Patent ID: 7897125
Filing Date: 2011-03-01
Classification: C01B,C01D,C01F,Y02P

Abstract:
1. A process for recovering useful compounds from a byproduct composition produced in a silicon tetrafluoride production process, comprising: calcining a byproduct composition comprising sodium sulfate and aluminum sulfate and forming an oxidized phase mixture comprising alumina solids, and sodium sulfate and a gaseous phase comprising sulfur trioxide; absorbing the gaseous sulfur trioxide in a mixture of sulfuric acid and water to produce oleum; cooling the oxidized phase mixture to produce a cooled solid phase mixture; mixing the cooled solid phase mixture with water to produce a dissolved product comprising dissolved sodium sulfate and suspended alumina solids; filtering the dissolved product to obtain a cake comprising alumina and a sodium sulfate salt solution; crystallizing the sodium sulfate salt solution to produce steam condensate and a sodium sulfate sludge; drying the cake to produce alumina solids; and drying the sludge to produce a dry sodium sulfate salt.