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.

Reaction kinetics of malachite in ammonium carbamate solution

2015 ◽  
Vol 69 (9) ◽  
Author(s):  
Ying-Bo Mao ◽  
Jiu-Shuai Deng ◽  
Shu-Ming Wen ◽  
Jian-Jun Fang
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Dissolution Rate ◽  
Batch Reactor ◽  
Shrinking Core Model ◽  
Surface Chemical ◽  
Surface Chemical Reaction ◽  
Ammonium Carbamate ◽  
Shrinking Core ◽  
Kinetics Of

AbstractThe dissolution of malachite particles in ammonium carbamate (AC) solutions was investigated in a batch reactor, using the parameters of temperature, AC concentration, particle size, and stirring speed. The shrinking core model was evaluated for the dissolution rate increased by decreasing particle size and increasing the temperature and AC concentration. No important effect was observed for variations in stirring speed. Dissolution curves were evaluated in order to test shrinking core models for fluid-solid systems. The dissolution rate was determined as being controlled by surface chemical reaction. The activation energy of the leaching process was determined as 46.04 kJ mol

Kinetics of Atmospheric Acid Leaching of a Limonitic Laterite

2013 ◽  
Vol 319 ◽  
pp. 14-18
Author(s):  
Kui Liu ◽  
Xi Liu
Keyword(s):  
Atmospheric Pressure ◽  
Acid Leaching ◽  
Shrinking Core Model ◽  
Surface Chemical ◽  
Surface Chemical Reaction ◽  
Nickel Laterite ◽  
Shrinking Core ◽  
Semi Empirical ◽  
Kinetics Of ◽  
Rate Controlling Step

A limonitic nickel laterite was leached by sulfuric acid at atmospheric pressure. Kinetics of leaching within the temperature range of 75-100°C was studied. The leaching kinetics followed the shrinking core model. The diffusion through the liquid film could be negligible under the agitation speed of 600rpm or above. Surface chemical reaction was the rate-controlling step. The semi-empirical kinetic equation was determined and the activation energy was 52.843kJ/mol.

Leaching Kinetics and Seperation of Antimony and Arsenic from Arsenic Alkali Residue

2011 ◽  
Vol 402 ◽  
pp. 57-60 ◽  
Author(s):  
Gui Sheng Zeng ◽  
Hui Li ◽  
Su Hua Chen ◽  
Xin Man Tu ◽  
Wen Bin Wang
Keyword(s):  
Shrinking Core Model ◽  
Leaching Kinetics ◽  
Surface Chemical ◽  
Leaching Rate ◽  
Kinetics Equation ◽  
Surface Chemical Reaction ◽  
Liquid Ratio ◽  
Shrinking Core ◽  
Solid Liquid ◽  
Kinetics Of

The separation of antimony and arsenic and leaching kinetics of arsenic from arsenic alkali residue were investigated. The influencing factors such as solid/liquid ratio, stir speed, temperature and time on leaching of arsenic were studied. The results show that the leaching rate reaches 87.75% at the condition of solid/liquid ratio of 1:4 , stir speed of 600r/min ,temperature of 90°C and time of 60min. The leaching process was controlled by the surface chemical reaction and the kinetics of leaching arsenic followed the model of shrinking core. The activation energy was found to be 666.57kJ/mol. The kinetics equation was expressed as shrinking core model.

scholarly journals Study on indium leaching from mechanically activated hard zinc residue

2011 ◽  
Vol 47 (1) ◽  
pp. 63-72 ◽  
Author(s):  
J.H. Yao ◽  
X.H. Li ◽  
Y.W. Li
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Planetary Mill ◽  
Leaching Rate ◽  
Obvious Effect ◽  
Diffusion Controlled ◽  
Leaching Reaction ◽  
Kinetics Of ◽  
Positive Effect ◽  
Solution Kinetics

In this study, changes in physicochemical properties and leachability of indium from mechanically activated hard zinc residue by planetary mill were investigated. The results showed that mechanical activation increased specific surface area, reaction activity of hard zinc residue, and decreased its particle size, which had a positive effect on indium extraction from hard zinc residue in hydrochloric acid solution. Kinetics of indium leaching from unmilled and activated hard zinc residue were also investigated, respectively. It was found that temperature had an obvious effect on indium leaching rate. Two different kinetic models corresponding to reactions which are diffusion controlled, [1-(1- x)1/3]2=kt and (1-2x/3)-(1-x)2/3=kt were used to describe the kinetics of indium leaching from unmilled sample and activated sample, respectively. Their activation energies were determined to be 17.89 kJ/mol (umilled) and 11.65 kJ/mol (activated) within the temperature range of 30?C to 90?C, which is characteristic for a diffusion controlled process. The values of activation energy demonstrated that the leaching reaction of indium became less sensitive to temperature after hard zinc residue mechanically activated by planetary mill.

β Grain Growth Kinetics of Hot-Rolled TB-13 Alloy

2011 ◽  
Vol 689 ◽  
pp. 472-478 ◽  
Author(s):  
Yue Fei ◽  
Bin Tang ◽  
Hui Chang ◽  
Zhi Shou Zhu ◽  
Zhong Bo Zhou ◽  
...  
Keyword(s):  
Activation Energy ◽  
Grain Growth ◽  
Kinetic Equations ◽  
Type Equation ◽  
Growth Exponent ◽  
Fine Grained ◽  
Solution Treated ◽  
Grain Growth Kinetics ◽  
Hot Rolled ◽  
Kinetics Of

A study on the kinetics of β grain growth of a fine-grained, hot-rolled TB-13 alloy was carried out by isochronal and isothermal solution treatments. The grain size of the as-rolled and as-solution-treated samples was determined by metallographic observation using the linear intercept method. The kinetic equations and the Arrhenius-type equation were applied to calculate the β grain growth exponent and the activation energy for β grain growth at special temperatures. The results showed that the β grain growth rate decreased with elongating solution treated time, but increased with increasing solution treated temperature. The β grain growth exponents (n) were 0.394, 0.403 and 0.406 during the solution treated temperatures at 1103K, 1153K and 1203K, respectively. The values of n increased with increasing solution treated temperature and the determined activation energy (Qm) for β grain growth after holding for 0.5h at 1103K-1203K was around 156KJ/mol.

The Effect of Temperature on the Leaching of Malachite in Phosphoric Acid Solution

2014 ◽  
Vol 962-965 ◽  
pp. 818-821 ◽  
Author(s):  
Cui Cui Ji ◽  
Dan Dan Wu ◽  
Shu Ming Wen ◽  
Jiu Shuai Deng
Keyword(s):  
Phosphoric Acid ◽  
Acid Solution ◽  
Phosphoric Acid Solution ◽  
Effect Of Temperature ◽  
Solution Temperature ◽  
Shrinking Core Model ◽  
Surface Chemical ◽  
Leaching Rate ◽  
Surface Chemical Reaction ◽  
Shrinking Core

In this study, the effect of leaching of malachite was investigated using phosphoric acid solution as leaching agent. The effect of temperature on the leaching of malachite was investigated. The leaching rate increased with increasing solution temperature, and a kinetic model was developed to represent this relationship. The leaching was controlled by the shrinking core model for surface chemical reaction. The activation energy of the leaching process was determined to be 30.65kJ/mol.

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.

The kinetics of a surface-chemical reaction

1989 ◽  
Vol 37 (2) ◽  
pp. 147-159 ◽  
Author(s):  
P.N.T. van Velzen ◽  
J.J. Ponjeé ◽  
A. Benninghoven
Keyword(s):  
Chemical Reaction ◽  
Surface Chemical ◽  
Surface Chemical Reaction ◽  
Kinetics Of
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