Acid Mine Drainage Causes, Consequences and Remediation Dr. David - - PowerPoint PPT Presentation

29 August 2019

EVOCRA.COM.AU

Acid Mine Drainage

Causes, Consequences and Remediation

• Dr. David M. Hunter

Introduction

My Details

Dr David M. Hunter Res Resea earch Engineer eer Evocra P: 0423-209-917 E: david.hunter@evocra.com.au

Why care about AMD?

Global Water Crisis

Total Volume of Water

• n Earth

1,386 x 1015 m3 1383 km

Slide References USGS, 2016.

Or 1.4 Sextillion Litres

Why care about AMD?

Global Water Crisis

1371 km 97.5% 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

• n Earth

1,386 x 1015 m3

Why care about AMD?

Global Water Crisis

360 km 68.6% Unaccessible 243 x 1014 m3 273 km

Slide References USGS, 2016.

Why care about AMD?

Global Water Crisis

0.8% Liquid Fresh Water 106 x 1014 m3 0.003% Renewable Fresh Water 428 x 1011 m3 0.00004% Australian Renewable Fresh Water 492 x 109 m3 43 km 10 km

Slide References UN Water, 2018. USGS, 2016. World Bank, 2019.

• Approx. 1000x

Sydney Harbour

Why care about AMD?

Global Water Crisis

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

Total Renewable Fresh Water 42,800,000 Billion Litres Renewable Fresh Water Per Capita 5,930,000 Litres Water Stress 13%

Kenya

Total Renewable Fresh Water 21,000 Billion Litres Renewable Fresh Water Per Capita 440,000 Litres Water Stress 14%

*Data from 2014.

Why care about AMD?

Global Water Crisis

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%

*Data from 2014.

Why care about AMD?

Global Water Crisis

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
• nto 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 International Network for Acid Prevention, 2019.

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 Mine Silverton, CO Berkeley Pit Butte, MT Falun Mine Falun, Sweden Mount Polley Quesnel 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

Legacy

AMD 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 Australian Government, 2016.

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 Australian Government, 2016.

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 AMD

Los Frailes Mine, Spain

Slide References Eriksson & 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 AMD

Gold 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 AMD

Macalder 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 AMD

Berkeley 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 2012 Berkeley 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 AMD

Berkeley Pit, Montana, USA

Slide References PitWatch, 2019.

Remediation Options

Passive vs. Active

Slide References International Network for Acid Prevention, 2019. Jacobs & Testa, 2014. Johnson & Hallberg, 2005.

Passive

Relative advantages:

• Smaller operating costs.
• Less maintenance.
• Less supervision.

Relative disadvantages:

• High capital cost.
• Not very flexible.
• Low level of control.

Active

Relative 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 Options

Passive Processes

References Ford, 2003.

Diagram in Ford, 2003.

Remediation Options

Neutralisation & Precipitation

References International Network for Acid Prevention, 2019. Johnson & Hallberg, 2005.

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

Neutralisation & Precipitation

References Kaur, Couperthwaite & Millar, 2018. Pepper, Couperthwaite & Millar, 2018. Stanford, 2016. WordPress, 2010.

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

structure.

• Can be used as filler in cement.
• Major global environmental liability.
• Researchers at QUT developing novel

approaches to using red mud:

• Thermally activated red mud found to

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

• Red Mud Akaganeite (RMA) shows an

enhanced ability to remove sulfur.

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

stream.

• Low throughput with low recovery,

typically only 60-80%.

• Research at UoN is developing mixed matrix

membrane technology:

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

Remediation Options

Membrane Technologies

Slide References Envirobay, N.D. Zarei et al., 2018.

Remediation Options

The OCRA Process

Iron Pourbaix (Eh-pH) Diagram

Slide References Materials Project, 2019.

Reagent Feed Output Water Ozone pH ORP Foam Fraction

Control Variables

pH Oxidisation Reduction Potential (ORP)

Remediation Options

The OCRA Process

Remediation Options

The OCRA Process

• Aims:
• Remove heavy metals.
• Decrease reagent consumption.
• Produce less waste.
• Results:
• Removes both dissolved iron and

manganese by >99%.

• Precipitates generated

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

• Decrease reagent consumption

by on average 70%.

• Decrease sludge generation by

60%.

Remediation Options

The OCRA Process

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

consumption.

• Significantly reduces waste

generation.

• Has the potential to recover

valuable materials.

• Limitations:
• Does not remove sulfate.
• Does not provide neutralisation.

Conclusion

Solving AMD

• Acid Mine Drainage is a complex multidimensional

problem.

• Solving this problem will contribute to:
• Improving mine profitability.
• Improving environmental protection.
• Improving water sustainability.
• Solving the global fresh water crisis.
• Finding a solution depends on open collaboration

between industry, researchers, governments and communities.

Conclusion

Solving AMD

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

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

• Value open, transparent communication and

collaboration with our clients and partners.

• Operate a treatability and demonstration

laboratory at the Newcastle Institute for Energy and Resources (NIER).

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

P: 0423-209-917 E: david.hunter@evocra.com.au

Additional Resources

GARD Guide http://www.gardguide.com/ PitWatch https://pitwatch.org Netflix’s Explained The World’s Water Crisis https://www.netflix.com/title/80216752 Industry Guide Preventing 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/

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/abs@.nsf/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.pdf Ford, 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=PDFCoverPages Gray, 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-

• n-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 david.hunter@evocra.com.au