4_paste pumping deposition field trials and concepts on syncrudes dewawtered mft_ahmed et al.pdf

7/22/2019 4_Paste pumping deposition field trials and concepts on syncrudes dewawtered mft_Ahmed et al.pdf

1/18

Paste Pumping and Deposition FieldTrials and Concepts on Syncrudes

Dewatered Mature Fine Tailings (MFT)

(Centrifuge Cake)

Tailings and Mine Waste 2009

Rick Lahaie Syncrude Canada Ltd.

Isaac Ahmed, Mark Labelle, Rob Brown Golder Paste Technology Ltd.


2/18

Outline Bench Scale to Pilot Testing

Brief introduction to MFT centrifuge process All testwork was completed at Syncrudes

Mildred Lake Operation

Two phase approach, with the objective -

determine pumpability of MFT centrifuge

cake (paste)

Bench scale rheological examination of

centrifuge cake at 50 to 60 wt.% solids

Design field testing (flow loop) of a

positive displacement pumping system for

the centrifuge cake

Preliminary deposition concepts


3/18

Scope of MFT Centrifuge Field Trials

Two pods of oilfield scale centrifuges wereoperated in parallel by Syncrude

Two Alfa Laval Lynx 40s running in parallelwith the prime focus provide centrifuge cakefor:

Transportation assessment conveyorand positive displacement pump / pipelinestudies (Golder PasteTec)

Bulk materials for geotechnical andenvironmental studies

Single MiSwaco 518 centrifuge used toAdvance MFT flocculation and MFT centrifugeprocess understanding:

Flocculant optimization studies

Centrifuge operational parameterassessments

MiSwaco

Alfa Laval


4/18

Overview MFT Centrifuge Pilot Plant Set-up

Golder Paste Tec

Set-Up Stacker

Centrifuges

FlocculantStorage/Mixing

Interim MFT

Supply

Pond

MFT Storage

Tanks

Centrifuge

Cake

Deposits


5/18

Bench Scale Phase I

Determine if MFT centrifuge cake can be pumped

First phase bench scale rheology testing

MFT centrifuge cake: 50 to 60 wt.% solids

Centrate to less than 1 wt.% solids

High flocculant content, 1300 g/tonne

Low slump values, less than 5

Results show

High yield stress, ranging from 600 to 1200 Pa

Metal mine pastes have yield stresses of about

200 Pa

High yield stress ~attributed to high flocculant

dosage. Metal mine pastes, 20 to 50 g/tonne


6/18

Bench Scale Phase I

Sampling of MFT centrifuge cake

Target conditions

Upset conditions

Sheared / unsheared

Yield stress values gives some

indication on ease of pumping

To pump MFT centrifuge cake

material must be sheared first

By shearing the sample the yield

stress can be reduced significantly0

200

400

600

800

1000

1200

1400

0% 20% 40% 60% 80%

Solids Content (wt%)

YieldStres

s(Pa)

9/12/2008 4:00 PM

Standard

9/12/2008 4:00 PM

Sheared


7/18

Field Pumping Phase II Equipment Set-Up

Field equipment was set-up to pump theMFT centrifuge cake

Data captured is used to determine

pipeline friction loss

MFT centrifuge cake pumping process

Material discharged from the stackerenters the paste / hopper truck

The truck shears and discharges into

the pump truck

Material is pumped via piston pump to

a deposition cell

Pressure sensors and flow meter are

used to capture data in real time for

interpretation under different conditions

Overall Set-Up

Piping & Instrumentation


8/18

Field Pumping Phase II Equipment Set-Up

Pressure

Transducer #1

Flowmeter

PressureTransducer #2

Pumper Truck

Hopper

Truck

Pipe Discharge

Reducer

Pipes

790 cm

2805 cm

3412 cm

915cm

615 cm

ANSI Flan ge

100 mm

Pipe Clamps

Shearing with screw auger

and mixer

Centrifuge Cake

Discharge


9/18

Field Pumping Phase II Data Acquisition

0

100

200

300

400

500

600

700

800

900

1000

0 10 20 30 40 50 60

Time (sec)

Press

ure(kPa)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Flow

(m/sec)

Transducer 1 (kPa) Transducer 2(kPa) FM (m/sec)

Pressure differential andflow-rate

Pump strokes can be

readily observed on

graph

Dataset is analysed andfollows the Bingham

plastic model

MFT centrifuge cake

has characteristics of

paste


10/18

Field Pumping Phase II Data Analysis

First step is to determinerelationship between

pressure loss and flow

rate

The raw data collected

(previous slide)

represents one point oneach curve

A series of runs at

different flow-rates at the

same material

consistency representsone test

0

10

20

30

40

50

60

70

80

0.00 0.50 1.00 1.50 2.00 2.50

Flow Velocity (m/sec)

PressureLosses(kPa/m)

Test 3 Test 4 Test 5


11/18

Field Pumping Phase II Pipe Friction Factors

Using the Bingham Plasticmodel, pipe friction factors

can be obtained

Data presented is scaled up

to 350 mm diameter

schedule 40 pipe from

field set-up of 40 mmdiameter pipe

0

1

2

3

4

5

6

7

8

9

10

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00

Flow Velocity (m/sec)

Pressure

Loss,(kPa/m)

Test 3 Test 4


12/18

Field Pumping Phase II Transport &

Deposition

MFT centrifuged cake (paste) waspumped and deposited

10 kPa/m for 8 pipe diameter (200

mm)

5 kPa/m for a 14 pipe diameter (350mm)

Values presented are for 1 m/s flow

velocity

Natural deposition angle was

apparent


13/18

Mixer Discharge (Click to Start)


14/18

Pipe Discharge (Click to Start)


15/18

Deposition (Click to Start)


16/18

Deposition Concepts

Subsequent dewatering of the cake bynatural processes; consolidation, desiccation

and freeze thaw via either / or:

1 to 2 m annual layers or lifts, delivering a

trafficable surface that can be reclaimed

terrestrially;

A very thick, potentially 30 m layer depositedin the mined out pits where, with time,

consolidation further dewaters the cake to

deliver a deposit that can be reclaimed

terrestrially or by water capping.


17/18

Conclusion

MFT centrifuge cake can be pumped, but it mustbe sheared first reduce yield stress

MFT centrifuge cake like paste can be

characterized (rheology) using the Bingham

Plastic model

Pipeline friction factors are relatively high but

can be pumped via positive displacement pumps

When deposited the material showed little water

bleed - an advancing front is apparent with

surface cracking

Syncrude is currently investigating all cake

transport alternatives - trucking with specialty

boxes, pumping, conveying and possibly directdeposit from floating centrifuge barges for some

in-pit deposition.


18/18

Thank you!Questions / Comments

Tailings and Mine Waste 2009

Rick Lahaie Syncrude Canada Ltd.Isaac Ahmed, Mark Labelle, Rob Brown Golder Paste Technology Ltd.

4_paste pumping deposition field trials and concepts on syncrudes dewawtered mft_ahmed et al.pdf

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