scholarly journals Dissolution of Tunisian phosphate ore by a mixture of sulfuric and phosphoric acid: Kinetics study by means of differential reaction calorimetry

2019 ◽  
Vol 55 (1) ◽  
pp. 9-19
Author(s):  
Olfa Lachkar-Zamouri ◽  
Khemaies Brahim ◽  
Faten Bennour ◽  
Ismail Khattech
Keyword(s):  
Experimental Data ◽  
Particle Size ◽  
Dissolution Rate ◽  
Dissolution Kinetics ◽  
Reaction Model ◽  
Reaction Calorimetry ◽  
Phosphate Ore ◽  
Differential Reaction ◽  
Apparent Activation Energies ◽  
Kinetics Of

A mixture of phosphoric and sulfuric acid was used to investigate the dissolution kinetics of phosphate ore by Differential Reaction Calorimetry (DRC). The effect of the solid-to-iquid ratio, concentration, stirring speed, particle size and temperature of the reaction is examined. It was established that the dissolution rate increased with stirring speed and particle size. However, rising the olid-to-iquid ratio, temperature and concentration decreased the dissolution rate. It was determined that the dissolution rate fits in the first order of the pseudo-homogeneous reaction model. Two negative values of apparent activation energies were found in the range of 25 to 60?C. The experimental data were tested by graphical and statistical methods and it was found that the following models were best fitted for the experimental data and an empirical equation for the process was developed. -ln (1 ? x) = [2,2 E-09((S/L)0.75C -0.461G0.447(SS) 0.471exp (2671/T)]t. T? 40?C -ln (1 ? x) = [2,2 E-09((S/L)0.75C -0.461G0.447(SS) 0.471exp (6959/T)]t. T > 45?C

The Dissolution Kinetics of Tincal in Phosphoric Acid Solutions

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Yuksel Abali ◽  
Salih U Bayca ◽  
Ayse E Guler
Keyword(s):  
Particle Size ◽  
Phosphoric Acid ◽  
Dissolution Rate ◽  
Acid Concentration ◽  
Reaction Temperature ◽  
Dissolution Kinetics ◽  
Reaction Model ◽  
Acid Solutions ◽  
Liquid Ratio ◽  
Kinetics Of

In this study, the dissolution kinetics of tincal in phosphoric acid solutions was investigated. The effects of reaction temperature, acid concentration, solid to liquid ratio, particle size and stirring speed were determined in the experiments. The results showed that the dissolution rate increased with increasing acid concentration, reaction temperature, stirring speed and increased with decreasing particle size and solid to liquid ratio. The dissolution rate was found to be based on the first order pseudo homogenous reaction model. The activation energy of the tincal in phosphoric acid solution was determined as 42.28 kJ.mol-1.

scholarly journals Kinetic Model for Dissolution of Cement Copper in Sulfuric Acid Solutions Containing Cupric Ions

2021 ◽  
Vol 15 (3) ◽  
pp. 395-402
Author(s):  
Nizamettin Demirkıran ◽  
◽  
G. Deniz Turhan Özdemir ◽  
Keyword(s):  
Sulfuric Acid ◽  
Dissolution Rate ◽  
Copper Powder ◽  
Dissolution Kinetics ◽  
Reaction Model ◽  
Ion Concentration ◽  
Acid Solutions ◽  
Cupric Ion ◽  
Sulfuric Acid Solutions ◽  
Kinetics Of

In this paper, the dissolution kinetics of cement copper powder in sulfuric acid solutions containing cupric ions was examined. It was observed that the dissolution rate of copper increased with increasing the acid concentration, temperature, and stirring speed. It was determined that the dissolution rate of copper enhanced with increasing the cupric ion concentration up to 0.025 M. It was found that the temperature and concentration of cupric ion had more considerable effects on the dissolution of copper powder. The kinetic analysis of the process was performed, and it was observed that it fits the first order pseudo-homogenous reaction model. The activation energy was calculated to be 31.1 kJ/mol.

scholarly journals Kinetics of proton transfer in the zeolitic tuff

2009 ◽  
Vol 7 (3) ◽  
pp. 508-511
Author(s):  
Fehime Çakıcıoğlu-Özkan ◽  
İlker Polatoğlu
Keyword(s):  
Particle Size ◽  
Proton Transfer ◽  
Size Fraction ◽  
Proton Transfer Reaction ◽  
Reaction Model ◽  
Zeolitic Tuff ◽  
Particle Size Fractions ◽  
Model Equations ◽  
Kinetics Of ◽  
And Diffusion

AbstractThe kinetics of a proton transfer into dilute acid solutions containing natural zeolitic tuff was studied by following the pH evolution of the liquid phase. Four different solutions with tuff contents of 9, 3, 1 and 0.5 (% wt) and three different particle size fractions (≤ 2000 μm) were studied. The proton concentration of the solution was decreased by increasing the zeolite amount and decreasing the particle size fraction. The proton transfer reaction was analyzed with chemical reactions and diffusion model equations. Analysis shows that the adsorption and/or ion exchange are possible mechanisms and are expressed by a second order reaction model.

Dissolution kinetics of colemanite in HCl solutions by measuring particle size distributions

2017 ◽  
Vol 53 (1) ◽  
pp. 198-205 ◽  
Author(s):  
Hikmet Sis ◽  
Ismail Bentli ◽  
Nizamettin Demirkiran ◽  
Ahmet Ekmekyapar
Keyword(s):  
Particle Size ◽  
Dissolution Kinetics ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Kinetics Of

Experimental Investigation of the SO2 Abatement Capacity of South African Calcium-Based Materials

2007 ◽  
Author(s):  
Zachary O. Siagi ◽  
Makame Mbarawa
Keyword(s):  
Particle Size ◽  
Dissolution Rate ◽  
South African ◽  
Efficient Operation ◽  
Shrinking Core ◽  
Caco3 Particle ◽  
Ph Stat ◽  
Kinetics Of ◽  
Different Sources ◽  
So2 Absorption

One of the most important steps in the wet limestone-gypsum flue gas desulphurization (WFGD) process is CaCO3 dissolution, which provides the dissolved alkalinity necessary for SO2 absorption. Accurately evaluating the CaCO3 dissolution rate is important in the design and efficient operation of WFGD plants. In the present work, the dissolution of limestone from different sources in South Africa has been studied in a pH-stat apparatus under conditions similar to those encountered in wet FGD processes. The influence of various parameters such as the reaction temperature (30 ≤ T ≤ 70°C), CaCO3 particle size (25 ≤ dp ≤ 63μm), solution acidity (4 ≤ pH ≤ 6), and chemical composition were studied in order to determine the kinetics of CaCO3 dissolution. The results obtained indicate that the dissolution rate increased with a decrease in particle size and an increase in temperature. The dissolution curves were evaluated in order to test the shrinking core model for fluid–solid systems. The analysis indicated that the dissolution of CaCO3 was controlled by chemical reaction, i.e. 1 − (1 − X)1/3 = kt.

Quantification Of Pyrrhotiye O2 Consumption By Using Pyrite Oxidation Kinetic Data

2014 ◽  
Vol 1665 ◽  
pp. 93-101
Author(s):  
I. Rojo ◽  
F. Clarens ◽  
J. de Pablo ◽  
C Domènech ◽  
L. Duro ◽  
...  
Keyword(s):  
Experimental Data ◽  
Pyrite Oxidation ◽  
Oxidation Kinetic ◽  
Dissolution Kinetics ◽  
Buffering Capacity ◽  
Uptake Capacity ◽  
Kinetic Rate ◽  
Oxidation Rates ◽  
Redox Pair ◽  
Kinetics Of

ABSTRACTExperiments on the dissolution kinetics of natural pyrrhotite (FeS1-x-) and pyrite (FeS2) under imposed redox conditions to evaluate the oxygen uptake capacity of both minerals were carried out at 25°C and 1 bar. Experimental data indicate that in both cases, Fe(II) released from dissolution of these Fe-bearing sulphides is kinetically oxidized to Fe(III) to precipitate as Fe(III)-oxyhydroxides. While the system is pH controlled by the extent of the sulphide oxidation, Eh is controlled by the redox pair Fe2+/Fe(III)-oxyhydroxides. Pyrrhotite dissolution is faster than that of pyrite but generates less acidity. Consequently, the achieved redox value is more reducing. Experimental data show that the oxidation rates of both minerals (in mol·g-1·s-1) are equivalent under the studied conditions. This fact gives a new opportunity to quantify the reductive buffering capacity of pyrrhotite, for which no kinetic rate law has been still established.

scholarly journals Treatment of black copper with the use of iron scrap - part I

2020 ◽  
Vol 74 (4) ◽  
pp. 237-245
Author(s):  
Norman Toro ◽  
Kevin Pérez ◽  
Manuel Saldaña ◽  
Eleazar Salinas-Rodríguez ◽  
Pía Hernández
Keyword(s):  
Particle Size ◽  
Dissolution Rate ◽  
Acidic Medium ◽  
Mineral Resources ◽  
Reducing Agent ◽  
Iron Scrap ◽  
Effect Of Particle Size ◽  
High Concentrations ◽  
Kinetics Of Dissolution ◽  
Kinetics Of

Currently, there is a large amount of mineral resources not being exploited in large copper minings, a clear example are black copper minerals. These resources are generally not incorpo-rated into the extraction circuits or are not treated, either in stocks, leach pads, or debris. These exotic minerals have considerable amounts of Cu and Mn, which are commercially very attractive. They are refractory to conventional leaching processes, therefore, the use of reducing agents is necessary for treatment of these minerals in order to dissolve the present MnO2, which in turn allows Cu extraction. In this research, iron scrap Fe0 was used as a reducing agent for the dissolution of Mn from a black copper mineral in an acidic medium and compared to previous studies of the use of Fe2+ under the same conditions. In addition, the effects of a pretreatment process (agglomeration and curing) by adding NaCl are investigated in order to favor the reduction of MnO2. Finally, it was discovered that there is a higher kinetics of dissolution of Mn when working with Fe0 in short periods of time, although similar extraction efficiencies are obtained after prolonged times. The pretreatment process by adding NaCl resulted in increased Mn extraction in short periods of time (30 min). At applying high concentrations of the reducing agent, the effect of particle size on the dissolution rate of MnO2 was shown to be insignificant.

scholarly journals Effect of Ethyl Acetate, Time and Particle Size on the Kinetics of the Oleoresin Extraction Process

2020 ◽  
Vol 7 (2) ◽  
pp. F15-F23
Author(s):  
M. S. Olakunle ◽  
A. O. Ameh ◽  
T. Oyegoke ◽  
H. U. Shehu
Keyword(s):  
Experimental Data ◽  
Particle Size ◽  
Kinetic Model ◽  
Ethyl Acetate ◽  
Extraction Process ◽  
Single Step ◽  
Particle Sizes ◽  
Order Model ◽  
First Order ◽  
Kinetics Of

The kinetics of the extraction of oleoresin from ginger using ethyl acetate as the solvent was studied in this work. The effects of particle size and extraction time on oleoresin’s solvent extraction were studied to obtain optimization data. The temperature of the process was kept constant at 40 °C. The Ginger particle sizes considered ranged between 1200-250 microns at extraction times ranging between 10–70 minutes. Experimental data generated were fitted into an empirical model to determine the kinetic parameters. The oleoresin yield increases with increasing extraction time up to an optimum time, after which the yield remains constant and yield also increases with decreasing particle size. The results obtained from the kinetics studies revealed that the introduction of the constant term accounting for the diffusion step separately (as an addition) into a single step first-order model (Patricelli’s first order model) raises the R-squared values from 87 % fitness of the model into becoming 99 % with the experimental data. This improved form of Patricelli’s first-order model was found to show a good agreement with Patricelli’s 2-step kinetic model. These findings confirmed that the oleoresin extraction process in the presence of ethyl acetate was found to be first-order kinetics involving two steps mechanism where the use of a single-step first-order model (Patricelli’s first-order kinetic model) and the choice of using ethyl acetate must have contributed to the strong resistance present in the first step of the extraction mechanism especially for the smaller particle size (250 microns). In getting the extraction yield improved, this study, therefore, recommends the use of small particle sizes (< 250 microns), higher temperatures (> 40 °C), and/or better alternative solvents like ethanol. Keywords: ethyl acetate, extraction, oleoresin, modeling.

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