[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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Manuel Soto vice presidente. The relatively high activation energy values indicate that the arsenical natrojarosite is stable under the studied conditions. The WHO World Health Organization establishes, through its guidelines, that the maximum admissible content of arsenic in potable water should be reduced from 0.

Furthermore, there are semi-empirical expressions to describe the autocatalytic kinetic processes, 17 as well as processes related to nucleation and growth. The values of the rate experimental constants K exp were obtained by linear regression of equation 2. The solid residues are amorphous, and do not evolve into crystal phases under the conditions of alkaline decomposition herein studied as observed in Figure meetalurgia.

Several impurities, like lead, iron and selenium, are often mixed with the arsenic wastes, becoming more difficult the removal. The resulting chemical composition 4.

Oscar Jaime Restrepo Baena

The kinetic data are consistent with the chemical control of the process. It is important to note that, during the alkaline decomposition process, arsenic was not detected in the samples analyzed by AAS and ICP. Treatment technologies are available and most of them have been developed for the removal of arsenic at an industrial scale in water treatment plants.


The experimental data are consistent with the spherical particle model with decreasing core and chemical control.

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.

This kind of dependence is related to the chemical control; therefore, it is incompatible metalrgia the control by diffusion of reactants through the layer of the product.

Alkaline reactivity of arsenical natrojarosite

Acta70 This leads to the conclusion that it is a surface phenomenon occurring at a level of molecular thickness, which is related to adsorption processes and whose detailed mechanism needs to be studied by means of techniques that were unavailable for this work. How to cite this article. Leandro Carrizo secretario general.

Madrid,chapter 7. Millions of people who have been exposed to high concentrations of arsenic through potable water have developed serious extractiiva problems. Modeling of liquid-liquid equilibrium for binary and ternary systems containing ionic liquids with the hexafluorophosphate anion using the ASOG method. The values of the dependence of energy in NaOH medium were of The decomposition curves show an induction period, followed by a conversion period.

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Dependence of the conversion period. The density measurement yielded a value of 2. Arsenic integrated in the structure could influence the solubility of the jarosite, potentially stabilizing the structure under a wide range of conditions that are tolerated by pure jarosite. In Ca OH 2 medium, a similar procedure was applied: Baker, in a total volume of 1 L at The conversion period is characterized by the formation of a hydroxide halo around an unreacted arsenical natrojarosite core.

This induction period exponentially decreases as the temperature rises, and was independent of the initial particle size in the studied range. The activation energy values are within the limits of chemical control. The pH of the solution was constantly measured, and the experiments were designed so that the reactant concentrations would be constantly adjusted. A plot of the rate experimental constants determined at constant temperature and concentration vs.


Rate experimental constant values corrected by the size factor are shown in Table ds. Jorge Coloma Apoyo Laboratorios. The conversion period is characterized by the formation of a reaction front with an unreacted arsenical natrojarosite core pgocesos a gel halo of iron hydroxide with adsorbed arsenate.

But if the arsenic is present as a separate phase, like scorodite or a similar phase, its chemical behavior will be different from that of the jarosite, and the dissolution of the arsenic will be able to occur under acidic conditions, which are common in the jarosite deposits.

A point cinetiac discussed procesox literature, but important when interpreting a kinetic study, regards morphology and particle size. Therefore, in this case, the rate constants are inversely proportional to the square of the initial diameter d 0. It seems that the arsenic contained in the natrojarosite structure studied in this work does not have a significant influence on the reaction rate compared to a natrojarosite without arsenic. The induction period is independent from the particle size and decreases exponentially as the temperature increases.

Carlos Carlesi Jara Jefe de Docencia.

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