Ore Deposits 101: Uranium Deposits Lecture

Speaker

• Name: Andrew Jackson
• Role: Economic Geologist at Sprach Global Resorts Investments
• Purpose of Talk: Help non-technical audience understand ore deposits, specifically uranium.

Overview of Uranium

• Economic Importance: Due to its radioactivity and energy production capabilities.
• Radioactivity: Uranium decays into other elements (thorium, radium, radon, lead), releasing energy.
• Abundance: Uranium is not rare, found more in felsic rocks like granite; average crustal abundance is 2.7 ppm.
• Grade: Uranium grades expressed in % U3O8; grades required for economic mining are much higher than average abundance.
• Product: Commonly sold as U3O8 or yellowcake.
• Public Perception: Nuclear power is controversial due to disasters (Three Mile Island, Chernobyl, Fukushima).

Global Uranium Production and Resources

• Top Producers: Kazakhstan, Canada, Australia, Namibia, Russia, etc.
• Large Resource Holders: Canada (Athabasca Basin), Brazil, Kazakhstan, Ukraine, etc.

Uranium Ore Minerals

• Common Minerals:
  • Uraninite (pitchblende)
  • Brannerite
  • Carnotite
  • Uranophane
  • Autunite

Types of Uranium Ore Deposits

• Primary Deposits: Uranium introduced with original magma.
  • Types: IOCGs, Mesothermal veins, Pegmatites.
• Secondary Deposits: Uranium dissolved by groundwater and redeposited.
  • Significant Types: Unconformity-related, Sandstone-hosted, Surficial deposits.

Primary Uranium Deposits

• IOCGs (Iron Oxide Copper Gold deposits):
  • Example: Olympic Dam, South Australia.
  • Characterized by low grade but large size; uranium is a by-product.
• Intrusive Related Deposits:
  • Example: Rossing, Namibia.
  • Generally low grade but can be economically viable due to size.

Secondary Uranium Deposits

• Unconformity-related Deposits:
  • Example: Cigar Lake, Saskatchewan.
  • High grade, often blind (do not outcrop).
• Sandstone-hosted Deposits:
  • Roll-front deposits where uranium is deposited in reduced zones.
• Surficial Deposits:
  • Formed by evaporation, example: Langer Heinrich in Namibia.

Exploration Techniques

• For Primary Deposits:
  • Heavy reliance on geophysics (magnetics, gravity, EM methods).
• For Secondary Deposits:
  • Focus on redox boundaries for uranium precipitation.
  • Methods: Airborne/surface gamma-ray spectrometry, lake sediment sampling, seismics.

Mining and Processing Uranium

• Methods: Open pit, underground mining, in situ leaching.
• ISL (In Situ Leaching): Preferred for porous sandstone deposits.
• Ore Processing: Involves crushing, dissolving uranium, filtering and precipitating it as yellowcake.

Conclusion

• Key Takeaways:
  • Uranium is abundant but requires high concentration for mining.
  • Exploration is challenging due to hidden deposits.
  • Uranium is crucial for nuclear energy yet controversial.
• Future Lecture: Exploration process and strategies for narrowing search for drill targets.