Kinetics of the non-isothermal reduction of Nb2O5 with aluminium

Abstract

The present paper presents the results of a thermoanalytical investigation on the kinetics of the aluminothermic reduction of Nb2O5 under non-isothermal conditions. Simultaneous differential thermal analysis (DTA) and thermogravimetry (TG) technique were used. It was determined the minimum molar ratio Nb2O5:Al for the completion of the reaction and the value of the change of enthalpy associated to the reduction. X-Ray diffraction was used in order to identify the products of reduction. Since the oxidation of aluminium and the reduction of Nb2O5 occur simultaneously, it was possible to study the kinetics by analysing the rate of generation of the peak area for the Nb2O5 reduction (DTA) and the mass gain due to the oxidation of some of the excess of aluminium (TG). The reduction was controlled by first order chemical reaction and the reduction was isokinetic within the experimental conditions of the present work. © 2005 ISIJ.