Process for obtaining precipitated calcium carbonate

Patent metadata

Field	Value
Publication number	US-10343929-B2
Application number	US-201715417578-A
Country	US
Kind code	B2
Filing date	Jan 27, 2017
Priority date	Aug 20, 2013
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

The present invention provides a process for preparing a precipitated calcium carbonate product comprising the steps of: (a) preparing an aqueous suspension of precipitated calcium carbonate seeds by carbonating a suspension of Ca(OH) 2 in the presence of 0.005 to 0.030 moles of Sr, in the form of Sr(OH) 2 , per mole of Ca(OH) 2 , (b) dewatering and dispersing the precipitated calcium carbonate seeds prepared in step (a) to obtain an aqueous suspension of precipitated calcium carbonate seeds having a d 50 of less than or equal to 0.1 to 0.3 μm and a BET specific surface area of 10 to 30 m 2 /g, and (c) forming an aqueous suspension of a precipitated calcium carbonate product by carbonating a slurry of Ca(OH) 2 in the presence of 0.5 to 5% by dry weight of the precipitated calcium carbonate seeds obtained in step (b), wherein the precipitated calcium carbonate seeds have a d 50 that is less than the d 50 of the precipitated calcium carbonate product and the precipitated calcium carbonate seeds have an aragonitic polymorph content greater than or equal to the precipitated calcium carbonate product obtained in step (c) characterized in that the dewatering of step (b) is carried out by the use of a tube press.

First claim

The invention claimed is:

1. An aqueous suspension of precipitated calcium carbonate seeds having a pH of less than or equal to 9, wherein the aqueous suspension is obtained by a process comprising the steps of:
(a) preparing an aqueous suspension of precipitated calcium carbonate seeds by carbonating a suspension of Ca(OH) 2 in the presence of 0.005 to 0.030 moles of Sr, in the form of Sr(OH) 2 , per mole of Ca(OH) 2 , and
(b) dewatering and dispersing the precipitated calcium carbonate seeds prepared in step (a) to obtain an aqueous suspension of precipitated calcium carbonate seeds having a d 50 of less than or equal to 0.1 to 0.3 μm and a BET specific surface area of 10 to 30 m 2 /g, and a pH of less than or equal to 9, wherein the precipitated calcium carbonate seeds comprise strontium, and wherein the dewatering is carried out by the use of a tube press.

2. The aqueous suspension of claim 1 , having a pH of 8.5 to 9.

3. The aqueous suspension according to claim 1 , wherein the suspension of Ca(OH) 2 in step (a) is carbonated in the presence of 0.01 to 0.02 moles of Sr per mole of Ca(OH) 2 .

4. The aqueous suspension according to claim 1 , wherein the Sr(OH) 2 in step (a) is formed in situ by the addition of a SrO—comprising mineral.

5. The aqueous suspension according to claim 1 , wherein the aqueous suspension of precipitated calcium carbonate seeds formed in step (a) has an aragonitic polymorph content of greater than 85% by dry weight.

6. The aqueous suspension according to claim 1 , wherein the aqueous suspension of precipitated calcium carbonate seeds formed in step (a) has an aragonitic polymorph content of greater than 90% by dry weight.

7. The aqueous suspension according to claim 1 , wherein the aqueous suspension of precipitated calcium carbonate seeds formed in step (a) has an aragonitic polymorph content of greater than 95% by dry weight.

8. The aqueous suspension according to claim 1 , wherein the dewatering of step (b) is carried out under a pressure in the range of 50 to 150 bar.

9. The aqueous suspension according to claim 1 , wherein the dewatering of step (b) is carried out under a pressure in the range of 60 to 120 bar.

10. The aqueous suspension according to claim 1 , wherein the dewatering of step (b) is carried out under a pressure in the range of 80 to 100 bar.

11. The aqueous suspension according to claim 1 , wherein the dewatering of step (b) is carried out at a starting temperature in the range of 15 to 80° C.

12. The aqueous suspension according to claim 1 , wherein the dewatering of step (b) is carried out at a starting temperature in the range of 20 to 70° C.

13. The aqueous suspension according to claim 1 , wherein the dewatering of step (b) is carried out at a starting temperature in the range of 30 to 60° C.

14. A material comprising the precipitated calcium carbonate product obtained in the process comprising the steps of:
(a) preparing an aqueous suspension of precipitated calcium carbonate seeds by carbonating a suspension of Ca(OH) 2 in the presence of 0.005 to 0.030 moles of Sr, in the form of Sr(OH) 2 , per mole of Ca(OH) 2 ,
(b) dewatering the precipitated calcium carbonate seeds prepared in step (a) in a tube press at a pressure in the range of 50 to 150 bar to obtain dewatered precipitated calcium carbonate seeds, and dispersing the dewatered precipitated calcium carbonate seeds so obtained in water to obtain an aqueous suspension of precipitated calcium carbonate seeds having a d 50 of less than or equal to 0.1 to 0.3 μm and a BET specific surface area of 10 to 30 m 2 /g, and a pH of less than or equal to 9, wherein step (b) is conducted without grinding, and
(c) forming an aqueous suspension of a precipitated calcium carbonate product by carbonating a slurry of Ca(OH) 2 in the presence of 0.5 to 5% by dry weight of the aqueous suspension of precipitated calcium carbonate seeds obtained in step (b),
wherein the precipitated calcium carbonate seeds have a d 50 that is less than the d 50 of the precipitated calcium carbonate product and the precipitated calcium carbonate seeds have an aragonitic polymorph content greater than or equal to the precipitated calcium carbonate product obtained in step (c), and wherein the precipitated calcium carbonate product obtained in step (c) has a total strontium quantity of 0.2 to 15 mol/dry metric tonne.

15. The material according to claim 14 , wherein the process further comprises the step of performing one or more of dewatering and dispersion of the precipitated calcium carbonate product obtained in step (c) to obtain a precipitated calcium carbonate product having a d 50 of between 0.30 and 0.45 micrometers and a BET specific surface area of between 8 and 20 m 2 /g.

16. The material according to claim 14 , wherein the precipitated calcium carbonate product obtained in step (c) has a total strontium quantity of 1 to 5 mol/dry metric tonne.

17. The material according to claim 14 , wherein the precipitated calcium carbonate product obtained in step (c) contains an aragonitic polymorph content of greater than 60% by dry weight.

18. The material according to claim 14 , wherein the precipitated calcium carbonate product obtained in step (c) contains an aragonitic polymorph content of greater than 70% by dry weight.

19. The material of claim 14 , which is selected from the group consisting of a paper, a paper product, an ink, a paint, a coating, a plastic, an adhesive, a building product, a foodstuff, and a pharmaceutical product.

Assignees

• Omya Int Ag

Inventors

• Maurer Marc
• Schlotterbach Thomas
• Skrzypczak Mathieu
• Pirker Robert

Classifications

• C01P2004/51

  Particles with a specific particle size distribution · CPC title

• C01F11/187

  Strontium carbonate · CPC title

• C01F11/182 Primary

  Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by an additive other than CaCO3-seeds · CPC title

• C01F11/181 Primary

  Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by control of the carbonation conditions · CPC title

• C01P2006/12

  Surface area · CPC title