Patent ID: 8709370

Claim:
A method for producing sodium silicate glass during a production of a high purity silicon (Si), comprising: precipitating sodium fluorosilicate (Na 2 SiF 6 ) from fluorosilicic acid (H 2 SiF 6 ); thermally decomposing the Na 2 SiF 6 to produce a silicon tetrafluoride gas (SiF 4 ) and sodium fluoride (NaF); reducing the SiF 4 with sodium (Na) to produce NaF and the high purity Si in a first reactor; providing the NaF from the reduction of the SiF 4 from the first reactor and silica sand (SiO 2 ) in a second reactor; and heating the second reactor to produce additional SiF 4 and the sodium silicate glass doped with fluorine ions (Na 2 SiO 3 (F)), wherein the heating comprises providing energy released from the first reactor in an exothermic reaction of the SiF 4 that is reduced with the Na; purifying the additional SiF 4 via a condenser absorber train; and recycling the additional SiF 4 back into the reducing step.