METHOD FOR PREPARING MACROCRYSTALLINE PRODUCT OF MIXTURE OF ZIRCONIUM AND HAFNIUM NITRATE AND OXYNITRATE Russian patent published in 2004 - IPC

FIELD: inorganic chemistry, chemical technology. SUBSTANCE: invention relates to methods for preparing zirconium and hafnium compounds. Invention provides preparing macrocrystalline product of mixture of zirconium and hafnium nitrate and oxynitrate and the enhanced extraction of nitric acid. Method involves opening zircon concentrate, preparing zirconium and hafnium nitrate solution followed by extractive separation of zirconium and hafnium to obtain zirconium re- extract and hafnium raffinate. Prepared solution are evaporated under rarefaction 0.6-0.95 atm, temperature 60-80 C and distillation degree 70-90% followed by separation of crystals of mixture of zirconium and hafnium nitrate and oxynitrate. In evaporation the solution containing mixture of zirconium and hafnium nitrate and oxynitrate is added additionally due to partial recirculation of solution from terminal evaporation stage at temperature 30-50 C in the amount providing concentration of zirconium and hafnium nitrate and oxynitrate 160-200 g/l in solution. Mixture of nitric acid and water vapors formed in evaporation is fed to the fractionating column avoiding condenser or recovered to evaporator device partially as phlegm. EFFECT: improved preparing method. 2 cl, 1 tbl, 2 ex