Process for the preparation of pure silica
AssigneeSTI Silicon Technologies Israel Ltd.
InventorsLev Shapira, Simcha Harel
Life of this patent
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Abstract
A production process for producing high-purity silica from a crude silica source by means of fluosilic acid, including the steps of: (a) subjecting the crude silica souce and the fluosilicic acid to a reaction in a reaction stage, so as to produce silicon tetrafluoride and water; (b) selectively evaporating the silicon tetrafluoride with respect to at least a portion of at least one impurity derived from the crude silica source, and (c) reacting the silicon tetrafluoride with water to produce the high-purity silica, wherein the reaction stage (a) is performed at a temperature above 75° C.
Claims22
A production process for producing a solid silica product from a crude, impure silica source by means of fluosilicic acid, the process comprising the steps of:
- (a) subjecting the crude silica source and the fluosilicic acid to a reaction in a first stage of the production process, to produce silicon tetrafluoride and water in a liquid phase, said reaction performed at a temperature above 75° C.;
- (b) selectively evaporating said silicon tetrafluoride and water with respect to at least a portion of at least one impurity derived from the crude silica source, to produce silicon tetrafluoride vapor and water vapor;
- (c) reacting said silicon tetrafluoride vapor with a water source in a second stage to produce the silica product and a regenerated fluosilicic acid, and
- (d) recycling said regenerated fluosilicic acid within the production process, wherein said water vapor is said water source, and wherein said silicon tetrafluoride vapor is indirectly condensed along with said water vapor, to produce the solid silica product and said fluosilicic acid,
- wherein the solid silica product has a silica (SiO2) content of at least 99.9%, and wherein said liquid phase from said first stage is restricted from entering said second stage.
A production process for producing a solid silica product from a crude, impure silica source by means of fluosilicic acid, the process comprising the steps of:
- (a) subjecting the crude silica source and the fluosilicic acid to a reaction in a first stage of the production process, to produce silicon tetrafluoride and water in a liquid phase, said reaction performed at a temperature above 75° C.;
- (b) selectively evaporating said silicon tetrafluoride and water with respect to at least a portion of at least one impurity derived from the crude silica source, to produce silicon tetrafluoride vapor and water vapor, and
- (c) reacting said silicon tetrafluoride vapor with a water source in a second stage to produce the silica product and a regenerated fluosilicic acid, wherein said water vapor is said water source, and wherein said silicon tetrafluoride vapor is indirectly condensed along with said water vapor, to produce the solid silica product and said fluosilicic acid,
- wherein the solid silica product has a silica (SiO2) content of at least 99.9%, and wherein said liquid phase from said first stage is restricted from entering said second stage,
- and wherein the high-purity silica has a surface area below 20 m2/g.
Dependencies are inferred from the claim text.