Renewable energy steelmaking: On a new process for ironmaking

The purpose of the present work is to assess the feasibility of a new ironmaking process combining a Rotary Hearth Furnace and a Bath Smelter to produce commercial iron. In the process proposed the RHF uses iron ore and wood charcoal as the energy source. Considering the regrowing of trees, wood charcoal is an energy source virtually free of net CO₂ emissions. However, it cannot be used in current large-scale blast furnaces with high productivity due to low strength and density. The new process can use wood charcoal would since the feed used in the RHF is of composite pellets formed from the agglomeration of powders of carbon and iron oxides.; The methodology used in the assessment of the new process was to start with the most fundamental aspect of reduction in composites measuring intrinsic rate constants for carbon oxidation by CO₂ and wustite reduction by CO in conditions set to minimize the influence of heat transfer and other phenomena. In this assessment, a reduction model for the chemical kinetics of reactions in composites of carbon and iron oxides was developed resulting in the measurement of intrinsic kinetic constants. The model developed for the intrinsic kinetics of reactions achieved good agreement in representing the rate data collected in small samples but overpredicted measured rates in pellets. Thus, a second model was developed considering the intrinsic kinetics of chemical reactions along with heat transfer for the reduction of composite pellets. In this model, the kinetic rate laws derived previously were used along with the equations of continuity and differential enthalpy balance providing a model of reduction in pellets. This model achieved good representation of the experimental data collected. For example, in simulating a large pellet of wood charcoal and hematite, a rate of mass loss of 0.2630g/min is computed from the model comparing well with a rate of 0.2877g/min measured experimentally. A third model used to predict the productivity and energy requirements of the RHF was constructed linking the model developed for a single pellet with macroscopic mass and enthalpy balances representing parts of the RHF. Retention times of pellets in the RHF estimated from the productivity model developed were in good agreement with plant data reported in spite of the number of simplifying assumptions used. (Abstract shortened by UMI.)...