Characterization of Bauxite Residue from a Press Filter System: Comparative Study and Challenges for Scandium Extraction
- PDF / 3,270,381 Bytes
- 16 Pages / 595.276 x 790.866 pts Page_size
- 95 Downloads / 211 Views
Characterization of Bauxite Residue from a Press Filter System: Comparative Study and Challenges for Scandium Extraction Amilton Barbosa Botelho Junior 1
&
Denise Crocce Romano Espinosa 1 & Jorge Alberto Soares Tenório 1
Received: 18 May 2020 / Accepted: 6 October 2020 # Society for Mining, Metallurgy & Exploration Inc. 2020
Abstract A new step in the Bayer process has been used to recover NaOH and to reduce its content in red mud. After digestion, the residue is separated from the Bayer liquor and goes through press filters, which enables the recovery of NaOH and decreases the moisture content. It is well known that red mud is one of the most important sources of scandium. For this reason, the goal of this work was to characterize a Brazilian red mud (BRM) for scandium recovery. The sample was collected after the press filter system process. Analysis of energy-dispersive X-ray fluorescence (EDXRF), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), and X-ray diffraction (XRD) was performed. Microwave digestion using an acid mixture was carried out to determine the concentration of the main elements. Fe2O3 represented 40% of the BRM, and the Sc concentration was 43 mg/kg. The SiO2 content was 24%, which is the highest value found in the literature, whereas the sodium concentration was the lowest. A literature review was carried out to compare results with BRM, as well as the current studies for recovery of scandium by the leaching/ion-exchange process. Scandium recovery using a leaching/ion exchange process may be possible with efficiency higher than 90%. The greatest challenge is the occurrence of silica gel formation during leaching. Keywords Brazilian red mud . Bauxite residue . Critical metals
1 Introduction Brazil is the third largest country in the world in bauxite resources and production [1, 2]. This ore is the raw material for alumina production through the Bayer process, where sodium hydroxide is used as leaching agent, which enables the selective leaching of alumina. After the leaching step, solid–liquid separation is required [3, 4]. The solid phase (residue) is called Statement of Novelty A Brazilian red mud (or bauxite residue) has been fully characterized. Because of its environmental risk and the huge amount stored in dams, and due to the recent accidents in Brazil caused by mine tailings dam collapse, it is important to develop new reuse and applications for these residues. A literature review demonstrated that bauxite residues may contain several rare earth elements, scandium being the most valuable and critical. However, there is a lack of literature about the red muds from Brazil. In light of this situation, the characterization and discussion regarding scandium recovery, focusing on a sustainable process by leaching/ion exchange, signifies the novelty of this work. * Amilton Barbosa Botelho Junior [email protected] 1
Department of Chemical Engineering, University of São Paulo, São Paulo, Brazil
red mud, or bauxite residue. For each tonne of alumina produced,
Data Loading...
