Method of beneficiating and drying trona ore useful for flue gas desulfurization

• US 9,327,233 B2
• Filed: 02/11/2011
• Issued: 05/03/2016
• Est. Priority Date: 09/14/2010
• Status: Active Grant

• Current Assignee: Genesis Alkali Wyoming LP (Genesis Energy LP)
• Original Assignee: Tronox Alkali Wyoming Corporation (Tronox Holdings Plc)
• Inventors: Kropf, Jared M.
• Primary Examiner(s): Swain, Melissa
• Application Number:
  US13/025,700
• Publication Number:
  US 20120063974A1
• Time in Patent Office: 1,908 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B01D 2251/304 of sodium
• CPC Class Codes: B01D 2251/606 Carbonates
• CPC Class Codes: B01D 2253/304 Linear dimensions, e.g. particle shape, diameter
• CPC Class Codes: B01D 2257/302 Sulfur oxides
• CPC Class Codes: B01D 2258/0283 Flue gases
• CPC Class Codes: B01D 53/508 by treating the gases with solids
• CPC Class Codes: B01D 53/83 with moving reactants
• CPC Class Codes: C01D 7/22 Purification

Abstract

A method of producing trona suitable for flue gas desulfurization comprising mechanically mining a trona ore deposit containing insoluble impurities; crushing the mined trona ore to create a mixture of uncalcined trona-rich particles and impurities-rich particles; beneficiating the crushed uncalcined trona ore to obtain a trona-rich, impurities-depleted ore fraction; and drying the trona-rich ore fraction under non-calcining conditions to yield a dry uncalcined trona ore. A preferred embodiment includes concurrently milling and drying the trona-rich, impurities-depleted ore fraction to recover a low moisture content trona product having a high NaHCO₃:Na₂CO₃ ratio, useful for the efficient dry injection desulfurization of flue gas streams.

Claims

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 NaHCO₃:

Na₂CO₃ 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 NaHCO₃:

Na₂CO₃ 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.

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.

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.