Abstract
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–CO2 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–CO2 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–CO2 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.
Highlights
An ore-carbon briquette is a composite briquette consisting of iron-bearing oxide and carbonaceous materials that were used as feed material in some coal-based direct reduction processes, such as FASTMET® (FASTMET is a trade mark of MIDREX Co., USA.) and ITMK3® (ITMK3 is a trademark of KOBE Steel Co., Japan.) [1,2,3,4]
After 15 min, the reduction degrees of the briquette under 1473 K and under 1373 K are quite close, and by 20 min, the reduction degrees under the three temperatures are nearly the same. These findings indicate that, under the oxidative atmosphere, increasing the temperature does not increase the final reduction degree of the briquette
The model included the kinetics of the stage-wise reduction of iron oxide, carbon gasification and metallic iron oxidation, and it was with the assumptions of constant porosity and size of the briquette
Summary
An ore-carbon briquette is a composite briquette consisting of iron-bearing oxide and carbonaceous materials that were used as feed material in some coal-based direct reduction processes, such as FASTMET® (FASTMET is a trade mark of MIDREX Co., USA.) and ITMK3® (ITMK3 is a trademark of KOBE Steel Co., Japan.) [1,2,3,4]. The use of these briquettes offers advantages, such as a high reduction rate, utilization of non-coking coal, and biochar for producing sponge iron economically.
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