
Reaction System ◽  
Reaction Products ◽  
Molybdenum Catalyst ◽  
Cobalt Molybdenum Catalyst ◽  
Kinetics Of ◽  
Reaction Schemes

Kinetics have been studied of the reaction system taking place during the reaction of thiophene on the cobalt-molybdenum catalyst in a gradientless circulation flow reactor at 360 °C and atmospheric pressure. Butane has been found present in a small amount in the reaction products even at very low conversion. In view of this, consecutive and parallel-consecutive (triangular) reaction schemes have been proposed. In the former scheme the appearance of butane is accounted for by rate of desorption of butene being comparable with the rate of its hydrogenation. According to the latter scheme part of the butane originates from thiophene via a different route than through hydrogenation of butene. Analysis of the kinetic data has revealed that the reaction of thiophene should be considered to take place on other active sites than that of butene. Kinetic equations derived on this assumption for the consecutive and the triangular reaction schemes correlate experimental data with acceptable accuracy.

scholarly journals Atmospheric Pressure Plasma Deposition of TiO2: A Review

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2931
Author(s):  
Soumya Banerjee ◽  
Ek Adhikari ◽  
Pitambar Sapkota ◽  
Amal Sebastian ◽  
Sylwia Ptasinska
Keyword(s):  
Atmospheric Pressure ◽  
Gas Flow ◽  
Plasma Deposition ◽  
Atmospheric Pressure Plasma ◽  
Cost Savings ◽  
Historical Background ◽  
Pressure Plasma ◽  
Wide Range ◽  
The Status ◽  
Deposition Techniques

Atmospheric pressure plasma (APP) deposition techniques are useful today because of their simplicity and their time and cost savings, particularly for growth of oxide films. Among the oxide materials, titanium dioxide (TiO2) has a wide range of applications in electronics, solar cells, and photocatalysis, which has made it an extremely popular research topic for decades. Here, we provide an overview of non-thermal APP deposition techniques for TiO2 thin film, some historical background, and some very recent findings and developments. First, we define non-thermal plasma, and then we describe the advantages of APP deposition. In addition, we explain the importance of TiO2 and then describe briefly the three deposition techniques used to date. We also compare the structural, electronic, and optical properties of TiO2 films deposited by different APP methods. Lastly, we examine the status of current research related to the effects of such deposition parameters as plasma power, feed gas, bias voltage, gas flow rate, and substrate temperature on the deposition rate, crystal phase, and other film properties. The examples given cover the most common APP deposition techniques for TiO2 growth to understand their advantages for specific applications. In addition, we discuss the important challenges that APP deposition is facing in this rapidly growing field.

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