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Iron ore-carbon briquette is often used as the feed material in the production of sponge iron via coal-based direct reduction processes. In this article, an experimental and simulation study on the reduction behavior of a briquette that is made by hematite and devolatilized biochar fines under CO-CO 2 atmosphere was carried out. The reaction model was validated against the corresponding experimental measurements and observations. Modeling predictions and experimental results indicated that the CO-CO 2 atmosphere significantly influences the final reduction degree of the briquette. Increasing the reduction temperature did not increase the final reduction degree but was shown to increase the carbon that was consumed by the oxidative atmosphere. The influence of the CO-CO 2 atmosphere on the briquette reduction behavior was found to be insignificant in the early stage but became considerable in the later stage; near the time of the briquette reaching its maximum reduction degree, both iron oxide reduction and metallic iron re-oxidation were able to occur.

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Based on the operation conditions of the iron making blast furnace of 580 m 3 in the industrial base of MCC Company, a threedimensional mathematical model for analyzing combustion behavior of gas, pulverized coal and coke bed in the tuyere-racewaydripping zone of blast furnace has been developed in the present research. The gas was modeled with steady-state turbulent Navier-Stokes equations; the pulverized coal particles were modeled by using a DPM (discrete particle model) approach and coke bed was treated simply as porous media. Two cases, the normal PCI case and the intensified PCI case, were then analyzed and compared. The simulation results indicate that, compared to the normal PCI case, the intensified PCI case has the advantage of an increase of 0.1 volume fraction of CO in the gas and moreover some 60 kg-coke/tHM could be saved. The negative effects of the proposed intensified PCI mode mainly include the drop of combustion temperature and the shrinkage of raceway.