Processing aids to improve the bitumen recovery and froth quality in oil sands extraction processes
View Patent ↗Disclosed and claimed is a method for improving the froth quality and bitumen recovery in primary bitumen extraction processes by coagulant addition in the underwash feed water. Preferred coagulants are cationic or amphoteric polymers. Coagulant addition in the underwash feed water reduces the solids content reporting to the primary bitumen froth in a primary separation vessel (PSC). This treatment program can also be combined with dispersant addition in the dilution make-up feed water into a PSC. Preferred dispersants are low molecular weight anionic polymers.
1. A method to improve froth quality and bitumen recovery from an oil sands slurry, the oil sands slurry comprising bitumen, mineral solids, and water, the method comprising:
(a) introducing the oil sands slurry into a primary separation cell;
(b) contacting an effective amount of a dispersant with the oil sands slurry via adding the dispersant to an ore feed and/or adding the dispersant to a dilution make-up water;
(c) contacting an underwash water with the oil sands slurry, wherein the underwash water comprises an effective amount of a coagulant, wherein the coagulant comprises one or more polymers selected from the group consisting of: about 5 to about 80% mol of DMAEA.MCQ-AcAm, DMAEA.MSQ-AcAm, or DMAEA.BCQ-AcAm copolymer class of approximate weight average molecular weight of about 10 million Da; and
(d) allowing the oil sands slurry to separate into a froth layer and a middlings layer, wherein the froth layer comprises a lower mineral solids content than would be present without the addition of coagulant in the underwash water;
wherein the coagulant and the dispersant are temporally positioned in the method so as to address the competing functions of the dispersant and the coagulant.
2. The method of claim 1 , wherein the dispersant comprises a low molecular weight polymer having a weight average molecular weight in the range from about 1,000 Da to about 100,000 Da.
3. The method of claim 1 , wherein the dispersant further comprises one or more polymers having a weight average molecular weight in the range from about 1,000 Da to about 100,000 Da.
4. The method of claim 1 , wherein the dispersant further comprises one or more polymers having a weight average molecular weight in the range from about 3,000 Da to about 30,000 Da.
5. The method of claim 1 , wherein the dispersant further comprises one or more polymers selected from the group consisting of: polyacrylic acid; polymethacrylic acid; polyacrylamide; polymethacrylamide and derivatives thereof; polyaspartic acid; polystyrene sulfonate; vinyl sulfonate copolymerized with acrylic acid; acrylamide copolymerized with sulfonate or ethylene oxide groups; polymers of maleic anhydride; methacrylic and maleic acid copolymers; acrylamide and acrylic acid copolymers; acrylic acid/polyethylene glycol copolymers; poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (polyAMPS); polymers comprising AMPS; and any combination thereof.
6. The method of claim 1 , wherein the dispersant further comprises one or more polymers selected from the group consisting of: acrylic acid polymer with a weight average molecular weight of about 2,000 Da to about 5,000 Da; acrylic acid polymer with sodium parastyrene sulfonate with a weight average average molecular weight of about 10,000 Da to about 30,000 Da; acrylic acid polymer with sodium AMPS (60/40 wt/wt) with a weight average molecular weight of about 15,000 Da to about 25,000 Da; polymethacrylate with a weight average molecular weight of about 13,000 Da to about 15,000 Da; sulfomethylated acrylic acid-acrylamide copolymer with a weight average molecular weight of about 25,000 Da to about 30,000 Da; and any combination thereof.
7. The method of claim 1 , wherein the mineral solids are selected from the group consisting of: coarse solids, fines, clays, and any combination thereof.
8. The method of claim 1 , wherein the method provides a 14.2% reduction in the mineral solids content of the froth layer compared to a method without any underwash treatment.
9. The method of claim 1 , wherein the method provides a 28% decrease in mineral solids content reporting to the froth layer compared to a blank trial without coagulant treatment.
10. The method of claim 1 , wherein the dispersant is an acrylic acid polymer dosed at 20 ppm wt/wt dose based on ore feed.
11. The method of claim 1 , wherein the coagulant is dosed into the underwash feed water at a dosage of 57 ppm based on the ore feed.