Mechanism Study on the High-Phosphorus Hematite Carbothermal Reduction in Microwave Field

2011 ◽  
Vol 291-294 ◽  
pp. 1358-1361 ◽  
Author(s):  
Zhi Jun He ◽  
Hui Zhang ◽  
Yong Long Jin
Keyword(s):  
Carbothermal Reduction ◽  
Iron Ore ◽  
Microwave Field ◽  
Reduction Rate ◽  
Lattice Energy ◽  
Reduction Reaction ◽  
Mechanism Study ◽  
High Phosphorus ◽  
Thermodynamics And Dynamics ◽  
Reaction Activation Energy

In the paper, the research on raising the grade of iron ore and dephosphorization for high-phosphorus oolitic hematite by coal-based carbothermal reduction in microwave field was carried out. The microwave action mechanism was analyzed by the aspects of ionic crystal lattice energy and thermodynamics and dynamics[1]. The possibility of the application of microwave in raising the grade of iron ore and dephosphorization for high-phosphorus hematite was discussed. The research indicated that the primary structure of the high-phosphorus hematite was changed by the high-phosphorus hematite carbothermal reduction in microwave field, meantime the carbothermal reduction reaction activation energy was decreased and the reduction rate was speeded up[2-4].

Experiment Study on the High-Phosphorus Hematite Carbothermal Reduction in Microwave Field

2011 ◽  
Vol 291-294 ◽  
pp. 1317-1320
Author(s):  
Zhi Jun He ◽  
Yong Long Jin ◽  
Hui Zhang
Keyword(s):  
Experimental Research ◽  
Iron Content ◽  
Carbothermal Reduction ◽  
Iron Ore ◽  
Microwave Field ◽  
Experiment Study ◽  
High Phosphorus ◽  
Reduction Of Iron ◽  
Speed Up ◽  
Dephosphorization Rate

In the paper, the experimental research on dephosphorization and iron yield for high-phosphorus oolitic hematite by coal-based carbothermal reduction was carried out. It indicated that microwave can speed up the rate of carbothermal reduction of iron ore and strengthen the effects of dephosphorization and increasing iron content. The dephosphorization rate and iron yield of high-phosphorus oolitic hematite exceeding 87.8% and 91.8% by the way of carbothermal reduction in the microwave field and a further fine-grinding and magnetic separation.

Reduction Behavior and Mechanism of Iron Ore in Molten Iron in the Process of Converter Steelmaking

2019 ◽  
Vol 17 (8) ◽  
Author(s):  
Deng Nanyang ◽  
Zhou Di ◽  
Wei Rufei ◽  
Deng Aijun ◽  
Xia Yunjin ◽  
...  
Keyword(s):  
Iron Ore ◽  
Gas Diffusion ◽  
Reduction Reaction ◽  
Molten Iron ◽  
Reduction Behavior ◽  
Gaseous Products ◽  
Maximum Reaction ◽  
Reduction Effect ◽  
Solid Liquid ◽  
Reaction Activation Energy

Abstract XRD and SEM methods were applied to the reduction behavior and mechanism of iron ore in molten iron at temperatures of 1400 °C, 1450 °C, and 1500 °C. The results showed that iron ore could be reduced by carbon in molten iron. When the reduction of iron oxide occurred at the reaction interface, carbon in the molten iron was affected by the concentration gradient. This promoted reduction and the reduction effect improved with increase in reaction temperature. After the carbon in the molten iron almost disappeared, the surfaces of the iron ore and molten iron exhibited oxidizing atmospheres causing different degrees of oxidation of the reduced metal iron and molten iron at 1500 °C. Through analysis of the reduction mechanism of iron ore, it was known that the maximum reaction activation energy during gas phase diffusion was 1612.1 kJ/mol, which restricts the iron ore reduction reaction. At low temperatures, the diffusion of gaseous products in solid-liquid is difficult. Increasing the temperature and stirring accelerate the reduction reaction while increasing gas diffusion.

scholarly journals Phase Equilibrium in Carbothermal Reduction Al2O3 → AlN Studied by Thermodynamic Calculations

2017 ◽  
Vol 1 (2) ◽  
pp. 30-37
Author(s):  
Chien Chon Chen ◽  
Chih Yuan Chen ◽  
Hsi Wen Yang ◽  
Yang Kuao Kuo ◽  
Jin Shyong Lin
Keyword(s):  
Carbon Monoxide ◽  
Partial Pressure ◽  
Carbothermal Reduction ◽  
Economic Value ◽  
Reduction Rate ◽  
Aluminum Carbide ◽  
Carbon Activity ◽  
Reduction Reaction ◽  
Thermodynamic Calculations ◽  
Carbothermal Reduction Reaction

As a ceramic with high economic value, aluminum nitride possesses high thermal conductivity, excellent electrical insulation, high mechanical strength and high melting temperature and these all are required in high technologies involving cooling, insulation, thermal expansion and corrosion. This paper deals with thermodynamic parameters which affect the Al2O3→AlN reduction efficiency during a carbothermal reduction. According to the carbothermal reduction reaction γ-Al2O3 + 3C + N2 → AlN + 3CO, if molar mixing ratio of γ-Al2O3:C = 1:3 at 1,601 °C or higher, the γ-Al2O3 can be reduced to AlN. This carbothermal reduction reaction is controlled by main parameters of carbon activity, and partial pressures of nitrogen, carbon monoxide and carbon dioxide. For example, if less carbon is added, a lower carbothermal reduction rate is resulted; however, if extra carbon is added, aluminum carbide (Al4C3) could be produced, or C could remain in AlN. Without N2(g) added in the carbothermal reduction, Al2O3(γ) may react with C to generate Al4C3 at a temperature higher than 2,250 °C. AlN prefers to form with an unity carbon activity, at a lower oxygen partial pressure, a higher carbon monoxide partial pressure, or at a higher temperature. In order to understand the relationship with N2, O2, CO, CO2, C, Al2O3, AlN and Al4C3, the Al-N-C-O system was investigated by thermodynamic calculations.

scholarly journals Carbothermic reduction kinetics of ilmenite concentrates catalyzed by sodium silicate and microwave-absorbing characteristics of reductive products

2013 ◽  
Vol 19 (3) ◽  
pp. 423-433 ◽  
Author(s):  
Wei Li ◽  
Jinhui Peng ◽  
Shenghui Guo ◽  
Libo Zhang ◽  
Guo Chen ◽  
...  
Keyword(s):  
Sodium Silicate ◽  
Carbothermic Reduction ◽  
Reduction Rate ◽  
Reduction Reaction ◽  
Great Change ◽  
Microwave Cavity ◽  
Reduction Kinetics ◽  
Microwave Absorbing ◽  
Reaction Activation Energy ◽  
Kinetics Of

Carbothermic reduction kinetics of ilmenite concentrates catalyzed by sodium silicate was investigated; the reduction degree of ilmenite concentrates reduction reaction was deduced as. R = (4(16y+56x)(?W? - fA-PW))/(7(16y + 56x + 112)). Results show that reaction activation energy of initial stage and later stage is 36.45 kJ/mol and 135.14kJ/mol, respectively. There is a great change for reduction rate at temperatures of 1100 ?C and 1150 ?C; the catalysis effect and great change of reduction rate were evaluated by TG and DSC curves of sodium silicate. Microwave-absorbing characteristics of reduction products were measured by the method of microwave cavity perturbation. It is found that microwave absorbing characteristics of reduction products obtained at temperatures of 900 ?C, 1100 ?C and 1150 ?C have great changes, combined XRD characterization, explaining the formation and accumulation of reduction product Fe, and great changes of microwave absorbing characteristics were due to the decrease of the content of ilmenite concentrates.

scholarly journals Effect of Prior Oxidation on the Reduction Behavior of Magnetite-Based Iron Ore During Hydrogen-Induced Fluidized Bed Reduction

2021 ◽  
Author(s):  
Heng Zheng ◽  
Daniel Spreitzer ◽  
Thomas Wolfinger ◽  
Johannes Schenk ◽  
Runsheng Xu
Keyword(s):  
Fluidized Bed ◽  
Partial Oxidation ◽  
Iron Ore ◽  
Reduction Rate ◽  
Deep Oxidation ◽  
Initial Reaction ◽  
Oxidation Treatment ◽  
Rate Limiting Step ◽  
Rate Limiting ◽  
Prior Oxidation

AbstractMagnetite-based iron ore usually shows a high sticking tendency and a poor reducibility in the fluidized bed because of its dense structure. To enhance the fluidization and reduction behaviors of magnetite-based iron ore during hydrogen-induced fluidized bed reduction, the effect of a prior oxidation treatment is investigated. The results show that the untreated magnetite-based iron ore cannot be fluidized successfully in the tested temperature range between 600 °C and 800 °C. At 600 °C reduction temperature, the de-fluidization can be avoided by a prior oxidation treatment. At higher reduction temperatures, the fluidization behavior can be further improved by an addition of 0.5 wt pct MgO. Magnesiowüstite (FexMg1−xO) is formed, which decreases the contact chance of the sticky surface between particles. Regarding to the reduction rate, a prior partial oxidation is more beneficial compared to deep oxidation. The kinetic analysis shows that MgO could promote the initial reaction. The reaction rate limiting step is no longer diffusion but chemical reaction for prior partly oxidized samples. A prior partial oxidation combined with an addition of MgO is considered to be a promising pretreatment method for a successful processing of magnetite-based iron ore.

Recent Advances in Non-Precious Metal Electrocatalysts for Oxygen Reduction in Acidic Media and PEMFCs: An Activity, Stability and Mechanism Study

2021 ◽  
Author(s):  
Suojiang Zhang ◽  
jiayao Cui ◽  
Qingjun Chen ◽  
Xiaojin Li
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Precious Metal ◽  
Platinum Group Metal ◽  
Reduction Reaction ◽  
Proton Exchange ◽  
Mechanism Study ◽  
Acidic Media ◽  
Intensive Research ◽  
Limited Supply

The high cost and limited supply of platinum has driven intensive research into the use of non-platinum group metal (PGM-free) as cathode oxygen reduction reaction (ORR) catalysts for proton exchange...

X-Ray Photoelectron Spectroscopy Study on Reduction of Graphene Oxide with Hydrazine Hydrate

2011 ◽  
Vol 287-290 ◽  
pp. 539-543 ◽  
Author(s):  
Wen Shi Ma ◽  
Jun Wen Zhou ◽  
Xiao Dan Lin
Keyword(s):  
Graphene Oxide ◽  
Hydrazine Hydrate ◽  
Photoelectron Spectroscopy ◽  
Reduction Rate ◽  
Reduction Reaction ◽  
Chemical Compositions ◽  
Total Oxygen ◽  
Graphene Oxides ◽  
X Ray ◽  
Oxygen Groups

Graphene oxide was prepared through Hummers' method，then different reduced graphenes were prepared via reduction of graphene oxide with hydrazine hydrate for 1h、12h and 24h. X-ray photoelectron spectroscopy (XPS) was used for the characterization of graphene oxide and the reduced graphenes. The variation of the contents of carbon in carbon and oxygen functional groups and chemical compositions of graphene oxides were investigated through analysis the content of different carbon atoms in different reduced graphenes. The results showed that the reduction reaction was very fast in the first 1 h, the content of total oxygen bonded carbon atoms decreased from 83.6% to 22.1%, and then after the reduction rate became very slow. After 12h, the content of total oxygen bonded carbon atom is 19.56%, only 2.54% lower than that of 1h’s. At the same time, C-N was introduced in the graphene oxides; this increased the stereo-hindrance for hydrazine hydrate attacking the C-Oxygen groups, thus reduced the reduction rate. After reduction for 24h, there still exists 16.4% oxygen bonded carbon atoms and the total conversion ratio of graphene approaches 70%.

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