H.Y. Sohn, and M.E. Wadsworth, Cinética de los procesos de metalurgia extractiva, Edited by Trillas, Mexico City, Mexico, , p  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 ..  A. Ballester, L.F. Verdeja, and J. Sancho, Metalurgia Extractiva, Vol. 1,  H.Y. Sohn, and M.E. Wadsworth, Cinética de los procesos de metalurgia.
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R; Handbook of Chemistry and Physics89 th ed. This occurs when the concentrations of sulfates and sodium are stabilized, indicating that the reaction has finished. In spite of these differences, the temperature effect was cibetica in both media. There are no morphological changes or formation of any detectable solid layer at practical resolution levels of the EDS technique ca.
The values of the dependence of energy in NaOH medium were of According to the previously stated, the stoichiometry of the process can be expressed according to the following reaction: The data are consistent with the model Figure 6. Carlos Carlesi Jara Jefe de Docencia. Patricio Proust Crovetto In order to study the stoichiometry of the reaction, samples of arsenical natrojarosite were treated for long periods with NaOH and Ca OH 2.
Experimental procedure The experiment for the alkaline decomposition was carried out in a meyalurgia thermostated glass kettle with magnetic stirring. Recently, it has been drawn attention to the jarosite-type compounds as a means to control the arsenic in water.
Boston,chapter 8. 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 – ] provesos. Policy10 As a consequence, Germany reduced its limit to 0. Juan Pablo Squella presidente.
Experimental Materials Arsenical natrojarosite was used for the reactivity study. Alkaline reactivity is characterized by the removal of sulfate and sodium ions from the lattice and by the formation of a gel consisting of iron hydroxides with adsorbed arsenate.
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. 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.
For [OH – ] concentrations below 2. Dependence of the conversion period.
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The characterization confirms a simple phase product. The results of the evolution of the reacted fraction of sulfates and sodium during decomposition are shown in Figure 3. This is consistent with the spherical particle model with decreasing core and chemical control equation 2.
For [OH – ] concentrations below 3. The activation energy for the decomposition process in NaOH medium was of 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.
However, these models were deduced by considering the constant increases in the reaction interface, which in this case did not happen.
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The kinetic expression of the decomposition of the arsenical natrojarosite in Ca OH 2 medium for [OH – ] concentrations ranging from 2. Dependence of the conversion period Figure 10 shows the particle size effect on the decomposition rate of the arsenical natrojarosite. N-methylformamide-water mixtures at The activation energy values are within the limits of chemical control. In Ca OH 2 medium, the reaction order was of 1.
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Several impurities, like lead, iron and selenium, are often mixed with the arsenic wastes, becoming more difficult the removal. Arsenical natrojarosite was used for the reactivity study. Millions of people who have been exposed to high concentrations of arsenic through potable water have developed serious health problems.
At higher OH – concentrations, t ind became independent from that value. The experiment for the alkaline decomposition was carried out in a conventional thermostated glass kettle with magnetic stirring.
Activity coefficients of NaClO4 in aqueous solution. The pH of the solution was constantly measured, and the experiments were designed so that the reactant concentrations would be constantly cinetifa. 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. The induction period is independent from the particle extrachiva and decreases exponentially as the temperature increases.
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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. Madrid,chapter 7.
The concentration of sulfates and sodium progressively increases, while simultaneously, the reflection intensities of ,os arsenical natrojarosite decrease until disappearing. The decomposition of the arsenical natrojarosite presents an induction period and a conversion period.