Solid-state reduction of an Indonesian iron sand concentrate using subbituminous coal
Zulfiadi Zulhan, Ida B. G. S. Adhiwiguna, Atneral Fuadi, Nuryadi Saleh
Abstract
The reduction of an Indonesian iron sand concentrate was studied using TG/DTA and XRD analyses. The iron sand concentrate was mixed with coal and formed into a cylindrical pellet. The experimental results show that magnetite was reduced into wustite at 700–800°C and into metallic iron at temperature above 800°C. The transformation of titanomagnetite into ulvospinel and ilmenite occurred between 900 and 1000°C, and ulvospinel transformed into ilmenite and iron at 1000–1100°C. To simulate the reduction process in a rotary kiln, iron sand concentrate pellets were hardened at 1250°C and reduced using coal, which was added to cover the surface of the pellet at a temperature range of 800–1100°C for 150 min. The reduction degree was calculated based on the weight loss and the metallization degree was determined by wet chemical analysis. Quasi-equilibrium values of the reduction and metallization degrees were obtained at a certain temperature. The reversible first-order kinetics equation was proposed to analyse the experimental data to predict the metallization degree as a function of the reduction time and temperature.