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Solvent Extraction of Scandium from the Waste Solution of TiO2 Production Process

Authors :
N. Murayama
J. Shibata
Source :
Transactions of the Indian Institute of Metals. 70:471-477
Publication Year :
2016
Publisher :
Springer Science and Business Media LLC, 2016.

Abstract

Extraction and stripping properties of Sc3+ were investigated by using a mixed extractant of Versatic Acid 10 (VA10) and Tri-n-butyl phosphate (TBP). The effect of adding TBP to VA10 was considered by analyzing the binding state of VA10 and TBP by FT-IR. Solvent extraction of scandium from an aqueous solution of Sc3+–Ti4+–Zr4+, which simulated waste water from the titanium oxide manufacturing process, the Bayers process and others, was performed, and the separation factor of Sc3+ over Ti4+ and Zr4+ was investigated. To clarify the operating conditions of a countercurrent multistage process for Sc3+, McCabe–Thiele analysis was applied to the extraction isotherm and stripping isotherm of Sc3+. The extraction pH of Sc3+ was found to shift to higher pH, and Sc3+ was stripped at a lower concentration of H2SO4 by adding TBP to VA10. Addition of TBP to VA10 suppresses the extraction of Sc3+ and promotes the stripping of Sc3+. IR spectra of the organic phase suggested that the dimeric portion of VA10 formed hydrogen bonds with TBP. The extractions of Sc3+, Ti4+ and Zr4+ were 77, 3 and 8%, respectively. The separation factors of these metal ions were βSc/Ti = 100 and βSc/Zr = 38 at pH4.6 on extraction with VA10 + TBP from aqueous solutionof Sc3+–Ti4+–Zr4+. Stripping efficiency of 100, 8 and 22% could be achieved for Sc3+, Ti4+ and Zr4+, respectively by using 0.5 mol/dm3 H2SO4. From these results, it was possible to separate Sc3+from impurities such as Ti4+ and Zr4+ by countercurrent multistage extraction, and Sc3+ was recovered by one-stage stripping with 0.5 mol/dm3 H2SO4. Extraction of Sc3+from the dilute aqueous solution containing 500 mg/dm3 of Sc3+reached 99% at the flow ratio (A/O) = 1.01 in the two-stage countercurrent extraction, and Sc3+ in the organic phase was stripped to attain a six-fold concentration by applying one-stage stripping with flow ratio of (O/A) = 6.00.

Details

ISSN :
09751645 and 09722815
Volume :
70
Database :
OpenAIRE
Journal :
Transactions of the Indian Institute of Metals
Accession number :
edsair.doi...........4fd5fca6c7a28bc90acd9d14469b3115
Full Text :
https://doi.org/10.1007/s12666-016-1008-3