The Dynamics Research Of Directly Reduced Iron Ore By Coke Oven Gas

The gas base direct reduction iron technolog is the main force of the world direct reductiontechnology.The purpose of the experiment is the influence of the coke oven gas with differentoxidiability on reduction and the reduction rate of iron and pellets. And on this base research ofmechanism has been carried out. The reseach has provided base information and theoretical basisfor the actual production.In the experiment iron and pellets is reduced by different oxidiability of oven gas with3-sectional shaft furnaces and then weight lost is measured by weighing equipment, which iscounted by the computer to get reduction process curve. Reduction rule of the iron and pellets isstudied by reduction mass loss way with CO+H₂+H₂O+CH₄gas mixtures.The result shows: the rate of reduction and Reduction Index （RI） of pellet had a littleimprovement with the increase of hydrogen gas.For example, the Reduction Index（RI） of pelletreaches90.79%and metallized rate is86.17%when the hydrogen gas content is68%. While theoxidation of reduction gas is0.087, the Reduction Index（RI） of pellet reaches the maximum of91%and metallized rate reached the maximum of86.5%; When the oxidation of reduction gas is lowerthan0.087,the Reduction Index（RI） and metallized rate is creasing with the oxidation increasing,while the oxidation of reduction gas is higher than0.087,the rule is opposite. Also, reduction andreduction rate is all augmenting in the condition of the same reduction gas. When the reductionreaction is to certain extent, reduction rate is hard to be increased though the reduction time isextended. optimum reduction condition is that the hydrogen gas content is68.3%,the oxidation ofreduction gas is0.087and the temperature is at900℃.The result shows that external diffusion resistance is growing with the temperature higher from750℃to800℃,850℃and900℃,and the interface-chemical reaction resistance is growingwith the temperature varying from900℃to850℃,750℃and800℃in the condition of the samereduction gas. External diffusion resistance quickly enlarges to be the main force with thetemperature of900℃. So external diffusion resistance played a crucial role in the process of hightemperature reduction. In every condition of reduction, the interface-chemical reaction resistanceincreases with the increase of reduction degree. external diffusion resistance reaches the maximumwhen the iron and pellets is reduced by coke oven gas in the condition of the same temperature, andthe interface-chemical reaction resistance reaches the maximum with the hydrogen gas content of68.3%.