METHOD OF PROCESSING BADDELEYITE Russian patent published in 1998 - IPC

FIELD: nonferrous metallurgy. SUBSTANCE: baddeleyite is processed to produce elevated-purity zirconium dioxide suitable in production of optic materials, base plates for integrated circuits, synthetic diamonds, special ceramics, and piezoceramics. In particular, baddeleyite is dissolved in boiling hydrofluoric acid, while simultaneously condensing its vapors and returning condensate into dissolution zone followed by sulfatization of zirconium fluorite solution obtained. The latter operation is carried out by adding zirconium fluorite solution to concentrated sulfuric acid preheated to 200-250 C to produce solid zirconium sulfate, after which hydrofluoric acid vapors are condensed and returned into baddeleyite dissolution process. Zirconium sulfate is converted into corresponding hydroxide which is calcined to form zirconium dioxide. In another embodiment of invention, zirconium hydroxide is produced by adding zirconium sulfate to ammonia water. Zirconium dioxide obtained in conformity with invention with high yield is virtually silicon-free and contains (in wt %): Fe, less than 0.005; Li, 0.001; Al, less than 0.001; Ti, less than 0.001; Th, less than 0.001. EFFECT: reduced hydrofluoric acid consumption and improved environmental safety. 2 cl