Process for flocculating and dewatering oil sand mature fine tailings

Abstract

A process for dewatering oil sand fine tailings is provided and comprises a dispersion and floc build-up stage comprising in-line addition of a flocculent solution comprising an effective amount of flocculation reagent into a flow of the oil sand fine tailings; a gel stage wherein flocculated oil sand fine tailings is transported in-line and subjected to shear conditioning; a floc breakdown and water release stage wherein the flocculated oil sand fine tailings releases water and decreases in yield shear stress, while avoiding an oversheared zone; depositing the flocculated oil sand fine tailings onto a deposition area to form a deposit and to enable the release water to flow away from the deposit, preferably done in a pipeline reactor and managing shear according to yield stress and CST information and achieves enhanced dewatering.

What is claimed is: 
     
         1 . A process for producing a hydrocarbon product derived from oil sands ore, the process comprising:
 subjecting an aqueous slurry comprising the oil sands ore to separation to produce the hydrocarbon product and fine tailings comprising water and fine solids; and   treating the fine tailings to separate the fine solids from the water, wherein the treating comprises:
 adding a flocculant in-line into a flow of the fine tailings to cause dispersion of the flocculant and build-up of flocs to form flocculated fine tailings; 
 transporting the flocculated fine tailings in-line and subjecting the flocculated fine tailings to in-line shear conditioning to increase a yield stress thereof to a peak yield stress and produce tailings material; 
 subjecting the tailings material to further in-line shear conditioning to reduce the yield stress from the peak yield stress and produce an in-line flow of a pipeline-conditioned flocculated tailings material; 
 discharging the pipeline-conditioned flocculated tailings material from a pipeline discharge outlet; and 
 dewatering the discharged pipeline-conditioned flocculated tailings material. 
   
     
     
         2 . The process of  claim 1 , wherein the dewatering comprises depositing the discharged pipeline-conditioned flocculated tailings material onto a deposition area formed of a solid land surface to form a non-flowing tailings material deposit and allow release water to drain and flow away from the non-flowing tailings material deposit. 
     
     
         3 . The process of  claim 2 , wherein the deposition area comprises at least one deposition beach having a sloped bottom surface. 
     
     
         4 . The process of  claim 1 , wherein the dewatering comprises providing the discharged pipeline-conditioned flocculated tailings material to a dewatering device. 
     
     
         5 . The process of  claim 4 , wherein the dewatering device comprises a filter, a thickener, a centrifuge, or a cyclone, or a combination thereof. 
     
     
         6 . The process of  claim 1 , wherein the dewatering comprises subjecting the discharged pipeline-conditioned flocculated tailings material to thickening. 
     
     
         7 . The process of  claim 6 , wherein the thickening is performed in a thickener unit that produces a thickened underflow that is removed from an overflow. 
     
     
         8 . The process of  claim 1 , wherein the dewatering comprises settling flocculated solids such that water separates upward away from the flocculated solids. 
     
     
         9 . The process of  claim 1 , wherein the dewatering comprises draining water from the discharged pipeline-conditioned flocculated tailings material. 
     
     
         10 . The process of  claim 1 , wherein the dewatering comprises subjecting the discharged pipeline-conditioned flocculated tailings material to filtration. 
     
     
         11 . The process of  claim 1 , wherein the adding of the flocculant into the flow of the fine tailings and the in-line shear conditioning to produce the pipeline-conditioned flocculated tailings material up to the discharging thereof are performed in a pipeline reactor. 
     
     
         12 . The process of  claim 11 , wherein the pipeline reactor comprises a co-annular injection device for in-line injection of the flocculant solution into the fine tailings. 
     
     
         13 . The process of  claim 1 , further comprising providing the in-line shear conditioning such that the pipeline-conditioned flocculated tailings material is discharged from the pipeline discharge outlet when the yield shear stress of the pipeline-conditioned flocculated tailings material is within a decrease zone following a plateau zone. 
     
     
         14 . The process of  claim 1 , wherein the in-line shear conditioning is controlled by a pipeline length through which the flocculated fine tailings travels prior to the discharging. 
     
     
         15 . The process of  claim 1 , wherein, immediately after addition of the flocculant, the flocculated fine tailings are transported in-line directly to the dewatering step via a pipeline assembly. 
     
     
         16 . The process of  claim 15 , wherein the pipeline assembly comprises a main pipeline section receiving the flocculated fine tailing from a flocculant addition point, and a plurality of spigots communicating with the main pipeline for expelling the conditioned flocculated fine tailings to be dewatered. 
     
     
         17 . The process of  claim 16 , wherein the spigots are arranged in spaced-apart relation with each other and in series so as to communicate with the main pipeline section. 
     
     
         18 . The process of  claim 16 , wherein the spigots are arranged in parallel, such that the main pipeline section is split to form multiple pipeline sections that communicate with respective spigots. 
     
     
         19 . The process of  claim 1 , wherein the flocculant is provided in the form of an aqueous flocculant solution that is added to the in-line flow of the fine tailings. 
     
     
         20 . A process for producing bitumen from oil sands fine tailings, the process comprising:
 retrieving oil sands fine tailings comprising bitumen, water and fine solids from a tailings pond;   subjecting the oil sands fine tailings to separation to produce recovered bitumen and a bitumen-depleted fine tailings;   treating the bitumen-depleted fine tailings to separate the fine solids from the water, wherein the treating comprises:
 adding a flocculant in-line into a flow of the bitumen-depleted fine tailings to cause dispersion of the flocculant and build-up of flocs to form flocculated fine tailings; 
 transporting the flocculated fine tailings in-line and subjecting the flocculated fine tailings to in-line shear conditioning to increase a yield stress thereof to a peak yield stress and produce a tailings material; 
 subjecting the tailings material to further in-line shear conditioning to reduce the yield stress from the peak yield stress and produce an in-line flow of a pipeline-conditioned tailings material; 
 discharging the pipeline-conditioned tailings material from a pipeline discharge outlet; and 
 dewatering the discharged pipeline-conditioned tailings material. 
   
     
     
         21 . A process for producing a mined product from mined ore, the process comprising:
 subjecting an aqueous slurry to separation to produce the mined product and fine tailings comprising water and fine solids; and   treating the fine tailings to separate the fine solids from the water, wherein the treating comprises:
 adding a flocculant in-line into a flow of the fine tailings to cause dispersion of the flocculant and build-up of flocs to form flocculated fine tailings; 
 transporting the flocculated fine tailings in-line and subjecting the flocculated fine tailings to in-line shear conditioning to increase a yield stress thereof to a peak yield stress and produce a tailings material; 
 subjecting the tailings material to further in-line shear conditioning to reduce the yield stress from the peak yield stress and produce an in-line flow of a pipeline-conditioned flocculated tailings material; 
 discharging the pipeline-conditioned flocculated tailings material from a pipeline discharge outlet; 
 dewatering the discharged pipeline-conditioned flocculated tailings material. 
   
     
     
         22 . The process of  claim 21 , wherein the mined product is bitumen and the mined ore is oil sands ore.