Methods of forming an aqueous silica suspension are provided. The methods include admixing water, an organic acid, a silica powder, and a siliconate under certain conditions. The silica powder includes undensified silica powder in an amount of at least about 50% by weight and has a specific gravity in the range of from about 2.1 to about 2.5, a bulk density in the range of from about 12 lb/ft3 to about 40 lb/ft3, and a water requirement of from about 80 to about 250 at a pH in the range of from about 5.5 to about 7.5. Also provided are aqueous silica suspensions, hydraulic cement compositions, and methods of cementing in a well.

A method for producing a dispersion liquid of silica particles, by simultaneously adding a liquid A containing silane alkoxide and a liquid B containing an alkali catalyst and water to a liquid I containing silica seed particles to cause the particles to grow, so as to produce silica particles; wherein the variation rate of the mole ratio of the alkali catalyst to silica components in the reaction system during a period from the start to the end of the addition relative to the initial mole ratio is 0.90 to 1.10; and the variation rate of the mole ratio of water to the silica components in the reaction system during a period from the start to the end of the addition relative to the initial mole ratio is 0.90 to 1.10.

A method for producing a dispersion liquid of silica particles, by simultaneously adding a liquid A containing silane alkoxide and a liquid B containing an alkali catalyst and water to a liquid I containing silica seed particles to cause the particles to grow, so as to produce silica particles; wherein the variation rate of the mole ratio of the alkali catalyst to silica components in the reaction system during a period from the start to the end of the addition relative to the initial mole ratio is 0.90 to 1.10; and the variation rate of the mole ratio of water to the silica components in the reaction system during a period from the start to the end of the addition relative to the initial mole ratio is 0.90 to 1.10.

The present invention provides a means capable of suppressing the formation of fine particles in a method for producing a silica sol. The present invention relates to a method for producing a silica sol, including synthesizing a silica sol by, in a reaction liquid containing an alkoxysilane or a condensate thereof, water, and an alkali catalyst, allowing the alkoxysilane or condensate thereof to react with the water in the presence of the alkali catalyst, wherein the alkali catalyst is not additionally supplied after the start of the synthesis until the finish time of the synthesis, and during 90% or more of the time between when 5 minutes have elapsed from the time point when the electrical conductivity of the reaction liquid reaches a local maximum for the first time and the finish time of the synthesis, the proportion of the value of the electrical conductivity of the reaction liquid is more than 90% relative to the value of the electrical conductivity at the time when 5 minutes have elapsed from the time point when the local maximum is reached.

The present invention provides a means capable of suppressing the formation of fine particles in a method for producing a silica sol. The present invention relates to a method for producing a silica sol, including synthesizing a silica sol by, in a reaction liquid containing an alkoxysilane or a condensate thereof, water, and an alkali catalyst, allowing the alkoxysilane or condensate thereof to react with the water in the presence of the alkali catalyst, wherein the alkali catalyst is not additionally supplied after the start of the synthesis until the finish time of the synthesis, and during 90% or more of the time between when 5 minutes have elapsed from the time point when the electrical conductivity of the reaction liquid reaches a local maximum for the first time and the finish time of the synthesis, the proportion of the value of the electrical conductivity of the reaction liquid is more than 90% relative to the value of the electrical conductivity at the time when 5 minutes have elapsed from the time point when the local maximum is reached.

The invention relates to aqueous silica dispersion with a pH in the range from 8 to 14, comprising a base chosen from the group consisting of alkali metal hydroxides, (akyl)ammonium hydroxides or a mixture thereof, at least 35% by weight of silica particles surface-treated with an amino-organosilane (I) and/or a product of hydrolysis of compound of formula (I), 3% to 35% by weight of at least one polyol, 20% to 60% by weight of water, preparation of such dispersion and the use thereof in fire-resistant glass.

Disclosed is a method of preparing colloidal silica, more particularly a method of producing high-concentration (10-55 wt %) colloidal silica by reacting water with a tetraalkyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS) based silane precursor as a starting material in the presence of a basic catalyst.

Disclosed is a method of preparing colloidal silica, more particularly a method of producing high-concentration (10-55 wt %) colloidal silica by reacting water with a tetraalkyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS) based silane precursor as a starting material in the presence of a basic catalyst.

Methods of forming an aqueous silica suspension are provided. The methods include admixing water, an organic acid, a silica powder, and a siliconate under certain conditions. The silica powder includes undensified silica powder in an amount of at least about 50% by weight and has a specific gravity in the range of from about 2.1 to about 2.5, a bulk density in the range of from about 12 lb/ft3 to about 40 lb/ft3, and a water requirement of from about 80 to about 250 at a pH in the range of from about 5.5 to about 7.5. Also provided are aqueous silica suspensions, hydraulic cement compositions, and methods of cementing in a well.

A colloidal silica is disclosed that contains, with high purity, silica particles having an appropriate particle density, a high aggregation ratio, and a high alkoxy group content, and to provide a method for producing the colloidal silica in a simple manner at reduced costs. The colloidal silica containing silica particles is disclosed, wherein the silica particles have an average primary particle size of 33 nm or more, an aggregation ratio of 1.2 or more, and a particle density of 1.95 or more, the silica particles contain 1000 ppm by mass or more of alkoxy groups per gram of the silica particles, the proportion of the number of silica particles having an equivalent circle diameter under 20 nm is less than 15%, and the silica particles contain a primary amine in an amount of 5 μmol or more per gram of the silica particles.