Managing Tailings and Waste Rock to Minimise Environmental Risk and

Liability

P Scott FeTech Conference

Perth November 2013

Introduction

A perspective on the Mining Industry and management of bulk wastes:

Waste Rock Tailings Focus on:

Materials characterisation;

Planning and designing for the life of the facility;

Management of risk along the way; and

Closure and rehabilitation.

Introduction

Industry has promoted itself as a temporary land use:

What is the post-mining land use?

How can I be sure that land use can be supported?

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Pilbara

Big

Hot, dry

Cyclones

Rocky hills, flat sheet flow areas

Land use:

Mining

Grazing and pastoralism

Conservation

Introduction – Life of Mine Approach

Materials Characterisation

WHY?

Understanding the nature of the materials is critical to planning

Geotechnical risk – will it stand up (earthquake, rainfall)?

Will it leach any thing to the environment or exhibit behaviour that prevents rehabilitation

What will I be able to rehabilitate it to – can it support the post-mine land use?

Iron Ore Tailings

Acid producing behaviour

Other leachates

Fibrous materials

Dust

Failure to consolidate

Runoff co-efficients/Water balance

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Waste Rock Waste rock generally

has a large footprint

Visible

Lots of it!

Cost

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Waste Rock - ARD

Numerous people

Exploration>Post Closure

Use geological knowledge

Prediction

Scaling issues

Construction

Historical legacies

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Waste Rock – Acid Rock Drainage

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Leachates can be long term problems – leachate capture system

Acid Rock Drainage (ARD)

Cyclone Bobby

Strategy and design at feasibility

Control over whole of life

Materials characterisation and use

Historical legacies

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Planning and Designing for the Life of the Facility

Some common pitfalls/issues:

Not including areas needed for clearing for direct and indirect footprint (eg Topsoil stockpiles)

Not salvaging closure materials – topsoil, subsoil

Not designing for closure

Making assumptions about materials. Use trials.

Encapsulation specifications – precision?

Lack of or poor materials available for lifts and closure

Water balance and management – operations and closure

Leaks/seepage

Blocking creeks and watercourses

Waste Rock - Dumps

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Waste Rock - Landforms

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Call it a “dump”?

Name it after a Mining Engineer

Find a natural analogue

Plan how you are going to keep it stable

Planning and Designing for the Life of the Facility

With a whole mine life leading up to closure – plenty can go off the rails

Materials characterisation and placement

Drainage controls

Topsoil deterioration

Weeds

Feral animals

Risk Management

Actions

Use formal risk assessment

Life of mine plans

Set some KPIs

Establish clear responsibilities:

o Planning

o Opening and closing

o Treat as a landform

Risk Management

Some issues to consider - Tailings

Tailings dam failure rates highly

Access during operations (risks to people and animals)

Management and freeboard

Drying and dust

Fibrous materials

Failure to consolidate

Pollution and contamination

Risk Management

Some issues to consider – Waste Rock

Leachates

Water management – shed, capture?

Fibrous materials

Rehabilitation materials – enough, quality?

Keeping it on track over the life of mine – systematic

approach

R&D R&D History

MERIWA – no projects completed that are specific to iron ore tailings or waste rock. Projects with general application to iron ore wastes include:

Slope stability – Telfer

Spinifex rehab – Kimberley

Gold tailings consolidation – Goldfields

AMIRA

Current projects with relevance:

Integrated tailings management – P1087 started 2012

Long Term Acid Rock and Tailings Drainage Mitigation through Source Control - P933B being written up

Closure and Rehabilitation

Stability and Growth Medium

Design for resilience

Soils are the key to plant growth and establishment

Do some trials

Tailings Consolidation

Getting on a tailings dam to cap and close

Consolidation

Retained water quality

Machinery to use

Tailings Rehabilitation

An example

Planning for access

Planning was based on salt tolerant vegetation

Materials to use

A trial here revealed that the best treatment was topsoil straight onto tailings!

Rehabilitation and Closure

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Rehabilitation and Closure

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Conclusion

Tailings and waste rock are part of mining – they need to be planned on a whole of life basis

Characterise materials

Establish clear responsibilities and plans

Identify the risks and manage

Treat them as landforms – consider whole of life issues

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THANK YOU

Acknowledgements: – This presentation was prepared following discussions with DMP and Industry personnel. Thanks in particular to Danielle Risbey, Phil Gorey, Ian Zlatnik and Gavin Price

Catherine Pinchin, Director Telephone: + 61 8 9221 0011 Mobile: + 61 412 196 497 Email: cpinchin@prestonconsulting.com.au

Phil Scott, Director Telephone: + 61 8 9221 0011 Mobile: + 61 418 954 467 Email: pscott@prestonconsulting.com.au

Preston Consulting Phone: + 61 8 9221 0011 Fax: + 61 8 9221 4783 Street Address: Level 3, 8/201 Adelaide Terrace, East Perth WA 6892 Postal Address: PO Box 3093, East Perth, Western Australia, 6892

27/11/2013