EP0384728A2 — Preparation method for zircon powder

USPTO Abstract

A preparation method for zircon powder, which comprises heating a feed powder mixture comprising: (1) silica and zirconia obtained by subjecting a liquid having a pH of not higher than 8 and containing silica and zirconia in a SiO₂/ZrO₂ molar ratio of substantially 1/1, to liquid-removing treatment, and (2) zircon in an amount of at least 0.1% by weight based on the total amount of said silica and zirconia, at a heating rate of not higher than 5°C/min from 1,200°C to a calcination temperature, and maintaining it at a calcination temperature of from 1,300° to 1,700°C for from 1.0 to 24 hours, or from 700° to 1,200°C over a period of at least 16 hours and maintaining it at a temperature of from 1,300° to 1,700°C for at least 10 hours. A method of making a mixture containing silica and zirconia which comprises dissolving (1) a silicon alkoxide and (2) a reaction mixture of a zirconium alkoxide with a chelating agent, in an organic solvent and contacting the resulting mixed solution with at least the stoichiometric amount of water required for hydrolysis.