Sintering behavior of combusted iron powder in a packed bed reactor with nitrogen and hydrogen

Sintering behavior of micron-sized combusted iron powder is studied in a packed bed reactor, at various temperatures under inert (nitrogen) and reducing (hydrogen) conditions. Compression tests are subse-quently used to quantify the degree of sintering. A sintering model, based on the formation of a solid bridge through solid state surface diffusion of iron atoms, matches the experimental results. Sintering of combusted iron occurs at temperatures >= 575 degrees C in both nitrogen and hydrogen atmospheres and in-creases exponentially with temperature. The observed decrease in reduction rate at high temperatures is not caused by the sintering process but by the formation of wustite as an intermediate species, leading to the formation of a dense iron layer. Iron whiskers form at high temperatures (>= 700 degrees C) in combination with low reduction rates (<= 25 vol% H2), leading to the production of sub-micron fines.(c) 2023 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creative commons.org/licenses/by/4.0/).

Automated summary

The sintering behavior of micron-sized combusted iron powder was investigated in a packed bed reactor under inert and reducing conditions. Compression tests were conducted to measure the degree of sintering. A sintering model based on solid state surface diffusion of iron atoms was developed and matched the experimental results. Sintering of combusted iron occurred at temperatures ≥ 575 degrees C and increased exponentially with temperature. The observed decrease in reduction rate at high temperatures was attributed to the formation of wustite as an intermediate species.