PROCESS FOR PREPARING A METAL HYDROXIDE

• US 20090214416A1
• Filed: 11/09/2006
• Published: 08/27/2009
• Est. Priority Date: 11/09/2005
• Status: Abandoned Application

• Current Assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno
• Original Assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno
• Inventors: Brouwer, Jan Peter
• Application Number:
  US12/092,776
• Publication Number:
  US 20090214416A1
• Time in Patent Office: Days
• US Class Current: 423/636
• CPC Class Codes: C01B 13/36 by precipitation reactions in aqueous solutions C01B13/328 takes precedence
• CPC Class Codes: C01B 33/142 by acidic treatment of silicates
• CPC Class Codes: C01B 33/187 by acidic treatment of silicates
• CPC Class Codes: C01F 11/12 from silicates
• CPC Class Codes: C01F 5/14 Magnesium hydroxide

Abstract

The invention provides a process for preparing a metal hydroxide comprising the steps of: (a) providing particles of a metal silicate; (b) mixing the particles with a mineral acid solution to obtain a slurry which comprises precipitated silica; (c) separating the precipitated silica from the slurry to obtain a remaining solution; (d) increasing the pH of the remaining solution to such an extent that a metal hydroxide is formed; (e) separating the metal hydroxide so obtained from the remaining solution; and (f) adding to the remaining solution obtained in step (e) an acid solution, thereby forming a salt containing solution, or (g) removing at least part of the base added in step (d) from the remaining solution obtained in step (e), thereby forming a salt containing solution.

Claims

1. A process for preparing a metal hydroxide comprising the steps of:

(a) providing particles of a metal silicate;

(b) mixing the particles with a mineral acid solution to obtain a slurry which comprises precipitated silica;

(c) separating the precipitated silica from the slurry to obtain a remaining solution;

(d) increasing the pH of the remaining solution to such an extent that a metal hydroxide is formed;

(e) separating the metal hydroxide so obtained from the remaining solution; and

(f) adding to the remaining solution obtained in step (e) an acid solution, thereby forming a salt containing solution, or

(g) removing at least part of the base added in step (d) from the remaining solution obtained in step (e), thereby forming a salt containing solution.

2. A process according to claim 1, wherein the mineral acid solution in step (b) comprises sulphuric acid and/or nitric acid.

3. A process according to claim 2, wherein the mineral acid solution in step (b) comprises nitric acid.

4. A process according to claim 1, wherein the mineral acid solution in step (b) has a concentration in the range of from 0.01 M to 15 M.

5. A process according to claim 1, wherein the mineral acid solution in step (b) has a concentration in the range of from 0.5 M to 5 M.

6. A process according to claim 1, wherein in step (d) the pH is increased to a value in the range of from 8-12.

7. A process according to claim 6, wherein in step (d) the pH is increased to a value in the range of from 9-11.

8. A process according to claim 1, wherein in step (d) the pH is increased by adding an ammonium hydroxide solution, an alkali-metal hydroxide solution or ammonia gas to the remaining solution.

9. A process according to claim 8, wherein in step (d) the pH is increased by adding ammonia gas to the remaining solution.

10. A process according to claim 9, wherein in step (d) also carbon dioxide is added to the remaining solution.

11. A process according to claim 1, wherein the metal silicate comprises magnesium silicate and/or calcium silicate.

12. A process according to claim 8, wherein the metal silicate comprises olivine and/or serpentine.

13. A process according to claim 1, wherein the acid solution applied in step (b) comprises a solution of sulphuric acid and/or nitric acid.

14. A process for preparing a metal hydroxide according to claim 1, comprising the steps of:

(a) providing particles of a metal silicate;

(b) mixing the particles with a mineral acid solution to obtain a slurry which comprises precipitated silica;

(c) separating the precipitated silica from the slurry to obtain a remaining solution;

(d) increasing the pH of the remaining solution to such an extent that a metal hydroxide is formed by adding an ammonium hydroxide solution or ammonium gas to the remaining solution;

(e) separating the metal hydroxide so obtained from the remaining solution; and

(f) adding a sulphuric acid solution and/or a nitric acid solution to the remaining solution obtained in step (e), thereby forming an ammonium sulphate and/or ammonium nitrate solution.

15. A process according to claim 13, wherein the acid comprises nitric acid.

16. A process according to claim 1, wherein the particles of the metal silicate have an average particle size of less than 1 mm.

17. A process according to claim 16, wherein the particles of the metal silicate have an average particle size of less than 0.5 mm.