Decomposition and Cyanidation Kinetics o

In this work, the synthesis, characterization, reactivity in NaOH media and the cyanidation of the ammonium jarosite are approached. The jarosite was synthesized and characterized by several analytical techniques; the granulometric analysis was also performed. The synthesis results show that the material consists of a solid ammonium-hydronium jarosite-argentojarosite solution of an approximate [(NH4(0.95) Ag0.025 H30 0.025)Fe2.66(SO4)2(OH)6] formula. This jarositic compounds synthesis, along with the mechanical agitation system with seed recycling, has a notable effect on the spheriodization degree and on the particles growth degree, reaching the highest particle sizes of the 44-37μm (> 61% ) kind. The decomposition and cyanidation curves show an induction period, a progressive conversion period and a stabilization zone. The SEM-EDS analysis shows an unreacting jarosite core in the progressive conversion period, as well as a gel layer, through which the sulphate ions easily diffuse towards the solution. The alkaline decomposition and the ammonium jarosite cyanidation is a process of two serial stages: a slow alkaline decomposition stage followed by an instant silver complexation stage.