Patent ID: 8512664

Claim:
A method for hydrothermal production of an aqueous sodium silicate solution having a SiO 2 :Na 2 O molar ratio of at least 3.0:1, said method comprising the steps of: (i) exfoliating and removing titanium dioxide particles adhering to surfaces of a precursor solid silica source, to form cleaned silica; (ii) producing an intermediate sodium silicate solution by a hydrothermal fusion reaction of the cleaned silica with a caustic soda in an autoclave; (iii) forming an amorphous silica source by transposing the SiO 2 content of the intermediate sodium silicate solution of step (ii) by a separate precipitation process; and (iv) dissolving the amorphous silica provided in step (iii) in the intermediate sodium silicate solution of step (ii) and raising the SiO 2 :Na 2 O molar ratio to result in a high modulus sodium silicate solution.