Mixing systems for mixing oil sands tailings and polymer

Abstract

A process for flocculating and dewatering oil sands fine tailings in a pipeline is provided, comprising: pumping a tailings feed having a solids content in the range of about 10 wt % to about 45 wt % through a pipeline; injecting an effective amount of a polymeric flocculant into the tailings feed to provide an initial quick dispersion of the polymeric flocculant into the tailings feed; and providing a subsequent conditioning environment to form flocs and release water without overshearing.

1 . A process for flocculating and dewatering oil sands fine tailings in a pipeline, comprising:
 (a) pumping a tailings feed having a solids content in the range of about 10 wt % to about 45 wt % through a pipeline;   (b) injecting an effective amount of a polymeric flocculant into the tailings feed to provide an initial quick dispersion of the polymeric flocculant into the tailings feed; and   (c) providing a subsequent conditioning environment to form flocs and release water without overshearing.   
     
     
         2 . The process as claimed in  claim 1 , further comprising:
 (d) optimizing the mixing potential of the tailings slurry by introducing the tailings feed through a static mixer prior to step (c).   
     
     
         3 . The process as claimed in  claim 1 , further comprising:
 (d) pre-shearing the tailings feed prior to step (b).   
     
     
         4 . The process as claimed in  claim 1 , whereby step (b) and step (c) occur at the end of the pipeline. 
     
     
         5 . The process as claimed in  claim 1 , whereby a coagulant is also added to the tailings feed. 
     
     
         6 . The process as claimed in  claim 1 , whereby the tailings feed is fluid fine tailings having a solids content in the range of about 30 wt % to about 45 wt %. 
     
     
         7 . The process as claimed in  claim 1 , whereby the polymeric flocculant is a water soluble polymer having a moderate to high molecular weight and an intrinsic viscosity of at least 3 dl/g (measured in 1N NaCl at 25° C.). 
     
     
         8 . The process as claimed in  claim 1 , whereby the flocculated tailings are added to at least one centrifuge to dewater the oil sands fine tailings and form a high solids cake and a low solids centrate. 
     
     
         9 . The process as claimed in  claim 1 , whereby the flocculated tailings are added to a thickener to dewater the oil sands fine tailings and produce thickened oil sands fine tailings and clarified water. 
     
     
         10 . The process as claimed in  claim 1 , whereby the removed flocculated tailings are transported to at least one deposition cell for dewatering. 
     
     
         10 . (canceled) 
     
     
         11 . The process of  claim 1 , wherein the polymeric flocculant is an anionic, nonionic, cationic or amphoteric polymer. 
     
     
         12 . The process of  claim 11 , wherein the dosage of polymeric flocculant ranges from about 400 grams to about 2000 grams per tonne of solids in the feed. 
     
     
         13 . The process of  claim 12 , wherein the polymeric flocculant is the form of a 0.2 to 2% by weight aqueous solution. 
     
     
         14 . The process of  claim 12 , wherein the flocculant is in the form of a 0.2 to 0.4% by weight aqueous solution. 
     
     
         15 . The process of  claim 11 , wherein the flocculant comprises a polyacrylamide anionic flocculant. 
     
     
         16 . The process as claimed in  claim 1 , wherein the flocculant is injected into the pipeline by means of a plurality of side ports in a section of the pipeline. 
     
     
         17 . The process as claimed in  claim 1 , wherein the flocculant is injected into the pipeline by means of a venturi inserted into the pipeline, said venturi having a plurality of polymer inlets. 
     
     
         18 . The process as claimed in  claim 3 , wherein the tailings feed is pre-sheared in an in-line mixer. 
     
     
         19 . The process as claimed in  claim 18 , wherein the in-line mixer is a static mixer. 
     
     
         20 . The process as claimed in  claim 1 , wherein the conditioning environment is a lower energy environment than the dispersion environment in step (b).