Process for preparing sodium bicarbonate particles

Patent metadata

Field	Value
Publication number	US-9695059-B2
Application number	US-201214365121-A
Country	US
Kind code	B2
Filing date	Dec 19, 2012
Priority date	Dec 21, 2011
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

A process for preparing sodium bicarbonate particles, comprising the steps of: (a) adding at least one alkali metal carbonate to an aqueous solution in order to form an aqueous composition; wherein the alkali metal carbonate comprises sodium carbonate and wherein the aqueous composition comprises at least one polycarboxylic acid and/or the salts thereof, in an amount of at least 200 ppm based on the weight of the aqueous composition; and (b) precipitating solid particles comprising sodium bicarbonate crystals and separating said sodium bicarbonate particles from the aqueous composition, in order to obtain sodium bicarbonate particles and an aqueous mother liquor.

First claim

The invention claimed is:

1. A process for preparing sodium bicarbonate particles, the process comprising the steps of:
(a) adding at least one alkali metal carbonate to an aqueous solution in order to form an aqueous composition; wherein the alkali metal carbonate comprises sodium carbonate and wherein the aqueous composition comprises at least one polycarboxylic acid and/or salts thereof, in an amount of at least 2500 ppm based on the weight of the aqueous composition; and
(b) precipitating solid particles comprising crystals of sodium bicarbonate in said aqueous composition of step (a) and separating said sodium bicarbonate particles from the aqueous composition, in order to obtain sodium bicarbonate particles and an aqueous mother liquor.

2. The process according to claim 1 , wherein step (b) comprises contacting the aqueous composition with a gas comprising carbon dioxide.

3. The process according to claim 1 , wherein the aqueous composition of step (a) comprises sodium carbonate and sodium bicarbonate, and wherein the weight ratio of sodium carbonate to sodium bicarbonate is higher than 1.0.

4. The process according to claim 1 , wherein the at least one polycarboxylic acid and/or the salt thereof is selected from the group consisting of sodium polyacrylate, copolymers of acrylic acid and maleic acid, polyacrylic acid, and blends thereof.

5. The process according to claim 1 , wherein the aqueous composition of step (a) has a pH of at least 8.

6. The process according to claim 1 , wherein the process is performed at a temperature of at most 70° C.

7. The process according to claim 1 , wherein the aqueous composition comprises at least 100 g of said alkali metal carbonate per kg of said aqueous composition.

8. The process according to claim 1 , wherein the aqueous composition comprises from 0.2 g to 5.0 g of the polycarboxylic acid and/or salts thereof per kg of said aqueous composition.

9. The process according to claim 1 , wherein the sodium bicarbonate particles have an average equivalent spherical diameter D50 of at least 10 μm, as measured by laser light scattering.

10. The process according to claim 1 , wherein the sodium bicarbonate particles have an average equivalent spherical diameter D90 of at least 60 μm, as measured by laser light scattering.

11. The process according to claim 1 , wherein the sodium bicarbonate particles have an average BET specific surface area of at least 2.0 m 2 /g.

12. The process according to claim 1 , wherein said sodium bicarbonate particles have an average equivalent spherical diameter D50 of at least 10 μm, a D90 of at least 60 μm, as measured by laser light scattering, and an average BET specific surface area of at least 1.0 m 2 /g.

13. The process according to claim 1 , wherein said at least one alkali metal carbonate added to said aqueous solution in step (a) comprises sodium sesquicarbonate.

14. The process according to claim 1 , wherein said at least one polycarboxylic acid or salt thereof has an average molar mass ranging from 1 to 200 kg/mol.

15. The process according to claim 1 , wherein said sodium bicarbonate particles prepared by said process have an average BET specific surface area of at least 4.0 m 2 /g.

16. The process according to claim 1 , wherein said sodium bicarbonate particles prepared by said process have an average BET specific surface area from 2.0 m 2 /g to 10.0 m 2 /g.

17. The process according to claim 1 , wherein said sodium bicarbonate particles prepared by said process comprise at least 90% by weight of sodium bicarbonate.

18. A process for preparing sodium carbonate particles, comprising performing the process according to claim 1 to prepare sodium bicarbonate particles and further comprising the step of converting the sodium bicarbonate particles to sodium carbonate by calcination at a temperature of at least 80° C. to form sodium carbonate particles, wherein the sodium carbonate particles have an average BET specific surface area of at least 10 m 2 /g.

19. Sodium bicarbonate particles, having an average equivalent spherical diameter D50 of at least 10 μm, a D90 of at least 60 μm, as measured by laser light scattering, and an average BET specific surface area of at least 4.0 m 2 /g, wherein at least one polycarboxylic acid and/or salts thereof is used as an additive in an amount of at least 2500 ppm in an aqueous composition containing at least one alkali metal carbonate from which sodium bicarbonate is formed during its preparation process.

20. The sodium bicarbonate particles according to claim 19 , wherein the average BET specific surface area is from 4.0 m 2 /g to 10.0 m 2 /g.

21. Sodium carbonate particles, having an average equivalent spherical diameter D50 of at least 10 μm, a D90 of at least 60 μm, as measured by laser light scattering, and an average BET specific surface area of at least 15 m 2 /g.

22. The sodium carbonate particles according to claim 21 , wherein at least one polycarboxylic acid and/or salts thereof is used as an additive during its preparation process.

Assignees

• Solvay

Inventors

• Chau Thoi-Dai
• Savary David Jean Lucien

Classifications

• C01D7/126

  Multi-step processes, e.g. from trona to soda ash · CPC title

• C01P2004/61

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

• C01D7/10 Primary

  Preparation of bicarbonates from carbonates (ammonia soda process C01D7/18) · CPC title

• C01P2006/13

  thermal stability thereof at high temperatures · CPC title

• C01D7/12

  Preparation of carbonates from bicarbonates {or bicarbonate-containing product} · CPC title