Production of zirconia from zircon by thermal reaction with calcium oxide

Thermal reaction of Zircon with lime is studied within the temperature range 1200-1500 degrees C for periods up to 4 h. 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 similar to 91%ZrO2 in monoclinic form is obtained by HCl acid leaching of the product fired at 1400 degrees C for 2 h 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)ln(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 205 kJ/mole.