SYNTHESIS, CHARACTERIZATION AND NATURE OF THE ALKALINE REACTION OF THALLIUM JAROSITE.

Abstract

In the hydrometallurgical process of Cinc, the precipitation of jarosite particles is employed as means of the elimination of iron, sulfate and alkaline metals such as thallium. Jarosites are considered a potentially hazardous industrial waste that can be easily filtered and accumulated in outdoors, which causes their decomposition by atmospheric agents and the liberation of toxic metals contained in the structure, including thallium, an element that is highly toxic to humans. This study comprises the synthesis and characterization of the thallium jarosite (SEM-EDS, XRD, ICP, gravimetry, etc.). With the results was possible to determine the chemical formulae of the compound: [Tl0.86(H3O)0.14]Fe3.11(SO4)2.11(OH)6.11(H2O)0.44]. The particles showed a semispherical geometry with an average size from 38-44 µm. The study of the nature of the decomposition of thallium jarosite was carried out in alkaline medium (NaOH). With the obtained results it was possible to elaborate a S type curve for the SO42- and Tl+ ions that were liberated throughout the entire decomposition process. The obtained experimental points fits to the model of decreasing core for spherical particles of constant size, where the chemical reaction controls the whole of the decomposition process. Moreover we studied the partial decomposed solids using SEM-EDS, where it was possible to observe an unreacted core, a reaction front and a layer of ashes. The products of total decomposition correspond to an amorphous compound according to XRD results.