Claims
- 1. A method for passivating sulfidic iron-containing rock comprising:
contacting sulfidic iron-containing rock with a magnesium containing substance comprising one or more members of the group consisting of: magnesium oxide, magnesium hydroxide, magnesium chloride, magnesium nitrate and magnesium carbonate; adjusting the pH of the system to between about 9-11.
- 2. The method of claim 1, further comprising adding a silicate.
- 3. The method of claim 2, wherein the silicate is selected from the group consisting of sodium and calcium silicate.
- 4. The method of claim 2, wherein the concentration of silicate is between 1-5 lb silicate/ton rock.
- 5. The method of claim 1, further comprising adding air.
- 6. The method of claim 1, further comprising adding an iron salt.
- 7. The method of claim 6, wherein ferrous iron-magnesium sulfates are formed.
- 9. The method of claim 6, wherein said iron salt is FeCl3.
- 10. The method of claim 6, wherein the concentration of iron salt added is sufficient to form the desired amount of ferrous iron-magnesium sulfates.
- 11. The method of claim 1, further comprising adjusting the pH of the system to below 5 before the contacting step.
- 12. The method of claim 1, wherein the magnesium containing substance is magnesium oxide.
- 13. The method of claim 11, wherein said magnesium oxide is present at a concentration of between 2.2-22.0 lbs MgO/ton of rock.
- 14. The method of claim 1, wherein the magnesium containing substance is magnesium hydroxide.
- 15. The method of claim 13, wherein said magnesium hydroxide is present at a concentration of about 2.5% by weight of solution.
- 16. The method of claim 1, wherein said rock is present in a slurry of 20-50% by weight of solids.
- 17. The method of claim 11, wherein the weight ratio of magnesium oxide: rock:
water is maintained at 1:100:400-10:100:400.
- 18. A method of reducing acid rock drainage from sulfidic iron-containing rock comprising the steps of:
contacting said rock with magnesium oxide wherein the concentration of magnesium oxide in the mixture is 0.1-1% by weight and the slurry density is about 20% by weight of solids in the mixture; allowing a reaction between said magnesium oxide and the sulfides in said rock to proceed so as to form in slurry dissolved magnesium sulfate; raising the pH of the slurry to about 10-10.5; adding silicate to said slurry.
- 19. The method of claim 17, further comprising contacting said slurry with air.
- 20. The method of claim 17, further comprising adding an iron-containing substance.
- 21. A method of reducing acid rock drainage from sulfidic iron-containing rock comprising the steps of:
contacting said rock with an aqueous colloidal suspension of 2.5% magnesium hydroxide; allowing a reaction between said magnesium hydroxide and the sulfides in said rock to proceed so as to form in slurry dissolved magnesium sulfate; raising the pH of the slurry to about 10-10.5; adding a silicate to the slurry.
- 22. The method of claim 21, further comprising contacting said slurry with air.
- 23. The method of claim 21, further comprising adding an iron-containing substance.
- 24. A method of passivating sulfidic iron-containing rock comprising:
contacting sulfidic iron-containing rock with a member of the group consisting of: magnesium oxide, magnesium hydroxide, magnesium chloride, magnesium nitrate and magnesium carbonate at a concentration of between about 25 moles Mg/ton of rock to 250 moles Mg/ton of rock and raising the pH to about 9-11.
- 25. The method of claim 24, further comprising adding one or more of sodium or calcium silicates at a concentration of between 1-5 lb silicate/ton rock.
- 26. The method of claim 24, further comprising oxidizing the rock.
- 27. The method of claim 24, further comprising adding iron chloride.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. provisional application Serial No. 60/304,599, filed Jul. 10, 2001, which is hereby incorporated by reference in its entirety to the extent not inconsistent with the disclosure herewith.
Provisional Applications (1)
|
Number |
Date |
Country |
|
60304599 |
Jul 2001 |
US |