Patent ID: 7534411
Filing Date: 2009-05-19
Classification: C01B,C01P

Abstract:
1. 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 (SiO 2 ) content of at least 99.9%, and wherein said liquid phase from said first stage is restricted from entering said second stage.