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).

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 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.

Reaction Laws and Macro-Kinetics of 4-Carboxybenzaldehyde Hydrogenation over Pd/TiO2 Catalyst

2013 ◽  
Vol 634-638 ◽  
pp. 587-594 ◽  
Author(s):  
Jin Cheng Gao ◽  
Ji Yuan Wang ◽  
Wen Bin Du ◽  
Ling Lin ◽  
Chong Yu Zeng
Keyword(s):  
Partial Pressure ◽  
Batch Reactor ◽  
Exothermic Reaction ◽  
Hydrogen Partial Pressure ◽  
Consecutive Reaction ◽  
Reaction Orders ◽  
Power Law Kinetics ◽  
Effects Of Temperature ◽  
Apparent Activation Energies ◽  
Kinetics Of

The effects of temperature and hydrogen partial pressure on 4-Carboxybenzaldehyde (4-CBA) hydrogenation over Pd/TiO2 catalyst were investigated in a batch reactor. The results show that 4-CBA hydrogenation is a consecutive reaction. And 4-CBA hydrogenation to 4-hydroxymethylbenzoic (4-HMBA) is a reversible exothermic reaction. Meanwhile, a parallel reaction of 4-CBA decarbonylation occurs during the process. The hydrogenation rate of 4-HMBA is more sensitive to temperature and hydrogen partial pressure than that of 4-CBA. Macro-kinetics of 4-CBA reaction over Pd/TiO2 was obtained from the experimental data using the power-law kinetics model. The apparent activation energies of 4-CBA hydrogenation, 4-HMBA hydrogenation, 4-CBA decarbonylation and 4-HMBA dehydrogenation are 29.65 kJ/mol, 42.55 kJ/mol, 74.32 kJ/mol and 69.34 kJ/mol, respectively. The reaction orders with respect to 4-CBA and 4-HMBA are both first-order.

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.

scholarly journals Leaching Kinetics of Valuable Metals

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 173
Author(s):  
Stefano Ubaldini
Keyword(s):  
Aqueous Solution ◽  
Leaching Kinetics ◽  
Hydrometallurgical Processing ◽  
Naturally Occurring ◽  
Valuable Metals ◽  
Kinetics Of

Leaching is a primary extractive operation in hydrometallurgical processing, by which a metal of interest is transferred from naturally-occurring minerals into an aqueous solution [...]

Kinetics of iron removal from quartz under ultrasound-assisted leaching

2020 ◽  
Vol 39 (1) ◽  
pp. 395-404
Author(s):  
Chang-Qiao Yang ◽  
Su-Qin Li
Keyword(s):  
Removal Rate ◽  
Input Power ◽  
Product Layer ◽  
Iron Removal ◽  
Ultrasonic Power ◽  
Leaching Process ◽  
Rate Determining Step ◽  
Shrinking Core ◽  
Ultrasound Assisted ◽  
Kinetics Of

AbstractKinetics of iron removal from quartz under the ultrasound-assisted leaching was explored in this paper, and the effects of temperature, leaching time, stirring speed and ultrasonic input power on iron removal were studied. The results revealed that the reaction kinetics followed the shrinking core model and the product layer internal diffusion was the rate-determining step in the ultrasound-assisted leaching process. The activation energy of the ultrasonic-assisted leaching reaction was 27.72 kJ/mol, which was 7.28 kJ/mol higher than that of the regular method. Moreover, the kinetic equation and mathematical model of iron removal from quartz were established. Compared with the regular leaching, only 40 min were required for the ultrasound-assisted leaching process to achieve an iron removal rate of up to 74%. Under the optimal parameters, SiO2 content of concentrate increased from 99.5828% to 99.9047%, and Fe2O3 content reduced from 0.0857% to 0.0223%. Additionally, it was found that the iron removal rate increased with increasing temperature, stirring speed or ultrasonic power.

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