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1er Sem inar io d e Geom ecanica Ap l icado y Segurid adPeru 2 009

M etod os de disposicion de relaves

Riesgo sism ico

RELAVES ESPESADOSEM M ANUEL PORNILLOS

GOLDER ASSOCIATES, LIM A PERUJ

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Manejo de Relaves de la Mina - Diseno

Use Design for Closure philosophy

System approach - Water and solids managementDesign for:

Climate conditions arctic to rain forest to desert

Geological conditions

Topography

Ore types

Mine throughputManagement method selected to suit the mine

Low density slurry

Thickened/Paste Tailings

Filtered Tailings

Co-mingled/co-disposed/Paste Rock

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Manejo de Relaves de la MinaConsideraciones

Regulatory requirements

Climate - dry or wet

Topography - natural containment

Natural hazards - including seismic events

Physical stability (static & dynamic earthquake)

Chemical stability potential acid generation & leachable contaminants

Environmental / social constraints

Decommissioning & closure - progressive closure & design for closureChemical stability potential acid generation & leachable contaminants

Mechanisms for contaminant transport groundwater, surface water & air

Surface & groundwater protection downstream users

Water management minimize water usage especially in a dry climate

Erosional stability from wind & runoff

Aesthetics especially in the closure mode

Foot print limit the area of disturbance & impact

Rheology - thickening & pumping characteristics

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Metodo de Disposion de los Relaves

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Metodo de Disposion de los Relaves

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Metodo de Disposion de los Relaves

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Metodo de Disposion de los Relaves

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Porque Desaguar el Relave?

Reduce overall water use by minimizing

water losses

Reduce Footprint or Containment Structures

Simplify Closure or Reduce Closure Period

Reduce Risk of Failure

Regulation

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Reduccion de Perdida de Agua

Slurrydensity

(% solids bymass)

Volume ofwater in the

tailings(m3/ ton of

tailings)20 4.0

30 2.3

50 1.0

75 0.3

Less water transported to

tailings area = less potential for

seepage or evaporation loss

No tailings pond = less

evaporation

Higher final density = less water

retained in voids

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Minimizar el Area o la Estructura de Contencion

Dam

Capacity for Slurry

ThickenedTailings

discharge

SlurryTailings

discharge

Slope 3 to 5 %

Note:The thickened tailings must beallowed to desiccate to be stable

Additional CapacityFor Thickened

Tailings

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Alternating, thinlayer deposition

Slopes typically

3 to 10%

Tailings discharge

Thickened

tailings

Runoff collection

Minimizar el Area o la Estructura de Contencion

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Simplificar el Cierre oReducir Periodo de Cierre Period

Denser tailings = less consolidation, less cover settlement/cracking

Denser tailings = trafficable sooner, concurrent reclamation

Less segregation = lower average permeability, less seepage, less acid

generation

Less or no water to treat at end of operation

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Reducir Riesgo de Falla

Riesgo = (Probabilidad de Falla)x(Consequencia)Consequence is a function area inundated by

tailings/water after failure

Reducing quantity of water reduces area of

inundation after failure

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Construccion Aguas Abajo Reglamentado en Peru

Date Location Incident Release Impact

March 28 1965 Chile - El Cobre Liquefaction of tailingsduring earthquake leading

to dam failure and flow

slides

New Dam 350 000 m3

Old Dam 1 900 000 m3Tailings travelled 12 kmdownstream, destroyed the

town of El Cobre and killed

more than 200 people

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Diseno de Dique con Arena Relaves Cicloneada

Sand dams constructed 3 ways

Upstream has smallestconstruction quantity, but

highest risk

Downstream has largest

construction quantity and

lowest risk

Centerline smaller quantity

than downstream, similar risk

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Diques de EnvergaduraDiques de Envergadura

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Notas y Observaciones

The tailings properties and projectrequirements greatly influence the method

that is selected for disposal.

What may be good for one type of tailings orproject location may not be suitable for

another type of tailings or project location.

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ESTABILIDADRELAVES ESPESADOS DEPOSITADOS

Segun Paste 2009 Vina del Mar

La estabilidad Se requiere deposicion en CAPAS DELGADAS

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ESTABILIDAD

Que es Deposicion en Capas Delgadas?

El depositar capas delgadas les da suficiente

tiempo para que el relave receintemente puesto the

a desicar y enduricir

De-saturar que genera una succion en los matrices que redusca la

void ratio (razon volumen/volumen)

Espesor de capa diferente para el tipo del relave, la

clima, tasa de produccion, la configuracion del vaso

El material se vuelve densa (dilativa) despues de

estar remojado/re-saturado

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Caracteristicas del Material de Relaves

Depende a:Mineralogia

Proceso estractiva del mineral yreactivos

Granulometria o grado de molienda

La S.G. de particulas

Grado de espesamiento odesaguado

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0.4

0.6

0.8

1

1.2

1.4

1.6

0.1 1 10 100 1000 10000

Void

Ratio

,e

M ean Effect ive Str ess, p' (kPa)

After Deposi t ion

Bleeding

CSL

DRY

Desiccation

Consol idation

W ett ing (un load curve)

Final St at e ofTailing s in StackW i th Dry ing

Contractiv

Di lat ive

q

Final St at e of Tail ingsin Stack W itho utDrying

After Been and Li 2009

Esquematico de Relave luego de Deposicionen un Estado mas Suelto que

en Estado Critico a Esfuerzo Bajo

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(%(% solidossolidos emem peso)peso)Variabilidad d e ConsistnciaVariabilidad d e ConsistnciaPulpa d e relaves

Relaves Espesad os

Altamen te Espesado

(Pasta)

Relave Filtrad o

< 60%

60 - 70%

70 - 78%

78 - 88%

Tecnologia de Espesamiento de Relaves(Cobre, SG=2.7)

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espessadosRejeitos

No cisallado

Pasta

Relaves de cobre tipoATorta de Filtrado

Resistenciaa

o

Fluxo

(Pa)

% Slidos

Cisallado

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0. 4

0. 6

0. 8

1

1. 2

1. 4

1. 6

0.1 1 10 100 1000 10000

Void

Ratio

,e

M ean Effect ive St ress, p' (kPa)

After Deposi t ion

Densi f icat ion/Compaction

CSL

DRY

Desiccation

Consol idation

W ett ing (un load curve)Final St ate o fTailings in St ack

Contractive

Di lat ive

q

q

Esquematico Cambio de Estado Geotecnicaen los Relaves luego de la Depositacion and Densificacion

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SLURRY DENSITY (% by weight)

TailingsSlopeAngleAchieved(%)

Li, Been, Ritchie and

Welch (2009)

Las Pendientes - Playas de Relaves Espesados

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Muchas Gracias