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Mining with Paste Fill

Mehmet Yumlu, Principal Mining Engineer

AMC Consultants Pty Ltd

AusIMM Cobar Mining Seminar

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6 August 2010

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A L I AOutline

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I t d ti• Introduction

• What is Paste Fill?

• Why Using Paste Fill?

• Paste Fill System Design

• Paste Fill Making Process

• Distribution and placement

• Mining with Paste Fill - Case Studies

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A L I AWhat is paste fill?

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Paste fill is dense non draining sl rr made from single or a combination ofPaste fill is dense non draining slurry made from single or a combination of several suitable solid materials produced to toothpaste consistency

– For surface disposal no cement required

– For underground backfill cement always required

Terminology– Paste (P)

– Paste fill (PF)

– Paste backfill (PB)

– Cemented paste backfill (CPB)

– Composite fill (CF)

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Composite fill (CF)

– Paste aggregate fill (rocky paste fill) (PAF)

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A L I AWhy Paste fill?

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i d d t i t t hi h lit• engineered product – consistent high quality

• suitable for most mining methods - versatile

• lower cost for a given exposure duty - economic

• reduces surface footprint - environment friendly

• allows extraction of ore pillars - increasing resource extraction

• allows effective local and regional ground support - safety

• fast filling rates enables shorter stope cycle times - productivity

• non segregating - reduced dilution

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A L I AWhat are Paste Fill Duties in UG Mining?

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Wh i t t d i t th i i l t b kfillWhen integrated into the mining cycle paste backfill serves

– as a working platform,

as a wall to work alongside– as a wall to work alongside

– as an engineered artificial back

As a local and regional ground support paste fillAs a local and regional ground support paste fill

– provides confinement to ore pillars and the host rock, and

– prevents unravelling, thereby limiting convergence and subsidence into the mine p g, y g gvoids.

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A L I ASome Myths….

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P t i NOT• Paste is NOT

– The solution to all future mine fill problems

A method which will enable a mine to place all tailings underground– A method which will enable a mine to place all tailings underground

– A fill type by which all the water is absorbed through cement hydration

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A L I APaste Fill Design

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• Paste fill is engineered to meet the following criteria• Paste fill is engineered to meet the following criteria

– Flow properties (rheology)

– delivery of paste from surface to underground via boreholes and pipes at the highest practical y p g p p g ppulp density

– Strength properties

paste to remain stable when exposed to static or dynamic loading conditions experienced by– paste to remain stable when exposed to static or dynamic loading conditions experienced by the mining operation

» This includes short term during the local mining operation and

» Long term stability against regional seismicity

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A L I AStrength Design

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A l ti l• Analytical

• Empirical

• Numerical

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A L I ARheology Design

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Rh l i th t d f th fl ti f fl id• Rheology is the study of the flow properties of fluids

• Water is a Newtonian fluid

– If you tip water out of a glass it will start to flow immediately

• Pastefill is a non-Newtonian fluid

– If you want to get toothpaste out of the tube, you must squeeze it first

– Yield stress is the measure of how much work is required for the paste to start flowing

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A L I ATypical Paste Fill Characteristics

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Particle si e distrib tion• Particle size distribution– Minimum 15% passing 20 micron

– No top sizeNo top size

• Rheological properties– Yield stress for surface disposal less than 100 Pa

– Yield stress for backfill 100 to 700 Pa

• Strength properties– Stiffness, E=150 to 450 MPa

– Can be engineered to desired strength ( 100 kPa to 5 MPa)

( CS)

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• 300 to 1,000 kPa for vertical exposures

• >1,000 kPa for undercut exposures

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A L I AWhat are methods of making paste fill?

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A L I AWhat are the delivery options?

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• Gravity delivery to borehole

• Surface conveyor to borehole

• Pump delivery thruPump delivery thru

– Borehole

– Decline

• Agi truck delivery to borehole

• Internal boreholes

• Level pipelines

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A L I APaste fill barricades

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• Engendered shotcrete barricades required to retain paste fill

– Planar

– Arched

• Mullock waste pile

• Combination of waste and shotcrete

• Cemented rockfill

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A L I APaste Fill Operations – Increasing Popularity

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Ab t 100 ti ld id• About 100 operations worldwide

• Many ongoing projects

• Canada = 35 / 2

• Australia = 24 / 5

• South America = 12 /4

• Europe = 11 /8

• Asia = 7 / 9

• Africa = 5 /1

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A L I ACase Study 1

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• Underground Cu and Zn operation

• Production 1.0 MTPA

• Mining methodsMining methods

– Longitudinal & transverse sublevel stoping

– Drift and fill

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A L I ACase Study 1

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• Online paste fill plant, 45 m3/hour

• Using full tailings, SG of 4.5

• PSD (50-60% passing 20 microns with P80 of 63 microns)

• Solid density 82%w/w (49.5%v/v)

• Slump: 7 – 10 inch

• Paste bulk and dry density: 2.6 and 2.0 tonnes/m3

• Stope size 20m H x 7m W x 30m L (panels)p (p )

• Target design strength: 1.0 MPa

• GP cement; 7% (150 kg/m3) for primaries and 5% (110kg/m3) for secondaries

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; ( g ) p ( g )

• Pump delivery, 125 mm diameter thru decline and boreholes

• Shotcrete barricades

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Shotcrete barricades

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A L I ACase Study 1

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A L I ACase Study 1

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A L I ACase Study 2

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U d d ld i• Underground gold mine

• Production 450 TPA

• Mining method

– Underhand cut and fill

• Backfill types

– Paste fill

– Rockfill

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A L I ACase Study 2

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Dr paste fill s stem 120 m3/ho r• Dry paste fill system, 120 m3/hour

• Using volcanic tuff

PSD (30% 20 i P80 100 i ) SG f 2 55• PSD (30% -20 micron, P80 100 micron), SG of 2.55

• Solids density 50%w/w (28%v/v)

W d d b lk d i 1 5 / 3 d 0 8 / 3• Wet and dry bulk density 1.5 t/m3 and 0.8 t/m3

• GP cement; 15 to 20%w/w (100 to 150 kg/m3)

• Target design UCS >1,500 kPa

• Stope size 5m W x 5m H x 30m L (cells)

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• Gravity delivery thru borehole, 150mm dia distribution system

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A L I ACase Study 2

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A L I ACase Study 2

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Previous cut – Lift 1

Next cut – Lift 2

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A L I ACase Study 3

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U d d Z d Pb i• Underground Zn and Pb mine

• Production 1.6 MTPA

• Tabular flat dipping massive sulphide orebody (dip <20° )

• Mining methods

– Drift and Fill

– Bench stoping

• Backfill

– Rockfill

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A L I ACase Study 3

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Online paste plant sing DCT 100 m3/ho r• Online paste plant using DCT, 100 m3/hour

• Full mill tailings (35% passing 20 micron, P80 100 micron), SG of 3.6

S lid d it 75% / (48% / )• Solids density 75%w/w (48%v/v)

• Wet and dry bulk density 2.15 t/m3 and 1.6 t/m3

Yi ld 50 100 P (10 10 5 i h l )• Yield stress 50 to 100 Pa (10 to 10.5 inch slump)

• Pump delivery through decline, 200 mm diameter, 3.5 km long

• Shotcrete barricades

• Stope size 10m W x 6m H x 150m L

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• Slag 60% : cement 40%

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A L I ACase Study 3

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A L I AThank you for listening…

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A ti ?• Any questions?

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