Synthesis of hectorite-type mineral

Patent metadata

Field	Value
Publication number	US-12338129-B2
Application number	US-201917415513-A
Country	US
Kind code	B2
Filing date	Dec 19, 2019
Priority date	Dec 21, 2018
Publication date	Jun 24, 2025
Grant date	Jun 24, 2025

Abstract

A method of making a synthetic hectorite-type mineral is described, along with its resulting physical and rheological properties. The synthetic hectorite-type mineral is a 2:1 phyllosilicate essentially free of aluminum, and having a trioctahedral structure with Mg2+ and Li+ occupying octahedral sites. As a hydrogel, the synthetic hectorite-type mineral has a swell index of greater than 55 mL, and a yield point of greater than 290 Pa. The method of making uses a MgO/MgCO3 buffer system, with heating for about 2 hours at temperatures of no higher than 300° C. and pressures of no higher than 600 psi.

First claim

What is claimed is:

1. A method of making a synthetic hectorite mineral, the method comprising:
mixing sodium silicate, a silica source, lithium hydroxide, sodium fluoride, and water to form a first mixture;
mixing a magnesium source and an acid with the first mixture to form a second mixture, wherein the magnesium source comprises magnesium carbonate and/or magnesium oxide;
heating the second mixture to form an intermediary product; and
drying and milling the intermediary product to form the synthetic hectorite mineral.

2. The method of claim 1 , wherein the silica source comprises silica gel having a BET surface area in a range of 400-550 m 2 /g.

3. The method of claim 1 , wherein the silica source comprises a diatomaceous earth product.

4. The method of claim 1 , wherein the silica source consists of silica gel, and wherein a mass ratio of the sodium silicate to silica gel is in a range of 1.0:1.2-1.2:1.0.

5. The method of claim 1 , wherein the second mixture is heated at a temperature of 200-500° C. and a pressure of 100-800 psi for 0.5-12 hours to form the intermediary product.

6. The method of claim 5 , wherein a mass ratio of magnesium carbonate to magnesium oxide is in a range of 1.0:1.2-1.2:1.0.

7. The method of claim 1 , wherein the second mixture is agitated during the heating.

8. The method of claim 1 , wherein the synthetic hectorite mineral is a 2:1 layered phyllosilicate having a tetrahedral double layer sandwiching an octahedral layer, the octahedral layer having a plurality of octahedral sites occupied by Mg 2+ or Li + ,
wherein the synthetic hectorite mineral has a formula of
Na a (Mg b Li c )(Si 4 O 10 )(F d (OH) e ),

wherein a is in a range of 0.3 to 0.4;
wherein b and c range from 0 to 3, and b+c=3, and
wherein d and e range from 0 to 2, and d+e=2.

9. The method of claim 8 , wherein a ratio of b to c ranges from 7.0:1 to 9.0:1.

10. The method of claim 9 , wherein a ratio of b to c ranges from 7.5:1 to 8.5:1.

11. The method of claim 8 , wherein at least 90% of the octahedral sites are occupied by Mg 2+ or Li + , relative to a total number of the octahedral sites.

12. The method of claim 8 , wherein d is in a range of 0.3 to 0.7.

13. The method of claim 8 , wherein the synthetic hectorite mineral has a D50 in a range of 8-30 μm.

14. The method of claim 8 , wherein the synthetic hectorite mineral has a mean crystallite size in a range of 18-38 nm.

15. The method of claim 8 , wherein the synthetic hectorite mineral is in the form of platelets having an aspect ratio in a range of 1.2:1 to 3.0:1.

16. The method of claim 8 , wherein the synthetic hectorite mineral has a swell index of at least 55 mL, the swell index according to ASTM D5890.

17. The method of claim 8 , wherein a suspension comprising 5 wt % of the synthetic hectorite mineral in water, relative to a total weight of the suspension, has a yield point of at least 290 Pa.

18. The method of claim 8 , wherein a suspension comprising 5 wt % of the synthetic hectorite mineral in water, relative to a total weight of the suspension, has a yield stress in a range of 350-450 Pa at a temperature of 50-85° C.

19. The method of claim 8 , wherein a suspension comprising 2 wt % of the synthetic hectorite mineral in water, relative to a total weight of the water, has a cation exchange capacity in a range of 95-130 meq per 100 g synthetic hectorite mineral.

Assignees

• Imerys Usa Inc

Inventors

• Lu Jie
• Yip Benjamin
• Greene Michael

Classifications

• C01P2006/22

  Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability · CPC title

• C01P2006/12

  Surface area · CPC title

• C01P2004/61

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

• C01P2004/54

  Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension · CPC title

• C01P2004/20

  extending in two dimensions, e.g. plate-like · CPC title