Effective reductive bleaching of mineral slurries
View Patent ↗Disclosed herein are a method of reductively bleaching a mineral slurry comprising adding in the mineral slurry an effective amount of a formamidine sulfinic acid (FAS) and an effective amount of a borohydride to reductively bleach the mineral slurry, compositions comprising a mineral slurry, a FAS, and a borohydride, and final products comprising a mineral obtained by the method disclosed herein.
1. A composition comprising:
a mineral slurry,
a formamidine sulfinic acid, and
a borohydride.
2. The composition according to claim 1 , wherein the mineral slurry comprises at least one ingredient chosen from kaolin, talc, gypsum, mica, silica, feldspar, barium sulfate, and alkaline earth metal carbonates.
3. The composition according to claim 2 , wherein the alkaline earth metal carbonate comprises calcium carbonate.
4. The composition according to claim 1 , wherein the formamidine sulfinic acid is present in a concentration ranging from about 125 ppm to about 2,500 ppm on a dry basis.
5. The composition according to claim 4 , wherein the formamidine sulfinic acid is present in a concentration ranging from about 250 ppm to about 1,000 ppm on a dry basis.
6. The composition according to claim 1 , wherein the borohydride comprises sodium borohydride.
7. The composition according to claim 6 , wherein the sodium borohydride is present in a concentration of at least about 5 ppm on a dry basis.
8. The composition according to claim 7 , wherein the sodium borohydride is present in a concentration ranging from about 20 ppm to about 1,000 ppm on a dry basis.
9. The composition according to claim 8 , wherein the sodium borohydride is present in a concentration ranging from about 50 ppm to about 500 ppm on a dry basis.
10. The composition according to claim 1 , wherein the formamidine sulfinic acid is present in a concentration ranging from about 125 ppm to about 2,500 ppm on a dry basis and the borohydride is present in a concentration ranging from about 125 ppm to about 1,000 ppm on a dry basis.
11. The composition according to claim 10 , wherein the formamidine sulfinic acid is present in a concentration ranging from about 250 ppm to about 750 ppm on a dry basis and the borohydride is present in a concentration ranging from about 125 ppm to about 500 ppm on a dry basis.
12. The composition according to claim 1 , wherein the composition has a pH value of higher than about 6.0.
13. The composition according to claim 12 , wherein the composition has a pH value ranging from about 8.0 to about 13.0.
14. A method of reductively bleaching a mineral slurry, comprising
including in the mineral slurry an effective amount of a formamidine sulfinic acid and an effective amount of a borohydride to reductively bleach the mineral slurry.
15. The method according to claim 14 , wherein the mineral slurry comprises at least one ingredient chosen from kaolin, talc, gypsum, mica, silica, feldspar, barium sulfate, and alkaline earth metal carbonates.
16. The method according to claim 15 , wherein the alkaline earth metal carbonate comprises calcium carbonate.
17. The method according to claim 14 , wherein the effective amount of the formamidine sulfinic acid ranges from about 125 ppm to about 2,500 ppm on a dry basis.
18. The method according to claim 17 , wherein the effective amount of the formamidine sulfinic acid ranges from about 250 ppm to about 1,000 ppm on a dry basis.
19. The method according to claim 14 , wherein the borohydride comprises sodium borohydride.
20. The method according to claim 19 , wherein the effective amount of the sodium borohydride is at least about 5 ppm on a dry basis.
21. The method according to claim 20 , where in the effective amount of the sodium borohydride ranges from about 20 ppm to about 1,000 ppm on a dry basis.
22. The method according to claim 21 , where in the effective amount of the sodium borohydride ranges from 50 ppm to 500 ppm on a dry basis.
23. The method according to claim 14 , where in the effective amount of the formamidine sulfinic acid ranges from about 125 ppm to about 2,500 ppm on a dry basis and the effective amount of the borohydride ranges from about 125 ppm to about 1,000 ppm on a dry basis.
24. The method according to claim 23 , wherein the effective amount of the formamidine sulfinic acid ranges from about 250 ppm to about 750 ppm on a dry basis and the effective amount of the borohydride ranges from about 125 ppm to about 500 ppm on a dry basis.
25. The method according to claim 14 , wherein the final slurry has a pH value of higher than about 6.0.
26. The method according to claim 25 , wherein the final slurry has a pH value ranging from about 8.0 to about 13.0.