Non-Isothermal Reduction Kinetics of Iron Ore Fines with Carbon-Bearing Materials

Abstract

This study investigates the non-isothermal reduction of iron ore fines with two different carbon-bearing materials using the thermogravimetric technique. The iron ore fines/carbon composites were heated from room temperature up to 1100 °C with different heating rates (5, 10, 15, and 20 °C/min) under an argon atmosphere. The effect of heating rates and carbon sources on the reduction rate was intensively investigated. Reflected light and scanning electron microscopes were used to examine the morphological structure of the reduced composite. The results showed that the heating rates affected the reduction extent and the reduction rate. Under the same heating rate, the rates of reduction were relatively higher by using charcoal than coal. The reduction behavior of iron ore-coal was proceeded step wisely as follows: Fe2O3 → Fe3O4 → FeO → Fe. The reduction of iron ore/charcoal was proceeded from Fe2O3 to FeO and finally from FeO to metallic iron. The reduction kinetics was deduced by applying two different methods (model-free and model-fitting). The calculated activation energies of Fe2O3/charcoal and of Fe2O3/coal are 40.50–190.12 kJ/mole and 55.02–220.12 kJ/mole, respectively. These indicated that the reduction is controlled by gas diffusion at the initial stages and by nucleation reaction at the final stages.

A Study of the Structure and Physicochemical Properties of the Mixed Basicity Iron Ore Sinter

“…The peculiarity of the medium basicity sinter is that despite its high mechanical strength, it tends to collapse in the upper part of the blast furnace shaft. It has been found that the decisive factor in this destruction is the reduction process: the maximum destruction is observed at a reduction rate of 25-40%, that is, at the stage of reduction Fe 2 O 3 →Fe 3 O 4 (which corresponds to temperatures of 500-700 • C, at higher temperatures, the softening slows down, and at temperatures above 900 • C, the strength even increases) [38]. Material destruction during reduction by carbon monoxide occurs more strongly than during reduction by hydrogen [39].…”

Recent Trends in the Technologies of the Direct Reduction and Smelting Process of Iron Ore/Iron Oxide in the Extraction of Iron and Steelmaking

“…There are two different types of composites were prepared which are made of iron ore fines and charcoal, respectively. Magnetite reduction with coal was discovered to be lean, resulting in poorer metallization; yet, the concentrate's increased iron-oxide content and also increases the iron extraction in terms of performance as compared to charcoal [69]. Regardless of thermal conditions, iron ore is reduced under the same heating rate, and coal has a lower reduction rate compared to charcoal.…”

Comparative Study on the Isothermal Reduction Kinetics of Iron Oxide Pellet Fines with Carbon-Bearing Materials

“…Iron oxide pellet fines utilized in this research were obtained from the transportation and handling of iron oxide pellets in the DR plant (Al-Ezz El-Dekheila steel Company, Alexandria, Egypt). The chemical composition, mean particle size, and main phases of iron oxide pellet fines are illustrated elsewhere [36].…”

“…During the second step, the reduction process is dominated by the chemical reaction, whereas the coupled solid-state diffusion and boundary reaction control the final stage. The reduction of iron ore fines with different carbon sources was investigated non-isothermally using different heating rates by Hammam et al [36]. It was concluded that the heating rates have a significant influence on the conversion degree and the rate of reduction.…”