Process for producing pure and dense amorphous synthetic silica particles
AssigneeInternational Minerals & Chemical Corp.
InventorVikram P. Mehrotra
Life of this patent
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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.sup.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.
Claims27
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.degree. and 1100.degree. 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.degree. C. and shorter at higher temperatures;
- (c) raising the temperature of the treated particles of step (b) to between about 1250.degree. and 1400.degree. 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.sup.3 ;
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- (d) cooling the dense particles of step (c) to a temperature below about 1000.degree. C.
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.degree. and 1100.degree. 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.degree. C. per minute to between about 1250.degree. and 1400.degree. 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.sup.3 ;
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- (d) cooling the dense particles of step (c) to a temperature below about 1000.degree. C. at a rate of at least about 20.degree. C. per minute.
Dependencies are inferred from the claim text.