[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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Alkaline reactivity of arsenical natrojarosite

Thomas Acevedo Departamento de deportes. Horacio Aros Meneses The end of the induction period was identified by a change in the surface color of the solid, which went from yellow to orange.

The resulting chemical composition 4. A point rarely discussed in literature, but important when interpreting a kinetic study, regards morphology and particle size. According to the previously stated, the stoichiometry of the process can be expressed according to the following reaction: Dependence of the induction period.

Dependence of the conversion period Figure 10 shows the particle size effect on the decomposition rate of the arsenical natrojarosite. In Ca OH 2 medium, the reaction order was of 1. 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.

The data are consistent with the model Figure 6. For these analyses, standards with an identical matrix were used. Jorge Coloma Apoyo Laboratorios. Catalina Vargas vice presidenta. The solids examination by EDS after the induction period indicates the presence of a reaction front with an unreacted arsenical natrojarosite core and a gel halo of iron hydroxide with adsorbed arsenate. 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.


Introduction The arsenic pollution of water is considered a problem of catastrophic proportions. Policy10 Teddy Gentina Soto The values of the rate experimental constants K exp ls obtained by linear regression of equation 2. The kinetic expression of the arsenical natrojarosite decomposition in NaOH medium for [OH – ] concentrations ranging from 3. The activation fe for the decomposition process in NaOH medium was of 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 in these kind of media, metaluriga, as previously mentioned, jarosites are very stable in acidic media.

The decomposition curves show an induction period, followed by a conversion period. There are no morphological changes or formation of any detectable solid layer at practical resolution levels of the EDS technique ca.

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In spite of these differences, the temperature effect was exponential in both media. Juan Pablo Squella presidente.

Temperature effect indicates an activation energy of 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. Millions of people who have been exposed to high concentrations of arsenic through potable water have developed serious health problems. The arsenic pollution of water is considered a problem of catastrophic proportions.

According to cihetica previous descriptions, it can be noted that the alkaline decomposition starts with an induction period t indduring which the cineticw appearance color, morphology etc. Arsenical natrojarosite was used for the reactivity study. Alkaline reactivity of arsenical natrojarosite. This is consistent with the spherical particle model with decreasing core and chemical control equation 2. 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.


The activation energy values are within the limits of chemical control.

Rate experimental constant values corrected by the size factor are shown in Table 1. There are few works on the dissolution and stability of such compounds, making the data insufficient for evaluating the real environmental risk caused by the improper disposal of the generated precipitates.

Thus, the use of innovative techniques for the elimination of arsenic is an important subject.

Several impurities, like lead, iron and selenium, are often mixed with the arsenic wastes, becoming more difficult the removal.

Figure 10 shows the particle size effect on the decomposition rate of the arsenical natrojarosite. Experimental procedure The experiment for the alkaline decomposition was carried out in metalurggia conventional thermostated glass kettle with magnetic stirring.

Kinetic Modeling of the Alkaline Decomposition and Cyanidation of Argentojarosite

Acta70 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 In addition, these results rule out the control by transport through the layer of the product.

SEM analysis indicated dw formation of a reaction front.

The concentration of sulfates and sodium progressively increases, while simultaneously, the reflection intensities of the arsenical natrojarosite decrease until disappearing. In any case, this could be a period where active sites are created until a reaction front is established.