US 2009/0022646 A1 · Process for hydrothermal production of sodium silicate solutions and precipitated silicas

Abstract

A method is provided for treating silica sand scrubs (SSS) generated and accumulated as waste in the chloride manufacturing process of titanium dioxide pigment. A hydrothermal process is used to produce sodium silicate solutions of modulus 3.0 to 3.8, and precipitated silicas. In some embodiments, the process uses two specific principal reaction stages. A sodium silicate solution having a low SiO2:Na2O molar ratio, in the range from 2.0 to 2.8, is first produced by reaction of the SSS, as a cost-effective SiO2 source, with aqueous caustic soda. The conversion of this intermediate sodium silicate solution of low modulus to a high SiO2:Na2O molar ratio is made possible by using a SiO2 source that is prepared as precipitated amorphous silica from the intermediate sodium silicate solution produced above.

Claims21

Dependent claims

A method for hydrothermal production of aqueous sodium silicate solution having a SiO2:Na2O molar ratio of at least 3.0:1, said method comprising the steps of:

(i) providing a precursor solid silica source;
(ii) producing an intermediate sodium silicate solution by a hydrothermal fusion reaction of the precursor solid silica source of step (i) with a caustic soda in an autoclave;
(iii) providing an amorphous silica source by transposing the SiO2 content of the intermediate sodium silicate 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 SiO2:Na2O molar ratio to result in a high modulus sodium silicate solution.

2 more elements

Dependencies are inferred from the claim text.

Process for hydrothermal production of sodium silicate solutions and precipitated silicas

Life of this patent

Process for hydrothermal production of sodium silicate solutions and precipitated silicas

Life of this patent

Abstract

Claims21