Aplicación de técnicas cinéticas no isotérmicas en la reducción de tres minerales de hierro de grado comercial

Abstract

The mechanism of reduction of iron ore agglomerates by both isothermal and nonisothermal TG studies was investigated, and the work was complemented with the structural characterization of the total and partially reacted samples. Three different commercial hematite pellets were studied. The mechanisms of reduction were obtained under isothermal conditions, resulting in a fitting to chemical reaction models. Nonisothermal reduction was carried out using a TGA system (CAHN TG-171) from 600 to 1,000 °C maintaining a lineal heating rate of 4, 7 and 10 °C/min, and the reducing atmospheres used were H2 (100 %) and H2-CO (95:5). The kinetic parameters were evaluated by Coats & Redfern, Dixit & Ray and Prakash & Ray techniques. It was found that the lower the heating rate, the higher the reduction degree and the higher activation energy. The activation energy for reduction with the mixture H2-CO was always higher than that obtained with pure H2.