Direct reduction of hematite powders in a fluidized bed reactor--颗粒学报PARTICUOLOGY

Zhu, Q., Wu, R., & Li, H. (2013). Direct reduction of hematite powders in a fluidized bed reactor. PARTICUOLOGY, 11(3), 294–300. https://doi.org/10.1016/j.partic.2012.10.001

Direct reduction of hematite powders in a fluidized bed reactor

Qingshan Zhu ^a *, Rongfang Wu ^{a b}, Hongzhong Li ^a

a State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
b Graduate University of Chinese Academy of Sciences, Beijing 100049, China

10.1016/j.partic.2012.10.001

Volume 11, Issue 3, June 2013, Pages 294-300

Received 8 June 2012, Revised 5 October 2012, Accepted 14 October 2012, Available online 21 December 2012.

E-mail: qszhu@home.ipe.ac.cn

Highlights

► Defluidization with raw hematite powder was found to occur at temperature as low as 450 °C.

► Granulation reduces the tendency of defluidization, without sacrificing hematite reduction rate.

► The as-reduced iron powders exhibit excellent sintering activity.

Abstract

Ultrafine hematite powder was reduced to produce ultrafine iron powder in a 50%Ar–50%H₂ atmosphere at 450–550 °C in a fluidized bed reactor. The ultrafine hematite powder shows the typical agglomerating fluidization behavior with large agglomerates fluidized at the bottom of the bed and small agglomerates fluidized at the upper part of the bed. It was found that defluidization occurred even at the low temperature of 450 °C with low metallization rate. Defluidization was attributed mainly to the sintering of the newly formed iron particles. Granuation was employed to improve the fluidization quality and to tackle the defluidization problem, where granules fluidized like a Geldart's group A powder. Granulation was found to effectively reduce defluidization during reduction, without however sacrificing reduction speed. The as-reduced iron powders from both the ultrafine and the granulated hematite exhibited excellent sintering activity, that is, fast sintering at temperature of as low as ∼580 °C, which is much superior as compared to that of nano/ultrafine iron powders made by other processes.

Graphical abstract

Keywords

Direct reduction; Granulation; Defluidization; Sintering; Ultrafine iron powder

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