acid mine drainage - evocra · lead, cadmium, arsenic and copper at a ph of 2.93. • animas river...

29 August 2019

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Acid Mine DrainageCauses, Consequences and RemediationDr. David M. Hunter

IntroductionMy Details

Dr David M. HunterResearch EngineerEvocra

P: 0423-209-917E: [email protected]

Why care about AMD?Global Water Crisis

Total Volume of Water on Earth

1,386 x 1015 m3

1383 km

Slide References

USGS, 2016.

Or 1.4 Sextillion Litres


1371 km97.5% Salt Water

1,351 x 1015 m3

406 km

2.5% Fresh Water

35 x 1015 m3

Slide References

USGS, 2016.

30.4% Liquid Fresh Water

106 x 1014 m3

Total Volume of Water on Earth

1,386 x 1015 m3


360 km

68.6% Unaccessible

243 x 1014 m3

273 km

Slide References

USGS, 2016.


0.8% Liquid Fresh Water

106 x 1014 m3

0.003% Renewable Fresh Water

428 x 1011 m3

0.00004% Australian Renewable Fresh Water492 x 109 m3

43 km

10 km

Slide References

UN Water, 2018.

USGS, 2016.

World Bank, 2019.

Approx. 1000x

Sydney Harbour


Slide References

Knoema, 2019.

UN Water, 2018.

World Bank, 2019.

Australia

Total Renewable Fresh Water

492,000 Billion Litres

Renewable Fresh Water Per Capita

21,000,000 Litres

Water Stress

5%

Global


42,800,000 Billion Litres


5,930,000 Litres

Water Stress

13%

Kenya




440,000 Litres

Water Stress

14%

*Data from 2014.


Slide References

Knoema, 2019.

UN Water, 2018.

World Bank, 2019.

Australia




21,000,000 Litres

Water Stress

5%

*Data from 2014.


Slide References

Asmelash, 2019.

Cheema, 2019.

Mellino, 2016.

Jakarta, Indonesia - 25 cm per year

Beijing, China - 10 cm per year

Houston, TX, USA - 5 cm per year

Mexico City, Mexico - 90 cm per year

Why care about AMD?Environmental Effects

ACID MINE DRAINAGE

Chemical• Increased acidity• Reduced pH• Destruction of

bicarbonate buffering system

• Increase in soluble metal concentrations

• Increase in particular metals

Physical• Substrate Modification• Increase in stream

velocity• Turbidity• Sedimentation• Adsorption of metals

onto sediment• Decrease in light

penetration

Biological• Behavioural• Respiratory• Reproduction• Osmoregulation• Acute and chronic

toxicity• Death of sensitive

species• Migration or avoidance

Ecological• Habitat modification• Food-chain

bioaccumulation• Loss of food source or

prey• Elimination of sensitive

species• Food chain

modification

*Adapted from Gray, 1997.Slide References

Gray, 1997.

Why care about AMD?Mining Economics

Water is vital to mining operations for:• Transport of materials (slurries/suspensions)• Mineral processing operations – gravity separation/flotation/screening etc.• Dust suppression• And many others.

Mining companies invest heavily in water infrastructure.

Slide References

Australian Bureau of Statistics, 2019.

Harries, 1997.

Ossa-Moreno, 2018.

Prevention and mitigation is better (and cheaper) than cure.

Maximising water recovery and re-use.

In 1997, Harries estimated the average cost of managing AMD in Australia to be $60m per year.

Acid drainage can be either natural (erosion/weathering) or anthropogenic (human activity) in nature.

Acid Rock Drainage (ARD), Acid Metalliferous Drainage (also AMD), Neutral Mine Drainage (NMD) and Saline Drainage (SD) are also common terms.

All of these generally occur due to the oxidation of sulfide minerals via exposure to oxygen and water.

Type pH Dissolved Metals/Sulfur

Acid Drainage <6.5 Generally High

Neutral Drainage >6.5 Low

Saline Drainage >6.5 High

Slide References

Australian Government, 2016.

International Network for Acid Prevention, 2019.

Jacobs & Testa, 2014.

What is Acid Mine Drainage (AMD)?Defining AMD

Acid drainage are generally referred to as acid mine drainage when cause by human activities, mining in particular.

Pyrite, pyrrhotite, chalcopyrite are common minerals that are known to be “acid generating” minerals.

Rate limiting factor is primarily the availability of oxygen.

FeS2 + 7/2O2 + H2O → Fe2+ + 2SO42- + 4H+

FeS2 + 14Fe3+ + 8H2O → 15Fe2+ + 2SO42- + 16H+

Fe2+ + 1/4O2 + H+ → Fe3+ + 1/2H2O

Slide References

Australian Government, 2016.International Network for Acid Prevention, 2019.Jacobs & Testa, 2014.

What is Acid Mine Drainage (AMD)?Basic Chemistry

Fe3+ + 3H2O ⇌ Fe(OH)3 + 3H+

AMD generation is often catalysed by acidophilic bacteria that oxidise metals and sulfur.

Slide References


What is Acid Mine Drainage (AMD)?Effect of Biology & Climate

Slide References

Atlas Obscura, 2010.

Bratty et al., 2017.

Gullufsen, 2018.

Parsons, 2016.

PitWatch, 2019.

Schlanger, 2015.

What is Acid Mine Drainage (AMD)?Example Sources

UNDERGROUND MINES

OPEN-CUT PITS TAILINGS DAMS

WASTE-ROCK DUMPS

Gold King MineSilverton, CO

Berkeley PitButte, MT

Falun MineFalun, Sweden

Mount PolleyQuesnel Lake, Canada

What is Acid Mine Drainage (AMD)?Modern vs. Legacy

Slide References

Bratty et al., 2017.

Johnson & Hallberg, 2005.

Ogola, Mitullah & Omulo, 2002.

Need to continue to prevent emergence of new AMDs while continuing the effort to remediate legacy AMD sources.

Modern (or Emerging)In developed countries:• Better managed and understood• Regulations and measures in place to prevent

AMD

In underdeveloped countries:• Miners (artisan & companies) turning a blind eye• Health implications for locals• Often contaminating primary water sources• Example: Macacalder Mine, Kenya

LegacyAMD has a long history:• Iberian Pyrite Belt, Spain• Falun Mine, Sweden• De Re Metallica by Agricola published in 1556

Extent of Legacy AMD:• 19,300 km of rivers and streams.• 72,000 ha of lakes and reservoirs

What is Acid Mine Drainage (AMD)?Predicting AMD

Slide References


Important to predict and understand the potential for acid generation.

Maximum Potential Acidity (MPA) in kg H2SO4/t = wt.% S x 30.6

Net Acid Producing Potential (NAPP) = MPA – ANC

Acid-Neutralising Capacity (ANC) => determined by addition of HCl and back titration with NaOH

This is often done using acid base accounting (ABA).

ANC/MPA Ratio

What is Acid Mine Drainage (AMD)?Characterising AMD

Slide References


Once AMD is already generated it is often characterised by its acidity or acidity load – often referred to as tonnes of acidity (TOA)

Total Acidity (mg/L CaCO3) = 50 x (3 x [Total Soluble Fe]/56 + 3 x [Al3+]/27 + 2 x [Mn2+]/55 + 1000x10-pH)

Acidity Load (tonnes CaCO3/day) = 10-9 x 86,400 x Flowrate (L/s) x Acidity (mg/L CaCO3)

Acidity Load (tonnes CaCO3) = 10-9 x Volume (L) x Acidity (mg/L CaCO3)

Total Acidity = Acid (H+) + Latent Acidity (Acidity from dissolved metals)

Case Studies of AMDLos Frailes Mine, Spain

Slide ReferencesEriksson & Adamek, 2016.Morin & Hutt, 2004.

• Tailings dam failure at Los Frailes Mine in 1998.• 5.5 billion litres of AMD into the Rio Agrio and

Rio Guadiamar.• Est. 1.3 - 1.9 billion litres of tailings spilt.• Spill affected 4634 ha. of land, 2600 ha. of

which were covered by tailings fines.Value Tailings Solids

(%)Tailings Liquids

(mg/L)

pH - 2.9

Sulfur 45 1200

Arsenic 0.6 0.2

Copper 0.2 17

Iron 45 80

Lead 1 3.5

Zinc 1 450

Case Studies of AMDGold King Mine, Colorado, USA

Slide References

Schlanger, 2015

Sullivan et al., 2017.

Weiser, 2018.

• Release of AMD from underground mine.• 11 million litres over 9 hrs released into Animas

River.• Estimated 24 to 45 tonnes of dissolved metals

delivered to Lake Powell, 550 km away.• Release included aluminium, iron, manganese,

lead, cadmium, arsenic and copper at a pH of 2.93.

• Animas River returned to pre-spill levels within 15 days.

• EPA says spill equivalent to 4 to 7 days of normal drainage rate suggests 1.8 to 2.7 ML per day.

• Producing approximately 3.5 ML of metal hydroxide sludge per year.

Case Studies of AMDMacalder Mine, Kenya

Slide References

Knoema, N.D.

Migori County, 2016.

Ogola et al., 2002.

• Mine in the Migori Gold Belt.• Population 1.1 million with 32% living below

poverty line.• In 2009, only 10.3% of population were

educated to high-school level.• 3 schools located within 500 m of mine.• Primarily artisanal mining – unregulated.• Run-off flows into Macalder Stream then

into the Kuja River which flows into Lake Victoria.

• Lake Victoria is Second largest freshwater lake in the world.

• Study found 13.75 mg/L of lead and 8.04 mg/L of arsenic in Macalder Stream.

Case Studies of AMDBerkeley Pit, Montana, USA

Slide References

Duaime et al., 2017.

PitWatch, 2019.

• Retired open-cut copper mine.• Operational from 1955-1982.• Currently utilising high density sludge for

treatment – 26.5 ML/day• Aim to maintain water level below the

“protective water level”.Value Units Berkeley Pit

June 2012Berkeley Pit

December 2016

pH pH Units 2.55 3.41

Sulfate mg/L 7,740 6,936

Acidity mg CaCO3/L 3,563 3,920

Arsenic mg/L 0.074 0.006

Copper mg/L 0.049 0.064

Iron mg/L 211 10.7

Zinc mg/L 631 615

Case Studies of AMDBerkeley Pit, Montana, USA

Slide References

PitWatch, 2019.

Remediation OptionsPassive vs. Active

Slide References


Jacobs & Testa, 2014.

Johnson & Hallberg, 2005.

PassiveRelative advantages:• Smaller operating costs.• Less maintenance.• Less supervision.Relative disadvantages:• High capital cost.• Not very flexible.• Low level of control.

ActiveRelative advantages:• Lower capital cost.• High flexibility and potentially mobile.• High level of control.Relative disadvantages:• High operating cost.• Higher level of supervision required.• Higher level of maintenance required.

Selection of treatment approach is generally dependent on the nature of the AMD.

Remediation OptionsPassive Processes

ReferencesFord, 2003.

Diagram in Ford, 2003.

Remediation OptionsNeutralisation & Precipitation

ReferencesInternational Network for Acid Prevention, 2019.Johnson & Hallberg, 2005.

• Addition of neutralising reagents such as:o Limestone (CaCO3)o Hydrated Lime (Ca(OH)2) (Most Common)o Quick Lime (CaO)o Soda Ash (Na2CO3)o Caustic Soda (NaOH)

• Effective at both removing heavy metals and neutralising water.

• Produces large quantities of waste.• Calcium makes recycling water in mine

problematic due to fouling.• High-density sludge (HDS) process can

concentrate waste by recycling sludge.

Remediation OptionsNeutralisation & Precipitation

ReferencesKaur, Couperthwaite & Millar, 2018.Pepper, Couperthwaite & Millar, 2018.Stanford, 2016.WordPress, 2010.

• Alternative reagent – Red Mud:o Waste material from bauxite refining.o Highly alkaline.o Adsorbs and binds heavy metals within

structure.o Can be used as filler in cement.

• Major global environmental liability.• Researchers at QUT developing novel

approaches to using red mud:o Thermally activated red mud found to

significantly reduce concentration of Al, Cu, Fe, Mn and Zn.

o Red Mud Akaganeite (RMA) shows an enhanced ability to remove sulfur.

• Reverse Osmosis/Nanofiltration:o Provides exceptionally clean water.o Highly energy intensive.o Produces concentrated brine waste

stream.o Low throughput with low recovery,

typically only 60-80%.• Research at UoN is developing mixed matrix

membrane technology:o Increased membrane hydrophilicity.o Increased throughput.o Decreased energy requirement.o Enhanced metal removal.o Possibility of using red mud.

Remediation OptionsMembrane Technologies

Slide References

Envirobay, N.D.

Zarei et al., 2018.

Remediation OptionsThe OCRA Process

Iron Pourbaix (Eh-pH) Diagram

Slide References

Materials Project, 2019.

Reagent

Feed

Output Water

Ozone

pHORP

Foam Fraction

Control VariablespH

Oxidisation Reduction Potential(ORP)


• Aims:o Remove heavy metals.o Decrease reagent consumption.o Produce less waste.

• Results:o Removes both dissolved iron and

manganese by >99%.o Precipitates generated

approximately 30% wt.% Fe and 20 wt.% Mn.

o Decrease reagent consumption by on average 70%.

o Decrease sludge generation by 60%.


• Advantages:o Can treat co-contaminants.o Can remove suspended solids.o Versatile design.o Significantly reduces reagent

consumption.o Significantly reduces waste

generation.o Has the potential to recover

valuable materials.• Limitations:

o Does not remove sulfate.o Does not provide neutralisation.

ConclusionSolving AMD

Complex puzzle.Solving issue means improving mine profitability, improving environmental protection, working towards sustainable water use and contributing to solution to global fresh water scarcity.Many tools in the toolbox.Needs collaboration between industry, researchers, governments and communities.

• Acid Mine Drainage is a complex multidimensional

problem.

• Solving this problem will contribute to:

o Improving mine profitability.

o Improving environmental protection.

o Improving water sustainability.

o Solving the global fresh water crisis.

• Finding a solution depends on open collaboration

between industry, researchers, governments and

communities.

ConclusionSolving AMD

Complex puzzle.Solving issue means improving mine profitability, improving environmental protection, working towards sustainable water use and contributing to solution to global fresh water scarcity.Many tools in the toolbox.Needs collaboration between industry, researchers, governments and communities.

• At Evocra, we:o Are utilising our patented OCRA technology to

treat AMD by removing heavy metals leading to reduced reagent consumption and waste generation.

o Value open, transparent communication and collaboration with our clients and partners.

o Operate a treatability and demonstration laboratory at the Newcastle Institute for Energy and Resources (NIER).

• For more information please:o Visit www.evocra.com.auo Or contact me by:

P: 0423-209-917E: [email protected]

http://www.evocra.com.au/

Additional Resources

GARD Guide http://www.gardguide.com/

PitWatch https://pitwatch.org

Netflix’s ExplainedThe World’s Water Crisis https://www.netflix.com/title/80216752

Industry GuidePreventing Acid and Metalliferous Drainage

https://www.industry.gov.au/sites/default/files/2019-04/lpsdp-preventing-acid-and-metalliferous-drainage-handbook-english.pdf

ABATES Software https://earthsystems.com.au/technologies/acid-base-accounting-tool/

AMDTreat Software https://amd.osmre.gov/

http://www.gardguide.com/

https://pitwatch.org/

https://www.netflix.com/title/80216752

https://www.industry.gov.au/sites/default/files/2019-04/lpsdp-preventing-acid-and-metalliferous-drainage-handbook-english.pdf

https://earthsystems.com.au/technologies/acid-base-accounting-tool/

https://amd.osmre.gov/

References

Atlas Obscura (2010). Berkeley Pit: New fungal and bacterial species call this deadly lake home. Retrieved August 26, 2019 from https://www.atlasobscura.com/places/berkeley-pit

Asmelash, L. (2019). Indonesia’s capital city isn’t the only one sinking. Retrieved August 28, 2019 from https://edition.cnn.com/2019/08/27/world/sinking-cities-indonesia-trnd/index.html

Australian Bureau of Statistics (2019). 4610.0 – Water Account Australia, 2016-17. Retrieved August 26, 2019 from https://www.abs.gov.au/AUSSTATS/[email protected]/DetailsPage/4610.02016-17?OpenDocument

Australian Government (2016). Preventing Acid and Metalliferous Drainage: Leading Practice Sustainable Development Program for the Mining Industry. Retrieved August 4, 2019 from https://www.industry.gov.au/sites/default/files/2019-04/lpsdp-preventing-acid-and-metalliferous-drainage-handbook-english.pdf

Bratty, M., Andersson, T., Holmstrom, H. & Gallagher, G. (2017). ARD Treatment in a Case Study on a Millennium of Mining: Falu Gruva, Sweden. Retrieved, August 26, 2019 from http://bc-mlard.ca/files/presentations/2016-25-BRATTY-ETAL-ard-treatment-falu-gruva-sweden.pdf

Cheema, S. (2019). Many parts of Jakarta could be submerged by 2050, experts warn. Retrieved August 28, 2019 from https://sea.mashable.com/science/5676/many-parts-of-jakarta-could-be-submerged-by-2050-experts-warn

Duaime, T.E., McGrath, S.F., Icopini, G.A. & Thale, P.R. (2017). Butte Mine Flooding Operable Unit Water-Level Monitoring and Water-Quality Sampling 2016 Consent Decree Update Butte Montana 1982-2016. Retrieved August 28, 2019 from https://pitwatch.org/wp-content/uploads/2019/06/mbmg700_BMF2016.pdf

Envirobay (N.D.). Sulfate and TDS Treatment. Retrieved August 29, 2019 from http://www.envirobay.com/services/sulphate-and-tds-treatment/Eriksson, N. & Adamek, P. (2016). The tailings pond failure at the Aznalcóllar mine, Spain. Retrieved August 28, 2019 from http://bc-mlard.ca/files/presentations/2016-19-ERIKSSON-

ADAMEK-tailings-pond-failure-aznalcollar.pdfFord, K.L. (2003). Passive Treatment System for Acid Mine Drainage. U.S. Bureau of Land Management Papers, 19. Accessible at

https://digitalcommons.unl.edu/usblmpub/19/?utm_source=digitalcommons.unl.edu%2Fusblmpub%2F19&utm_medium=PDF&utm_campaign=PDFCoverPagesGray, N.F. (1997). Enviornmental impact and remediation of acid mine drainage: a management problem. Environmental Geology, 30(1-2); pp. 62-71.Gullufsen, K. (2018). Transboundary mine faces $200-million cash crunch. Retrieved August 26, 2019 from https://www.homernews.com/news/transboundary-mine-faces-200-million-

cash-crunch/.

References

Harries, J. (1997). Acid mine drainage in Australia: Its extent and potential future liability. Retrieved August 7, 2019 from http://www.environment.gov.au/science/supervising-scientist/publications/ssr/acid-mine-drainage-australia-its-extent-and-potential-future-liability

International Network for Acid Prevention (INAP) (2019). Global Acid Rock Drainage Guide (GARD GUIDE). Retrieved August 14, 2019 from http://www.gardguide.com/

Jacobs, J.A & Testa, S.M. (2014). Acid Drainage and Sulfide Oxidation: Introduction. In Jacobs, J.A., Lehr, J.H. & Testa, S.M. (Eds.), Acid Mine Drainage, Rock Drainage and Acid Sulfate Soils: Causes, Assessment, Prediction, Prevention, and Remediation. Hoboken, NJ: John Wiley & Sons, Inc.

Johnson, D.B. & Hallberg, K.B. (2005). Acid mine drainage remediation options: a review. Science of the Total Environment, 338; pp. 3-14.

Kaur, G., Couperthwaite, S.J. & Millar, G.J. (2018). Performance of bauxite refinery residues for treating acid mine drainage. Journal of Water Process Engineering, 26; pp. 28-37.

Knoema (2019). Population Estimates and Projections. Retrieved August 27, 2019 from https://knoema.com/WBPEP2018Oct/population-estimates-and-projections

Knoema (N.D.). Migori. Retrieved August 28, 2019 from https://knoema.com/atlas/Kenya/Migori

Materials Project (2019). Materials Project – Pourbaix Diagrams. Retrieved August 29, 2019 from https://www.materialsproject.org/#apps/pourbaixdiagram/{"chemsys"%3A["Fe"]}

Mellino, C. (2016). Why This City of 21 Million People Is Sinking 3 Feet Every Year. Retrieved August 28, 2019 from https://www.ecowatch.com/why-this-city-of-21-million-people-is-sinking-3-feet-every-year-1882187727.html

Migori County (2016). Supporting Mining. Retrieved, August 28, 2019 from https://migori.go.ke/index.php/portfolio/development-matters-in-migori/goldmines-of-migori

Morin, K.A. & Hutt, N.M. (2004). Los Frailes, Aznalcollar, Spain. Retrieved August 28, 2019 from http://www.tailings.info/casestudies/losfrailes.htm

Ogola, J.S., Mitullah, W. & Omulo, M.A. (2002). Impact of Gold Mining on the Environment and Human Health: A Case Study in the Migori Gold Belt, Kenya. Environmental

Geochemistry and Health, 24(2); pp. 141-158.

Ossa-Moreno, J., McIntyre, N., Ali, S., Smart, J.C.R., Rivera, D., Lall, U. & Keir, G. (2018). The Hydro-economics of Mining. Ecological Economics, 145; 368-379.

References

Parsons, B. (2016). Mount Polley – the aftermath. Retrieved August 26, 2019 from https://www.canadianconsultingengineer.com/features/mount-polley-aftermath/

Pepper, R.A., Couperthwaite, S.J. & Millar, G.J. (2018). Re-use of waste red mud: Production of a functional iron oxide adsorbent for the removal of phosphorus. Journal of Water Process Engineering, 25; pp. 138-148.

Pitwatch (2019). PitWatch: Your Source for All Things Berkeley Pit. Retrieved August 26, 2019 from https://pitwatch.org.

Schlanger, Z. (2015). EPA Narrowly Avoided Fatalities in Gold King Mine Spill Blowout, Internal Review Finds. Retrieved August 26, 2019 from https://www.newsweek.com/epa-lucky-no-one-was-killed-mine-spill-blowout-internal-review-finds-366146

Stanford, K. (2016). Red Mud – addressing the problem. Retrieved August 29, 2019 from https://aluminiuminsider.com/red-mud-addressing-the-problem/

Sullivan, K., Cyterski, M., Knightes, C., Kraemer, S.R., Washington, J., Preito, L. & Avant, B. (2017). Analysis of the Transport and Fate of Metals Released from the Gold King Mine in the Animas and San Juan Rivers. Retrieved, August 28, 2019 from https://cfpub.epa.gov/si/si_public_record_report.cfm?Lab=NERL&dirEntryID=325950 The World Bank (2019). Renewable internal fresh water resources per capita (cubic meters). Retrieved August 27, 2019 from https://data.worldbank.org/indicator/ER.H2O.INTR.PC?end=2015&locations=AU-1W-KE&start=2015&view=map

UN Water (2018). 6 Clean Water and Sanitation: Progress on Level of Water Stress. Retrieved August 28, 2019 from http://www.unwater.org/app/uploads/2018/08/642-progress-on-level-of-water-stress-2018.pdf

USGS (2016). Water Science Photo Gallery: How much water is on Earth?. Retrieved August 28, 2019 from https://water.usgs.gov/edu/gallery/global-water-volume.html

Word Press (2010). Red Mud in Hungary. Retrieved August 29, 2019 from https://aboutenvironment.wordpress.com/2010/10/07/red-mud-in-hungary/

Zarei, M.M., Neville, F., Moreno-Atanasio, R. & Webber, G.B. (2018). Synthesis and characterisation of a PPSU/PEI/SiO2 nanocomposite membrane with enhanced hydrophilicity for copper removal from aqueous solution. Chemeca 2018; Christchurch, NZ.

David Hunter

Research Engineer

[email protected]

acid mine drainage - evocra · lead, cadmium, arsenic and copper at a ph of 2.93. • animas river...

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