| 摘要 |
PROBLEM TO BE SOLVED: To provide a nearly spherical porous silica granule having homogeneous texture, small pore diameter, pore volume and specific surface area, high bulk specific gravity and capable of forming a quartz glass without causing the shrinkage, provide its production process and provide a process for producing synthetic quartz glass powder by using the porous silica granule. SOLUTION: The porous silica granule is characterized by a nearly spherical form, a carbon concentration of <1 ppm, a pore volume of <=0.5 cm3/g per 1 g of the granule, an average pore diameter of <=50 nm, a specific surface area of <=100 m2/g and a bulk density of >=0.7 g/cm3. The invention further discloses its production process and a process for producing synthetic quartz glass powder by using the porous silica granule.
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