High velocity, low pressure process for making silica gels and microgels
AssigneeCiba Specialty Chemicals Corporation
InventorsWalter Simmons, Walter Simmons
Life of this patent
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Abstract
This invention relates to a process for converting silica to polysilicate gels or hydrogels by combining an aqueous silica source with a CO2 feed stream as the gel initiator, whereby the reaction stream is propelled at high velocity and turbulence maintaining the CO2 uptake rate in the reaction stream. The invention also relates to a process for converting silica to polysilicate by pre-carbonating water at pressures of equal to or greater than 100 psig before initiating the polysilicate reaction.
Claims23
A process for preparing polysilicate gels comprising the steps of
- (a) contacting a first feed stream wherein the first feed stream comprises a silica source selected from the group consisting of an aqueous solution of a water-soluble silicate, a colloidal silica sol and combinations thereof with a second feed stream comprising CO2 to form a reaction stream,
- and
- (b) maintaining the velocity or flow of the reaction stream and turbulence of the reaction stream with at least one propelling device wherein the propelling device propels the reaction stream along a reaction vessel and wherein the turbulence is at least 2300 Reynolds number or the velocity is at least about 3 ft/sec.
A process for pre-carbonating an aqueous solution for making polysilicates comprising
- carbonating an aqueous solution at a pressure of greater than or equal to at least about 25 psig,
- wherein the aqueous solution is carbonated before combining an aqueous solution of a water-soluble silicate, a colloidal silica sol, and combinations thereof to form a reaction mixture.
Dependencies are inferred from the claim text.