[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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However, since it is a common phenomenon in the decomposition of this type of compounds, the induction period has not mtalurgia eliminated in this research work, and its dependence on OH – concentration, temperature and particle size have been determined.

However, these models were deduced by considering the constant increases in the reaction interface, which in this case did not happen. R; Handbook of Chemistry and Metaljrgia89 th ed. Barcelona,chapter Besides, in both media, t ind is independent from the particle size Figure 9which confirms that the activation process is a phenomenon occurring at levels of molecular thickness, involving only the initial surface.

Policy10 Leandro Carrizo secretario general. 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 According to the previously stated, several experiments were carried out in order to observe the evolution of the solids at different conversion values.

A plot of the rate experimental constants determined at constant temperature and concentration vs. In any case, this could be a period where active sites are created until a reaction front is established.

The density measurement yielded a value of proesos. For [OH – ] concentrations below 3. It is important to note that, during the alkaline decomposition process, arsenic was cineticaa detected in the samples analyzed by AAS and ICP. Figure 10 shows the particle size effect on the decomposition rate of the arsenical natrojarosite.


Dependence of the conversion period. Samuel Navarrete Cifuentes The relatively high activation energy values indicate that the arsenical natrojarosite is stable under the studied conditions.

The resulting chemical composition 4.

Cinética de los procesos de la metalurgia extractiva – Google Books

The kinetic data are consistent with the chemical control of the process. The study provides the kinetics and nature of the decomposition reaction topology, reaction rates and dependence of the reaction on variables such as medium concentration, temperature and particle size. According to the previous descriptions, it can be noted that the alkaline decomposition starts with an induction period t indduring which the external appearance color, morphology etc.

Boston,chapter 8.

Therefore, in this case, the rate constants are inversely proportional to the square of the initial diameter d 0. The OH – concentration was calculated on the base of lis pH of the solution, and the ionic constant of the water was calculated on the base of the working temperature.

The decomposition curves show an induction period, followed by a conversion period. 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. How to cite this article. Furthermore, there are semi-empirical expressions to describe the autocatalytic kinetic processes, 17 as well as processes related to nucleation and growth.

This is consistent with the spherical particle model with decreasing core and chemical control equation 2.

The objective of this article is to present a detailed kinetic study on the alkaline reactivity in NaOH and CaO media of the sodium jarosite with arsenic in order to provide information regarding the stability of these compounds procrsos these kind of media, because, as previously mentioned, jarosites are very stable in acidic media.


Decomposition curves 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.

The experiment for the alkaline decomposition was carried out in a conventional thermostated glass kettle with magnetic stirring.

Sergio Pinedo Fuenzalida The values of the induction times t ind were obtained from the intersections of the regression straight line with the time axis. The alkaline decomposition of the arsenical natrojarosite is characterized proceos the removal of sulfate and sodium ions from the lattice and their diffusion to the solution, while a gel of iron dde with adsorbed arsenate is formed.

During the induction period, there are no morphological changes or formation of any detectable solid layer at practical resolution levels of the EDS technique ca. Arsenic incorporated in the structure could influence the solubility of jarosite, potentially stabilizing the structure under a wide range of conditions that are tolerated by the pure jarosite.

The values of the rate experimental constants K exp were obtained by linear regression of equation 2. This occurs when the concentrations of sulfates and sodium are stabilized, indicating that the reaction has finished. SEM analysis indicated the formation of a reaction front.

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. The solids were analyzed by EDS during this period.

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Juan Pablo Squella presidente. Activity coefficients of NaClO4 in aqueous solution. Valentina Alliende vice presidenta. Manuel Soto vice presidente.