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In order to reduce the burden of electric arc furnace dust on steel recycling plants, a new technology called in-process separation (IPS) was proposed. By separating Zn vapor from the solid particles in the electric arc furnace off-gas, production of Zn-containing electric arc furnace dust may be prevented. However, the spinel formation reaction at high temperatures and its impact on the technology's feasibility still require better understanding. This paper demonstrates a model that was developed to provide this insight, based on the results of our previous work on the kinetics of the spinel formation.This model evaluates the performance of IPS based on four key process parameters: the position of the separation unit, the timetemperature profile inside the off-gas duct, the solid particle size distribution, and the initial Zn and Fe content of the off-gas. The impact on the efficiency of each parameter was demonstrated using the results of the model for a specific off-gas treatment setup.

The reaction kinetics of Zn vapor with Fe3O4 (magnetite) were studied from 907 to 1100 °C using a new experimental setup that only allows contact between the reactants through a gas-solid reaction. Hematite was used to create the reaction pellets. Because of the reducing atmosphere in the setup, a magnetite layer is formed on the outside of the pellet, which in turn reacts with the Zn vapor. After reaction, Zn concentration profiles were measured in the reacted magnetite layer using field-emission gun electron probe microanalysis. The reaction was confirmed to be diffusion-controlled. The effect of both volume and grain-boundary diffusion was observed in each experiment. The temperature dependence of both the volume and grain-boundary diffusion coefficients was obtained along with the activation energies of the diffusion coefficients. This study provides crucial information for the development of technologies that are dependent on the reaction. One example is the in-process separation technology for the separation of Zn vapor from electric arc furnace off-gas.

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