No abstract

No abstract

Recently a special attention is being paid on the combination of different ironmaking technologies in the integrated steel plant to maximize the efficiency of the overall process. The utilization of coke oven gas for production of direct reduced iron (DRI) in the integrated steelmaking route is still under evaluation and discussion. In this study, iron ore pellets were isothermally reduced with simulated original and reformed coke oven gas (RCOG) at 700-9808C. The results were compared with those obtained by the reduction of pellets with the original and reformed natural gas (RNG). The highest reduction degree was obtained for the pellets reduced with RCOG while the lowest reduction degree was exhibited by original natural gas. On the other hand the rate of reduction with original coke oven gas was sharply increased at temperature of about 9008C to become higher than that of RNG. A slow down phenomenon appeared at the later stage of reduction due to the intensive carbon deposition. The soot formation increased as CH 4 content and/or the temperature of reducing gas increased. Reflected light microscope, scanning electron microscope with EDX, and high performance X-ray diffraction analysis were used to estimate the reduction kinetics and mechanism.

In recent years an intensive work has been carried out to decrease the coke losses of the blast furnace through mixing small‐sized coke called “nut coke” in the iron ore burden layers. In order to clarify the influence of nut coke on the pellets reducibility, industrial iron ore pellets were reduced with and without nut coke participation under different temperatures and atmospheres. Isothermal and non‐isothermal reduction tests under simulating blast furnace conditions were performed using an experimental laboratory rig. Furthermore, reflected light microscopy, scanning electron microscopy and X‐ray technique were applied to characterize the microstructure and different phases developed in the origin and reduced pellets. Pellets reduced isothermally without nut coke participation exhibited reduction retardation (RR) at elevated temperature (≥1373 K) whereas the presence of nut coke had a positive effect of preventing such phenomena. The non‐isothermal reduction of pellets showed that, as the amount of nut coke in pellets bed increased, the reducibility of pellets increased, too. The rate controlling mechanism of pellets and pellets‐nut coke mixtures was predicted from the correlation between apparent activation energy calculations and microstructure examination.

No abstract