Process for treating a sulfurous fluid to form gypsum and magnesium carbonate

Patent metadata

Field	Value
Publication number	US-10399862-B2
Application number	US-201615543594-A
Country	US
Kind code	B2
Filing date	Jan 14, 2016
Priority date	Jan 14, 2015
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

A process for treating a sulfurous fluid to form gypsum and magnesium carbonate, whereby the sulfurous fluid is scrubbed with a sequestrating agent to yield a scrubbed fluid, gypsum and magnesium sulfate. The flue gas desulfurized gypsum is isolated from the magnesium sulfate solution by filtration or centrifugation. The magnesium sulfate is reacted with a carbonate salt to produce a magnesium carbonate whereby the reaction conditions are controlled to control the properties of the magnesium carbonate produced.

First claim

What is claimed is:

1. A process for treating a sulfurous fluid to form gypsum and magnesium carbonate, comprising:
contacting the sulfurous fluid with a sequestrating agent to yield a scrubbed fluid, gypsum and magnesium sulfate; and
reacting a carbonate salt with the magnesium sulfate to produce a magnesium carbonate; wherein the carbonate salt comprises a carbonate anion and at least one cation selected from the group consisting of sodium, calcium, potassium, ammonium, magnesium, and hydronium.

2. The process of claim 1 , further comprising separating at least a portion of the gypsum from the magnesium sulfate to form a gypsum product.

3. The process of claim 2 , wherein the separating is by filtration or centrifugation.

4. The process of claim 2 , wherein the moisture content of the gypsum product after separating does not exceed 10%.

5. The process of claim 2 , wherein the gypsum product comprises at least one impurity selected from the group consisting of a carbonate, a sulfate, an iron mineral, and an organic species.

6. The process of claim 1 , wherein the sequestrating agent is a calcium-containing carbonate mineral.

7. The process of claim 6 , wherein the calcium-containing carbonate material is dolomite or dolomitic limestone.

8. The process of claim 6 , wherein the calcium-containing carbonate mineral has an average particle size ranging from 50 μm to 100 μm.

9. The process of claim 1 , wherein the sulfurous fluid is a flue gas with a temperature ranging from 350° C. to 1200° C.

10. The process of claim 1 , wherein the contacting removes 98 to 99% of sulfur from the sulfurous fluid.

11. The process of claim 1 , further comprising flowing a sulfurous fluid into a mixture comprising water and a sequestrating agent, wherein the pH of the mixture is controlled during the flowing by controlling a flow rate of the sulfurous fluid into the mixture, adding a buffer to the mixture, or both.

12. The process of claim 11 , wherein the buffer is ammonia, a dibasic acid, or both.

13. The process of claim 11 , wherein the mixture has a pH from 5 to 6 during the flowing.

14. The process of claim 11 , further comprising flowing oxygen into the mixture concurrently with the sulfurous fluid to reduce a concentration of sulfites in the mixture.

15. The process of claim 1 , wherein the magnesium carbonate is amorphous with a surface area greater than or equal to 20 m2/g.

16. The process of claim 1 , further comprising seeding the magnesium sulfate prior to the reacting by adding gypsum, a carbonate salt seed, or both to control the production of the magnesium carbonate.

17. The process of claim 1 , wherein said magnesium carbonate is in the form magnesite.

18. The process of claim 1 , further comprising: separating at least a portion of the gypsum from the magnesium sulfate to form a gypsum product; and processing the gypsum to form a processed gypsum.

19. The process of claim 18 , wherein the processing is at least one process selected from the group consisting of grinding, milling, recrystallizing, magnetically separating, bleaching, acid washing, and beneficiating.

20. The process of claim 18 , wherein the processed gypsum is 90 to 99% pure gypsum.

Assignees

• Imerys Usa Inc

Inventors

• Paynter Christopher
• Stovall Kalena
• Wicks Douglas
• Butler-Lee Gavin
• Golbayani Parvin
• Jarvis Nigel Victor
• Pring Graham M
• Taylor David
• Perez Ricardo M

Classifications

• C01P2004/51

  Particles with a specific particle size distribution · CPC title

• C08K3/26

  Carbonates; Bicarbonates · CPC title

• C01P2004/03

  obtained by SEM · CPC title

• C01F11/18 Primary

  Carbonates · CPC title

• C01F11/468

  Purification of calcium sulfates · CPC title