Behaviour of wüstite prepared from Baharia iron ore sinter during reduction with CO–CO₂–N₂gas mixture

Abstract

Two wu ¨stite samples were prepared from reagent grade hematite and Baharia iron ore sinter by a gaseous reduction with 50%CO-CO 2 gas mixture at 1273 K. Both wu ¨stite samples were isothermally reduced at 1173-1373 K by different ratios of CO/CO 2 /N 2 which closely represent the coke gases in the blast furnace. The influences of temperature and gas composition on the reduction behaviour and the morphology were investigated. The reduction rate of both wu ¨stite samples increased gradually with increasing reaction temperature and also by increasing the CO concentration in the reducing gas mixture. The apparent activation energy values were calculated and correlated with the gas-solid reaction formulations to elucidate the corresponding mechanism at both early and final reduction stages. The reduction rate of pure wu ¨stite samples is most likely controlled by the combined effect of chemical reaction and gaseous diffusion mechanisms while the reduction rate of wu ¨stite from iron ore sinter is most likely controlled by interfacial chemical reaction mechanism.

Kinetic analysis for non-isothermal solid state reduction of nickel laterite ore by carbon monoxide

“…Bahgat studied the behaviour of wustite prepared from Baharia iron ore sinter during reduction with CO-CO 2 -N 2 gas mixture. These results showed the reduction rate of pure wustite samples that was most likely controlled by the combined effect of chemical reaction and gaseous diffusion mechanisms while the reduction rate of wustite from iron ore sinter was most likely controlled by interfacial chemical reaction mechanism (Bahgat et al, 2011). Therefore, the gas-solid reaction of nickel laterite ore was controlled by interfacial chemical reaction, and the reaction rate was determined by the chemical reaction rate.…”

Enhancement of wüstite reducibility in blast furnace: reaction kinetics and morphological changes

“…As mentioned previously,18, 19 the total reduction process in BF lasts for 120 min, but the reduction status at 90 min attracted more attention because it is the time needed for the burden to pass through the temperature region of 900–1100°C in BF. From the isothermal reduction curves of pure wüstite, it was found that at 900–1100°C, comparatively, the reduction extent was clearly enhanced as it mainly reached 100% after 40–90 min while the reduction extent after 90 min was in the range of 50–75 or 81–99·5% for samples isothermally reduced with CO/CO 2 /N 2 (coke gases) or H 2 /CO/CO 2 /N 2 (low natural gases injection with low oxygen enrichment) respectively 20,21…”

“…On the other hand, from isothermal reduction curves, it was found that the reduction extent after 90 min was in the range of 70-80%, which is relatively higher compared with the wu ¨stite from iron ore sinter reduced with CO/CO 2 /N 2 (34-48%) or with H 2 /CO/CO 2 /N 2 (54-69%). 20,21 Enhancement of wu ¨stite reducibility at 900-1100uC decreases the remaining quantity of unreduced wu ¨stite, which descends to the high temperature region in BF. This will consequently lead to the reduction in coke consumption and CO 2 emission.…”

“…From the isothermal reduction curves of pure wü stite, it was found that at 900-1100uC, comparatively, the reduction extent was clearly enhanced as it mainly reached 100% after 40-90 min while the reduction extent after 90 min was in the range of 50-75 or 81-99?5% for samples isothermally reduced with CO/CO 2 /N 2 (coke gases) or H 2 /CO/CO 2 / N 2 (low natural gases injection with low oxygen enrichment) respectively. 20,21 At lower H 2 content, by increasing the reduction temperature, the total porosity decreases from 49?99 to 47?17% for pure wü stite compacts reduced by H 2 / (H 2 zCO)50?42 at 950 and 1050uC respectively. Figure 3 shows the relation between incremental pore volume and pore diameter for pure wü stite compacts reduced by H 2 /(H 2 zCO)50?42 at 950 and 1050uC respectively.…”

Reduction Behavior of Low Grade Iron Ore at Reducing Conditions Simulating Different Zones of Blast Furnace

“…The behavior of wustite prepared from Baharia iron ore sinter during reduction with different ratios of CO-CO 2 -N 2 gas mixture at 800 -1100ºC was investigated 10 . The influence of temperature and gas composition on the reduction behaviour and the morphology was investigated.…”