Production of Zirconia from Zircon by Thermal Reaction with Calcium Oxide

Abstract

Thermal reaction of Zircon with lime is studied within the temperature range 1200-1500°C for periods up to 4h. The heating products are examined physically, chemically and mineralogically. The extent of reaction is determined from the solubilized silica obtained by leaching the sintered products in hydrochloric acid. A product assaying -91% ZrO₂ in monoclinic form is obtained by HCl acid leaching of the product fired at 1400°C for 2h in presence of 1.2 stoichiometry calcium oxide. The thermal reaction of decomposition at the aforementioned temperature seem to follow a diffusion kinetic model in the form of x+(1-x)In(1-x)=kt, where x is the extent of solubilized silica in time t and k is the rate constant. The apparent activation energy of the process was calculated and found to be 205kJ/mole.