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Article

Influence of Sodium Sulfate Addition on Iron Grain Growth during Carbothermic Roasting of Red Mud Samples with Different Basicity

1
Laboratory of Physical Chemistry and Technology of Iron Ore Processing, A.A. Baikov Institute of Metallurgy and Materials Science, Russian Academy of Science, 49 Leninsky Prosp, 119334 Moscow, Russia
2
Department of Radiochemistry, Faculty of Chemistry, Lomonosov Moscow State University (MSU), 1-3 Leninskiye Gory, 119991 Moscow, Russia
3
National University of Science & Technology (MISIS), 4 Leninsky Prosp, 119049 Moscow, Russia
*
Author to whom correspondence should be addressed.
Metals 2020, 10(12), 1571; https://doi.org/10.3390/met10121571
Received: 20 October 2020 / Revised: 18 November 2020 / Accepted: 21 November 2020 / Published: 24 November 2020
(This article belongs to the Section Extractive Metallurgy)
Red mud is an iron-containing waste of alumina production with high alkalinity. A promising approach for its recycling is solid-phase carbothermic roasting in the presence of special additives followed by magnetic separation. The crucial factor of the separation of the obtained iron metallic particles from gangue is sufficiently large iron grains. This study focuses on the influence of Na2SO4 addition on iron grain growth during carbothermic roasting of two red mud samples with different (CaO + MgO)/(SiO2 + Al2O3) ratio of 0.46 and 1.21, respectively. Iron phase distribution in the red mud and roasted samples were investigated in detail by Mössbauer spectroscopy method. Based on thermodynamic calculations and results of multifactorial experiments, the optimal conditions for the roasting of the red mud samples with (CaO + MgO)/(SiO2 + Al2O3) ratio of 0.46 and 1.21 were duration of 180 min with the addition of 13.65% Na2SO4 at 1150 °C and 1350 °C followed by magnetic separation that led to 97% and 83.91% of iron recovery, as well as 51.6% and 83.7% of iron grade, respectively. The mechanism of sodium sulfate effect on iron grain growth was proposed. The results pointed out that Na2SO4 addition is unfavorable for the red mud carbothermic roasting compared with other alkaline sulfur-free additives. View Full-Text
Keywords: red mud; bauxite residue; reduction roasting; sodium sulfate; iron grain growth; magnetic separation; recycling; utilization red mud; bauxite residue; reduction roasting; sodium sulfate; iron grain growth; magnetic separation; recycling; utilization
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MDPI and ACS Style

Grudinsky, P.; Zinoveev, D.; Pankratov, D.; Semenov, A.; Panova, M.; Kondratiev, A.; Zakunov, A.; Dyubanov, V.; Petelin, A. Influence of Sodium Sulfate Addition on Iron Grain Growth during Carbothermic Roasting of Red Mud Samples with Different Basicity. Metals 2020, 10, 1571. https://doi.org/10.3390/met10121571

AMA Style

Grudinsky P, Zinoveev D, Pankratov D, Semenov A, Panova M, Kondratiev A, Zakunov A, Dyubanov V, Petelin A. Influence of Sodium Sulfate Addition on Iron Grain Growth during Carbothermic Roasting of Red Mud Samples with Different Basicity. Metals. 2020; 10(12):1571. https://doi.org/10.3390/met10121571

Chicago/Turabian Style

Grudinsky, Pavel, Dmitry Zinoveev, Denis Pankratov, Artem Semenov, Maria Panova, Alex Kondratiev, Andrey Zakunov, Valery Dyubanov, and Alexander Petelin. 2020. "Influence of Sodium Sulfate Addition on Iron Grain Growth during Carbothermic Roasting of Red Mud Samples with Different Basicity" Metals 10, no. 12: 1571. https://doi.org/10.3390/met10121571

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