| 摘要 |
<p>Hafnium values are extracted from an aqueous acidic phase containing Hf and Zr values and impurities by (a) acidifying the aqueous acid phase to at least 7 N, (b) emulsifying the aqueous phase with an organic solvent, (c) thereafter separating an organic solution containing some Hf and all the Zr, an aqueous solution containing remaining Hf and some impurities, and a sludge interlayer containing impurities. (d) Thereafter, the organic solution of Hf and Zr may be contacted in countercurrent with an acidic aqueous phase, which extracts some Zr but preferentially extracts Hf; (e) the Hf: Zr ratio in this aqueous solution may then be further increased by countercurrent contact with fresh organic solvent. (f) Ti values may then be removed by known method from the resultant aqueous solution. Starting with an Hf: (Hf + Zr) molar ratio of 20%, a final ratio of 99-99.5% may result. (g) The Hf in the enriched aqueous solution may then be precipitated as HfO2. The acid may be a mineral acid, e.g. HNO3, HCl, H2SO4. Before the acid is added in step (a) the initial aqueous solution may contain 4-60 g. ZrO2, 1-20 g. HfO2, and the following impurities: Si, Fe, Ca, Mg, Al, P, Ti and Na values. The organic solvent may be mono-, di- or tributyl phosphate, trioctyl phosphate, butyl phenyl phosphate, butyl acetate, and isoamyl acetate. Tributyl phosphate may be used diluted with petroleum hydrocarbons; at least 1-5 volumes tributyl phosphate are used per volume of solution to be heated. Zirconium values may be recovered from the Hf-depleted organic solution from stage (c) by counter-current contact with demineralized water which extract Zr. Specification 800,426 is referred to.</p> |
