| 摘要 |
PURPOSE:To prepare high-purity cristobalite in an extremely short time, by calcining silica raw material powder having >=given specific surface area by Blain permeability method at a temperature to cause transition to cristobalite. CONSTITUTION:Silica raw material powder such as silica, silica sand, etc. having a powder degree of >=4,000cm<2>/g specific surface area by Blain permeability method is calcined at a temperature to cause transition to cristobalite, so that it can be converted to high-purity cristobalite in a short time of <=about 30min. A composition comprising the raw material powder and a binder such as an aqueous solution of sodium carbonate is granulated, molded, and calcined, so that handling of the raw material during process of preparation and calcined material is made easy. A composition comprising the raw material powder and 0.1-5wt% mineralizer such as a compound containing an alkali or alkaline earth metal is calcined, so that high-purity cristobalite can be prepared in a shorter time.
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