scholarly journals Reduction Kinetics Of NiS Sulphide

2015 ◽  
Vol 60 (2) ◽  
pp. 981-983
Author(s):  
G. Smoła ◽  
A. Poczekajło ◽  
Z. Grzesik
Keyword(s):  
Activation Energy ◽  
Heterogeneous Catalysis ◽  
Reduction Process ◽  
Reduction Kinetics ◽  
Reduction Mechanism ◽  
Nickel Sulphide ◽  
Linear Kinetics ◽  
Developed Surface ◽  
Mechanism And Kinetics ◽  
Kinetics Of

Abstract Reduction mechanism and kinetics of NiS nickel sulphide obtained during the process of nickel sulphidation, have been studied as a function of temperature (723-873 K). It has been found that the reduction process follows linear kinetics with activation energy of 103 kJ/mol. It is important to note that during nickel sulphidation and after the reduction of nickel sulphide, the product sample shows highly developed surface, creating thus the potential possibilities to be applied in heterogeneous catalysis.

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.

scholarly journals Fluoride Leaching of Titanium from Ti-Bearing Electric Furnace Slag in [NH4+]-[F−] Solution

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1176
Author(s):  
Fuqiang Zheng ◽  
Yufeng Guo ◽  
Feng Chen ◽  
Shuai Wang ◽  
Jinlai Zhang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Electric Furnace ◽  
Kinetic Equations ◽  
Surface Chemical ◽  
Leaching Rate ◽  
Surface Chemical Reaction ◽  
Mechanism And Kinetics ◽  
Semi Empirical ◽  
Kinetics Of ◽  
Furnace Slag

The effects of F− concentration, leaching temperature, and time on the Ti leaching from Ti-bearing electric furnace slag (TEFS) by [NH4+]-[F−] solution leaching process was investigated to reveal the leaching mechanism and kinetics of titanium. The results indicated that the Ti leaching rate obviously increased with the increase of leaching temperature and F− concentration. The kinetic equation of Ti leaching was obtained, and the activation energy was 52.30 kJ/mol. The fitting results of kinetic equations and calculated values of activation energy both indicated that the leaching rate of TEFS was controlled by surface chemical reaction. The semi-empirical kinetics equation was consistent with the real experimental results, with a correlation coefficient (R2) of 0.996. The Ti leaching rate reached 92.83% after leaching at 90 °C for 20 min with F− concentration of 14 mol/L and [NH4+]/[F−] ratio of 0.4. The leaching rates of Si, Fe, V, Mn, and Cr were 94.03%, 7.24%, 5.36%, 4.54%, and 1.73%, respectively. The Ca, Mg, and Al elements were converted to (NH4)3AlF6 and CaMg2Al2F12 in the residue, which can transform into stable oxides and fluorides after pyro-hydrolyzing and calcinating.

Catalytic Decomposition of Ethylene on Nanocrystalline Cobalt

2007 ◽  
Vol 128 ◽  
pp. 249-254 ◽  
Author(s):  
Urszula Narkiewicz ◽  
Marcin Podsiadły ◽  
Iwona Pełech ◽  
Waleran Arabczyk ◽  
M.J. Woźniak ◽  
...  
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Reduction Process ◽  
Catalytic Decomposition ◽  
Carbon Deposit ◽  
Reduction Kinetics

Nanocrystalline cobalt was carburised with ethylene in the range 340– 500°C to obtain Co(C) nanocapsules. The carbon deposit was reduced by a flow of hydrogen in the range 500– 560°C. The reduction kinetics were studied using thermogravimetry, described by the equation: α = Α[1-exp(-kt)n]. The apparent activation energy of the reduction process of the carbon deposit was determined. After carburisation and reduction the samples were examined by XRD and HRTEM.

scholarly journals Kinetics of carbothermic reduction of synthetic chromite

2014 ◽  
Vol 50 (1) ◽  
pp. 15-21 ◽  
Author(s):  
Y. Wang ◽  
L. Wang ◽  
J. Yu ◽  
K.C. Chou
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Reduction Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chromite Ore ◽  
Current Reduction ◽  
Increasing Temperature ◽  
Isothermal Mode ◽  
Kinetics Of

In order to optimize the current reduction process of chromite, a good knowledge of reduction mechanism involved is required. The basic component in chromite ore is FeCr2O4, thus, kinetic investigation of synthetic FeCr2O4 with different amount of carbon were carried out in the temperature range of 1473K to 1673K under both isothermal and non-isothermal mode. The iron can be easily reduced compared with chromium. And higher reduction degree of chromite can be achieved by increasing temperature and carbon content. With the supporting of X-ray Diffraction and Scanning Electron Microscope methods, the formation of metallic products followed the sequence: Fe-C alloy, (Fe,Cr)7C3and Fe-Cr-C alloy. Kinetics analysis showed that the first stage was controlled by nucleation with an apparent activation energy of 120kJ/mol, while the chromium reduction was controlled by crystallochemical transformation with an apparent activation energy of 288kJ/mol.

Investigation of Reduction Mechanism and Kinetics of Vanadium Titanomagnetite Carbon Composite Hot Briquette at 1173-1373 K

2016 ◽  
Vol 88 (5) ◽  
pp. 1600306 ◽  
Author(s):  
Wei Zhao ◽  
Hongtao Wang ◽  
Zhenggen Liu ◽  
Mansheng Chu ◽  
Ziwei Ying ◽  
...  
Keyword(s):  
Carbon Composite ◽  
Reduction Mechanism ◽  
Mechanism And Kinetics ◽  
Kinetics Of

scholarly journals Mechanism and kinetics of the oxidation of synthetic α-NiS

2008 ◽  
Vol 73 (2) ◽  
pp. 211-219 ◽  
Author(s):  
Nada Strbac ◽  
Dragana Zivkovic ◽  
Ivan Mihajlovic ◽  
Boyan Boyanov ◽  
Zivan Zivkovic
Keyword(s):  
Activation Energy ◽  
Oxidation Process ◽  
Second Stage ◽  
Stability Diagrams ◽  
Calculation Process ◽  
Reac Tions ◽  
Desulfurization Process ◽  
Mechanism And Kinetics ◽  
Kinetic Investigations ◽  
Kinetics Of

The results of an investigation of the mechanism and kinetics of the oxidation process of synthetic ?-NiS are presented in this paper. The mechanism of ?-NiS oxidation was investigated based on the comparative analysis of DTA-TG-DTG and XRD results, as well as the constructed phase stability diagrams (PSD) for the Ni-S-O system. The kinetic investigations of the oxidation process were performed under isothermal conditions (temperature range 823-1073 K). The obtained degrees of desulfurization were used in the calculation process according to the Sharp model and the kinetic parameters, inclu?ding the activation energies and the rate constants of the characteristic reac?tions, for the oxidation of ?-NiS were determined. These results enabled the formulation of a kinetic equation for the desulfurization process: -ln (1 ? ?) = = k1? = 27.89 exp(-9860/T)?, with an activation energy of 82?4 kJ mol-1, for the first stage of the process and -ln (1 ? ?) = k2? = 1.177 exp(-4810/T)?, with an activation energy of 40?2 kJ mol-1, for the second stage.

Intrinsic reduction kinetics of cobalt- and nickel-titanates by hydrogen

2000 ◽  
Vol 15 (2) ◽  
pp. 338-346 ◽  
Author(s):  
I. Arvanitidis ◽  
A. Kapilashrami ◽  
Du Sichen ◽  
S. Seetharaman
Keyword(s):  
Electron Microscopy ◽  
Activation Energy ◽  
Hydrogen Reduction ◽  
High Flow ◽  
Reduction Kinetics ◽  
Isothermal Reduction ◽  
Analysis Technique ◽  
Kinetics Of ◽  
Scanning Electron ◽  
Cobalt And Nickel

The isothermal reduction of synthetic CoTiO3 and NiTiO3 in hydrogen (1 atm) was investigated using thermogravimetric analysis technique in the temperature range, 928–1287 K (CoTiO3) and 884–1387 K (NiTiO3). Shallow beds of fine titanate powders were reduced by hydrogen at a high flow rate. Quenched samples were analyzed by scanning electron microscopy. The rates of the reaction of the titanates with H2 were very fast during the reduction of Co2+, Ni2+, or Fe2+ ions into metals. The reduction of the remaining titanium oxide was very slow. The activation energy for the reduction of CoTiO3 by hydrogen to Co and TiO2 was evaluated to be 151 ± 1 kJ/mol, and the activation energy for the reduction of NiTiO3 by hydrogen to Ni and TiO2 was evaluated to be 153 ± 1 kJ/mol. The study was complemented by hydrogen reduction of synthetic TiO2 (rutile). The results were also compared with the hydrogen reduction of FeTiO3.

scholarly journals Reduction Mechanism and Kinetics of a Low Grade Iron Ore-coal Composite Pellets Improved by Sodium Salt

2020 ◽  
Vol 60 (4) ◽  
pp. 649-655 ◽  
Author(s):  
Ronghai Zhong ◽  
Lingyun Yi ◽  
Zhucheng Huang ◽  
Xiong Jiang ◽  
Wei Cai
Keyword(s):  
Sodium Salt ◽  
Iron Ore ◽  
Low Grade ◽  
Reduction Mechanism ◽  
Composite Pellets ◽  
Mechanism And Kinetics ◽  
Kinetics Of

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.

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