scholarly journals Kinetics of stibnite (Sb2S3) oxidation at roasting temperatures

2014 ◽  
Vol 50 (2) ◽  
pp. 127-132 ◽  
Author(s):  
R. Padilla ◽  
A. Aracena ◽  
M.C. Ruiz
Keyword(s):  
Partial Pressure ◽  
Intrinsic Rate ◽  
Analysis Method ◽  
Surface Chemical Reaction ◽  
Partial Pressures ◽  
Rate Of Reaction ◽  
Detectable Rate ◽  
Shrinking Core ◽  
One Step ◽  
Kinetics Of

Experimental work on the oxidation of stibnite (Sb2S3) was carried out at temperatures between 350 and 500?C and oxygen partial pressures between 1.01 and 21.28 kPa by using a thermogravimetric analysis method. The oxidation rate of stibnite was significantly influenced by both temperature and partial pressure of oxygen. Stibnite oxidized in one step to valentinite (Sb2O3) and neither stibnite nor valentinite showed a detectable rate of volatilization at these low temperatures. The oxidation reaction of stibnite was analyzed by using the shrinking core model and it was found that the rate of reaction was controlled by the surface chemical reaction and it was of 3/5 order with respect to the oxygen partial pressure. The intrinsic rate constants were determined and an activation energy value of 90.3 kJ/mol was obtained for the range of temperature studied.

scholarly journals Kinetic study of CO2 reaction with CaO by a modified random pore model

2016 ◽  
Vol 18 (1) ◽  
pp. 93-98 ◽  
Author(s):  
S.M.M. Nouri ◽  
H. Ale Ebrahim
Keyword(s):  
Mercury Porosimetry ◽  
Nitrogen Adsorption ◽  
Intrinsic Rate ◽  
Product Layer ◽  
Carbonation Reaction ◽  
Pore Model ◽  
Partial Pressures ◽  
Pore Size Distributions ◽  
Kinetics Of ◽  
Random Pore Model

Abstract In this work, a modified random pore model was developed to study the kinetics of the carbonation reaction of CaO. Pore size distributions of the CaO pellets were measured by nitrogen adsorption and mercury porosimetry methods. The experiments were carried out in a thermogravimeter at different isothermal temperatures and CO2 partial pressures. A fractional concentration dependency function showed the best accuracy for predicting the intrinsic rate of reaction. The activation energy was determined as 11 kcal/mole between 550–700°C. The effect of product layer formation was also taken into account by using the variable product layer diffusivity. Also, the model was successfully predicted the natural lime carbonation reaction data extracted from the literature.

KINETICS OF THE CUPRIC ACETATE CATALYZED HYDROGENATION OF DICHROMATE IN AQUEOUS SOLUTION

1955 ◽  
Vol 33 (2) ◽  
pp. 356-364 ◽  
Author(s):  
E. Peters ◽  
J. Halpern
Keyword(s):  
Activation Energy ◽  
Aqueous Solution ◽  
Partial Pressure ◽  
Kinetic Study ◽  
Reaction Rates ◽  
Homogeneous Catalyst ◽  
Cupric Acetate ◽  
Partial Pressures ◽  
Kinetics Of

In aqueous solution, cupric acetate was found to act as a homogeneous catalyst for the reduction of dichromate by hydrogen, i.e.[Formula: see text] The paper describes a kinetic study of this reaction. Rates were determined at temperatures between 80° and 140 °C. and hydrogen partial pressures up to 27 atmospheres. The rate is independent of the dichromate concentration but varies directly with the partial pressure of hydrogen and is nearly proportional to the concentration of cupric acetate. The activation energy is 24,600 calories per mole. Cupric acetate, apparently acting as a true catalyst, activates the hydrogen through formation of a complex with it. An extension of the mechanism proposed earlier for the reaction of cupric acetate itself with hydrogen also accounts for the kinetics of the dichromate reaction.

Arterial and Mixed Venous Kinetics of Desflurane and Sevoflurane, Administered Simultaneously, at Three Different Global Ventilation to Perfusion Ratios in Piglets with Normal Lungs

2021 ◽  
Author(s):  
Moritz Kretzschmar ◽  
James E. Baumgardner ◽  
Alf Kozian ◽  
Thomas Hachenberg ◽  
Thomas Schilling ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Minute Ventilation ◽  
Arterial Partial Pressure ◽  
Arterial Blood ◽  
Partial Pressures ◽  
Inhaled Anesthetic ◽  
Kinetics Of ◽  
Normal Lungs ◽  
Mixed Venous

Background Previous studies have established the role of various tissue compartments in the kinetics of inhaled anesthetic uptake and elimination. The role of normal lungs in inhaled anesthetic kinetics is less understood. In juvenile pigs with normal lungs, the authors measured desflurane and sevoflurane washin and washout kinetics at three different ratios of alveolar minute ventilation to cardiac output value. The main hypothesis was that the ventilation/perfusion ratio ( .VA/.Q  ) of normal lungs influences the kinetics of inhaled anesthetics. Methods Seven healthy pigs were anesthetized with intravenous anesthetics and mechanically ventilated. Each animal was studied under three different .VA/.Q conditions: normal, low, and high. For each .VA/.Q condition, desflurane and sevoflurane were administered at a constant, subanesthetic inspired partial pressure (0.15 volume% for sevoflurane and 0.5 volume% for desflurane) for 45 min. Pulmonary arterial and systemic arterial blood samples were collected at eight time points during uptake, and then at these same times during elimination, for measurement of desflurane and sevoflurane partial pressures. The authors also assessed the effect of .VA/.Q on paired differences in arterial and mixed venous partial pressures. Results For desflurane washin, the scaled arterial partial pressure differences between 5 and 0 min were 0.70 ± 0.10, 0.93 ± 0.08, and 0.82 ± 0.07 for the low, normal, and high .VA/.Q conditions (means, 95% CI). Equivalent measurements for sevoflurane were 0.55 ± 0.06, 0.77 ± 0.04, and 0.75 ± 0.08. For desflurane washout, the scaled arterial partial pressure differences between 0 and 5 min were 0.76 ± 0.04, 0.88 ± 0.02, and 0.92 ± 0.01 for the low, normal, and high .VA/.Q conditions. Equivalent measurements for sevoflurane were 0.79 ± 0.05, 0.85 ± 0.03, and 0.90 ± 0.03. Conclusions Kinetics of inhaled anesthetic washin and washout are substantially altered by changes in the global  .VA/.Q   ratio for normal lungs. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

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.

Kinetics of Leaching Vanadium with Sulfuric Acid from Carbonaceous Shale Containing Vanadium

2011 ◽  
Vol 402 ◽  
pp. 7-11
Author(s):  
Yan Liu ◽  
Cong Sun ◽  
Wei Jun Zhong ◽  
Yu Chun Zhai
Keyword(s):  
Sulfuric Acid ◽  
Carbonaceous Shale ◽  
Particle Sizes ◽  
Shrinking Core Model ◽  
Leaching Rate ◽  
Stone Coal ◽  
Rate Of Reaction ◽  
Shrinking Core ◽  
Kinetics Of ◽  
Arrhenius Expression

ηA kinetic study of the leaching of stone coal ore with sulfuric acid has been investigated. The effects of the stirring speed, particle sizes of stone coal, acid concentration, leaching temperature and acid-ore ratio on the leaching rate of vanadium were examined. It was found that the leaching rate of vanadium was significantly influenced by leaching temperature. The shrinking core model was applied to the leaching process and the results showed that the process was based on chemical reaction control. And the rate of reaction was expressed as 1-(1-η)1⁄3=4.98×106·e-55488⁄RT·t. The apparent activation energy for the leaching of vanadium⁄ was calculated to be ¾5⁄5.49 kJ/mol using Arrhenius expression.

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.

Dissolution kinetics of cerussite in an alternative leaching reagent for lead

2015 ◽  
Vol 69 (3) ◽  
Author(s):  
Qi-Cheng Feng ◽  
Shu-Ming Wen ◽  
Yi-Jie Wang ◽  
Qin-Bo Cao ◽  
Wen-Juan Zhao
Keyword(s):  
Dissolution Kinetics ◽  
Product Layer ◽  
Surface Chemical ◽  
Surface Chemical Reaction ◽  
Mixed Control ◽  
Shrinking Core ◽  
Two Stages ◽  
Kinetics Of ◽  
And Diffusion ◽  
Rate Controlling Step

AbstractThe dissolution kinetics of cerussite was investigated using methanesulphonic acid (MSA) as an alternative leaching reagent. The effects of particle size, stirring speed, acid concentration, and reaction temperature on the lead dissolution rate were determined. The dissolution process followed the kinetic law of the shrinking-core model, and a corresponding mixed control model was found suitable for representing the rate-controlling step. The mixed kinetic model comprised two stages: surface chemical reaction (283 K to 303 K) and diffusion through the product layer (303 K to 323 K). The activation energies of these sequential stages were 43.20 kJ mol

Effect of H2O Partial Pressure on Reduction Kinetics of Iron-Based Fischer-Tropsch Catalyst

2010 ◽  
Vol 31 (2) ◽  
pp. 205-212
Author(s):  
Hong WANG ◽  
Yong YANG ◽  
Baoshan WU ◽  
Jian XU ◽  
Hulin WANG ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Reduction Kinetics ◽  
Fischer Tropsch ◽  
Iron Based ◽  
Kinetics Of

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.

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