advances towards more sustainable management of mine tailings · advances towards more sustainable...

www.eng.monash.edu.au

ADVANCES TOWARDS MORE SUSTAINABLE MANAGEMENT OF MINE

TAILINGS

David V Boger, FRS

Engineering Professor, Monash Universityand

Emeritus Laureate Professor,The University of Melbourne

www.eng.monash.edu.au2

Second International Mining Future Conference22-2 November, 2011

University of Sydney, New South Wales, Australia

SUSTAINABLE DEVELOPMENT AND TAILINGS

Hugh Jones, FAusIMM(CP), Senor Consultantand

David Boger,FRS, Engineering Professor, Monash University, and

Laureate Professor Emeritus, The University of Melbourne

Making an Unsustainable Industry More Sustainable (The Three Rs)

•REDUCE•RE-USE

•RECYCLE

Making an Unsustainable Industry More Sustainable (The Three Rs)

•REDUCE•RE-USE

•RECYCLE


MINING INDUSTRY AND WASTE

World’s largest waste producer

51 billion tonnes of waste rock(mine overburden)

14 billion tonnes of fine particle tailings

Based on 2010 production figures (Mudd, 2011)

D. V. BogerBHP Billiton Fellow


Tailings Dam Failures

Hungary’s Bauxite Disaster


HUNGARY TAILINGS DAM DISASTER(RTT NEWS)

The Hungarian Aluminium Company (MAL Zrt)

was fined $646 million for Environmental

Damages

The spill of pH 13 Red Mud flooded several

towns and killed ten people


HEADLINES

• “Hungary battles to clean up killer sludge”

• “Mini Tsunami of toxic sludge hits villages”

• “Toxic sludge floods several villages in Hungary”


WHEN WILL WE LEARN!

• 21 tailings dam failures in the last decade

• 22 in the previous decade

www.wise-uranium.org/mdaf.html


Eight Tailings Dam Failures

(2012 – 2014)


Mount Polly FailureBritish ColumbiaAugust 4, 2014

7.3 million cubic metres tailings


Mount Polley Tailings Dam failure, British Columbia, 4 August , 2014

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The Achilles’ Heel of themining industry is itsenvironmental record


REGULATIONS


CHANGES ARE OCCURRING

The Energy Resource Conservation Board (ERCB) in Alberta, Canada, Directive 074 (2009) requires:

“A trafficable surface of the tar sands tailings foundation has to be established within ten years for final closure”

This step will impact worldwide.

Oil Sands Tailings Deposition


The Canadian Oil Sands Industry“By 2010 the oil sands industry will be producing about one million barrels of oil per dayfrom surface mined oil sands. This equates to about one million cubic metres of coarsetailings deposit per day and 0.2 to 0.3 million cubic metres of fine tailings per day.To date the industry has produced 400 million cubic metres of fine tailings.”

D.V.BogerParticulate Fluids Processing Centre

Department of Chemical & Biomolecular EngineeringThe University of Melbourne

Victoria Australia


Pebble MineOriginally 50% Northern Dynasty

(Canadian Company)

50% Anglo American

Anglo spent about 0.5 billion and walked away from the project in 2013.

Rio Tinto also walked away from its 20% interest in Northern Dynasty.

“World’s Best Practice” Two Tailings Dams

1 - 740 foot tall and 4.3 miles long filling the entire valley to a depth covering the person on the ridge


LIABILITY

Regulation is not enough -even in the USA

According to the US EPA

• 500,000 abandoned mine sites –reclamation would cost tens of billions of dollars

• portions of the headwaters of 40% of watersheds are contaminated from mining in the western continental USA


Landowner pays $100 for troubled Solomon Islands mine Gold Ridge from Australian miner

A landowner company in Solomon Islands has bought the troubled Gold Ridge mine for just $100 from Australian gold miner Saint Barbara.

By Pacific affairs reporter Liam Fox, Jemima GarrettPosted 4 May 2015, 10:30pm


As heavy rain continues to fall in the Solomon Islands following Tropical Cyclone Raquel last week,fears the Gold Ridge mine's toxic tailings dam will overflow are starting to intensify.

Gold Ridge mine: Toxic tailings dam on the brink of overflow; environmentalists fear mass contaminationPacific Beat By Michael Walsh and staffPosted Mon 13 Jul 2015, 6:09pm


Tailings Waste Cleanup, Regeneration and Maintenance

AN UNFUNDED LIABILITY

Tailings Waste Cleanup, Regeneration and Maintenance

AN UNFUNDED LIABILITY


TECHNOLOGY


INNOVATION TO IMPROVE TAILINGS MANAGEMENT

•Compression Thickeningand Paste Pumping

Dry Stacking•Inline Flocculation

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Suggested approach for determination of tailings disposal system

ThickenerconcentratesPlant WastePipe flow

(low shearbreakdown)

Pumping(high shearbreakdown)

- Thickened tailings disposal- Dry Stacking- Paste Backfill

1. Choice of disposal method,Depositional requirements.

2. Rheology requirementsfor pipeline transport.

3. Thickenerdesign.

DESIGN SEQUENCE


• Paste stacking extends back to the 1980s in the alumina industry

• Alcoa (WA) commissioned the first super thickener (compression thickener) in 1987, one in 1989, and another in 1991

• Alcan brought “deep cone thickening” to the industry and was already dry stacking in Jamaica in 1986 (Chandler) and centrally discharging a high yield stress tailings in Quebec

• A key was exploiting Rheology


RHEOLOGY

• Discovered and exploited for tailingmanagement by the aluminium industryin the 1970s

• Discovered by the traditional miners inabout 2000

Yield Stress MeasurementYield Stress Measurement

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Developments motivated by applications in minerals industry

The Vane Yield Stress Rheometer (J. Rheol., 27: 321, 1983; and 29: 335, 1985) The Cylindrical Slump Test for Yield Stress

Measurement (50 cent Rheometer) (J. Rheol., 40: 1119, 1996) The Bucket Rheometer for shear stress-shear rate

measurement of industrial suspensions (J. Rheol., 51(5): 821, 2007)

Dry Disposal Dam

Alcoa discharge onto “dry” tails

Paste placement at a gold mine

Paste placement at operating tailings storage facility


INNOVATION TO IMPROVE TAILINGS MANAGEMENT

•Compression Thickeningand Paste Pumping

Dry Stacking•Inline Flocculation


END OF PIPE FLOCCULATION WITH POLYMER SOLUTIONS FOR RAPID CLEAR WATER RELEASE AND

STACKING OF FINE COAL TAILINGS

•R. R. Backer and R. A. Bush. “Fine Coal-Refuse Dewatering, Report of Investigation 8581”, U.S. Department of the Interior, Bureau of Mines, U.S. Government Printing Office; 1981-505-002/94

•B.M. Stewart, R.R. Backer and R.A. Bush. “Thickening Fine Coal Refuse Slump for Rapid Dewatering and Enhanced Safety, Report of Investigation 9057”, U.S. Government Printing Office, 1986.

In‐Line Flocculation of Tailings

water recoverytailings

Paste tailings to disposal (dry stacking)

THICKENING

powder flocculant

tailings

emulsion flocculant

polymer solution flocculant

tailings to disposalRapid water recovery

IN‐LINE FLOCCULATION


NALCO OREBIND TECHNOLOGY

Reasons for thickening• Reclaim water• Reclaim process reagents• Reclaim energy (heat)• Maximise density of tailings in tailings storage

facility• Minimize tailings storage facility footprint• Render suitable for mine backfill• Reduce potential for acid drainage


WORLD’S BEST PRACTICEPaste and Thickened Tailings technology has now matured to the extent that:• Traditional tailings dams can and should be

eliminated for flocculated fine particlesuspensions

and• Reclamation can and should occur

concurrently with the paste stacking

14th Int’l Seminar on Paste & Thickened Tailings (April 2011):Paste & Thickened Tailings – Friend Against Acid & Metalliferous Drainage? / 59

Mine Waste v Climate Change?

“problems related to mining waste may be rated as second only to global warming and stratospheric ozone depletion in terms of ecological risk. The release to the environment of mining waste can result in profound, generally irreversible destruction of ecosystems”

- attributed to the US EPA (1987)


ACKNOWLEDGEMENTS

Thank you to the great group of research students who worked on mineral waste related issues. Also thanks to Alcoa W.A. for ongoing support, in particular I would like to acknowledge David Cooling and Don Glenister for their friendship and support. Finally, this paper could not have been put together without the support of my friend and colleague, Christine Collis.

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