Removing finely dispersed particulate matter from a fluid stream
Disclosed herein are systems and methods for removing fine particulate matter from a fluid, comprising a separator that separates an inflow fluid stream into an overflow fluid path and an underflow fluid path, where the underflow fluid path is treated with a tethering material that attaches to the coarse particulate matter to form tether-bearing anchor particles and where the overflow fluid path is treated with an activating material so that the activating material interacts with the fine particulate matter to form activated particles. After these treatments, the underflow fluid path containing the tether-bearing anchor particles is commingled with the overflow fluid path containing the activated particles, so that a removable complex is produced that can be removed in a settling facility, thereby removing the fine particulate matter from the fluid. The systems and methods are particularly advantageous for removing particulate matter from a fluid waste stream following mining or ore processing operations, such as oil sands mining or processing.
1. A method for removing fine particles from an inflow liquid fluid stream, wherein the inflow fluid stream comprises a suspension of fine particles and coarse particles, wherein the fine particles have a mean diameter of less than 50 microns and the coarse particles have a mean diameter of greater than about 70 microns, the method comprising:
separating the inflow fluid stream with a mechanical separator into an overflow fluid path comprising the fine particles and an underflow fluid path comprising the coarse particles;
introducing into the underflow fluid path a tethering polymer that affixes to the coarse particles to form tether-bearing coarse particles to form a tether-treated fluid stream, said tether-bearing coarse particles being suspended in the tether-treated fluid stream;
admixing the overflow fluid path with the tether-treated fluid stream to form a conjoined fluid stream;
introducing into the conjoined fluid stream an activating polymer that affixes to the fine particles to form activated particles, wherein the activating polymer of the activated particles attaches to the tethering polymer of the tether-bearing coarse particles to form removable complexes comprising the fine particles and the coarse particles; and
separating the removable complexes from the conjoined fluid stream, thereby removing the fine particles from the fluid stream.
2. The method of claim 1 , further comprising removing bitumen from the fluid stream before the addition of the activating polymer.
3. The method of claim 1 , further comprising adding an additional activating polymer to the overflow fluid path before admixing the overflow fluid path with the treated fluid stream.
4. The method of claim 3 , wherein the activating polymer introduced into the conjoined fluid stream and the additional activating polymer are the same.
5. The method of claim 1 , wherein the inflow fluid stream is separated into the overflow path and the underflow path using a hydrocyclone.
6. The method of claim 1 , wherein the underflow fluid path is split into a plurality of underflow fluid subpaths.
7. The method of claim 6 , wherein a first underflow subpath contains untreated cyclone underflow fluid.
8. The method of claim 6 , wherein a second underflow subpath is directed to a second separator that produces cyclone overflow and cyclone underflow.
9. The method of claim 8 , wherein the second separator is a hydrocyclone.
10. The method of claim 6 , wherein one of the plurality of underflow subpaths is treated with the tethering polymer.
11. The method of claim 8 , wherein cyclone underflow from the second separator is treated with the tethering polymer.
12. A method for removing fine particles from an inflow liquid fluid stream, wherein the inflow fluid stream comprises a suspension of fine particles, wherein the fine particles have a mean diameter of less than 50 microns, the method comprising:
separating the inflow fluid stream with a mechanical separator into an overflow fluid path containing suspended fine particles, and an underflow fluid path;
introducing tether-bearing anchor particles into the underflow fluid path to form a treated underflow fluid path, wherein the tether-bearing anchor particles are anchor particles to which a tethering polymer is affixed and wherein the anchor particles have a mean diameter of greater than about 70 microns;
introducing a first activator polymer into the overflow fluid path to form a treated overflow fluid path, wherein the first activator polymer complexes with the fine particles to form a first set of activated particles;
admixing the treated underflow fluid path and the treated overflow fluid path to form a conjoined fluid stream;
introducing a second activator polymer into the conjoined fluid stream, wherein the second activator polymer complexes with residual fine particles to form a second set of activated particles, wherein the tethering polymer of the tether-bearing anchor particles interacts with the first and second activating polymers of the first and second sets of activated particles to form removable complexes comprising the fine particles and the anchor particles; and
separating the removable complexes from the conjoined treated fluid stream, thereby removing the fine particles from the fluid.
13. The method of claim 12 , wherein the first activator polymer and the second activator polymer are the same.
14. The method of claim 1 , wherein the activator polymer is an anionic polymer.
15. The method of claim 14 , wherein the anionic polymer is partially hydrolyzed polyacrylamide, or a salt, ester or copolymer thereof.
16. The method of claim 1 , wherein the tethering polymer is a cationic polymer.
17. The method of claim 16 , wherein the cationic polymer is selected from the group consisting of polydiallyldimethylammonium chloride (poly(DADMAC)) and epichlorohydrin dimethylamine (epi/DMA).
18. The method of claim 14 , wherein the tethering polymer is a cationic polymer and the cationic polymer is selected from the group consisting of polydiallyldimethylammonium chloride (poly(DADMAC)) and epichlorohydrin dimethylamine (epi/DMA).
19. The method of claim 15 , wherein the tethering polymer is a cationic polymer.
20. The method of claim 19 , wherein the cationic polymer is selected from the group consisting of polydiallyldimethylammonium chloride (poly(DADMAC)) and epichlorohydrin dimethylamine (epi/DMA).