Selective separation of Sc(III) and Zr(IV) from the leaching of bauxite residue using trialkylphosphine acids, tertiary amine, tri-butyl phosphate and their mixtures

Author(s)

Botelho, Amilton Barbosa Junior ^[1] ; Espinosa, Denise Crocce Romano ^[1] ; Tenorio, Jorge Alberto Soares ^[1]

Affiliation

^[1] Univ Sao Paulo, Dept Chem Engn, Sao Paulo - Brazil

• Document type: Journal article
• Source: Separation and Purification Technology; v. 279, DEC 15 2021.
• Web of Science Citations: 0

Abstract

The separation of scandium from the solution generated in acid leaching is one of the main challenges for the hydrometallurgical processing of bauxite residue. Several organic extractants were evaluated, being the most prominent phosphine acids, while amine-based compounds have shown great results for separating metallic ions. The present study aims at the separation of scandium and zirconium from the Brazilian bauxite residue. The acid leaching was carried out using 20% of H2SO4, S/L ratio equals 1/10, for 8 hat 90 degrees C. Further, solvent extraction experiments were carried out using D2EHPA, Cyanex 923, and Alamine 336 diluted in kerosene, evaluating the effect of pH, temperature, extractant concentration, synergism with TBP and A/O ratio. After optimizing various process parameters, Alamine 336 has obtained separation factors of Zr/Al, Zr/Fe, and Zr/Ti equal to 15150, 45054, and 19713, respectively, at pH 1.0, A/O ratio equals to 1:1 and 25 degrees C. The stripping rate achieved 92% using Na2CO3 0.25 mol/L. The scandium separation ratio reached higher values for 10% of Cyanex Cyanex 923 than D2EHPA 10% + TBP 5%. Scrubbing for contaminants removal may be carried out using HCl 5 mol/L with 0.1% of scandium losses, and all scandium was stripped by H3PO4 5 mol/L. Despite the works reported in the literature, there a few of them exploring the recovery of scandium and zirconium by the leaching-solvent extraction process. The flowchart proposed is strictly connected to the sustainable development goals 7, 8, 9, and 12. (AU)

• FAPESP's process: 12/51871-9 - Study Center for Technology in Waste Solid Treatment and Recycling - SCTWSTR
• Grantee: Jorge Alberto Soares Tenório
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 18/03483-6 - Kinect and thermodynamic studies for scandium recovery from Brazilian red mud using hydrometallurgical techniques
• Grantee: Amilton Barbosa Botelho Junior
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 19/11866-5 - Development of innovative processes for the recovery of critical metals
• Grantee: Denise Crocce Romano Espinosa
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 18/11417-3 - Obtaining Scandium from bauxite residue red mud by leaching process in acidic medium
• Grantee: Jorge Alberto Soares Tenório
• Support Opportunities: Regular Research Grants