Studies on the Preparation of Zirconium oxide from Zircon sands of Formosa

With the object of determinating an industrial preparation method of pure zirconium oxide from zircon sands of Formosa, we tried to fuse the very finely pulverized powder of them with the fusing mixture, NaOH and Na2O2, and to lixiviate with hot water.The remaining residues were treated with HCl and dissolved into chloride solution.The solution was evaporated to dryness on heating to expel acid fune, and the dried mass wass held at about 100°C during several hours to dehydrated silica gel and then lixiviated with water to remove the silica. The silica-free solution of ZrCl4 containing of FeCl3 and TiCl4 as impurities, wa neutralized with ammonium water to very weak acidity not to distinguish the precipitated hydroxides and boiled, bubbling SO2 gas into it, when Zr-hydroxide falled by hydrolysis with Ti-hydroxide and Fe-chloride remained in the mother liquor.The hydroxides were dissolved in the small amount of H2SO4 and the sulphate solution was evaporated to dryness and heated to 650°C in the electric furnace to expel the excess of H2SO4.After lixiviating the cold mass with small water and filtering the insoluble matters, the sulphate solution was diluted to the ratio 1:50 of the cake and water.On standing of the diluted solution during a week, the pure Zr-basic sulphate was crystalized out and calcinedd at 1000°C, when the ZrO2 of 99% purity was prepared.