scholarly journals Temperature-dependent kinetics of aluminum leaching from peat clay

2020 ◽  
Vol 16 (2) ◽  
pp. 248-251
Author(s):  
Agus Mirwan ◽  
Susianto Susianto ◽  
Ali Altway ◽  
Renanto Handogo
Keyword(s):  
Leaching Kinetics ◽  
Particle Structure ◽  
Temperature Dependent ◽  
Reaction Rate Constants ◽  
Aluminum Recovery ◽  
Proposed Model ◽  
Shrinking Core ◽  
Increasing Temperature ◽  
Solid Liquid ◽  
Kinetics Of

The leaching kinetics of aluminum from peat clay using 4 M HCl at dissimilar leaching temperatures (30–90 °C) was investigated. The maximum of aluminum recovery was 91.27% after 60 min of leaching in agitated Pyrex reactor at 90 °C. The model involved the concept of shrinking core in order to describe aluminum that is located inside the core solid particle of peat clay that shrinks as the extracted solute, and it assumed the unchanged particle structure, a first-order leaching kinetics mechanism and a linear equilibrium at the interface of solid-liquid. The proposed model was corresponding to fit experimental data and to simulate the aluminum leaching from peat clay with four fitting parameters of temperature, which was confirmed with the mass transfer coefficient (kc, cm/s), diffusion coefficient (De, cm2/s), and reaction rate constants (k, cm/s) by following an increasing trend with increasing temperature. Moreover, it was validated by the correlation coefficient (ccoef ≥ 0.9794), the root means square error (RMSE ≤ 0.485), the mean relative deviation modulus (E ≤ 3.290%), and the activation energy value (Ea = 19.15 kJmol-1). This model could describe the aluminum leaching kinetics from peat clay that suitable with experiment parameters and statistical criteria, by giving useful information for optimization, scaling-up, and design.

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.

Experimental and Numerical Study on Dynamic Properties of Viscoelastic Microvibration Damper Considering Temperature and Frequency Effects

2016 ◽  
Vol 11 (6) ◽  
Author(s):  
Chao Xu ◽  
Zhao-Dong Xu ◽  
Teng Ge ◽  
Ya-Xin Liao
Keyword(s):  
Loss Factor ◽  
Numerical Study ◽  
Dynamic Properties ◽  
Frequency Effect ◽  
Solid Model ◽  
Temperature Dependent ◽  
Frequency Effects ◽  
Proposed Model ◽  
Different Temperatures ◽  
Increasing Temperature

This work presents an experimental and numerical study on the dynamic properties of viscoelastic (VE) microvibration damper under microvibration conditions at different frequencies and temperatures. The experimental results show that the storage modulus and the loss factor of VE microvibration damper both increase with increasing frequency but decrease with increasing temperature. To explicitly and accurately represent the temperature and frequency effects on the dynamic properties of VE microvibration damper, a modified standard solid model based on a phenomenological model and chain network model is proposed. A Gaussian chain spring and a temperature-dependent dashpot are employed to reflect the temperature effect in the model, and the frequency effect is considered with the nature of the standard solid model. Then, the proposed model is verified by comparing the numerical results with the experimental data. The results show that the proposed model can accurately describe the dynamic properties of VE microvibration damper at different temperatures and frequencies.

Solid-Liquid Extraction Kinetics of Flavonoids in Ficus microcarpa

2011 ◽  
Vol 396-398 ◽  
pp. 575-581
Author(s):  
Li Sheng Wang ◽  
Li Heng Liu ◽  
Man Duan ◽  
Xiong Min Liu
Keyword(s):  
Liquid Extraction ◽  
Diffusion Control ◽  
Extraction Kinetics ◽  
Leaching Process ◽  
Shrinking Core ◽  
Higher Temperature ◽  
Ficus Microcarpa ◽  
Solid Liquid Extraction ◽  
Solid Liquid ◽  
Kinetics Of

The solid-liquid extraction kinetics of flavonoids from Ficus microcarpa with ethanol was studied. The effects of temperature and concentration of ethanol on extraction kinetics were examined. It is found that the higher temperature and concentration of ethanol, the higher leaching yields. The leaching process can be described by outer diffusion control model before 60 min and the shrinking-core model between 60 min and 150 min. The leaching process kinetics equations were established, respectively.

scholarly journals Leaching Kinetics and Mechanism of Laterite with NH4Cl-HCl Solution

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 754
Author(s):  
Jinhui Li ◽  
Yang Yang ◽  
Yaoru Wen ◽  
Wenxin Liu ◽  
Yuhang Chu ◽  
...  
Keyword(s):  
Leaching Kinetics ◽  
Leaching Process ◽  
Exploitation And Utilization ◽  
Valuable Metals ◽  
Solid Film ◽  
Shrinking Core ◽  
Reaction Orders ◽  
Apparent Activation Energies ◽  
Kinetics Of ◽  
Leaching Mechanism

Following the growing demand for Ni and Co and the dwindling supplies of sulfide nickel ore, attention has turned toward the more efficient exploitation and utilization of laterite ore. Using ammonium chloride acid solution to leach is an effective method. Our research concerned investigations on the leaching mechanism and leaching kinetics of laterite. XRD was used to demonstrate the leaching mechanism through analysis of the pattern of the leaching residue and raw ore, showing that acid concentration affects the leaching process more significantly than other factors, and that valuable metals are mainly released from goethite and serpentine. The leaching order of these materials are as follows: Goethite > serpentine > magnetite and hematite. The leaching kinetics were analyzed and this leaching process followed a shrinking core model controlled by a combination of interfacial transfer and diffusion across the solid film. Leaching data fitted to the kinetic equation perfectly, and the apparent activation energies for the leaching of nickel, cobalt, and iron were calculated to be 4.01 kJ/mol, 3.43 kJ/mol, and 1.87 kJ/mol, respectively. The Arrhenius constants for Ni, Co, and Fe were 204.38, 16.65, and 7.12 × 10−3, respectively, with reaction orders of Ni (a 1.32, b 0.85, c 1.53), Co (a 1.74, b 1.12, c 1.22), and Fe (a 2.52, b −0.11, c 0.94).

Mechanism and kinetics of inactivation at 40–70°C of the extracellular proteinase from Pseudomonas fluorescens 22F

1998 ◽  
Vol 65 (2) ◽  
pp. 261-272 ◽  
Author(s):  
ERIX P. SCHOKKER ◽  
MARTINUS A. J. S. VAN BOEKEL
Keyword(s):  
Molecular Mass ◽  
Pseudomonas Fluorescens ◽  
Computer Simulations ◽  
Rate Constants ◽  
Size Exclusion ◽  
Temperature Dependent ◽  
Extracellular Proteinase ◽  
Reaction Rate Constants ◽  
Exclusion Chromatography ◽  
Kinetics Of

HPLC size exclusion chromatography experiments showed that during inactivation at 40–70°C of the extracellular proteinase from Pseudomonas fluorescens 22F small molecular mass fragments were formed, indicating that autoproteolysis was at least one of the major causes of inactivation. The formation of small molecular mass fragments and the reaction order indicated that intermolecular autoproteolysis was more likely than intramolecular autodigestion. This was confirmed by computer simulations. The rate constants and the activation enthalpy (ΔH[Dagger]) and entropy (ΔS[Dagger]) for the reactions of the intermolecular autoproteolysis model were derived from computer simulations. ΔH[Dagger] and ΔS[Dagger] of the unfolding reaction were 504 kJ mol−1 and 1252 J mol K−1 respectively. ΔH[Dagger] and ΔS[Dagger] of the refolding reaction were strongly temperature dependent. The estimates for the enthalpy (ΔH0) and entropy (ΔS0) difference between the folded and unfolded state as derived from the reaction rate constants of unfolding and refolding were subject to large deviations, owing to accumulation of errors in the estimation of the kinetic characteristics.

Thermal degradation kinetics of sepiolite

Clay Minerals ◽  
2020 ◽  
Vol 55 (1) ◽  
pp. 96-100 ◽  
Author(s):  
Yüksel Sarıkaya ◽  
Müşerref Önal ◽  
Abdullah Devrim Pekdemir
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Thermal Degradation ◽  
Degradation Kinetics ◽  
Analysis Data ◽  
Thermal Degradation Kinetics ◽  
Temperature Dependent ◽  
Thermal Change ◽  
Increasing Temperature ◽  
Kinetics Of

AbstractThe kinetic parameters of the thermal degradation of sepiolite were evaluated with a new method based on thermal analysis data. Thermogravimetric/differential thermal analysis curves were recorded for the natural and preheated sepiolite samples in the temperature range 25–800°C for 4 h. The temperature-dependent height of the exothermic heat flow peak for the thermal decomposition of sepiolite located at ~850°C on the differential thermal analysis curve was taken as a kinetic variable for the thermal degradation. A thermal change coefficient was defined depending on this variable because this coefficient fit to the Arrhenius equation was assumed as a rate constant for the thermal degradation. The Arrhenius plot showed that the degradation occurs in three steps. Two of these are due to stepwise dehydration and the third originated from dehydroxylation of sepiolite. Three activation energies were obtained that increase with the increasing temperature interval of the steps.

scholarly journals Leaching Kinetics of Sulfides from Refractory Gold Concentrates by Nitric Acid

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 465 ◽  
Author(s):  
Denis A. Rogozhnikov ◽  
Andrei A. Shoppert ◽  
Oleg A. Dizer ◽  
Kirill A. Karimov ◽  
Rostislav E. Rusalev
Keyword(s):  
Mineral Resources ◽  
Product Layer ◽  
Yenisei Ridge ◽  
Effect Of Temperature ◽  
Leaching Kinetics ◽  
Iron Recovery ◽  
Refractory Gold ◽  
Shrinking Core ◽  
Semi Empirical ◽  
Kinetics Of

The processing of refractory gold-containing concentrates by hydrometallurgical methods is becoming increasingly important due to the depletion of rich and easily extracted mineral resources, as well as due to the need to reduce harmful emissions from metallurgy, especially given the high content of arsenic in the ores. This paper describes the investigation of the kinetics of HNO3 leaching of sulfide gold-containing concentrates of the Yenisei ridge (Yakutia, Russia). The effect of temperature (70–85 °C), the initial concentration of HNO3 (10–40%) and the content of sulfur in the concentrate (8.22–22.44%) on the iron recovery into the solution was studied. It has been shown that increasing the content of S in the concentrate from 8.22 to 22.44% leads to an average of 45% increase in the iron recovery across the entire range temperatures and concentrations of HNO3 per one hour of leaching. The leaching kinetics of the studied types of concentrates correlates well with the new shrinking core model, which indicates that the reaction is regulated by interfacial diffusion and diffusion through the product layer. Elemental S is found on the surface of the solid leach residue, as confirmed by XRD and SEM/EDS analysis. The apparent activation energy is 60.276 kJ/mol. The semi-empirical expression describing the reaction rate under the studied conditions can be written as follows: 1/3ln(1 − X) + [(1 − X)−1/3 − 1] = 87.811(HNO3)0.837(S)2.948e−60276/RT·t.

Beneficiation of rejects slime of iron ore by means of sequential leaching

2019 ◽  
Vol 116 (2) ◽  
pp. 202 ◽  
Author(s):  
Santanu Sarkar ◽  
Supriya Sarkar
Keyword(s):  
Hydrofluoric Acid ◽  
Iron Ore ◽  
Research Work ◽  
Shrinking Core Model ◽  
Leaching Kinetics ◽  
Iron Recovery ◽  
Weight Percentage ◽  
Leach Rate ◽  
Shrinking Core ◽  
Kinetics Of

The present research work has been conducted to remove gangue contents from rejects slime of iron ore, having particle size < 20 µm by circulating leaching with aqueous hydrofluoric acid (HF) followed by nitric acid (HNO3) washing. Effects of acid concentration, slurry ratio, reaction time, stirring speed and temperature on gangue removal have been examined. The gangue contents (alumina and silica) are reduced from 13 weight percentage (wt.%) to around 1 wt.%. The iron value has also been increased from 58.74 wt.% to 68.47 wt.% with more than 95% iron recovery. The gangue matter remaining after leaching consists mainly of aluminium and silicon, which is most likely encapsulated in the goethite phase. The leaching kinetics has also been studied to establish an overall leach-rate equation. The shrinking core model is very suitable to describe the kinetics of gangue removal.

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