Uranium Ore Processing – Key

Considerations Based on Mineralogy and Ore

Type

IAEA Technical Cooperation Project INT-2019

Interregional Workshop on Case Study of Conventional Uranium Production from

Exploration to Closure

Prague, Czech Republic

14-18 October 2019

Brett MoldovanTeam Leader Uranium Resources and Production Specialist

International Atomic Energy Agency (IAEA), Vienna, Austria

Uranium content of various sources

Uranium Processing

• Crushing

• Grinding

• Leaching

• Liquid-solid separation

• Purification and concentration

• Precipitation and drying

• Packing & Transport

Cameco Key Lake uranium mill

From Ore to Concentrates

Underground mine

Open-cut mine

In situ leaching

Mill

Crushing / milling

Acid or Alkaline leaching

Extraction or IX

Precipitation

Concentrates 75% U

Conditionning / shipment

Enriched solution

ore

Enriched solution

Heap leaching

Implications of mineral composition

Implications of gangue minerals

Implications of gangue minerals (cont.)

Implications of gangue minerals (cont.)

Implications of gangue minerals (cont.)

Key Takeaway Messages

• An understanding of ore mineralogy is required

• May impact crushing and grinding efficiencies

• Mineralogy will determine leaching process

• High clay content can affect quality of SX or IX feed

• Mineralogy of the ore may impact IX/SX performance and overall

product quality

• Mineralogy may impact effluent, waste rock and tailings disposal

(e.g. arsenic, selenium)

11

Questions

Uranium Processing

• Crushing

• Grinding

• Leaching

• Liquid-solid separation

• Purification and concentration

• Precipitation and drying

• Packing & Transport

Cameco Key Lake uranium mill

From Ore to Concentrates

Underground mine

Open-cut mine

In situ leaching

Mill

Crushing / milling

Acid or Alkaline leaching

Extraction or IX

Precipitation

Concentrates 75% U

Conditionning / shipment

Enriched solution

ore

Enriched solution

Heap leaching

Uranium Mining Methods

Uranium is currently mined in one of three ways:

• In-situ leach mining – ISL [also ISR or solution mining]

• Underground with tunnels, galleries etc.

• Open pit, including surface excavations

In 2018 about 6% of mined uranium production was as a by-product from the mining of other minerals

Olympic Dam, Australia (photo courtesy of BHP)

Uranium Mining Methods:

In-situ Leach Mining (ISL)

• Sometimes may be called solution

mining or ISR (in situ recovery)

• ~48% of world mined uranium was

produced this way in 2018

•Can be acid or alkali leach solution

•Very small volume of waste

generation

•Limited surface disturbance

Beverley ISL mine, Australia

Uranium Mining Methods:

In-situ Leach Mining (ISL)

Advantages

Lower capital and operating costs

Shorter lead times to production, that is, it is quicker to produce Uranium

Miners are not directly exposed to the orebody. There is reduced radon release and radiation because the ore is in solution.

There is no solid waste. Waste is confined to evaporation ponds.

There is much less ground disturbance. There are no open pits, shafts, tunnels, earth moving equipment or grinding and crushing facilities.

There is less rehabilitation required because there is less ground disturbance.

Access to additional resources

In-situ Leaching (ISL)

Disadvantages

Applicability limited to specific types of deposits (sandstone deposits)

Uranium deposits must be located below the water table in permeable sandstone aquifers

Ore must be soluble

The host rock must be mineralogically adapted to the method

Lower recovery factor of in place reserves

Risk of groundwater contamination

In-situ Leaching (ISL)

Ore Extraction

Underground mine (UG)

Where orebodies are deeper, underground mining is usually employed, involving

construction of access shafts and tunnels but with less waste rock removed and

less environmental impact.

Choice of mining method :

· Shape of the deposit

· Size of the deposit

· Distribution of uranium ore. Selective or non selective mining method

Important phases of underground mining:

. Ventilation: All underground mines are ventilated, but in uranium

mines, extra care is taken with ventilation to minimise the amount of

radiation exposure and dust inhalation.

. Ground support

. Water extraction

Underground mining

– ~32% of 2018 mined uranium production

– Much smaller waste rock production volumes, frequently very little at the surface

– Smaller infrastructure footprint at the surface

– May be possible to dispose of much of the waste underground as backfill in the workings

McArthur River Uranium Mine, Canada

(photo courtesy of Cameco Corporation)

Uranium Mining Methods:

Underground

Note:

• Main access shaft

• Ventilation shafts

• Underground network

• Small waste piles at

surface

Uranium Mining Methods:

Underground

Open pit / surface excavations

–~14% produced this way in 2018

–Relatively large footprint at the surface

– Manage stockpiles of waste rock, sub-economic ore and/or overburden

–Waste water, drainage and seepage

–May be a possibility for in-pit disposal of tailings

Uranium Mining Methods: Open Pit

Langer Heinrich Mine (Photo courtesy Paladin Resources)

Somair Open Pit Mine (Niger) (Photo courtesy of World

Nuclear News)

Addis Abeba March 2019

Open Pit Mine

Rössing (Namibia)

Heap Leach Mining

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Another consideration for mining and extraction of

uranium is heap leaching

• Geotechnical characteristics

• Hydraulic characteristics

• Geochemical characteristics

• Kinetics – steady state conditions

• Recovery of uranium may be lower than

conventional methods

Heap Leaching

Somair (Niger)

Trekopje (Namibia)

Keys to successful project development

Keys to successful project development (cont.)

Keys to successful project development (cont.)

Keys to successful project development (cont.)

Keys to successful project development (cont.)

Keys to successful project development (cont.)

Keys to successful project development (cont.)

Keys to successful project development (cont.)

Scoping phase – typical activities

Typical scoping phase scale-up factors

Prefeasibility study – typical activities

Prefeasibility study – typical activities (cont.)

Prefeasibility study – typical activities (cont.)

Typical prefeasibility phase scale-up factors

Final feasibility study – typical activities

Final feasibility study – typical activities (cont.)

Typical final feasibility phase scale-up factors