As part of efforts to reduce anthropogenic CO2 emissions by the steelmaking industry, this study investigated the direct reduction of industrially produced hematite pellets with H2 using the Doehlert experimental design to evaluate the effect of pellet diameter (10.5–16.5 mm), porosity (0.36–0.44), and temperature (600–1200℃). A strong interactive effect between temperature and pellet size was observed, indicating that these variables cannot be considered independently. The increase in temperature and decrease in pellet size considerably favor the reduc-tion rate, while porosity did not show a relevant effect. The change in pellet size during the reduction was negligible, except at elevated temper-atures due to crack formation. A considerable decrease in mechanical strength at high temperatures suggests a maximum process operating temperature of 900℃. Good predictive capacity was achieved using the modified grain model to simulate the three consecutive non-catalytic gas–solid reactions, considering different pellet sizes and porosities, changes during the reaction from 800 to 900℃. However, for other tem-peratures, different mechanisms of structural modifications must be considered in the modeling. These results represent significant contribu-tions to the development of ore pellets for CO2-free steelmaking technology.

Chemical Systems Engineering Center,Department of Chemical Engineering,University of S?o Paulo,S?o Paulo 05508-900,Brazil;Metallurgical Process Laboratory,Institute of Technological Research,S?o Paulo 05508-901,Brazil

[1]Patrícia Metolina;Tiago Ramos Ribeiro;Roberto Guardani-.Hydrogen-based direct reduction of industrial iron ore pellets: Statistically designed experiments and computational simulation)[J].矿物冶金与材料学报,2022(10):1908-1921

Doehlert

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