Investigation of alkali metal oxides as supporting electrolytes for metal production via high temperature molten oxide electrolysis.
| dc.contributor.author | Newport, Rebecca | |
| dc.date.accessioned | 2022-01-26T01:44:56Z | |
| dc.date.available | 2022-01-26T01:44:56Z | |
| dc.date.issued | 2021 | en |
| dc.description.abstract | This thesis investigates the use of alkali metal oxides (Na₂O and K₂O) as supporting electrolytes in molten oxide electrolysis for the reduction of TiO₂ into Ti metal. Based on previous work, the TiO₂-Na₂O system was considered, as when it was modelled thermodynamically, the results suggested that Ti could be selectively reduced over Na from melts containing at least 38 mol% TiO₂. According to the model, this selectivity improved as the TiO₂ content increased and the operating temperature decreased. This trend was generally observed during electrolysis experiments, with the maximum current efficiency for Ti extraction being 0.51% at 958 °C and 38 mol% TiO₂. The TiO₂-K₂O system was then considered, as it was assumed the two systems would behave similarly due to the similar properties of Na₂O and K₂O. Experiments to investigate the electrochemical behaviour confirmed this hypothesis as the results were similar. There were also similar trends observed in the thermodynamic model of TiO₂-K₂O system. However, the reduction potentials in this model also suggested that Ti could not be selectively extracted over K, which was confirmed during electrolysis experiments. Based on these results, the TiO₂-Na₂O-K₂O ternary system was initially analysed to see if combining the two oxides created a better supporting electrolyte. The model suggested this was the case, with the combined electrolyte having more favourable results than the individual binary systems. Finally, the initial ternary analysis of the TiO₂-Na₂O-K₂O system was extended to other ternary oxide systems containing TiO₂ and either Na₂O or K₂O. In this analysis, the thermodynamic model suggested that systems containing CaO would be the most viable option for Ti extraction. However, all the systems considered had points where Ti could be selectively extracted, with experiments required to confirm the model. | en |
| dc.identifier.uri | https://hdl.handle.net/10092/103314 | |
| dc.identifier.uri | http://dx.doi.org/10.26021/12416 | |
| dc.language | English | |
| dc.language.iso | en | en |
| dc.rights | All Right Reserved | en |
| dc.rights.uri | https://canterbury.libguides.com/rights/theses | en |
| dc.title | Investigation of alkali metal oxides as supporting electrolytes for metal production via high temperature molten oxide electrolysis. | en |
| dc.type | Theses / Dissertations | en |
| thesis.degree.discipline | Chemical Engineering | en |
| thesis.degree.grantor | University of Canterbury | en |
| thesis.degree.level | Masters | en |
| thesis.degree.name | Master of Engineering | en |
| uc.bibnumber | 3118875 | |
| uc.college | Faculty of Engineering | en |