4 research outputs found
Correlating Chemical Reaction and Mass Transport in Hydrogen-based Direct Reduction of Iron Oxide
Steelmaking contributes 8% to the total CO2 emissions globally, primarily due
to coal-based iron ore reduction. Clean hydrogen-based ironmaking has variable
performance because the dominant gas-solid reduction mechanism is set by the
defects and pores inside the mm-nm sized oxide particles that change
significantly as the reaction progresses. While these governing dynamics are
essential to establish continuous flow of iron and its ores through reactors,
the direct link between agglomeration and chemistry is still contested due to
missing measurements. In this work, we directly measure the connection between
chemistry and agglomeration in the smallest iron oxides relevant to magnetite
ores. Using synthesized spherical 10-nm magnetite particles reacting in H2, we
resolve the formation and consumption of w\"ustite (FeO) - the step most
commonly attributed to agglomeration. Using X-ray scattering and microscopy, we
resolve crystallographic anisotropy in the rate of the initial reaction, which
becomes isotropic as the material sinters. Complementing with imaging, we
demonstrate how the particles self-assemble, subsequently react and sinter into
~100x oblong grains. Our insights into how morphologically uniform iron oxide
particles react and agglomerate H2 reduction enable future size-dependent
models to effectively describe the multiscale iron ore reduction
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SOLUTION-PROCESSED TELLURIDE GLASS FOR FAR-INFRARED DEVICES
Tellurium-based chalcogenide glasses are materials that are transparent over a range of long infrared wavelengths, making them applicable for many uses such as thermal imaging for the security and defense industries. Because they are glasses, they also offer an advantage over modern infrared optical materials, which are crystalline and more difficult to fabricate. In addition, chalcogenide glasses in general have the potential to be 3D printed from glass solutions, which can enable intricate optical designs that are not possible using today’s methods. Chalcogenide glasses made from solution have already been developed for glasses such as arsenic sulfides and arsenic selenides, however, this has not been shown yet for tellurides. The focus of the study was to bridge this gap by investigating the viability of producing a germanium arsenic telluride chalcogenide glass from solution. The chemical composition, structure, and transmission of the solution-processed telluride glass were measured. The composition of glass studied in this project was found to maintain very similar stoichiometry and structure to the starting glass, which suggests that the optical properties may also be similar
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Correlating chemistry and mass transport in sustainable iron production.
Steelmaking contributes 8% to the total CO2 emissions globally, primarily due to coal-based iron ore reduction. Clean hydrogen-based ironmaking has variable performance because the dominant gas-solid reduction mechanism is set by the defects and pores inside the mm- to nm-sized oxide particles that change significantly as the reaction progresses. While these governing dynamics are essential to establish continuous flow of iron and its ores through reactors, the direct link between agglomeration and chemistry is still contested due to missing measurements. In this work, we directly measure the connection between chemistry and agglomeration in the smallest iron oxides relevant to magnetite ores. Using synthesized spherical 10-nm magnetite particles reacting in H2, we resolve the formation and consumption of wüstite (Fe1-xO)-the step most commonly attributed to whiskering. Using X-ray diffraction, we resolve crystallographic anisotropy in the rate of the initial reaction. Complementary imaging demonstrated how the particles self-assemble, subsequently react, and grow into elongated whisker structures. Our insights into how morphologically uniform iron oxide particles react and agglomerate in H2 reduction enable future size-dependent models to effectively describe the multiscale aspects of iron ore reduction