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US 6,274,112 B1Granted
Continuous production of silica-based microgels
AssigneeE. I. Du Pont de Nemours and Company
InventorsRobert Harvey Moffett, Walter John Simmons
Life of this patent
Estimating the term…
Abstract
A continuous process is provided for preparing silica microgels using carbon dioxide as a gel initiator at a pressure of at least about 172 kPa (about 25 psig). Consistent performance of microgel can be produced with varying production rates.
Claims20
A continuous process for preparing polysilicate microgels comprising:
- (a) contacting a feed stream comprising a silica source, wherein the silica source is selected from the group consisting of an aqueous solution of a water soluble silicate and a colloidal silica sol, with a feed stream comprising carbon dioxide in a contacting vessel to produce a mixture;
- and
- (b) aging the mixture in an aging vessel to partially gel the mixture to produce an aged mixture,
- wherein the contacting step, the aging step, or both, is performed at a pressure of at least about 172 kPa.
1 more element
A continuous process for preparing polysilicate microgels comprising:
- (a) contacting a feed stream comprising a silica source, wherein the silica source is an aqueous solution of a water soluble silicate, with a feed stream comprising carbon dioxide in a contacting vessel to produce a mixture;
- and
- (b) aging the mixture in an aging vessel to partially gel the mixture to produce an aged mixture,
- wherein the concentration of silica in the feed stream comprising the silica source is in the range of 0.5 to 15%, by weight;
- carbon dioxide is present in an amount that is at least 80% of the stoichiometric amount needed to neutralize the alkalinity of said silica, and said process is carried out at a pressure in the range of about 344 kPa to 1380 kPa.
2 more elements
A continuous process for preparing polysilicate microgels comprising:
- (a) contacting a feed stream comprising a silica source, wherein the silica source is an aqueous solution of a water soluble silicate, with a feed stream comprising carbon dioxide in a contacting vessel to produce a mixture having a pH in the range of 6.5 to 7.5;
- (b) aging the mixture in an aging vessel to partially gel the mixture to produce an aged mixture;
- (c) diluting the aged mixture to a silica concentration of less than 5%,
- wherein carbon dioxide is present in an amount that is at least the stoichiometric amount needed to neutralize the alkalinity of said silica, and said process is carried out at a pressure in the range of about 344 kPa to 1380 kPa.
1 more element
Dependencies are inferred from the claim text.