Method for preparing particles of alkali metal bicarbonate

Patent metadata

Field	Value
Publication number	US-9815708-B2
Application number	US-201414900524-A
Country	US
Kind code	B2
Filing date	Jun 26, 2014
Priority date	Jun 26, 2013
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

A method for preparing particles of alkali metal bicarbonate by crystallization from a solution of alkali metal carbonate and/or bicarbonate in the presence of an additive in the solution, selected from the sulfates, sulfonates, the polysulfonates, the mines, the hydroxysultaines, the polycarboxylates, the polysaccharides, the polyethers and the etherphenols, alkali metal hexametaphosphate, the phosphates such as the organophosphates or the phosphonates, the sulfosuccinates, the amido-sulfonates, the aminosulfonates, preferably selected from: the phosphates, the organophosphates or the phosphonates, and such that the additive is present in the solution at a concentration of at least 1 ppm and preferably of at most 200 ppm.

First claim

The invention claimed is:

1. A method for preparing, by crystallization, alkali metal bicarbonate particles starting from a solution of alkali metal carbonate and/or bicarbonate in the presence of an additive in the solution,
wherein the additive is an amine selected from the group consisting of hexamethylenediamine, hydroxysultaines, and quaternary amines comprising at least one carboxylic acid group, and wherein the additive is present in the solution at a concentration of at least 1 ppm.

2. The method as claimed in claim 1 , wherein the additive is present at a concentration of at most 200 ppm.

3. The method as claimed in claim 1 , wherein crystallization of the alkali metal bicarbonate particles is carried out by cooling the solution.

4. The method as claimed in claim 3 , wherein cooling of the solution is carried out between 70° and 30° C.

5. The method as claimed in claim 1 , wherein crystallization of the alkali metal bicarbonate particles is carried out by carbonation of the solution with carbon dioxide.

6. The method as claimed in claim 5 , wherein carbonation of the solution is carried out at a temperature of at least 20° C.

7. The method as claimed in claim 5 , wherein carbonation of the solution with carbon dioxide is carried out with a gas comprising: 10 to 100% of CO2 by volume based on dry gas.

8. The method as claimed in claim 1 , wherein crystallization of the alkali metal bicarbonate particles is carried out by evaporation of at least a proportion of the solution.

9. The method as claimed in claim 1 , wherein crystallization of the alkali metal bicarbonate particles is carried out by concomitant cooling and carbonation of the solution; or by concomitant cooling and carbonation and evaporation of the solution.

10. The method as claimed in claim 1 , being carried out at a temperature between 20° C. and 95° C.

11. The method as claimed in claim 1 , wherein addition of the additive to the solution is carried out for controlling or modifying:
the granulometry, or
the undersize or oversize on a sieve at 125 μm, or
the undersize or oversize on a sieve at 250 μm,

of the alkali metal bicarbonate particles obtained after separation of the crystallization solution and of the alkali bicarbonate particles.

12. The method as claimed in claim 11 , being carried out for controlling the size of the alkali bicarbonate particles to control the sieve undersize at 125 μm or the sieve oversize at 250 μm of the alkali bicarbonate particles.

13. The method as claimed in claim 1 , wherein addition of the additive to the solution is carried out for controlling or modifying:
the dissolution time, or
the bulk density (BD), or
the flow rate in a calibrated orifice, or
the abrasion index,

of the alkali metal bicarbonate particles obtained after separation of the crystallization solution and of the alkali bicarbonate particles, then drying of the alkali metal bicarbonate particles.

14. The method as claimed in claim 13 , wherein addition of the additive to the solution makes it possible to reduce the BD of the alkali metal bicarbonate particles by at least 10% relative to the BD of alkali metal bicarbonate particles obtained in the same conditions of crystallization but without addition of the additive.

15. The method as claimed in claim 13 , wherein addition of the additive to the solution makes it possible to increase the BD of the alkali metal bicarbonate particles by at least 10% relative to the BD of alkali metal bicarbonate particles obtained in the same conditions of crystallization but without addition of the additive.

16. Alkali metal bicarbonate particles obtainable by the method as claimed in claim 1 and comprising at least 10 ppm of the additive.

17. The method as claimed in claim 1 , wherein the additive is selected from the group consisting of quaternary amines comprising at least one carboxylic acid group.

18. The method as claimed in claim 1 , wherein the additive is selected from the group consisting of:
quaternary amines comprising at least one carboxylic acid group and being of formula:
(H 3 C) 3 —N—R—COOH with R═(CH 2 ) n and n =1 to 4.

19. The method as claimed in claim 18 , wherein the additive is trimethylglycine.

20. The method as claimed in claim 1 , wherein the additive is hexamethylenediamine.

21. The method as claimed in claim 1 , wherein the additive is a hydroxysultaine.

Assignees

• Solvay

Inventors

• Savary David Jean Lucien

Classifications

• C01P2004/61

  Micrometer sized, i.e. from 1-100 micrometer · CPC title

• C01P2004/02

  obtained by optical microscopy · CPC title

• C01P2006/10

  Solid density · CPC title

• C01D7/40 Primary

  Influencing the crystallisation process · CPC title

• C01D7/24

  Crystallisation · CPC title