Estudo da influência dos ânodos recicláveis cozidos nas propriedades físicas, mecânicas e químicas, dos ânodos de carbono usados nas células electrolíticas de extracção do alumínio: caso de estudo Mozal

Abstract

The present study of the influence of recyclable anodes on physical properties, chemical and mechanical characteristics of carbon anodes used in electrolytic cells extraction of aluminum from MOZAL, had the following specific objectives: evaluation of the effect of recyclable anodes in the density of the new ones, correlation of the properties of the new ones anodes with recyclable ones and evaluation of the chemical composition of recyclable anodes in the quality of the new ones. To meet the specific objectives, they were produced in the pulp factory of Mozal, four groups of anodes, with 21, 23, 25 and 27 percent recyclable anodes in anode recipe. The physical, mechanical and chemical properties obtained by the laboratory from the factory after baking the anodes were correlated with the formulations of the anodes with the help of the Excel and MiniTab tools, obtaining the respective polynomial models. A total of 2200 anodes were produced and evaluated for the density and 90 samples taken from these anodes to evaluate the other physical, mechanical and chemical properties. The anodes, in general, presented low air permeability, low reactivity to air and CO2, high mechanical resistance, as the number of anodes was increased recyclable, which can help evaluate anode performance and contribute to greater operational stability of electrolytic cells and, consequently, greater productivity. For a 2% increase in the fraction of recycled anodes, the density of the anode registered a variation of 0.0223 g/cm3, with a loss of mass during 0.0142 g/cm3 anode baking. It was also observed that vanadium impurities, sodium, calcium and iron present in the analyzed samples, negatively influence the reactivity to air and carbon dioxide (TRADUÇÃO NOSSA).