scholarly journals Hydrothermal Treatment of Arsenopyrite Particles with CuSO4 Solution

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7472
Author(s):  
Aleksei Kritskii ◽  
Stanislav Naboichenko
Keyword(s):  
Hydrothermal Reaction ◽  
Metallic Copper ◽  
Sulfate Solution ◽  
Product Layer ◽  
Copper Sulfate Solution ◽  
Diffusion Controlled ◽  
Shrinking Core ◽  
Reaction Orders ◽  
Apparent Activation Energies ◽  
Stage 1

The nature of the hydrothermal reaction between arsenopyrite particles (FeAsS) and copper sulfate solution (CuSO4) was investigated in this study. The effects of temperature (443–523 K), CuSO4 (0.08–0.96 mol/L) and H2SO4 (0.05–0.6 mol/L) concentrations, reaction time (1–120 min), stirring speed (40–100 rpm) and particle size (10–100 μm) on the FeAsS conversion were studied. The FeAsS conversion was significant at >503 K, and it is suggested that the reaction is characterized by the formation of a thin layer of metallic copper (Cu0) and elemental sulfur (S0) around the unreacted FeAsS core. The shrinking core model (SCM) was applied for describing the process kinetics, and the rate of the overall reaction was found to be controlled by product layer diffusion, while the overall process was divided into two stages: (Stage 1: mixed chemical reaction/product layer diffusion-controlled) interaction of FeAsS with CuSO4 on the mineral’s surface with the formation of Cu1+ and Fe2+ sulfates, arsenous acid, S0, and subsequent diffusion of the reagent (Cu2+) and products (As3+ and Fe2+) through the gradually forming layer of Cu0 and molten S0; (Stage 2: product layer diffusion-controlled) the subsequent interaction of CuSO4 with FeAsS resulted in the formation of a denser and less porous Cu0 and S0 layer, which complicates the countercurrent diffusion of Cu2+, Cu1+, and Fe2+ across the layer to the unreacted FeAsS core. The reaction orders with respect to CuSO4 and H2SO4 were calculated as 0.41 and −0.45 for Stage 1 and 0.35 and −0.5 for Stage 2. The apparent activation energies of 91.67 and 56.69 kJ/mol were obtained for Stages 1 and 2, 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).

Kinetic investigation of a complex curing of the guaiacol bio-based benzoxazine system

e-Polymers ◽  
2016 ◽  
Vol 16 (3) ◽  
pp. 199-206 ◽  
Author(s):  
Aleš Ručigaj ◽  
Špela Gradišar ◽  
Matjaž Krajnc
Keyword(s):  
Curing Kinetics ◽  
Second Stage ◽  
Diffusion Controlled ◽  
Polymerization Behavior ◽  
Overlapped Peaks ◽  
Friedman Method ◽  
Apparent Activation Energies ◽  
Stage 1 ◽  
Kinetics Of ◽  
And Diffusion

AbstractCuring kinetics of guaiacol based benzoxazine synthesized from guaiacol, furfurylamine and formaldehyde forming bio-based polybenzoxazine was investigated. The curing process showed complex polymerization behavior, as the exothermal signal consisted of several overlapped peaks. Differentiation and fitting of overlapped peaks was performed by Pearson VII distribution obtaining two separate exothermal signals further associated to stage 1 and stage 2. The apparent activation energies of both stages were determined to be 113.8 kJ mol-1 and 117.5 kJ mol-1, respectively, according to Kissinger. The first could be explained by benzoxazine ring-opening and electrophilic substitution, whereas the second stage corresponds to the rearrangement and diffusion-controlled step. Kinetics of each stage was studied separately. As a result, the first stage was described by Šesták-Berggren autocatalytic model, whereas the second stage appeared to follow nth order kinetics proved by the Friedman method. Application of both kinetic models demonstrated that the predicted curves fit well with the non-isothermal DSC thermograms and as such sufficiently describes the complex curing behavior of guaiacol based benzoxazine.

Antibacterial mechanism of biogenic copper nanoparticles synthesized using Heliconia psittacorum leaf extract

2016 ◽  
Vol 5 (6) ◽  
Author(s):  
Kaushik Roy ◽  
Chandan K. Sarkar ◽  
Chandan K. Ghosh
Keyword(s):  
Green Synthesis ◽  
Copper Sulfate ◽  
Copper Nanoparticles ◽  
Leaf Extract ◽  
Metallic Copper ◽  
Sulfate Solution ◽  
Antibacterial Mechanism ◽  
The Novel ◽  
Copper Sulfate Solution

AbstractHere, we report on the novel green synthesis of metallic copper nanoparticles from copper sulfate solution by using the leaf extract of

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 A Kinetic Model for the Modification of Al2O3 Inclusions during Calcium Treatment in High-Carbon Hard Wire Steel

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1305
Author(s):  
Zuobing Xi ◽  
Changrong Li ◽  
Linzhu Wang
Keyword(s):  
Kinetic Model ◽  
Early Stage ◽  
Morphological Evolution ◽  
Product Layer ◽  
Melting Time ◽  
Calcium Treatment ◽  
High Carbon ◽  
Inclusion Modification ◽  
Shrinking Core ◽  
Wire Steel

Laboratory-scale experiments for the modification of Al2O3 inclusions by calcium treatment in high-carbon hard wire steel were performed and the compositions and morphological evolution of inclusions were studied. The kinetics of the modification of Al2O3 inclusions by calcium treatment were studied in high-carbon hard wire steel based on the unreacted shrinking core model, considering the transfer of Ca and Al through the boundary layer and within the product layer, coupled with thermodynamic equilibrium at the interfaces. The diffusion of Al in the inclusion layer was the limiting link in the inclusion modification process. The Ca concentration in molten steel had the greatest influence on the inclusion modification time. The modification time for inclusions tended to be longer in the transformation of higher CaO-containing calcium aluminate. The modification of Al2O3 into CA6 was fastest, while the most time was needed to modify CA into C12A7. It took about six times time longer at the later stage of inclusion modification than at the early stage. The complete modification time for inclusions increased with the square of their radii. The changes of CaO contents with melting time were estimated based on a kinetic model and was consistent with experimental results.

Computed tomography assessment of soil and sediment porosity modifications from exposure to an acid copper sulfate solution

2021 ◽  
Vol 108 ◽  
pp. 103194
Author(s):  
Francisco R.A. Ziegler-Rivera ◽  
Blanca Prado ◽  
Alfonso Gastelum-strozzi ◽  
Jorge Márquez ◽  
Lucy Mora ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Copper Sulfate ◽  
Sulfate Solution ◽  
Copper Sulfate Solution ◽  
Soil And Sediment

Combustion characteristics of biomass and bituminous coal co-firing in non-isothermal and isothermal conditions

BioResources ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 9490-9506
Author(s):  
Meijing Chen ◽  
Baojun Yi ◽  
Zhigang Li ◽  
Qiaxia Yuan
Keyword(s):  
Bituminous Coal ◽  
Reaction Model ◽  
Combustion Characteristic ◽  
Thermogravimetric Method ◽  
Characteristic Index ◽  
Isothermal Conditions ◽  
Diffusion Controlled ◽  
Chemical Reaction Model ◽  
Stage 1 ◽  
Model Diffusion

A thermogravimetric method was used to study the combustion of bituminous coal (BC), diverse biomass (wood chips: WC, chaff: CH), and their blends under non-isothermal conditions and isothermal conditions. A higher blending amount of WC or CH under non-isothermal conditions resulted in a lower ignition temperature, burnout temperature, and a greater comprehensive combustion characteristic index. Meanwhile, the co-combustion of BC, WC, and CH all showed inhibiting effects. The inhibition effect was prominent when the blending ratio of WC was below 30%. Under isothermal conditions, with the increase of oxygen concentration and blending amount, the combustion performance of BC improved gradually. The synergistic effect between BC and biomass dominated, and the interaction was more distinct when WC content exceeded 50%. Under both non-isothermal and isothermal conditions, the interaction between CH and BC did not vary at diverse blending ratios. The dynamic results suggested that the chemical reaction model O1 was suitable for stage 1 of the co-combustion of WC and BC, the model diffusion controlled D4 controlled the co-combustion of CH and BC and stage 2 of the co-combustion of WC and BC. The blending ratio of WC or CH with the lowest activation energy was 50%.

scholarly journals Visualization of Latent Fingerprints on Aluminum

2019 ◽  
Vol 73 (11) ◽  
pp. 945-946
Author(s):  
Rachel Fischer ◽  
Marco Oetken
Keyword(s):  
Corrosion Inhibitor ◽  
Copper Sulfate ◽  
Direct Contact ◽  
Sulfate Solution ◽  
Copper Deposition ◽  
Decisive Factor ◽  
Visualization Method ◽  
Latent Fingerprints ◽  
Copper Sulfate Solution ◽  
Negative Image

For aluminum, a new visualization method is presented in which copper is deposited electrochemically. The fingerprint on the aluminum (trace carrier) serves as an insulator as it prevents direct contact between electrolyte and aluminum. The decisive factor is the choice of an ammoniacal copper sulfate solution, which acts as a corrosion inhibitor due to the ammonia molecules. This enables uniform copper deposition on aluminum and thus the development of a clearly defined negative image.

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