Effects of polymer dosage on rheology spread ability of polymer amended mft
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“ Effects of polymer dosage on rheology / spread-ability of polymer-amended MFT. Civil and Environmental Department, Carleton University 17 June 2013. Shabnam Mizani 3 years experience with AMEC. Bereket Fisseha ( at U of A ) 5 years experience with Golder in Mining

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Effects of polymer dosage on rheology spread ability of polymer amended mft

Effects of polymer dosage on rheology / spread-ability of polymer-amended MFT

Civil and Environmental Department, Carleton University

17 June 2013


Shabnam Mizani

3 years experience

with AMEC

Bereket Fisseha

(at U of A)

5 years experience with

Golder in Mining

Geotechnical Services

Team manager

Sahar Soleimani

PhD Environmental Engineering

3 years experience in Civil Engineering

Projects

Expertise in numerical modelling

Tariq Bajwa

5 years in Civil and Hydropower

Engineering


Project background
Project Background

  • Part of a larger project funded by COSIA looking at optimization of polymer-amended mature fine tailings

  • Optimization includes:

  • i) Short-term dewatering due to action of polymer and consolidation under self-weight in a thin (< 1 m ) lift

  • ii) Dewatering due to desiccation

  • Iii) Dewatering and geotechnical behaviour after consolidation under addition of new lifts

  • Iv) Spread-ability (rheological behaviour after material emerges from the pipe)


Objective improve understanding of out of pipe rheology
Objective – Improve understanding of “out of pipe” rheology

Controlling stack geometry (slope and lift heights)

  • Designing deposition cells

  • Trade off between deposition and dewaterability

    Flow Behaviour of the Amended Oil Sand Tailings upon Deposition

  • Objective

  • Introduction

  • Methodology

  • Results

  • Conclusion

  • Future Work

Topography

Operational Parameters

Rheology


Introduction
Introduction

  • Objective

  • Introduction

  • Methodology

  • Results

  • Conclusion

  • Future Work

  • Flocculation: Aggregation Process

  • Alters the Rheology significantly (Yield Stress, Viscosity)

  • Mixing intensity and duration (shear caused during transportation can disintegrate the flocs)


Rheological behaviour
Rheological Behaviour

  • Tailings show Non-Newtonian behaviour

  • Polymer amended MFT especially sensitive to aging and shearing

  • Objective

  • Introduction

  • Methodology

  • Results

  • Conclusion

  • Future Work

Rheology

??


Methodology
Methodology

  • Slump Tests

  • Back analysis of bench /field scale deposition

  • Rheometer (Anton Paar Physica MCR301)

  • Objective

  • Introduction

  • Methodology

  • Results

  • Conclusion

  • Future Work

A.Stress growth (Rate control mode)

B. Stress relaxation

C. Creep (Stress controlled mode)

Application of constant stress

Application of constant stress rate



In line mixing
In Line Mixing

In Field

  • rapid mixing of polymer occurs in a 17 ft pipeline

    In Laboratory

  • First a four blade impeller with radius of 8.5 cm was immersed in 1,800 g of MFT.

  • The mixing was then started at a fixed speed of 250 rpm.

  • The flocculant solution was then added but was mainly directed near the impeller during mixing.

  • After adding the 0.4% flocculant solution the mixing was continued for another 10 seconds

  • Objective

  • Introduction

  • Methodology

  • Results

  • Conclusion

  • Future Work


Mixing time dewaterbility
Mixing Time & Dewaterbility

Highest water release


Results
Results

  • Stress Growth

  • Objective

  • Introduction

  • Methodology

  • Results

  • -Rheology

  • -Flume Test

  • Conclusion

  • Future Work

Shear Rate=0.1s-1

Shear Rate=1s-1

11


Constant stress test decreasing 850gr ton
Constant stress test (Decreasing)-850gr/ton

30s each step (800-5Pa)

10min each step (250-30Pa)


Flume 3 d bench deposition tests
Flume / 3-D bench deposition tests

  • Using Funnel-9L of flocculated Tailings

  • Objective

  • Introduction

  • Methodology

  • Results

  • -Rheology

  • -Spreadibility

  • Conclusion

  • Future Work

Yield stress from best fits of

lubrication theory – JNNFM 2013


Comparison with field data pilot scale test oct2012
Comparison With Field Data (Pilot scale Test Oct2012)

  • Stress Growth Shear rate=0.1s-1

mixing time and intensity used to prepare the flocculated MFT in the laboratory was representative of field mixing conditions



Summary conclusion
Summary & Conclusion

  • Objective

  • Introduction

  • Methodology

  • Results

  • -Rheology

  • -Spreadibility

  • Conclusion

  • Future Work


Microstructure sem
Microstructure SEM

  • Scanning electron microscopy (Vega-II XMU VPSEM, Tescan)

  • speed of 148 µs/pixel and a working distance of 6-8 mm.

  • acceleration voltage of 20 kV using a cold stage to freeze the samples(prevent excessive water withdrawal during the observation under the vacuum condition of the SEM chamber)

    Raw MFT 1000 g/ton

  • Objective

  • Introduction

  • Methodology

  • Results

  • Conclusion

  • Future Work



Summary conclusion1
Summary & Conclusion

  • Laboratory prepared samples could mimic field samples in the stress growth tests

  • Yield stress calculated from the flume and other tests employing lubrication theory was in best agreement with slump and controlled decreasing shear stress test.

  • Lift thickness control likely needs to consider increase in effective yield stress of the deposit over deposition time

  • Even high sheared polymer amended MFT still manifests a significant yield stress


Future ongoing work
Future/Ongoing Work

Rate of shear

Rheology

  • Characterise the dependence of spreadability on both aging and shearing (i.e. Coussot Model )

    Spreadibility

  • finite element non-Newtonian flow codes such as ANYS Polyflow or ANSYS CFX 14 (Finite Volume)

  • SPH – smooth particle hydrodynamics

  • Objective

  • Introduction

  • Methodology

  • Results

  • -Rheology

  • -Spreadibility

  • Conclusion

  • Future Work

Characteristic time



Acknowledgements
Acknowledgements

  • COSIA and NSERC

  • Shell Canada and Barr Engineering


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