The gas-solid-based synergistic reduction of pellets is an innovative and
effective method for iron ore smelting. With the development and utilization
of iron resources, ore reserves have been greatly depleted; therefore, as a
lean mineral resource, the comprehensive utilization of limonite has become
increasingly important. To study the reduction kinetics of pellets in depth,
this study used coke and reducing gases (CO and H2) to study the reduction
characteristics and changes occurring in carbon-containing limonite pellets.
The results showed that the total weight loss percentage of pellets
gradually increased with the temperature. The C/O molar ratio had a greater
effect on the total weight loss percentage of pellets in a N2atmosphere, but
it had no significant effect in CO or H2atmospheres. The maximum reaction
rate increased with increasing temperature. The reduction reaction was the
most difficult to proceed in the N2atmosphere, and the reaction was most
likely to occur in the CO atmosphere. The analysis of pellets by EPMA and
XRD found that the pellets reduced in the N2atmosphere had the lowest
porosity, and the pellets reduced in the H2atmosphere had the highest
porosity, which is more conducive to gas diffusion. Some of the unreduced
Si, Al, Mn, Ca, and Fe in the pellets reduced in the N2atmosphere
precipitated in the form of oxides, but when a reducing gas (CO, H2) was
introduced, precipitation did not occur.
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