Mining Remed ediation on T Technol olog ogy Advancements U - - PowerPoint PPT Presentation

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Mining Remed ediation on T Technol olog ogy Advancements U - - PowerPoint PPT Presentation

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Mining Remed ediation on T Technol olog ogy Advancements U Using Magnesia Applied Chemistries and New Methods to Remediate and Mitigate Heavy Metal Contamination and Mine Drainage Derek Pizarro, CPG General Manager - EnviroBlend - Premier

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SLIDE 1

Mining Remed ediation

  • n T

Technol

  • log
  • gy

Advancements U Using Magnesia

Applied Chemistries and New Methods to Remediate and Mitigate Heavy Metal Contamination and Mine Drainage

Derek Pizarro, CPG General Manager - EnviroBlend - Premier Magnesia, LLC for RE3 Conference, 15-17 September 2015

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SLIDE 2

Mine I e Issues es No Not Rare

  • Mining has contaminated 40% of Western

headwaters (EPA, 2011)

  • Issues besides traditional mines
  • Mid-Atlantic
  • 4,785 mi streams, pH impacted (EPA, 2012)
  • Mainly coal mining (SO2)
  • In-situ mined waste, Bevill-exempt under RCRA
  • Incomplete Inventory
  • US GAO, 2015
  • Estimated 4,722 mine sites contaminated
  • Abandoned Mines (BLM, 2015)
  • >30,000 sites (47 states)
  • 100,000 sites (CA, NV, UT)
  • USDA Forest Service, 2015
  • 27,000 to 39,000 abandoned mines
  • 20% pose HH/Eco risk
  • Notable
  • Columbia River, MT
  • As, Cd, Cu, Hg, Zn
  • AMD and MD
  • Lake Coeur d’Alene, ID
  • 75 million tons of heavy metal-impacted

sediment, mainly mine-derived

  • Cd, Cu, Pb, Zn
  • Irwin Syncline, PA
  • Metals, AMD
  • Deep mine discharge
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SLIDE 3

Mine P e Proc

  • ces

esses es

  • Techniques
  • Shaft
  • Open Pit
  • Dredging
  • In-Situ Solution
  • Processes
  • Gravity Concentration
  • Magnetic Separation
  • Electrostatic
  • Flotation
  • Leaching
  • Acid (Cu)
  • Cyanide (Au)
  • Salt solution
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SLIDE 4

Acid Rock Dr ck Drai ainag age

  • Many mines are not underground
  • Construction projects/sites
  • Road cuts
  • OB removal
  • Same problems in different setting
  • AMD  ARD
  • EPA 1994, Technical Document- Acid Mine Drainage Prediction
  • “Mining is a Western problem”
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SLIDE 5

AMD/ARD RD, Ho How does es it form?

  • Pathway 1, water floods mine
  • Initial leaching
  • Pathway 2, rock exposed to oxygen
  • Excavation
  • Collapse/slide
  • Metal sulfides oxidize in
  • re/tailings/dump/ponds
  • Typically Pyrite
  • Bacteria can catalyze
  • H+ released
  • pH decrease is continual
  • Amplification cycling
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SLIDE 6

Why P Problematic?

  • Formational
  • Less competent rock
  • Outcropping
  • Type
  • Open Pit
  • Strip
  • Mountain Topping
  • Dry deposition (air)
  • Abandoned/sealed/compromised shafts
  • Slides
  • Underground Tunnels
  • Tailing piles/dumps
  • Documentation and History
  • Water source
  • Rain
  • Snowmelt
  • Pond water
  • Groundwater
  • Weather event types
  • Slug
  • Flushing
  • Freeze-thaw
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SLIDE 7

Off ff-Site I Impact

  • Dry riverbeds
  • Not connecting to streams or water bodies
  • Rain event, flash-flood mobilization
  • Rivers
  • Path of least resistance
  • Ecological impacts
  • pH/sediment flux
  • Conversion from “dead” to functional stream, 6-11 years avg. (EPA, 2012)
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SLIDE 8

Remed edies es

  • Chemical Stabilization
  • Chemically less hazardous
  • Convert solubility, toxicity, species, or

mobility

  • Not necessarily physical change(s)
  • Solidification
  • Physical, possibly monolithic, alters

mobility

  • Not necessarily complete envelopment
  • Not necessarily without chemical

change(s)

  • Encapsulation
  • Complete envelopment of contaminant
  • Coating deprives interaction
  • Monolithic
  • Selection
  • Interactions
  • Metal affinities
  • Exothermic
  • Adverse Interactions
  • Cost/ton vs. Dosage rate
  • Neutralization/buffering capacity
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SLIDE 9

Amen endmen ents/Trea eatmen ent Chem emicals

Conventional

  • Lime
  • Limestone
  • Slag

Modern

  • Resin
  • Wetlands
  • Paste
  • Magnesia
  • Oxide
  • Hydroxide
  • Blend
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SLIDE 10

Max B Buff ffers

  • Magnesium hydroxide
  • pH = 10.35
  • pOH = 3.65
  • Calcium hydroxide
  • pH = 12.40 (concentration 112x that of mag)
  • pOH = 1.60
  • Portland Cement Type I, cured 28 days
  • pH = 13.48 (concentration 1,349x that of mag)
  • pOH = 0.52
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SLIDE 11

Granular M Magnesia

  • Non-hazardous
  • Non-toxic
  • Neutralization capacity
  • 25-40% more than lime
  • 35-50% more than caustic
  • Product tolerances
  • GRAS
  • pH
  • Range control
  • 6-10 S.U.
  • Additives
  • Easily mixed
  • Compatibility
  • Application
  • Mixed
  • Hydraulically emplaced
  • Activated magnesia (alternative)
  • Same chemistries
  • Plus activator
  • Solidification
  • Magnesia-amended OPC
  • More competent unit
  • Durability, reduced cracking and

shrinkage

  • 1-5% wt./wt. addition
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SLIDE 12

Magnesia Slurry y

  • Non-hazardous
  • Non-toxic
  • Neutralization capacity
  • 21% more lime
  • 27% more caustic
  • Product tolerances
  • GRAS
  • Lower freezing point
  • Less sludge formation in RWTP
  • Compact sludge
  • Easily dewatered
  • pH
  • Simple rise to 6 S.U.
  • Control options
  • Microns matter
  • Liquor (10)
  • Slurry (45)
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SLIDE 13

Blends ds

  • pH control
  • Fixative
  • Redox
  • Autocatalytic
  • Benefits of both fixation and

stasis

  • Co-beneficial effects
  • Most suitable treatment for

SPLP, MEP, and LEAF

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SLIDE 14

Case Studies

  • Ore Hill Mine (NH)
  • Confidential Client (Rare Earth Metals)
  • Callahan Mine Superfund (ME)
  • Confidential Client (Closed Mine)
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SLIDE 15

Ore H Hill M ill Min ine

  • Former mineral mine (est. ca. 1834)
  • Fe, Pb, Zn, Ag
  • Up to 100,000 tons total production
  • Onsite smelter
  • 36,000 yd3 tailings and rock
  • pH (3.3 S.U.)
  • Pb, Zn, Cu, Cd, As
  • Previous pumping efforts
  • Surface water, seeps, tributaries
  • Toxic, aquatic life impacts up to one mile
  • Reduce leachability and bioavailability- TCLP, SPLP, MEP
  • Chemical stabilization, unlined cradle with soil cap
  • Buffered fixation > PC Type I
  • Freeze/thaw climate
  • Lower-construction costs
  • Lower O&M costs
  • 50 years vs. 100-1,000 years (PC vs. EB)
  • Treated leachable metals at or below background
  • pH restored to neutral range (6.2 S.U.)
  • Cost Summary
  • Capital: $3.2M
  • O&M: $10k/yr (engineering controls)
  • Monitoring: $30k/yr (testing)

CERCLA removal action Treatment area with repository area Human & Biota Exposure New Hampshire Owner: USDA Forest Service

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SLIDE 16

Rare E Earth M Metal al Min inin ing S Sit ite

  • Site Access
  • Mine tailings (5,000 tons) chemically stabilized
  • Pond sludge (2,500 tons) neutralization and

treatment

  • Treatment in-situ with EnviroBlend
  • Offsite disposal
  • Site improvements to manage/minimize run-off
  • Low dosages for both tailings and sludge
  • Less over-road trucking
  • Product
  • Disposal
  • Lower disposal fees

Former open-pit mine Waterway receptors Off-site impact, long-term exposure, and pond concerns Continental United States Owner: Confidential

Commons, wikipedia

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SLIDE 17

Ch Chart rter Co r Contracting Callahan Mine S Super erfund Site R Rem emedia ial A l Actio ion

  • 3,000 tons Pb mine waste treated on-site with

EnviroBlend; offsite disposal (TCLP)

  • 5,000 cy Pb- and As-impacted soil removed and relocated

from residential properties

  • Excavated, stockpiled, characterized, and disposed of

15,000 tons PCB-impacted soils

  • Reutilized 22,000 cy of ore/tailings material as multi-layer

soil and geotextile cap of soils <10ppm PCBs

  • Managed a total of 65,000 tons impacted material from

mine and adjacent properties

  • Site improvements to minimize discharge run-off

150-acre former zinc/copper open-pit mine Adjacent residential neighborhood Human contact, long-term exposure, and groundwater concerns Brooksville, ME Owner: Maine Department of Environmental Protection

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SLIDE 18

Form rmer M r Min ine Sit ite- Leachate Co Colle lectio ion Syst stem

  • Initially, caustic treatment for drainage

collection system

  • Changeover to EnviroBlend AQ slurry

Industrial mineral mine Managed landfill unit Rain event management Continental U.S. Owner: Confidential

  • No over-treatment problems (pH 9 max)
  • Personnel safety/easy handling
  • Low system maintenance
  • Low 32˚F freezing point
  • No sulfate sludge
  • High solids level
  • Produces less soluble salts (TDS)
  • Reduces metal sludge volume

Equivalent Ratio to Other Alkali EnviroBlend AQ 1.00 Hydrated Lime 1.27 Caustic Soda 1.37 Soda Ash 1.82 Caustic Potash 1.92

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SLIDE 19

Question

  • ns?

Derek Pizarro, CPG EnviroBlend Premier Magnesia, LLC dpizarro@premiermagnesia.com 610-517-8242 EnviroBlend Sales Offices: Philadelphia (PA), Columbus (NJ), Raleigh (NC), Holland (OH), Sacramento (CA)