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Metals 2017, 7(11), 458; https://doi.org/10.3390/met7110458

A Mineralogical Assessment on Residues after Acidic Leaching of Bauxite Residue (Red Mud) for Titanium Recovery

1
IME-Process Metallurgy and Metal Recycling, RWTH Aachen University, Intzestraße 3, 52056 Aachen, Germany
2
IML-Chair of Applied Mineralogy and Economic Geology, RWTH Aachen University, Wüllnerstraße 2, 52062 Aachen, Germany
*
Author to whom correspondence should be addressed.
Received: 27 September 2017 / Revised: 20 October 2017 / Accepted: 23 October 2017 / Published: 28 October 2017
(This article belongs to the Special Issue Advances in Hydrometallurgy)
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Abstract

Due to its alkalinity, red mud produced by the Bayer process may affect both the environment and human health. For this reason, its further utilization instead of disposal is of great importance. Numerous methods have already been studied for hydrometallurgical treatment of red mud, especially for the recovery of various metallic components such as iron, aluminum, titanium or rare earth elements. This study focuses on the extraction of titanium from red mud and in particular the mineralogical changes, induced by leaching. Sulfuric acid, hydrochloric acid and their combination have been utilized as leaching agents with the same leaching parameters. It has been determined that sulfuric acid is the best candidate for the red mud treatment in terms of titanium leaching efficiency at the end of 2 h with a value of 67.3%. Moreover, samples from intermediate times of reaction revealed that leaching of Ti exhibit various reaction rates at different times of reaction depending on acid type. In order to explain differences, X-ray Diffraction (XRD), scanning electron microscope (SEM) and QEMSCAN techniques were utilized. Beside titanium oxide (TiO2) with available free surface area, a certain amount of the TiO2 was detected as entrapped in Fe dominating oxide. These associations between Ti and Fe phases were used to explain different leaching reaction rates and a reaction mechanism was proposed to open a process window. View Full-Text
Keywords: bauxite residue; red mud; leaching; titanium; metal recovery bauxite residue; red mud; leaching; titanium; metal recovery
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Alkan, G.; Schier, C.; Gronen, L.; Stopic, S.; Friedrich, B. A Mineralogical Assessment on Residues after Acidic Leaching of Bauxite Residue (Red Mud) for Titanium Recovery. Metals 2017, 7, 458.

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