advances towards more sustainable management of mine tailings · advances towards more sustainable...
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ADVANCES TOWARDS MORE SUSTAINABLE MANAGEMENT OF MINE
TAILINGS
David V Boger, FRS
Engineering Professor, Monash Universityand
Emeritus Laureate Professor,The University of Melbourne
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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
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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)
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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
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HEADLINES
• “Hungary battles to clean up killer sludge”
• “Mini Tsunami of toxic sludge hits villages”
• “Toxic sludge floods several villages in Hungary”
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WHEN WILL WE LEARN!
• 21 tailings dam failures in the last decade
• 22 in the previous decade
www.wise-uranium.org/mdaf.html
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Mount Polly FailureBritish ColumbiaAugust 4, 2014
7.3 million cubic metres tailings
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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.
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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
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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
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
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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
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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
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Tailings Waste Cleanup, Regeneration and Maintenance
AN UNFUNDED LIABILITY
Tailings Waste Cleanup, Regeneration and Maintenance
AN UNFUNDED LIABILITY
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INNOVATION TO IMPROVE TAILINGS MANAGEMENT
•Compression Thickeningand Paste Pumping
Dry Stacking•Inline Flocculation
Why
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Impo
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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
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• 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
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RHEOLOGY
• Discovered and exploited for tailingmanagement by the aluminium industryin the 1970s
• Discovered by the traditional miners inabout 2000
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)
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INNOVATION TO IMPROVE TAILINGS MANAGEMENT
•Compression Thickeningand Paste Pumping
Dry Stacking•Inline Flocculation
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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
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
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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)
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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.