Treatment of tailings with deionized silicate solutions
View Patent ↗A process for treating a tailings stream comprises (a) contacting a deionized silicate solution with a tailings stream whereby the solids are entrapped within a gel produced from the silicate solution; and (b) allowing the gel to strengthen and solidify. The process may further comprise spreading the gel produced in step (a) over a surface. The present invention is particularly useful to treat tailings streams produced in processes to extract bitumen from oil sands ores.
1. A process for treating a tailings stream without use of an activator comprising (a) contacting a deionized silicate solution having a molar ratio of Si:M of at least 2.6, wherein M is an alkali metal, with a tailings stream comprising water and solids whereby the solids are entrapped within a gel produced from the silicate solution; and (b) allowing the gel to strengthen and solidify.
2. A process according to claim 1 wherein the deionized silicate solution is prepared by contacting a solution of sodium silicate with a strong cation exchange resin.
3. A process according to claim 1 wherein the deionized silicate solution is prepared by contacting a solution of sodium silicate with a weak cation exchange resin.
4. A process according to claim 1 wherein the deionized silicate solution is prepared by removing alkali metal from a solution of alkali metal silicate using bipolar electrolysis.
5. A process according to claim 1 further comprising adding a reinforcing agent in the contacting step (a).
6. A process according to claim 5 further comprising spreading the gel produced in step (a) over a surface.
7. A process according to claim 6 wherein the surface is a sloped surface.
8. A process according to claim 1 further comprising depositing the gel produced in step (a) in a dewatering pit.
9. A process according to claim 1 wherein the tailings stream is produced in a process to extract bitumen from oil sands ores.
10. A process according to claim 1 wherein step (b) comprises a dewatering step.
11. A process according to claim 10 wherein dewatering occurs by air drying (evaporation), water runoff, compression, syneresis, exudation, freeze/thaw, sublimation or combination thereof.
12. A process according to claim 11 wherein the water runs off is recovered and recycled.
13. A process according to claim 5 wherein the reinforcing agent is selected from the group consisting of gravel, sand from mining operations, waste rock from mining operations; petroleum coke, coal particles; elemental crystalline sulfur; inorganic fibers; organic fibers, and combinations of two or more thereof.
14. A process according to claim 1 wherein the deionized silicate solution is added in an amount equal to 0.01 to 20 kg on a SiO 2 basis per metric tonne of solids in the tailings stream.
15. A process according to claim 5 wherein the reinforcing agent is added in an amount equal to 0.01 to 700 kg/tonne of solids in the tailings stream.
16. A process for treating a tailings stream comprising (a) contacting a deionized silicate solution having a molar ratio of Si:M of at least 2.6, wherein M is an alkali metal, with a tailings stream comprising water and solids whereby the solids are entrapped within a gel produced from the silicate solution; and (b) allowing the gel to strengthen and solidify; wherein the process is completed without use of an activator.
17. The process according to claim 16 wherein the deionized silicate solution is prepared by contacting a solution of sodium silicate with a strong cation exchange resin.
18. The process according to claim 16 wherein the deionized silicate solution is prepared by contacting a solution of sodium silicate with a weak cation exchange resin.
19. The process according to claim 16 further comprising adding a reinforcing agent in the contacting step (a).
20. The process according to claim 16 wherein the tailings stream is produced in a process to extract bitumen from oil sands ores.