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.

scholarly journals Leaching Kinetics of Rare Earth Elements in Phosphoric Acid from Phosphate Rock

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 239
Author(s):  
Zhili Li ◽  
Zhihao Xie ◽  
Jie Deng ◽  
Dongsheng He ◽  
Hengqin Zhao ◽  
...  
Keyword(s):  
Rare Earth ◽  
Phosphate Rock ◽  
Empirical Equation ◽  
Product Layer ◽  
Fast Reaction ◽  
Solid Product ◽  
Reaction Stage ◽  
Shrinking Core ◽  
Semi Empirical ◽  
Kinetics Of

Phosphate rock has been considered as one of the most significant secondary rare-earth resource, and the utilization of rare earth elements (REEs) in phosphate rock has attracted increasing attention. In this study, the leaching kinetics of REEs from a phosphate ore from China was studied with the variation of temperature and phosphoric acid concentration under the conditions: ratio of liquid to solid of 12 mL/g, stirring speed of 120 r/min, and phosphate particle size of −0.074 mm amounts 61.1%. The results suggest that there were two distinct stages in leaching process and kinetics of both stages followed shrinking core model. At fast reaction stage, the semi-empirical equation describing the kinetics was 1 − 3(1 − α)2/3 + 2(1 − α) = 1.885CH3PO40.89exp(−11220/8.31T)t. The semi-empirical equation for slow reaction stage was 1 − 3(1 − α)2/3 + 2(1 − α) = 0.299CH3PO42.50exp(−18720/8.31T)t. Using shrinking core model and time-to-a-given-fraction method, we found that leaching rate of fast reaction stage was controlled by solid product layer diffusion, and both solid product layer diffusion and chemical reaction determined slow reaction stage.

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 Application of the Shrinking-Core Models for Determination of Dissolution Kinetics of Mn and Zn from Spent Zinc–Carbon Battery Powder in Organic Acid Solution

2019 ◽  
Vol 27 (1) ◽  
pp. 99-109 ◽  
Author(s):  
Tevfik Agacayak ◽  
Hasan Ali Taner
Keyword(s):  
Acetic Acid ◽  
Acid Solution ◽  
Acetic Acid Solution ◽  
Dissolution Kinetics ◽  
Kinetic Studies ◽  
Product Layer ◽  
Different Temperatures ◽  
Shrinking Core ◽  
Kinetics Of Dissolution ◽  
Kinetics Of

Abstract In this study, dissolution kinetics of manganese and zinc from spent zinc–carbon batteries in acetic acid solution was investigated. To determine the kinetics of dissolution of manganese and zinc, shrinking core model was applied to dissolution recoveries obtained at different temperatures. As a result of kinetic studies, it was determined that manganese and zinc were dissolved in acetic acid solution by diffusion from product layer and then activation energies (Ea) were calculated.

Kinetics of limestone decomposition in hot metal

2018 ◽  
Vol 115 (6) ◽  
pp. 611 ◽  
Author(s):  
Biao Tang ◽  
Qifu Xiang ◽  
Jing Wang ◽  
Yunlong Zhang ◽  
Xingyi Li ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Heat Conduction ◽  
Cross Section ◽  
Gas Flow ◽  
Kinetic Equations ◽  
Product Layer ◽  
Hot Metal ◽  
Shrinking Core ◽  
Kinetics Of ◽  
Limestone Calcination

Compared with the traditional limestone calcination, this paper focuses on the conditions and temperature in hot metal where limestone calcines in converter steelmaking process. Considering heat transfer, mass transfer driven by concentration gradient and mass transfer (CO2 gas flow) driven by pressure gradient, macro kinetic models are established to describe limestone decomposition rate respectively. The method of rotating cylinder sample is used in the experiment of limestone decomposition in hot metal. The image processing software Image-Pro Plus is used to analyze the cross section of limestone calcined to get the unreacted core radius of cross section of cylindrical limestone. The results show that the decomposition mechanism of limestone follows the unreacted shrinking core model, the heat conduction of lime layer is the controlling step, the heat conduction and CO2 migration through the product layer determine the rate of limestone decomposition, and the corresponding kinetic equations are established.

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).

scholarly journals Leaching Kinetics of Arsenic Sulfide-Containing Materials by Copper Sulfate Solution

Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 7
Author(s):  
Kirill A. Karimov ◽  
Denis A. Rogozhnikov ◽  
Evgeniy A. Kuzas ◽  
Andrei A. Shoppert
Keyword(s):  
Copper Sulfate ◽  
Raw Materials ◽  
Sulfate Solution ◽  
Effect Of Temperature ◽  
Arsenic Sulfide ◽  
Copper Sulfate Solution ◽  
X Ray ◽  
Shrinking Core ◽  
Multicomponent Solutions ◽  
Kinetics Of

The overall decrease in the quality of mineral raw materials, combined with the use of arsenic-containing ores, results in large amounts of various intermediate products containing this highly toxic element. The use of hydrometallurgical technologies for these materials is complicated by the formation of multicomponent solutions and the difficulty of separating copper from arsenic. Previously, for the selective separation of As from copper–arsenic intermediates a leaching method in the presence of Cu(II) ions was proposed. This paper describes the investigation of the kinetics of arsenic sulfide-containing materials leaching by copper sulfate solution. The cakes after leaching of arsenic trisulfide with a solution of copper sulfate were described using methods such as X-ray diffraction spectrometry (XRD), X-ray fluorescence spectrometry (XRF), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy analysis (EDS). The effect of temperature (70–90 °C), the initial concentration of CuSO4 (0.23–0.28 M) and the time on the As recovery into the solution was studied. The process temperature has the greatest effect on the kinetics, while an increase in copper concentration from 0.23 to 0.28 M effects an increase in As transfer into solution from 93.2% to 97.8% for 120 min of leaching. However, the shrinking core model that best fits the kinetic data suggests that the process occurs by the intra-diffusion mode with the average activation energy of 44.9 kJ/mol. Using the time-to-a-given-fraction kinetics analysis, it was determined that the leaching mechanism does not change during the reaction. 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] = 4560000Cu3.61e−44900/RT t.

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.

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 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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