US5030433A
Expired / Lapsed
US
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Process for producing pure and dense amorphous synthetic silica particles
Assignee: International Minerals and Chemical Corp
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Filing: 1988-07-18
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Granted: 1991-07-09
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Expires: 2008-07-18
Abstract
Abstract A method of producing pure and dense amorphous fused synthetic silica. Silica of desired purity is wet pelletized or agglomerated to form particles having an average particle size of between about 5 and 2500 microns. These particles are calcined to volatilize impurities and increase density to at least about 0.9 g/cm 3 . Calcined particles are classified by size or reduced in size if desired or needed by grinding in such a way that the purity of the product is maintained.
Inventors
- 👤 Vikram P. Mehrotra
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 08:58
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C09; C09C; C09C1/00; C09C1/28; C09C1/30; C09C1/3009; C09C1/3036; C01P; C01P2002/00; C01P2002/02; C01P2004/00; C01P2004/50; C01P2004/51; C01P2004/60; C01P2004/61; C01P2006/00; C01P2006/10; C01P2006/14
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
160 words
A method of producing pure and dense amorphous fused silica particles comprising: (a) agglomerating pure, synthetic amorphous silica to form agglomerated particles having a size of 5-2500 microns; (b) heating the agglomerated particles of step (a) to a temperature of between about 1000° and 1100° C. under an atmosphere inert to silica and essentially devoid of oxygen and water and maintaining said temperature for a for a period sufficient to volatize impurities said period being at least least about 0.5 hour at 1000° C. and shorter at higher temperatures; (c) raising the temperature of the treated particles of step (b) to between about 1250° and 1400° C. under an atmosphere inert to silica and essentially devoid of oxygen and water and maintaining the temperature for at least about 0.25 hours to achieve an average bulk density of at least about 0.9 g/cm 3 ; and (d) cooling the dense particles of step (c) to a temperature below about 1000° C.
Claim 2
Independent Claim
160 words
A method of producing pure and dense amorphous fused silica particles comprising: (a) agglomerating pure, synthetic amorphous silica to form agglomerated particles having a size of 5-2500 microns; (b) heating the agglomerated particles of step (a) to a temperature of between about 1000° and 1100° C. under an atmosphere inert to silica and essentially devoid of oxygen and water and maintaining said temperature for a for a period sufficient to volatize impurities said period being at least least about 0.5 hour at 1000° C. and shorter at higher temperatures; (c) raising the temperature of the treated particles of step (b) to between about 1250° and 1400° C. under an atmosphere inert to silica and essentially devoid of oxygen and water and maintaining the temperature for at least about 0.25 hours to achieve an average bulk density of at least about 0.9 g/cm 3 ; and (d) cooling the dense particles of step (c) to a temperature below about 1000° C.
Claim 3
Dependent Claim
35 words
The method of claim 1 wherein the agglomeration of step (a) is carried out in the presence of water in a quantity up to about 200 wt. percent based on the weight of dry silica.
Claim 4
Dependent Claim
25 words
The method of claim 2 wherein the quantity of water is between about 20 and 150 wt. percent based on the weight of dry silica.
Claim 5
Dependent Claim
10 words
The method of claim 3 wherein the water is steam.
Claim 6
Dependent Claim
27 words
The method of claim 1 wherein agglomeration is carried out in a tumbling device which has been coated with material which does not permanently contaminate the silica.
Claim 7
Dependent Claim
27 words
The method of claim 1 wherein the atmosphere of step (b) is selected from the group consisting of nitrogen, helium, argon, neon, krypton, xenon, and mixtures thereof.
Claim 8
Dependent Claim
17 words
The method of claim 6 wherein the period of step (b) is at least about 0.5 hours.
Claim 9
Dependent Claim
18 words
The method of claim 7 wherein the period of step (b) is between about 0.5 and 12 hours.
Claim 10
Dependent Claim
18 words
The method of claim 7 wherein the period of step (c) is between about 0.5 and 2.5 hours.
Claim 11
Dependent Claim
18 words
The method of claim 8 wherein the period of step (c) is between about 0.5 and 2.5 hours.
Claim 12
Dependent Claim
22 words
The method of claim 1, further comprising comminuting the cooled particles of step (d) to yield particles smaller than about 200 microns.
Claim 13
Dependent Claim
18 words
The method of claim 11 wherein the cooled particles are comminuted to particles smaller than about 100 microns.
Claim 14
Dependent Claim
18 words
The method of claim 12 wherein the cooled particles are comminuted to particles smaller than about 75 microns.
Claim 15
Dependent Claim
22 words
The method of claim 8, further comprising comminuting the cooled particles of step (d) to yield particles smaller than about 200 microns.
Claim 16
Dependent Claim
22 words
The method of claim 10, further comprising comminuting the cooled particles of step (d) to yield particles smaller than about 200 microns.
Claim 17
Dependent Claim
21 words
The method of claim 11 wherein the average bulk density after size reduction is at least about 1.2 g/cm 3 .
Claim 18
Dependent Claim
29 words
The method of claim 1 wherein the rate of temperature increase of step (c) and the cooling rate of step (d) are at least about 9° C. per minute.
Claim 19
Dependent Claim
19 words
The method of claim 17 wherein each rate of temperature change is at least about 20° C. per minute.
Claim 20
Dependent Claim
19 words
The method of claim 18 wherein each rate of temperature change is at least about 30° C. per minute.
Claim 21
Dependent Claim
36 words
The method of claim 17 wherein the agglomeration of step (a) is carried out in the presence of water at a quantity between about 20 and 150 weight percent based on the weight of dry silica.
Claim 22
Dependent Claim
58 words
The method of claim 11 wherein the comminution is carried out in a fluid energy mill lined with a material which can be oxidized and further comprising oxidizing said material which contaminates the pure silica at a temperature between 500° and 1000° C. for up to about one hour to remove said material from the pure silica particles.
Claim 23
Dependent Claim
58 words
The method of claim 14 wherein the comminution is carried out in a fluid energy mill lined with a material which can be oxidized and further comprising oxidizing said material which contaminates the pure silica at a temperature between 500° and 1000° C. for up to about one hour to remove said material from the pure silica particles.
Claim 24
Dependent Claim
58 words
The method of claim 15 wherein the comminution is carried out in a fluid energy mill lined with a material which can be oxidized and further comprising oxidizing said material which contaminates the pure silica at a temperature between 500° and 1000° C. for up to about one hour to remove said material from the pure silica particles.
Claim 25
Independent Claim
195 words
A method of producing pure and dense amorphous fused silica particles comprising: (a) agglomerating synthetic amorphous silica with water and essentially completely evaporating the water to form agglomerated particles having a size of 5-2500 microns; (b) heating the particles of step (a) to a temperature of between about 1000° and 1100° C. under an atmosphere selected from the group consisting of nitrogen, helium, argon, neon, krypton, xenon, and mixtures thereof, and which is essentially devoid of oxygen and water, for a period of at least about 0.5 hours; (c) raising the temperature of the treated particles of step (b) at a rate of at least about 20° C. per minute to between about 1250° and 1400° C. under an atmosphere selected from the group consisting of nitrogen, helium, argon, neon, krypton, xenon, and mixtures thereof, and which is essentially devoid of oxygen and water, and maintaining the temperature for at least about 0.25 hours to achieve an average bulk density of at least about 1.0 g/cm 3 ; and (d) cooling the dense particles of step (c) to a temperature below about 1000° C. at a rate of at least about 20° C. per minute.
Claim 26
Independent Claim
195 words
A method of producing pure and dense amorphous fused silica particles comprising: (a) agglomerating synthetic amorphous silica with water and essentially completely evaporating the water to form agglomerated particles having a size of 5-2500 microns; (b) heating the particles of step (a) to a temperature of between about 1000° and 1100° C. under an atmosphere selected from the group consisting of nitrogen, helium, argon, neon, krypton, xenon, and mixtures thereof, and which is essentially devoid of oxygen and water, for a period of at least about 0.5 hours; (c) raising the temperature of the treated particles of step (b) at a rate of at least about 20° C. per minute to between about 1250° and 1400° C. under an atmosphere selected from the group consisting of nitrogen, helium, argon, neon, krypton, xenon, and mixtures thereof, and which is essentially devoid of oxygen and water, and maintaining the temperature for at least about 0.25 hours to achieve an average bulk density of at least about 1.0 g/cm 3 ; and (d) cooling the dense particles of step (c) to a temperature below about 1000° C. at a rate of at least about 20° C. per minute.
Claim 27
Dependent Claim
24 words
The method of claim 24 wherein the rates of temperature change of steps (c) and (d) are at least about 30° C. per minute.
Claim 28
Dependent Claim
35 words
The method of claim 24, further comprising comminuting the cooled particles of step (d) to yield particles smaller than about 200 microns and having an average bulk density greater than about 1.2 g/cm 3 .
Claim 29
Dependent Claim
35 words
The method of claim 25, further comprising comminuting the cooled particles of step (d) to yield particles smaller than about 200 microns and having an average bulk density greater than about 1.2 g/cm 3 .
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| 7.5 Years (Year 8) | 1998-07-08 | 1999-01-07 | 1999-07-09 | $3760.00 | Window Closed / Lapsed |
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