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US 5,030,286 AGranted
High solids aqueous silica slurry
AssigneePPG Industries, Inc.
InventorsRoger A. Crawford, Thomas G. Krivak, Patrick G. Malloy, Da-Hung Yang
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AssigneePPG Industries, Inc.
InventorsRoger A. Crawford, Thomas G. Krivak, Patrick G. Malloy, Da-Hung Yang
Estimating the term…
Described are high solids aqueous slurries of amorphous precipitated hydrated silica, which slurries are of relatively low viscosity. The slurry typically contains from about 40 to about 60 weight percent of hydrated precipitated high structure silica. The viscosity of the high solids slurry is less than about 1000 centipoises. Processes for producing the aqueous high solids silica slurry are disclosed. In one embodiment, a wet cake of amorphous precipitated hydrated silica is liquified and the liquified wet cake charged to a high intensity mill wherein the silica is wet milled until the median agglomerate particle size of the silica is between about 0.3 and about 3 microns. In a further embodiment, finely-divided dry amorphous precipitated silica is slurried in a dispersion mill to the desired solids level and this slurry charged to a high-intensity mill and wet milled therein until the aforesaid agglomerate particle size range is attained. The resulting high solids slurry can be shipped in bulk with only mild agitation to prevent setting. A dispersant may also be added to the slurry prior to milling to retard settling of the silica.
A pumpable aqueous slurry of precipitated silica wherein the slurry contains from about 40 to about 60 weight percent of amorphous precipitated silica having a median agglomerate particle size of from about 0.3 to about 3 microns and a pH of from about 4 to about 8.5, said aqueous slurry having a Brookfield viscosity of less than 1000 centipoises.
A process for producing a pumpable slurry of precipitated silica, comprising wet milling amorphous, precipitated silica having a median agglomerate particle size of from above 3 microns to less than 30 microns and a pH of from about 4 to about 8.5 for a time sufficient to reduce the silica agglomerates to a median agglomerate particle size of from about 0.3 to about 3 microns, thereby to produce a pumpable, aqueous silica slurry having a Brookfield viscosity of less than 1000 centipoises.
A process for producing a pumpable, aqueous silica slurry, which comprises wet milling an aqueous slurry of amorphous, precipitated silica, said slurry containing at least about 35 weight percent silica having a median agglomerate particle size of from above 3 to less than about 30 microns and a pH of from about 4 to about 8.5, in a high speed, fluid shear mill for a time sufficient to reduce the silica agglomerates to a median particle size of from about 0.5 to about 2 microns, thereby to produce a pumpable, aqueous silica slurry having a Brookfield viscosity of less than 500 centipoises.
A process for producing a pumpable, aqueous silica slurry, which comprises wet milling an aqueous slurry of amorphous precipitated silica containing at least about 35 weight percent silica, said silica having a pH of from about 4 to about 8.5, in a moderate intensity mill for a time sufficient to reduce the silica agglomerates to a median agglomerate particle size of from about 7 to about 25 microns, thereby to produce a first milled aqueous silica slurry, milling first milled aqueous slurry in a high speed, fluid shear mill for a time sufficient to reduce further the silica agglomerates to a median particle size of from about 0.3 to about 3 microns, thereby to produce a pumpable, aqueous silica slurry product having a Brookfield viscosity of less than 1000 centipoises.
Dependencies are inferred from the claim text.