Treatment of tailing streams

Patent metadata

Field	Value
Publication number	US-9789457-B2
Application number	US-201414777608-A
Country	US
Kind code	B2
Filing date	Mar 20, 2014
Priority date	Mar 22, 2013
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

A process for treating a tailings stream comprising water, solids, and optionally polyacrylamide. The process involves (a) contacting the tailings stream with a silicate source for a pre-determined period of time to form a mixture; b) after a pre-determined period of time of at least 5 minutes, contacting the mixture with an activator to initiate gel formation, wherein the gel entraps the solids within the gel; and c) allowing the gel to strengthen and solidify; wherein the gel formation is delayed compared with a non-delayed process.

First claim

What is claimed is:

1. A process for treating a tailings stream comprising water, solids, and optionally polyacrylamide, comprising: (a) contacting the tailings stream with a silicate source to form a mixture; b) after a pre-determined period of time of at least 5 minutes, contacting the mixture with an activator to initiate gel formation, wherein the gel entraps the solids within the gel; and c) allowing the gel to strengthen and solidify.

2. A process according to claim 1 , wherein the pre-determined period of time is at least 10 minutes.

3. A process according to claim 1 , wherein the pre-determined period of time is at least 15 minutes.

4. A process according to claim 1 , wherein the silicate source comprises an alkali metal silicate; a polysilicate microgel; a deionized silicate solution having a molar ratio of Si:M of at least 2.6, wherein M is an alkali metal; colloidal silica; or combinations thereof.

5. A process according to claim 1 , wherein the activator is selected from the group consisting of acids, alkaline earth metal salts, aluminum salts, organic esters, dialdehydes, organic carbonates, organic phosphates, amides, carbon dioxide, sodium aluminate, and combinations thereof.

6. A process according to claim 1 , further comprising spreading the gel over a surface prior to step (c).

7. A process according to claim 6 , wherein the surface is a sloped surface.

8. A process according to claim 1 , further comprising adding a polyacrylamide to the tailings stream or the mixture prior to step (c).

9. A process according to claim 1 , further comprising adding a reinforcing agent to the tailings stream or the mixture prior to step (c).

10. A process according to claim 1 , wherein the tailings stream is produced in a process to extract bitumen from oil sands ores.

11. A process according to claim 1 , further comprising dewatering the gel in step (c).

12. A process according to claim 11 , wherein dewatering occurs by air drying (evaporation), water run-off, compression, syneresis, exudation, freeze/thaw, sublimation, or any combination thereof.

13. A process according to claim 12 , wherein dewatering occurs by evaporation.

14. A process according to claim 12 , wherein dewatering occurs by water run-off.

15. A process according to claim 12 , wherein the water run-off is recovered and recycled.

16. A process according to claim 1 , wherein the tailings stream is chemically thickened, mechanically thickened, or both, forming a partially dewatered tailings stream, prior to step a).

17. A process according to claim 16 , wherein the chemically thickening is by flocculation.

18. A process according to claim 16 , wherein the mechanically thickening is by centrifuge.

Assignees

• Chemours Co Fc Llc
• Chemours Co Fc Llc

Inventors

• Moffett Robert Harvey

Classifications

• C04B24/2652

  Nitrogen containing polymers, e.g. polyacrylamides, polyacrylonitriles · CPC title

• C02F2103/10

  from quarries or from mining activities · CPC title

• C02F11/121 Primary

  by mechanical de-watering · CPC title

• Y02W30/91

  Use of waste materials as fillers for mortars or concrete · CPC title

• B01J13/0056 Primary

  containing inorganic material and water · CPC title