Process for the joint production of sodium carbonate and sodium bicarbonate

Patent metadata

Field	Value
Publication number	US-9868644-B2
Application number	US-201214367737-A
Country	US
Kind code	B2
Filing date	Dec 19, 2012
Priority date	Dec 23, 2011
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

Process for producing sodium carbonate and sodium bicarbonate in a continuous mode out of trona comprising: c) feeding crushed trona, an extraction water and an additive in a first leaching tank containing a dissolution solution comprising sodium carbonate and sodium bicarbonate, wherein the additive is selected from the group consisting of: anionic hexametaphosphate, anionic polyphosphate, anionic polyphosphonate, soja lecithine, anionic polycarboxylate polymer, anionic polyacrylate polymer, anionic polyacrylate-polyacrylamide co-polymer, anionic hydrolyzed polymaleic polymers, anionic maleic-acrylic acids copolymers, anionic acrylic acid-phosphonic acid copolymers and combinations thereof; d) dissolving at least partially the crushed trona in the dissolution solution in order to produce a first suspension; e) removing continuously the first suspension from the first leaching tank and feeding it with an additive into a second leaching tank wherein the additive is selected from the same group of additives of step c); f) dissolving at least partially the remaining crushed trona from step d) in the second leaching tank in order to produce a second suspension; g) separating the second solid particles from the second solution to produce a production solution comprising sodium carbonate and to produce a production solid comprising the second solid particles comprising sodium bicarbonate.

First claim

The invention claimed is:

1. A process for producing sodium carbonate and sodium bicarbonate in a continuous mode from trona, comprising the following steps:
c. feeding crushed trona, extraction water and an additive in a first leaching tank containing a dissolution solution comprising sodium carbonate and sodium bicarbonate, saturated or super-saturated in sodium bicarbonate, wherein the additive is selected from the group consisting of: anionic hexametaphosphate, anionic polyphosphate, anionic polyphosphonate, soja lecithine, anionic polycarboxylate polymer, anionic polyacrylate polymer, anionic polyacrylate-polyacrylamide co-polymer, anionic hydrolyzed polymaleic polymers, anionic maleic-acrylic acids copolymers, anionic acrylic acid-phosphonic acid copolymers, and combinations thereof;
d. dissolving at least partially the crushed trona in the dissolution solution in order to produce a first suspension comprising solid particles comprising sodium bicarbonate and a first solution comprising sodium carbonate;
e. removing continuously the first suspension from the first leaching tank to obtain a removed first suspension, and feeding the removed first suspension and an additive into a second leaching tank, wherein the additive fed to the second leaching tank is the same or different than the additive fed to the first leaching tank, and wherein the additive fed to the second leaching tank is selected from the group consisting of: anionic hexametaphosphate, anionic polyphosphate, anionic polyphosphonate, soja lecithine, anionic polycarboxylate polymer, anionic polyacrylate polymer, anionic polyacrylate-polyacrylamide co-polymer, anionic hydrolyzed polymaleic polymers, anionic maleic-acrylic acids copolymers, anionic acrylic acid-phosphonic acid copolymers, and combinations thereof;
f. dissolving at least partially the crushed trona remaining in the removed first suspension from step e) in the dissolution solution present in the second leaching tank in order to produce a second suspension comprising second solid particles comprising sodium bicarbonate and a second solution comprising sodium carbonate; and
g. separating the second solid particles from the second solution to produce a production solution comprising sodium carbonate and to produce a production solid comprising the second solid particles, said second solid particles comprising sodium bicarbonate.

2. The process according to claim 1 , wherein the additive fed in step c), or fed in step e), or fed in both steps c) and e) is selected from the group consisting of: anionic polyacrylate polymer, anionic polyacrylate-polyacrylamide co-polymer, anionic maleic-acrylic acids copolymers, anionic acrylic acid-phosphonic acid copolymers and combinations thereof.

3. The process according to claim 2 , wherein the additive has a molecular weight of at least 20,000.

4. The process according to claim 1 , wherein the quantity of the additive added in the first leaching tank and the quantity of the additive added in the second leaching tank are each separately at least 0.01g per kilogram of the crushed trona introduced in the first leaching tank.

5. The process according to claim 1 , wherein the additives added in the first and second leaching tanks are the same; wherein the proportion of the additive added in the first leaching tank is from 10% by weight to 90% by weight based on the total quantity of the additive added in the first and the second leaching tanks, and wherein the quantity of the additive added in the second leaching tank is the complement to 100% by weight of the total quantity of the additive added in the first and the second leaching tanks.

6. The process according to claim 1 , wherein the mean residence time of the first suspension in the first leaching tank is from 10 seconds to 30 minutes.

7. The process according to claim 1 , wherein the crushed trona particles have a particle size less than a quarter of an inch.

8. The process according to claim 1 , wherein at least one of the temperature of the first suspension in the first leaching tank and the temperature of the second suspension in the second leaching tank is from 20° C. to 90° C.

9. The process according to claim 1 , wherein the first and second leaching tanks are stirred leaching tanks, and wherein the stirring speed of the second leaching tank is less than the stirring speed of the first leaching tank.

10. The process according to claim 1 , wherein the production solution comprises at least 100 g/kg sodium carbonate.

11. The process according to claim 1 , wherein the production solution comprises at most 180 g/kg sodium carbonate.

12. The process according to claim 1 , wherein the production solid comprising the second solid particles from step (g) is further dried.

13. The process according to claim 1 , wherein the production solid contains at least 70% by weight sodium bicarbonate.

14. The process according to claim 1 , wherein the extraction water of step c) comprises 1 to 70 g/kg of sodium carbonate.

15. The process according to claim 1 , further comprising before step c), the steps:
a. dissolving crushed trona with an aqueous solution in a pre-leaching tank to obtain extraction water undersaturated relative to sodium bicarbonate and/or to sodium sesquicarbonate, along with trona insolubles and optionally undissolved crushed trona particles; and
b. separating the trona insolubles and optionally undissolved crushed trona particles from the extraction water to obtain extraction water from which trona insolubles and optionally undissolved crushed trona particles have been separated and feeding the obtained extraction water to the first leaching tank from step c).

16. The process according to claim 1 , further comprising:
optionally debicarbonating at least part of the production solution to obtain a partially debicarbonated production solution comprising sodium carbonate, and
crystallizing part of the sodium carbonate from the production solution comprising sodium carbonate from step g) or from the partially debicarbonated production solution from step m), as sodium carbonate decahydrate or as sodium carbonate heptahydrate or as sodium carbonate monohydrate or as anhydrous sodium carbonate.

17. The process according to claim 16 , wherein the production solution at step m) is partly debicarbonated by: adding calcined trona comprising sodium carbonate to saturate the production solution in sodium sesquicarbonate and to precipitate sodium sesquicarbonate, and removing sodium sesquicarbonate to remove part of the bicarbonate from the production solution.

18. The process according to the claim 16 , wherein the production solution at step m) is partly debicarbonated thermally or chemically by reaction with hydroxide ions.

19. The process according to claim 1 , wherein part of the production solution comprising sodium carbonate is further introduced in an electrodialysis process to debicarbonate part of the production solution.

20. The process according to claim 1 , wherein part of the production solution is introduced into less basic compartments of an electrodialyzer, and wherein a solution comprising sodium bicarbonate is then extracted from the less basic compartments of the electrodialyzer, and is optionally cooled to produce a suspension comprising sodium bicarbonate crystals.

21. A solid particles powder comprising at least 70% by weight of sodium bicarbonate, at least 2% by weight of trona insoluble impurities, and at least 100 ppm of an additive selected from the group consisting

Assignees

• Solvay

Inventors

• Piet Joffrey
• Nicolas Frederic

Classifications

• C01D7/24

  Crystallisation · CPC title

• Y10T428/2982

  Particulate matter [e.g., sphere, flake, etc.] · CPC title

• C01D7/32

  by dialysis · CPC title

• C01D7/40

  Influencing the crystallisation process · CPC title

• C01D7/126 Primary

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