| Autor: |
Tanvar, Himanshu, Sinha, Manish Kumar, Habinshuti, Jean Baptiste, Mishra, Brajendra |
| Předmět: |
|
| Zdroj: |
Metallurgical & Materials Transactions. Part B; Apr2023, Vol. 54 Issue 2, p621-634, 14p |
| Abstrakt: |
The industrial processes for recovery of niobium and tantalum oxides depend on hydrofluoric acid, which is a highly toxic and corrosive reagent with significant environmental consequences. This study presents a fluoride-free, rapid, and energy-efficient process for niobium and tantalum extraction from columbite using microwave-assisted alkali treatment and solvent extraction. Microwave treatment was optimized using an experimental design to obtain a statistical model for maximum dissolution. It was found that it is possible to obtain a temperature of more than 600 °C within 4 min of microwave treatment with potassium hydroxide. Water leaching of the microwave-treated sample resulted in dissolution of 93.57 pct niobium, 88.12 pct tantalum, 11.17 pct tin, and 21.09 pct iron. Solvent extraction with methyltrioctylammonium chloride was used to separate niobium and tantalum from aqueous solution. Approx. 96.2 pct niobium along with 93.4 pct tantalum was co-extracted at the organic-to-aqueous phase ratio of 2/1 in a two-stage counter-current extraction with 0.29 M extractant. Selective stripping of niobium from the loaded organic solution was performed with a mixture of 0.5 M nitric and oxalic acid, while tantalum stripping was achieved with high nitric acid concentration (1 M). Finally, > 98 pct pure niobium oxide and Ta-rich mixed oxide were prepared by the precipitation of the purified solution. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
Full text from SpringerLink