PREPARATION OF HIGH-PURITY ZIRCONIA FROM ZIRCON - AN ANION-EXCHANGE PURIFICATION PROCESS

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 f iltered, and the residue is leached with a (6 N HCl)-(2 N H2SO4) mixtu re. 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 resultin g zirconium sulfate tetrahydrate is filtered, washed, dried, and calci ned at 1000 degrees C for 6-8 hours. A high-purity zirconium dioxide i s obtained which has a variety of industrial and scientific applicatio ns, especially for the preparation of artificial gems.