Preparation of high-purity zirconia from Egyptian zircon: an anion-exchange purification process

This paper deals with the preparation of high-purity zirconia from Egyptian zircon using a selective anion-exchange resin. Egyptian zircon was decomposed with sodium hydroxide at 650 °C. Then it was cooled and leached with water. After filtration, the residue was digested with concentrated hydrochloric acid, the slurry was filtered and the residue leached with a (6 M HCl)–(1 M H2SO4) mixture. The slurry was further aged and finally filtered. The filtrate was passed through an anion exchange resin bed. The effluent was treated by using 1.57 M sulphuric acid and the resulting zirconium sulfate tetrahydrate was filtered, washed, dried and calcined at 1000 °C. This ion-exchange purification process has great potential for application in industry for preparation of high-purity zirconia powders because of its simplicity, low cost and capability to produce high quality powder.