Kinetics of the Non-isothermal Reduction of Cr2O3 with Aluminium

Abstract

The present paper presents the results of a thermoanalytical investigation on the kinetics of the aluminothermic reduction of Cr 2 O 3 under non-isothermal conditions. Simultaneous differential thermal analysis (DTA) and thermogravimetry (TG) technique were used. It was determined the minimum molar ratio Cr 2 O 3 : 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 Cr 2 O 3 occur simultaneously, it was possible to study the kinetics by analysing the rate of generation of the peak area for the Cr 2 O 3 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.

Mechanical–thermal synthesis of chromium carbides

“…At about 800 • C, a large exothermic peak related to the reduction of Cr 2 O 3 by liquid Al, plus the oxidation of excess of aluminium is noticed. The curve presents the same shape as notice before [10,11]. Fig.…”

Reduction of chromium oxides in stainless steel dust

“…Extensive research has been conducted on the reduction of pure Cr 2 O 3 or Cr 2 O 3 in a complicated system using C [2][3], FeSi [4], Al [4][5], Fe-C melt [6], or Fe-C-Si melt [7]. Most studies have focused on the reduction mechanism of Cr 2 O 3 and have kinetically promoted the recovery of Cr.…”

Study of the aluminothermic reduction of niobium pentoxide through thermal analysis experiments and high energy milling processing

“…The aluminothermic reduction of Cr 2 O 3 4 , Fe 2 O 3 5,6 , MnO 2 6,7 and V 2 O 5 7 , have been studied using the simultaneous differential thermal analysis (DTA) -thermogravimetry (TG) techniques. In a DTA apparatus the heat losses cannot be accurately predicted, therefore it is impossible to estimate precisely the maximum temperature attainable by aluminothermic reacting mixtures in a DTA set-up.…”

“…In a DTA apparatus the heat losses cannot be accurately predicted, therefore it is impossible to estimate precisely the maximum temperature attainable by aluminothermic reacting mixtures in a DTA set-up. Therefore an excess of aluminium has been used in order to use the excess enthalpy [4][5][6][7] .…”