Granted Patent B2

US 9,327,233 · App. 13/025,700 · Granted May 3, 2016

Abstract

Claims (29)

1. A method of producing trona suitable for dry injection pollution control comprising

mechanically mining a trona ore deposit containing at least about 5 wt % insoluble impurities;

crushing the mined trona ore to create a mixture of uncalcined trona ore particles comprising trona-rich particles and impurities-rich particles;

beneficiating the crushed uncalcined trona ore, via a dry separation procedure selected to recover trona-rich particles larger than about ¼ inch in size, wherein the dry separation procedure is selected from the group consisting of density separation, magnetic separation, electrostatic separation, optical separation, x-ray imaging separation, infrared imaging separation and combinations of these, without prior drying of the unbeneficiated ore and the trona-rich particles larger than about ¼ inch in size, to obtain a trona-rich, impurities-depleted ore fraction; and

then drying the trona-rich impurities-depleted ore fraction under non-calcining conditions to yield a dry uncalcined trona ore containing less than about 0.1 wt % free moisture.

2. The method of claim 1 wherein the mined trona ore contains an average of at least about 10 wt % insoluble impurities.

3. The method of claim 1 wherein the beneficiation comprises at least two beneficiation operations.

4. The method of claim 1 wherein the size separation beneficiation recovers trona-rich particles larger than about 1 inch that are size-separated from smaller impurity-rich particles.

5. The method of claim 1 wherein the beneficiated trona-rich, impurities-depleted ore fraction contains less than about half of the insoluble impurities content of the mined trona ore.

6. The method of claim 1 wherein the beneficiated trona-rich, impurities-depleted ore fraction contains less than 5 wt % insoluble impurities.

7. The method of claim 1 wherein the beneficiated trona-rich, impurities-depleted ore fraction contains less than 3 wt % insoluble impurities.

8. The method of claim 1 wherein the trona-rich, impurities-depleted ore fraction is dried using a heated gas stream, with the trona solids being maintained at a temperature that avoids calcination of the trona during drying.

9. The method of claim 1 wherein the trona-rich, impurities-depleted ore fraction is dried using a heated gas stream, with the trona solids being maintained at a temperature below about 130° F.

10. The method of claim 8 wherein the trona-rich, impurities-depleted ore fraction is dried using a dryer selected from the group consisting of fluid bed dryers, flash dryers, rotary kiln dryers, pneumatic conveying dryers, oven dryers and tumble dryers.

11. The method of claim 1 wherein the trona-rich, impurities-depleted ore fraction is dried to yield a trona product containing less than about 0.05 wt % free moisture.

12. The method of claim 1 wherein the dried trona-rich, impurities-depleted ore fraction has a weight ratio of NaHCO 3 :Na 2 CO 3 of at least about 0.75:1.

13. The method of claim 1 wherein the dried trona-rich, impurities-depleted ore fraction has a weight ratio of NaHCO 3 :Na 2 CO 3 of at least about 0.78:1.

14. The method of claim 1 which further comprises milling the trona-rich, impurities-depleted ore fraction to provide particulate trona sizing having a mean particle size that is less than about 100 microns.

15. The method of claim 1 which further comprises milling the trona-rich, impurities-depleted ore fraction to provide particulate trona sizing having a mean particle size that is less than about 50 microns.

16. The method of claim 14 wherein the trona-rich, impurities-depleted ore fraction subjected to the milling step is concurrently contacted with a sweep gas stream during milling to effect drying of the milled trona-rich ore fraction.

17. A method of producing trona suitable for dry injection pollution control comprising

mechanically mining a trona ore deposit containing at least about 5 wt % insoluble impurities;

crushing the mined trona ore to create a mixture of uncalcined trona ore particles comprising trona-rich particles and impurities-rich particles;

beneficiating the crushed uncalcined trona ore, via a dry separation procedure selected to recover trona-rich particles larger than about ¼ inch in size, wherein the dry separation procedure is selected from the group consisting of density separation, magnetic separation, electrostatic separation, optical separation, x-ray imaging separation, infrared imaging separation and combinations of these, without prior drying of the unbeneficiated ore and the trona-rich particles larger than about ¼ inch in size; and

concurrently milling and then drying the trona-rich impurities-depleted ore fraction under non-calcining conditions to yield a dry uncalcined trona ore having a mean particle size less than about 50 microns and containing less than about 0.1 wt % free moisture.

18. The method of claim 17 wherein the concurrent milling and then drying of the trona-rich fraction comprises the sole trona drying operation to remove free moisture from the mined and beneficiated trona.

19. A process for flue gas desulfurization comprising injecting a particulate dry trona sorbent made by the method of claim 1 into a hot combustion gas stream containing SO x , maintaining the trona sorbent in contact with the SO x -containing flue gas stream for a time sufficient to react with at least a portion of the SO x , collecting the injected and reacted trona sorbent downstream of the injection point in a solids collection device, and releasing the gas stream into the atmosphere.

20. The process of claim 19 wherein the flue gas stream at the trona sorbent injection point has a temperature of about 250° F. to about 900° F.

21. The process of claim 19 wherein the trona sorbent has a mean particle size smaller than about 50 microns.

Assignments (10)