Process for producing oleum or sulfamic acid from spent sulfuric acid and process for regenerating spent sulfuric acid

Abstract

This disclosure relates to a method and system for regenerating waste sulfuric acid solution. The waste sulfuric acid solution regeneration method disclosed herein is a method for preparing fuming sulfuric acid from waste sulfuric acid solution. In this method, waste sulfuric acid solution is used as the main raw material, and the waste sulfuric acid solution reacts with sulfur trioxide to form fuming sulfuric acid. Therefore, waste sulfuric acid can be converted into an economically valuable and recyclable product through a simple process.

Claims

1. A method for preparing fuming sulfuric acid from waste sulfuric acid solution, comprising the following steps: a) Provide a waste sulfuric acid solution as the main raw material, and b) React the waste sulfuric acid solution with sulfur trioxide in the presence of a catalyst in a fuming sulfuric acid generating unit to generate fuming sulfuric acid, wherein the sulfur trioxide is obtained by reacting sulfur with oxygen in the sulfur trioxide generating unit.

2. The method of claim 1, wherein the ratio of the waste sulfuric acid solution (in moles of sulfuric acid) fed into the fuming sulfuric acid generating device to the sulfur (in moles of elemental sulfur) fed into the sulfur trioxide generating device is 1:0.1 to 1:1.

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3. The method of claim 1, wherein the waste sulfuric acid solution contains about 10% to about 98% sulfuric acid.

4. The method of claim 1, wherein the waste sulfuric acid solution is pretreated to contain at least 40% sulfuric acid before being fed into the fuming sulfuric acid generating device.

5. The method of claim 1, wherein the waste sulfuric acid solution is pretreated to form concentrated sulfuric acid with a concentration of 93% or higher before being fed into the fuming sulfuric acid generating unit.

6. The method of claim 1, wherein the sulfur trioxide generating device is a small-scale sulfur trioxide generating device.

7. The method of claim 6, wherein the sulfur trioxide generating device is a sulfur trioxide generator for a detergent sulfonation / sulfation process.

8. The method of claim 1, wherein a portion of the sulfur trioxide is absorbed by the waste sulfuric acid solution in the fuming sulfuric acid generating device to form fuming sulfuric acid, and another portion of the unabsorbed sulfur trioxide is fed into the sulfuric acid generating device to be absorbed by water, dilute sulfuric acid or another waste sulfuric acid solution to form sulfuric acid.

9. The method of claim 8, wherein the ratio (by weight) of the amount of fuming sulfuric acid generated by the fuming sulfuric acid generating apparatus to the amount of sulfuric acid generated by the sulfuric acid generating apparatus is between 2:1 and 5:

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10. The method of claim 1, wherein in step b), the waste sulfuric acid solution is pretreated to remove a portion of the water or hydrogen peroxide.

11. A method for preparing aminosulfonic acid from waste sulfuric acid solution, comprising the following steps: c) React fuming sulfuric acid prepared by any of the methods described in claims 1 to 10 with urea to produce aminosulfonic acid.

12. The method of claim 11 further comprises: d) performing solid-liquid separation on the product of step c) to remove the aminosulfonic acid solid, and reacting the remaining liquid with ammonia to produce ammonium sulfate or converting it into concentrated sulfuric acid.

13. The method of claim 12, wherein the remaining liquid contains sulfuric acid.

14. The method of claim 12, wherein the ammonia is derived from ammonia nitrogen wastewater from semiconductor manufacturing processes or other industrial processes.

15. A method for regenerating waste sulfuric acid solution, comprising the following steps: a) Heating the waste sulfuric acid solution under vacuum or low pressure to generate a first product stream containing water and a second product stream containing concentrated waste sulfuric acid solution; and b) Feeding the second product stream into a fuming sulfuric acid generating unit, whereby the concentrated waste sulfuric acid solution, as the main raw material, reacts with sulfur trioxide in the fuming sulfuric acid generating unit in the presence of a catalyst to generate fuming sulfuric acid, wherein the sulfur trioxide is obtained by reacting sulfur with oxygen in the sulfur trioxide generating unit.

16. The method of claim 15 further comprises: d) reacting the fuming sulfuric acid with urea to generate aminosulfonic acid.

17. The method of claim 16 further comprises: e) performing solid-liquid separation on the product of step d) to remove the aminosulfonic acid solid, and reacting the remaining liquid with ammonia to produce ammonium sulfate or converting it into concentrated sulfuric acid.

18. The method of claim 17, wherein the remaining liquid contains sulfuric acid.

19. The method of claim 15, wherein the first product stream comprises water and hydrogen peroxide, and the method further comprises: c) reacting the hydrogen peroxide with sodium carbonate to generate sodium percarbonate.

20. The method of claim 15, wherein the ratio of concentrated waste sulfuric acid solution (in moles of sulfuric acid) fed into the fuming sulfuric acid generating unit to sulfur (in moles of elemental sulfur) fed into the sulfur trioxide generating unit is 1:0.1 to 1:1.

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21. The method of claim 15, wherein the sulfur trioxide generating device is a small-scale sulfur trioxide generating device.

22. The method of claim 15, wherein the sulfur trioxide generating apparatus is a sulfur trioxide generator for a detergent sulfonation / sulfation process.

23. The method of claim 1, wherein a portion of the sulfur trioxide is absorbed by the concentrated waste sulfuric acid solution in the fuming sulfuric acid generating unit to form fuming sulfuric acid, and another portion of the unabsorbed sulfur trioxide is fed into the sulfuric acid generating unit and absorbed by water, dilute sulfuric acid or another waste sulfuric acid solution to form sulfuric acid.

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