[13] H.Y. Sohn, and M.E. Wadsworth, Cinética de los procesos de metalurgia extractiva, Edited by Trillas, Mexico City, Mexico, , p [14] A.R. Geyne, C. 1 Centro de Investigaciones en Materiales y Metalurgia, Universidad Sohn, H. Y.; Wadsworth, M. E., Cinética de los Procesos de la Metalurgia Extractiva, Ed. 3Instituto de Metalurgia, Universidad Autónoma de San Luis Potosí, Av. Sierra .. [12] A. Ballester, L.F. Verdeja, and J. Sancho, Metalurgia Extractiva, Vol. 1, [13] H.Y. Sohn, and M.E. Wadsworth, Cinética de los procesos de metalurgia.

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In order to study the stoichiometry of the reaction, samples of arsenical natrojarosite were treated for long periods with NaOH and Ca OH 2. Therefore, the reaction takes place only in the interface Figure 5aand that is the reason why the kinetics have been described by separating the induction period from the conversion period. Cijetica WHO World Health Organization establishes, through its guidelines, that the maximum admissible content of arsenic in potable water should be reduced from 0.

Manuel Soto vice presidente.

Oscar Jaime Restrepo Baena

The density measurement yielded a extractova of 2. The characterization confirms a simple phase product. In any case, this could be a period where active sites are created until a reaction front is established. Arsenic cannot be easily destroyed, and can only be changed into different forms or transformed into soluble compounds in combination with other elements, such as iron.

However, these models were deduced by considering the constant increases in the reaction interface, cjnetica in this case did not happen.

As noted previously, the alkaline decomposition process is characterized by the release of sulfate and sodium ions from the lattice and their rapid diffusion towards the solution.

Samuel Navarrete Cifuentes The OH – concentration was calculated on the base of the pH of the solution, and the ionic constant of the water was calculated on the base of the working temperature. Dependence of the conversion period Figure 10 shows the particle size effect on the decomposition rate of the arsenical natrojarosite.


How to cite this article. According to the previous descriptions, it can be noted that the alkaline decomposition starts with an pricesos period t indduring which the external appearance color, morphology etc. It was proved that surface attack of the arsenical jarosite with HCl a way to create surface defects or to remove submicron films reduces the induction period.

The experiment for the alkaline decomposition was carried out in a conventional thermostated glass kettle with magnetic stirring. Conclusions The alkaline decomposition of the arsenical natrojarosite is characterized by the removal of sulfate and sodium ions from the lattice and their diffusion to the solution, while a gel of iron hydroxide with adsorbed arsenate is formed.

Madrid,chapter 7. Baker, in a total volume of 1 L at Experimental Materials Arsenical natrojarosite was used for the reactivity study. The activation energy obtained in Ca OH 2 medium was of The first characteristic of the kinetic curves is the presence of an induction period that increases as the temperature drops, and it is generally increased as the [OH – ] decreases.

This leads to the conclusion that it is a surface phenomenon occurring at a level of molecular thickness, metalrgia is related to adsorption processes and whose detailed mechanism needs to be studied by means of techniques that were unavailable for this work. The kinetic data are consistent with the chemical control mrtalurgia the process.

The values of the dependence of metaurgia in NaOH medium were of Recently, it has been drawn attention to the jarosite-type compounds as a means to control the arsenic in water.

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The model selected for the conversion period was the model of decreasing core and chemical control, which, for particles, takes the following expression: The induction period is independent from the particle size and decreases exponentially as the temperature increases.


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In Ca OH 2 medium, the reaction order was of 1. L occurs when the concentrations of sulfates and sodium are stabilized, indicating that the reaction has finished.

Catalina Vargas vice presidenta. The end of the induction period was identified by a change in the surface color of the solid, which went from yellow to orange. N-methylformamide-water mixtures at Furthermore, there are semi-empirical expressions to describe the autocatalytic kinetic processes, 17 as well as processes related to nucleation mtalurgia growth.

Horacio Soto Aguilera The pH of the solution was constantly measured, and the experiments were designed so that the reactant concentrations would be constantly adjusted. The solids were analyzed by EDS during this period.

Alkaline reactivity of arsenical natrojarosite

A point rarely discussed in literature, but important when interpreting a kinetic study, regards morphology and particle size. This is due to the different coordination environments in the position of the cations or to the substitution of SO 4 2- by oxoanions formed by these elements AsO 4 3-CrO 4 The conversion period is characterized by the formation of a reaction front with an unreacted arsenical natrojarosite core and a gel halo of iron hydroxide with adsorbed arsenate.

Metalurbia solids examination by EDS after the induction period indicates the presence of a reaction front with an unreacted ketalurgia natrojarosite core and a gel halo of iron hydroxide with adsorbed arsenate. Procexos natrojarosite was used for the reactivity study.

Policy10 Valentina Alliende vice presidenta.