Alkali metal ion source with moderate rate of ion release and methods of forming

Patent metadata

Field	Value
Publication number	US-9340465-B2
Application number	US-201414271042-A
Country	US
Kind code	B2
Filing date	May 6, 2014
Priority date	May 6, 2013
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

An alkali metal ion source with a moderate rate of release of the ion (e.g. potassium) is formed by a method that includes: 1) combining an particulate ore that contains at least one of an alkali metal ion-bearing framework silicate (e.g. syenite ore) with at least one of an oxide and hydroxide of at least one of an alkali metal and alkaline earth metal such as calcium hydroxide; 2) milling the mixture of these two components optionally, with water, optionally, milling the dry components separately and blended thereafter, optionally, with water; 3) forming a mixture by adding water to the solid mixture after milling, if water was not added before milling; 4) exposing the mixture to an elevated temperature and pressure to form a gel that includes silica and the alkali metal of the framework silicate.

First claim

What is claimed is:

1. A method for forming an alkali metal ion source with a moderate rate of the ion release, comprising the steps of:
a) combining a first component particulate alkali metal ion-bearing framework silicate with a second component that includes at least one of an oxide and a hydroxide of at least one of an alkaline earth metal and an alkali metal to form a solid mixture, wherein the molar ratio of the silicon to the at least one of the alkaline earth metal and alkali metal of the second component in the solid mixture is in a range of between about 1.0:0.1 and about 1.0:0.3; and
b) exposing the solid mixture to a hydrothermal treatment to form a gel that includes the silicon and the alkali metal of the first component, thereby forming the source of alkali metal ion.

2. The method of claim 1 , wherein the alkali metal of the first component includes at least one member of the group consisting of lithium, sodium and potassium.

3. The method of claim 2 , wherein the alkali metal of the first component includes potassium.

4. The method of claim 3 , wherein the particulate alkali metal ion-bearing framework silicate is an aluminosilicate.

5. The method of claim 4 , wherein the alkali metal ion-bearing framework aluminosilicate includes at least one member selected from the group consisting of potassium feldspar (KAlSi 3 O 8 ), leucite (KAlSi 2 O 6 ), kalsilite (KAlSiO 4 ) and nepheline (Na 3 KAl 4 Si 4 O 16 ).

6. The method of claim 4 , wherein the first component includes at least about 5% by weight of an equivalent amount of K 2 O.

7. The method of claim 1 , wherein the second component includes an alkali metal.

8. The method of claim 7 , wherein the alkali metal of the second component includes at least one member of the group consisting of lithium (Li), sodium (Na), and potassium (K).

9. The method of claim 1 , wherein the second component includes an alkaline earth metal.

10. The method of claim 9 , wherein the alkaline earth metal of the second component includes at least one member of the group consisting of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr).

11. The method of claim 10 , wherein the alkaline earth metal of the second component includes calcium (Ca).

12. The method of claim 11 , wherein the calcium of the second component is in the form of calcium hydroxide (Ca(OH) 2 ).

13. The method of claim 12 , wherein the amount of calcium hydroxide is present in the combined solid mixture in a range of between about 5% and about 30% by weight.

14. The method of claim 1 , further including the step of combining the mixture with liquid water to form a liquid-and-solid mixture prior to hydrothermal treatment.

15. The method of claim 14 , wherein the amount of liquid present in the liquid-and-solid mixture is in a weight ratio of liquid-to-solid in a range of between about 0.05:1 and about 5:1.

16. The method of claim 15 , further including the step of milling the solid mixture to thereby reduce the mean particle size of the first component until the volume percent of said particles having a diameter of 5 μm or less is at least about 30%.

17. The method of claim 16 , further including the step of milling the solid mixture to thereby reduce the mean particle size of the first component until the volume percent of said particles having a diameter of 5 μm or less is at least about 50%.

18. The method of claim 16 , wherein the liquid water is added before the milling step.

19. The method of claim 16 , wherein the liquid water is added after the milling step.

20. The method of claim 16 , wherein the hydrothermal treatment includes exposing the liquid-and-solid mixture to a temperature in a range of between about 100° C. and about 350° C. for a period of time sufficient enough to form the gel that includes the silica and alkali metal of the first component in the amount not less than 10 wt. %.

21. The method of claim 20 , wherein the alkali metal of the first component is potassium.

22. The method of claim 16 , wherein the hydrothermal treatment includes exposing the solid mixture to a pressure of between about 100 psig and about 500 psig during at least a portion of the period of time the mixture is exposed to a temperature of between about 100° C. and about 350° C. to thereby form the silicate gel.

23. The method of claim 22 , further including the step of forming the first component by reducing the particles size to a particle size of equal to or less than about 5 mm.

24. The method of claim 23 , further including the step of combining the alkali metal ion source with soil.

25. The method of claim 1 , wherein the solid mixture is exposed to the elevated temperature and pressure until essentially all of the alkaline earth metal of the first component is present as a component of the gel.

26. The method of claim 1 , wherein the weight ratio of tobermorite phase to the unreacted alkali metal ion-bearing framework silicate phases of the alkali metal ion source is between about 1:1 and about 0:1.

27. The method of claim 1 , wherein the weight percent of K(Na)-A-S—H gel of the alkali metal ion source is between about 10% and about 100%.

28. The method of claim 1 , wherein the specific surface area of the alkali metal ion source is between about 8 m 2 /g and 50 m 2 /g.

29. An alkali metal ion source with a moderate rate of ion release, formed by a method comprising the steps of:
a) combining a first component particulate alkali metal ion-bearing framework silicate with a second component that includes at least one of an oxide and a hydroxide of at least one of an alkaline earth metal and an alkali metal to form a solid mixture, wherein the molar ratio of the silicon to the at least one of the alkaline earth metal and alkali metal of the second component is in a range of between about 1.0:0.1 and about 1.0:0.3; and
b) exposing the solid mixture to a hydrothermal treatment to form a gel that includes the silica and the alkali metal of the first component, thereby forming the alkali metal ion source, comprised of the alkali metal ion bearing silicate gel in amount of not less than 10 wt. %, wherein the alkali metal ion source has a specific surface area (BET) between about 8 m 2 /g and about 50 m 2 /g, wherein the alkali metal ion source releases not less than 1 g of potassium per 1 kg of the alkali metal ion source and not less than 1 wt. % of silica acid within 24 hours upon exposure to aqueous solution that is undersaturated with respect to potassium and silica.

Assignees

• Massachusetts Inst Technology
• Massachusetts Inst Technology

Inventors

• Skorina Taisiya
• Allanore Antoine

Classifications

• C01B33/36

  having base-exchange properties but not having molecular sieve properties (regeneration thereof B01J49/00) · CPC title

• C01B33/26

  Aluminium-containing silicates {, i.e. silico-aluminates} · CPC title

• C05D9/02

  containing trace elements · CPC title

• C01B33/32

  Alkali metal silicates ({C01B33/24} , C01B33/26 take precedence) · CPC title

• C05G1/00

  Mixtures of fertilisers belonging individually to different subclasses of C05 · CPC title