Process for water based mineral material slurry surface whitening

Patent metadata

Field	Value
Publication number	US-9556320-B2
Application number	US-201113996719-A
Country	US
Kind code	B2
Filing date	Dec 22, 2011
Priority date	Jan 7, 2011
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

The present invention is directed to a process for surface whitening mineral matter in a slurry that includes the following steps: (a) preparing by dispersing and/or grinding at least one water based mineral matter slurry; and (b) adding during and/or after step a) 0.005 wt % to 0.5 wt %, based on dry weight of the mineral matter, of at least one alkylene oxide block co-polymer or at least one alkylene oxide random co-polymer.

First claim

The invention claimed is:

1. A process for improving the whitening of a mineral matter slurry surface by reducing flotation of impurities to the slurry surface which cause darkening of the slurry surface, the process comprising the following steps:
(a) preparing by dispersing and/or grinding at least one water based mineral matter slurry, wherein the mineral matter comprises calcium carbonate and impurities that can cause darkening of a slurry surface, wherein the impurities comprise one or more oxides, sulphides, silicates, and crystalline and/or amorphous carbon; and
(b) adding to the slurry during and/or after step a), 0.005 wt % to 0.5 wt %, based on dry weight of the mineral matter, of at least one alkylene oxide block co-polymer or at least one alkylene oxide random co-polymer, to obtain a slurry of mineral matter in which the slurry surface has improved surface whiteness over the same slurry in which the at least one alkylene oxide block co-polymer or the at least one alkylene oxide random co-polymer is not added, wherein the whitening of the slurry surface is improved by reducing flotation of impurities to the slurry surface which cause darkening of the slurry surface.

2. The process according to claim 1 , wherein the co-polymer added in step b) is at least one alkylene oxide block co-polymer.

3. The process according to claim 1 , wherein 0.005 wt % to 5 wt %, based on dry weight of the mineral matter, of at least one dispersing and/or grinding aid is added during and/or after step a) and/or step b).

4. The process according to claim 1 , wherein the at least one alkylene oxide block co-polymer is a bi-block copolymer.

5. The process according to claim 4 , wherein the bi-block copolymer is an EO/PO block polymer.

6. The process according to claim 1 , wherein the at least one alkylene oxide block co-polymer is a tri-block copolymer.

7. The process according to claim 6 , wherein the tri-block copolymer is an EO/PO/EO or a PO/EO/PO block copolymer.

8. The process according to claim 6 , wherein the tri-block copolymer has the general structure:

and wherein x, y, and z each independently represents any single integer between, or equal to 1 and 120, and wherein x and z are the same or different integer(s), or

in which a, b, or c each independently represent any single integer between, or equal to 1 and 120, and wherein a and c are the same or different integer(s), and wherein R and R′ in formulas (I) - (II) are alkyl residues and/or hydrogen.

9. The process according to claim 8 , wherein x, y, and z each independently represent any single integer between, or equal to 1 and 80, and a, b, or c each independently represent any single integer between, or equal to 1 and 80.

10. The process according to claim 8 , wherein x, y, and z each independently represent any single integer between, or equal to 3 and 70, and a, b, or c each independently represent any single integer between, or equal to 3 and 30.

11. The process according to claim 8 , wherein x, y, and z each independently represent any single integer between, or equal to 5 and 34, and a, b, or c each independently represent any single integer between, or equal to 4 and 34.

12. The process according to claim 4 , wherein the bi-block has the general structure:

or

wherein d, e, f or g each independently represent any single integer between, or equal to 1 and 120, d and e are the same or different integer(s), and for g are the same or different integer(s), and wherein R and R′ in formulae (III) - (IV) are alkyl residues and/or hydrogen.

13. The process according to claim 12 , wherein d, e, for g each independently represent any single integer between, or equal to 1 and 80.

14. The process according to claim 12 , wherein d, e, for g each independently represent any single integer between, or equal to 2 and 70.

15. The process according to claim 12 , wherein d, e, for g each independently represent any single integer between, or equal to 4 and 40.

16. The process according to claim 3 , wherein the at least one dispersing and/or grinding aid is an anionic dispersing and/or grinding aid.

17. The process according to claim 3 , wherein the at least one anionic dispersing and/or grinding aid is selected from organic or inorganic dispersing and/or grinding aids.

18. The process according to claim 3 , wherein the at least one anionic dispersing and/or grinding aid is an organic dispersing and/or grinding aid selected from the group consisting of sodium citrate, a sodium acrylate, a homo- or copolymer of sodium acrylate or sodium methacrylate, and any combination thereof.

19. The process according to claim 3 , wherein the at least one anionic dispersing and/or grinding aid is an inorganic dispersing and/or grinding aid selected from the group consisting of sodium pyrophosphate, sodium polyphosphate, sodium hexametaphosphate and sodium tripolyphosphate.

20. The process according to claim 3 , wherein the at least one anionic dispersing and/or grinding aid is an anionic polymeric dispersant selected from the group consisting of polymeric dispersants comprising at least one group chosen form a hydroxyl group, an amido group, a carboxyl group, a sulfo group and a phosphono group, and alkali, earth alkali metal and ammonium and/or amine salts thereof.

21. The process according to claim 20 , wherein the anionic polymeric dispersant is a polymeric acrylic dispersant having a molecular weight from 1000 g/mol to 30000 g/mol.

22. The process according to claim 20 , wherein the anionic polymeric dispersant is a polymeric acrylic dispersant having a molecular weight from 2500 g/mol to 16000g/mol.

23. The process according to claim 20 , wherein the anionic polymeric dispersant is a polymeric acrylic dispersant having a molecular weight from 3200 g/mol to 13000 g/mol.

24. The process according to claim 20 , wherein the anionic polymeric dispersant is a polymeric acrylic dispersant having a molecular weight from 3300 g/mol to 7500 g/mol.

25. The process according to claim 20 , wherein the anionic polymeric dispersant has acid groups that are partially or fully neutralized, by at least one mono and/or bivalent and/or trivalent and/or tetravalent neutralizing agent.

26. The process according to claim 25 , wherein the at least one mono- or bivalent neutralizing agent is lithium, sodium, potassium, magnesium, calcium, ammonium, or any combination thereof.

27. The process according to claim 1 , wherein the mineral matter is natural calcium carbonate obtained from one or more of marble, limestone, chalk and calcite.

28. The process according to claim 1 , wherein the mineral matter is precipitated calcium carbonate.

29. The process according to claim 1 , wherein the mineral matter comprises calcium carbonate and one or more of kaolin, talc, mica, dolomite, bentonite, TiO 2 and Al(OH) 3 .

30. The process according to claim 1 , wherein the oxides include iron oxides, the sulphid

Assignees

• Buri Matthias
• Rentsch Samuel
• Pudack Claudia
• Omya Int Ag

Inventors

• Buri Matthias
• Rentsch Samuel
• Pudack Claudia

Classifications

• C09C1/021 Primary

  Calcium carbonates · CPC title

• C08K3/26

  Carbonates; Bicarbonates · CPC title

• C08K3/0033 Primary

  Chemistry & Metallurgy · mapped topic

• C01P2006/60

  Optical properties, e.g. expressed in CIELAB-values · CPC title

• C09C1/3676

  Treatment with macro-molecular organic compounds · CPC title