Thermodynamy And Laboratory Study Of The Reaction Behavior Of The Mixed Charging Composed Of Iron Coke And Agglomerates

With the growth of coal injection into the blast furnace, coke consumption per ton hotmetal becomes less and less, leading to the increase of coke load, the decrease ofthickness of coke layer, and the rise of thickness of iron ore layer. Furthermore, cokebreakage is more serious as the number of coke in the soft melting zone reducesrelatively. Thus, to keep the permeability of blast furnace, the skeleton effect of coke ismore outstanding. So coke should have a higher both cold strength and strength afterreaction(CSR). But, as the CSR increases, the CRI reduces, which is not conducive toefficient smelting of the blast furnace, because of the low CRI resulting in the increaseof reductant consumption and the pig iron cost. In order to solve the contradictionbetween the efficient smelting and the smooth operation in the blast furnace, coke withhigh strength and high reactivity is expected.Based on the catalytic effect of Fe, FeOxon the gasification reaction of carbon,ferro-cokes were made in the coke oven chamber in the laboratory by adding iron oresto blending coals. Because ferro-coke’s strength is poorer than the ordinary coke, it cannot be used as a single fuel of blast furnace, but its strength is enough as a nut coke usewhich is a additional fuel of blast furnace. This paper mainly studied the reactionbehavior of the mixed samples of iron ore and ferro-coke. The change of coke behaviorwas discussed as it moved downward in the blast furnace, and the results showed thatthe influence of the CO2and water vapor on coke degradation is very large. Besides,thermodynamic software Factsage was uesed to carry on the numerical simulationcalculation, and the thermodynamic of the iron ore reduction reaction、the cokegasification reaction as well as the coupling of both reactions was analyzed, finding thewater vapor had a greater influence on coke degradation than CO2. Otherwise,considering the shape of coke used in the actual blast furnace, the dynamic model ofcube shaped coke reacted with CO2was established, and the coke gasification reactionexperiments were done in the laboratory, confirming that the model was reliable. What’smore, in the iron ore reduction experiment oven, a series of isothermal or nonisothermal reaction behavior about the mixed samples were researched, revealing thatferro-coke had promoting effect on iron ore reduction reaction during the experiment, and also the coupling reaction mechanism of mixed samples was analyzed under hightemperature condition(the equivalent temperature of the blast furnace soft meltingzone), finding ferro-coke in the mixed sample played the role of delaying reductionhysteresis phenomenon of iron ore.