Journal
POWDER TECHNOLOGY
Volume 372, Issue -, Pages 1-7Publisher
ELSEVIER
DOI: 10.1016/j.powtec.2020.05.112
Keywords
High-iron bauxite; Pre-roasting; Suspension roasting; Magnetic separation; Phase transformation
Categories
Funding
- National Natural Science Foundation of China [51904058]
- National Key Research and Development Program of China [2018YFC1901902]
- Open Foundation of State Key Laboratory of Mineral Processing [BGRIMM-KJSKL-2020-17]
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High-iron bauxite, which is a typically unmanageable form of bauxite due to its high contents of iron and diaspore, has not been used by alumina producers. An advanced roasting technique for removing iron from high-iron bauxite, based on static pre-roasting in air and suspension roasting by hydrogen under fluidized conditions followed by magnetic separation was developed in this study. The influences of pre-roasting temperature, suspension roasting temperature, roasting time, and H-2 concentration were investigated. The phase transformations of the samples were investigated using X-ray diffraction, vibrating sample magnetometry, field emission scanning electron microscopy, and Brunauer-Emmett-Teller method. After pre-roasting at a temperature of 750 degrees C for 30 min, diaspore (AlOOH) and goethite (FeOOH) in the raw high-iron bauxite ore were transformed into Al2O3 and Fe2O3, respectively. The optimal suspension roasting conditions were determined to be a roasting temperature of 600 degrees C with a H-2 concentration of 25% for 4 min.The reduction sample was subjected to magnetic separation and a non-magnetic product (aluminum concentrate), with alumina recovery of 80.64% and iron removal of 85.32%, was obtained. Such a non-magnetic product could be used as a raw material for the Bayer process in the alumina production industry, while the magnetic product could be used as a supplementary material for iron ore resources. (C) 2020 Published by Elsevier B.V.
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