Process for the preparation of crystalline sodium silicates having a sheet structure

Patent 5211930 Issued on May 18, 1993. Estimated Expiration Date:

April 26, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

3208822

3377134

3687640

3748103

3884645

3918921

Zeolite A crystals of uniformly small particle size and the manufacture thereof
Patent #: 4173622
Issued on: 11/06/1979
Inventor: Robertson

Process for the preparation of crystalline sodium silicates
Patent #: 4585642
Issued on: 04/29/1986
Inventor: Rieck

Use of crystalline layered sodium silicates for softening water and a process for softening water Patent #: 4664839
Issued on: 05/12/1987
Inventor: Rieck

Inventors

Application

No. 693782 filed on 04/26/1991

US Classes:

423/333, By precipitating or gelling from silicate solution423/326, Metal containing (i.e., silicate)423/332, Alkali metal containing (Li, Na, K, Rb, or Cs)423/334By heat treating silica and the alkali metal

Examiners

Primary: Breneman, R. Bruce

Attorney, Agent or Firm

Connolly & Hutz

Foreign Patent References

57-175725 JP 10/13/1982

International Class

C01B 033/32

Foreign Application Priority Data

1987-06-01 DE

Abstract

For the preparation of crystalline sodium silicates having a sheet structure and an SiO2 /Na2 O molar ratio of 1.9:1 to 3.5:1 from waterglass solutions having a solids content of 20 to 65% by weight, the waterglass solutions are first treated in a spray-drying zone. This gives a pulverulent amorphous sodium silicate having a maximum ignition loss of 20% by weight, while the waste gas leaving the spray-drying zone is at a temperature of at least 140° C. Thereafter, the spray-dried sodium silicate is heated in an ignition zone containing an agitated solid bed at temperatures of 500° to 800° C. for 1 to 60 minutes in the presence of at least 10% by weight of recycled material. This recycled material was obtained by mechanical comminution of crystalline sodium silicate discharged from the ignition zone.