Conventional heap leaching of uranium ore in the western United ...

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TAILINGS AND MINE WASTE 2014 Conventional heap leaching of uranium ore in the western United States Kimberly Morrison, PE, RG Morrison Geotechnical Solutions, Inc. Frank Filas, PE Energy Fuels Resources (USA), Inc.

Transcript of Conventional heap leaching of uranium ore in the western United ...

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TAILINGS AND MINE WASTE 2014

Conventional heap leaching of uranium ore in the western United States

Kimberly Morrison, PE, RG Morrison Geotechnical Solutions, Inc.

Frank Filas, PE Energy Fuels Resources (USA), Inc.

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Uranium Heap Leaching - Introduction -

• Heap leaching: – Practiced since the mid-sixteenth century in Hungary – Low capital and operating costs make it an attractive

option • Uranium recovery:

– Main types: (i) conventional milling; (ii) ISR; (iii) heap leaching

– Historically in US, heap leaching of low grade ores – Low uranium prices in 1980s combined with

increasingly strict environmental regulations halted use of heap leaching for uranium recovery in the US

– Heap leaching of uranium making a resurgence

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- Summary - • History of uranium heap leaching in the US • Uranium heap leaching technologies • Energy Fuels’ proposed uranium heap leach projects

in Wyoming • Regulatory framework surrounding uranium heap

leaching

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Uranium Heap Leaching in the US - A History Lesson -

• Historically, source material defined by AEC as ores containing ≥0.05% uranium/thorium

• 1950s/1960s – ore containing <0.05% uranium occasionally processed in small heaps

= mining operation ≠ processing operation

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Uranium Heap Leaching in the US - A History Lesson -

• 1970s – Regulatory transition to NRC / Agreement State – Defined byproduct materials under Section 11e.(2) as

the tailings or wastes produced by the extraction or concentration of uranium or thorium from “any ore” processed primarily for its source material content

• 1970s/1980s – several larger scale uranium heap leach facilities operated

Uranium heap leaching = processing operation

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Ranchers Exploration & Development Corp. Durita Heap Leach, Colorado

• Operated from 1977 to 1979 – Secondary-extraction heap leach facility – Processed 630,000 tons of agglomerated tailings from

Naturita Mill using sulfuric acid – Recovered >380,000 lbs U3O8 and 1.8M lbs V2O5

Photo source: Beahm, 2013

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Umetco Mineral Corporation East Gas Hills Heap Leach, Wyoming

• Operated 1960 to early 1980s: – Low grade (<0.05%

U3O8 ) run-of-mine uranium ore

– Leached in series of cells “ponded” with sulfuric acidic solution

– Reported 82% U3O8 recovery

Photo source: Beahm, 2013

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Umetco Minerals Corporation Maybell Heap Leach, Colorado

• Operated 1975 through 1982 – Locally-mined low grade

uranium ore – Placed in heap leach

cells (35-55’ berms) and leached with sulfuric acid

– Upgraded leachate processed using IX

• Potential development opportunity

Photo source: DOE, 2011

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Uranium Heap Leaching - Considerations -

• Heap leaching of uranium ore: – Conventional heap leach

facility – On-off heap leach facility – Vat leach

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Uranium Recovery - Conventional Heap Leaching -

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Uranium Recovery - On-Off Heap Leach Facility -

• Best suited for ores with short leach cycles (30 days or less) or low permeability

• At closure, facility removed and reclaimed • Technology proposed for projects in Africa and Australia

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Uranium Recovery - Vat Leaching -

• Ore is placed into large tanks or vats containing a leaching solution (acidic or alkaline)

• Spent ore is placed in a waste repository

• Temporary structures associated with the plant

Source: http://vatleach.com

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Uranium Recovery - Agglomeration -

• Agglomeration: – Improves the heap leaching process in some ores by

increasing ore permeability and allowing pre-mixing of solution with the ore fines

Non-agglomerated ore Agglomerated ore

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A s s e t S u m m a r y A central mill supplied by regional mines

1 Operating Mill

2 Producing Mines

5 Permitted Mines on Standby

6 Permitted Development Projects

12 Additional Development Projects

A position in three of the most important uranium districts in the U.S.

Colorado Plateau Arizona Strip

Wyoming TAILINGS AND MINE WASTE 2014

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Energy Fuels’ Proposed Uranium Heap Leach Projects – Wyoming

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Energy Fuels’ Proposed Uranium Heap Leach Projects - Wyoming

Project Tons (‘000)

Grade (% eU3O8)

Pounds U3O8 (‘000)

Sheep Mountain 12,895 0.12% 30,285

Gas Hills 2,300 0.13% 5,400

Juniper Ridge 5,233 0.06% 6,120

• Measured and indicated uranium reserves (Beahm, 2012; Beahm & McNulty, 2014; Nielsen et al., 2013):

Excludes inferred uranium resources

• Limited ISR feasibility as mineralized units not hydrogeologically confined

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Sheep Mountain Project, Wyoming - Overview -

• Energy Fuels acquired property in early 2012 • Proposed conventional open pit and modified room and pillar

underground mine with and onsite heap leach facility • Historic uranium mining development dating back to 1950s • Bottle roll tests using alkaline and acid – acid preferred • Column leach testing showed potential for high uranium

recovery, in excess of 90%

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Sheep Mountain Project - 3D Rendering -

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Sheep Mountain Project - Processing Facility Layout -

• Agglomerated ore • Radial belt conveyor

and stacker system • 40 acre footprint,

partially below grade • Sulfuric acid leach

using low flow drip emitters Source: Engineering Analytics, 2014

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Lower Gas Hills Project, Wyoming - Overview -

• Energy Fuels acquired project in August 2013

• Proposed open pit mine and heap leach processing facility

• Bottle roll test recovery 82-94%

• Preliminary column leach test recovery of 91%

• Acid or alkaline leach

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Juniper Ridge Project, Wyoming - Overview -

• Energy Fuels acquired project in August 2013

• Proposed open pit mine and heap leach processing facility

• Loaded resin to be sent to a central processing facility for concentration of the uranium via IX

• Mineralization in same deposit as Maybell

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Uranium Heap Leaching in US - Regulatory Framework -

• Spent ore = 11e.(2) byproduct material once uranium extraction process is complete

• Under UMTRCA (1978), EPA responsible for establishing standards for exposure of the public to radioactive materials for active uranium extraction facilities

• Licensed by the NRC (or Agreement State)

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NRC Regulatory Authority

• 10 CFR Part 40 and Appendix A to Part 40 – Siting requirements; permanent radon barrier and

closure cover; groundwater protection standards; etc. – Regulations considered to extend to design, construction,

operation and closure of a uranium heap leach facility • Standards set by EPA in 40 CFR Part 192, Subpart D

– In 1992, more stringent regulations included prescriptive liner (reference to 40 CFR 264), or approved equivalent

• NRC developing a guidance document for uranium heap leaching – TBD

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Sheep Mountain Project - Proposed Liner System -

• Triple HDPE geomembrane liner system

• Microspikes, texturing, and basal spike layer for increased shearing resistance

• Two intervening leak detection systems using manufactured drain liners

• Overlying drainage network significantly reduces driving head

Source: Engineering Analytics, 2014

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EPA Regulatory Authority

• 40 CFR Part 61 – National Emission Standards for Hazardous Air Pollutants (NESHAPs)

• “Proposed” Subpart W (National Emission Standards for Operating Uranium Mill Tailings) Rulemaking (April 2014) – Extends authority over uranium heap leach facilities and

non-conventional impoundment – Limits maximum footprint size to 40 acres, and no more

than two facilities operating at once – Proposes high ore saturation levels (>30% moisture

content)

Public comments due end of October

Saturation > 180% for Sheep Mountain ore

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Concluding Remarks • Due to its low capital and operating costs, heap

leaching is an attractive option for recovering uranium from low grade ore

• Technology has been employed successfully in the past in the US

• Energy Fuels is investigating this technology for new development projects in Wyoming

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Concluding Remarks

• Industry remains optimistic that regulatory controls currently in-place for uranium mill tailings may be applied to uranium heap leach projects in the US

• This would allow for economic extraction of uranium while providing practical controls that are protective of the environment and public health and safety

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Thank you for your time… Questions?

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The U.S. is the World’s largest consumer of uranium … • ~20% of electricity generated from nuclear power • ~50 million lbs. U3O8 per year consumed • Over 90% dependent on imported uranium (more than imported oil)

… yet only produces about 4 million lbs. of U3O8 per year • This represents only about 3% of the World’s primary uranium production • Expiration of Russian HEU Agreement by end of 2013 expected to remove

up to 24 million lbs. U3O8 from U.S. supplies (~50%) • Historically, the U.S. was the World’s largest producer of uranium • Intense competition expected for the World’s uranium supplies

S i g n i f i c a n c e o f t h e U S U ra n i u m M a r ke t

Source – Energy Fuels corporate presentation