Kinetics of aluminothermic reduction of Cr2O3 - A thermoanalytical investigation

Abstract

Aluminothermic reduction of metal oxides is an established industrial process. However this reaction often requires skill because there are some procedural technique which the operator is required to know. Essentially, the reaction requires an initial input of heat which is obtained through an external reaction and/or oxidation of aluminium. As aluminothermic reduction of Cr2O3 is a simultaneous process of reduction of metal oxide and oxidation of excess aluminium; determination of reduction kinetics separately is difficult. The aim of the present work is to describe the kinetics of reduction of Cr2O3 during aluminothermic reductions, using the simultaneous DTA/TG technique. Taking the 2 reactions to occur simultaneously, it is possible to study the overall kinetics by analysing the single DTA peak obtained during heating of Cr-2 O-3-Al mixture. However, if one understands the aluminium oxidation reaction, then kinetics for the reduction of Cr2O3 alone can be obtained from the DTA data for the overall reaction. A theoretical DTA curve is generated from the TG data using a suitable calibration procedure to describe oxidation of aluminium. The oxidation data were compared with the experimental overall DTA data on reduction. The rate of generation of the peak area for Cr2O3 reduction thus obtained was a measure of the reaction rate.