Methods of treating tailings

Patent metadata

Field	Value
Publication number	US-11242492-B2
Application number	US-201916438856-A
Country	US
Kind code	B2
Filing date	Jun 12, 2019
Priority date	Jun 12, 2018
Publication date	Feb 8, 2022
Grant date	Feb 8, 2022

Abstract

The present embodiments generally relate to methods for the treatment of tailings, e.g., oil sands tailings, including methods comprising the use of one or more flocculants, one or more coagulants and one or more oxidants to treat said tailings and/or to improve the performance of said one or more flocculants.

First claim

The invention claimed is:

1. A method of treating tailings stream comprising adding to the tailings stream (i) at least one anionic polyacrylamide flocculant, and further adding to the anionic polyacrylamide flocculant containing tailings stream (ii) at least one oxidant, which is in the form of a solid and/or slurry, and further wherein the at least one oxidant dissolves over a prolonged time period thereby providing for prolonged oxidation and (iii) at least one iron containing coagulant, wherein the added amount(s) of the at least one oxidant which is in the form of a solid and/or a slurry and the at least one coagulant when added to the anionic polyacrylamide flocculant containing tailings stream results in a greater decrease in the chemical oxygen demand (COD) and the turbidity of the treated tailings stream compared to the decrease in COD and turbidity obtained upon the addition of the same at least one oxidant which is in the form of a solid and/or slurry, when added in the same amount to the anionic polyacrylamide flocculant containing tailing stream in the absence of the at least one coagulant.

2. The method of claim 1 , wherein when the same at least one oxidant which is in the form of a solid and/or slurry, when added to the tailings in the same amount in the absence of the at least one coagulant elicits no significant effect on COD.

3. The method of claim 1 , wherein when the same at least one oxidant which is in the form of a solid and/or slurry, when added to the tailings in the same amount in the absence of the at least one coagulant elicits no significant effect on turbidity.

4. The method of claim 1 , wherein the combined dosage of the at least one coagulant and the at least one oxidant which is in the form of a solid and/or slurry, when added to the tailings elicits an additive or synergistic effect on the removal of toxic contaminants and/or promotes the breakdown of polymers and polymer/flocs added and produced during flocculation.

5. The method of claim 1 , wherein the at least one iron containing coagulant comprises ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, and/or polyferric sulphate.

6. The method of claim 5 , wherein the at least one coagulant comprises ferrous chloride.

7. The method of claim 1 , wherein the at least one oxidant which is in the form of a solid and/or slurry, when added to the tailings comprises a peroxide-containing compound.

8. The method of claim 1 , wherein the at least one oxidant which is in the form of a solid and/or slurry, comprises calcium peroxide, magnesium peroxide, a persulfate anion, sodium percarbonate, permanganate, and/or hypochlorite.

9. The method of claim 1 , wherein the at least one oxidant which is in the form of a solid and/or slurry, comprises calcium peroxide.

10. The method of claim 1 , wherein the at least one coagulant comprises ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, and/or polyferric sulphate and the at least one oxidant which is in the form of a solid and/or slurry, comprises calcium peroxide, magnesium peroxide, a persulfate anion, sodium percarbonate, permanganate, and/or hypochlorite.

11. The method of claim 1 , wherein the added dosages of the at least one coagulant and the at least one oxidant, which is in the form of a solid and/or slurry, comprise amounts which in combination provide for a maximum decrease in the turbidity and COD of the treated tailings stream.

12. The method of claim 11 , wherein the at least one oxidant which is in the form of a solid and/or slurry, is calcium peroxide and the added dosage is at least 80 ppm and the at least one coagulant comprises ferrous chloride and the added dosage is at least 170 ppm.

13. The method of claim 1 , wherein the at least one oxidant, which is in the form of a solid and/or slurry, and the at least one coagulant are added to a mature tailings stream after the addition of the at least one anionic polyacrylamide flocculant.

14. The method of claim 1 , wherein the at least one oxidant, which is in the form of a solid and/or slurry, and the at least one coagulant are added in combination to a mature tailings stream after the addition of the at least one anionic polyacrylamide flocculant.

15. The method of claim 1 , wherein combined treatment of said tailings stream with said at least one oxidant, which is in the form of a solid and/or slurry, and the at least one coagulant results in a reduction of chemical oxygen demand (“COD”) to 300 mg/L or less.

16. The method of claim 1 , wherein combined treatment of said tailings stream with said at least one oxidant, which is in the form of a solid and/or slurry, and the at least one coagulant results in a reduction of chemical oxygen demand (“COD”) to 200 mg/L or less.

17. The method of claim 1 , wherein treatment of said tailings stream with said at least one oxidant, which is in the form of a solid and/or slurry, when added to the tailings in combination with the at least one coagulant results in a treated tailings stream having a turbidity of 150 FAU or less.

18. The method of claim 1 , wherein treatment of said tailings stream with said at least one oxidant, which is in the form of a solid and/or slurry, when added to the tailings in combination with the at least one coagulant results in a treated tailings stream having a turbidity of 100 FAU or less.

19. The method of claim 1 , wherein treatment of said tailings stream with said at least one oxidant, which is in the form of a solid and/or slurry, when added to the tailings in combination with the at least one coagulant results in a treated tailings stream having a turbidity of 50 FAU or less.

20. The method of claim 1 , wherein said at least one oxidant is added in solid form to said tailings.

21. The method of claim 1 , wherein said at least one oxidant is added in the form of a slurry to said tailings.

22. A method of treating tailings stream comprising adding to the tailings stream:
(a) at least one anionic polyacrylamide flocculant, and further adding to the anionic polyacrylamide flocculant containing tailings stream,
(b) at least one solid oxidant which is in the form of a solid and/or slurry, such that when added to the tailings it dissolves over a prolonged duration thereby providing for the prolonged release of peroxides, and
(c) at least one iron containing coagulant,
wherein:
(i) the at least one coagulant comprises ferrous chloride,
(ii) the at least one oxidant which is in the form of a solid and/or slurry,

comprises calcium peroxide, and
(iii) the added amount(s) of the ferrous chloride and the calcium peroxide, when added to the anionic polyacrylamide flocculant containing tailings stream results in the prolonged release of peroxides as the calcium peroxide dissolves over a prolonged time period thereby providing for the prolonged oxidation of the treated tailings stream, and further wherein the combination of (i) and (ii) results in a greater decrease in the chemical oxygen demand (COD) and the turbidity of the treated tailings stream compared to the decrease in COD and turbidity obtained upon the addition of the calcium peroxide in the same amount to the anionic polyacrylamide flocculant containing tailing stream in the absence of the at least one coagulant.

23. The method of claim 22 , wherein said calcium peroxide oxidant is added in solid form to said tailings.

24. The method of claim 22 , wherein said calcium peroxide oxidant is added in the form

Assignees

• Kemira Oyj

Inventors

• Pelaez Miguel
• Fenderson Thomas

Classifications

• C10G33/06 Primary

  with mechanical means, e.g. by filtration · CPC title

• C10G27/02

  with halogen or compounds generating halogen; Hypochlorous acid or salts thereof · CPC title

• C10G29/20

  Organic compounds not containing metal atoms · CPC title

• C10G2300/1003

  Waste materials · CPC title

• C10G2300/202

  Heteroatoms content, i.e. S, N, O, P · CPC title