Dynamit Nobel Aktiengesellschaft

Rainer Haase

Arnold Lenz

Gerhard Kreuzburg

Volker Hunger

Method of preparing granular quartz glass which comprises heating a porous granulated silica gel having an alkoxy group content equal to or less than 1 weight percent and a total impurity content of less than 1 part per million, the porous granulated silica gel obtained by hydrolysis of an orthosilicic acid ester of an aliphatic alcohol at a temperature up to 1400.degree. C.

Granular quartz glass product

A process for the preparation of an aqueous alkali metal polysilicate solution having an SiO.sub.2 : alkali metal oxide mole ratio of 2.5 - 5.5 : 1 and a silica content of 16 - 23% by weight which comprises contacting a tetraalkoxysilane of the formula Si(OR).sub.4 wherein each R is independently a straight or branched-chain alkyl group of 1 to 3 carbon atoms with an aqueous alkali metal hydroxide solution at a temperature between room temperature and the boiling point of the reaction mixture and at a temperature up to 100.degree. C. distilling over alcohol formed by the reaction of the silane with the alkali metal hydroxide.

Aqueous solutions of alkali polysilicates

Process for the production of granular quartz glass

A process for the preparation of an aqueous alkali metal polysilicate solution having an SiO.sub.2 : alkali metal oxide mole ratio of 2.5 - 5.5 : 1 and a silica content of 16 - 23% by weight which comprises contacting a tetraalkoxysilane of the formula Si(OR).sub.4 wherein each R is independently a straight or branched-chain alkyl group of 1 to 3 carbon atoms with an aqueous alkali metal hydroxide solution at a temperature between room temperature and the boiling point of the reaction mixture and at a temperature up to 100.degree.C. distilling over alcohol formed by the reaction of the silane with the alkali metal hydroxide.

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Bokel, Oldenburg, Germany

Rainer Haase