Preparation of High-Purity Zirconia from Zircon: An Anion-Exchange Purification Process

Abstract

This paper describes the preparation of high-purity zirconia involving an anion-exchange purification step. The zirconium wet cake (residue obtained after water-leaching of alkali-fused zircon) is digested with concentrated hydrochloric acid, the slurry is sufficiently aged and filtered, and the residue is leached with a (6 N HCl)-(2 N H₂SO₄) mixture. The slurry is further aged and finally filtered using a filter-aid. The filtrate is passed through an anion-exchange resin. The effluent is treated with 25% (v/v) concentrated sulfuric acid and the resulting zirconium sulfate tetrahydrate is filtered, washed, dried, and calcined at 1000°C for 6–8 hours. A high-purity zirconium dioxide is obtained which has a variety of industrial and scientific applications, especially for the preparation of artificial gems.