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Uranium Recovery from Phosphates

(last updated 9 May 2008)

URANIUM RESOURCES IN PHOSPHATE ROCK

The world average uranium content in phosphate rock is estimated at 50 - 200 ppm. Marine phosphorite deposits contain averages of 6 - 120 ppm, and organic phosphorite deposits up to 600 ppm.
World uranium resources in phosphate rock are not very well known; the following table shows approximate inventories.

Approximate uranium inventories in phosphate deposits
Country million t U

Marine phosphorite

Morocco 6.9
USA 1.2

Mexico 0.15

Jordan 0.1

Others 0.65

Subtotal 9

Organic phosphorite

Kazakhstan 0.12

Russia

Subtotal 0.12

Total 9.12

Source: after [IAEA 2001]

**Approximate uranium inventories in phosphate deposits**
Country	million t U
Marine phosphorite
Morocco	6.9
USA	1.2
Mexico	0.15
Jordan	0.1
Others	0.65
Subtotal	9
Organic phosphorite
Kazakhstan	0.12
Russia
Subtotal	0.12
Total	9.12

URANIUM RECOVERY

The widely used sulphuric acid process concentrates most of the uranium in the product stream (fertilizers, detergents, etc.).

Various technologies exist to recover the uranium from the product stream, based on solvent extraction:

DEPA-TOPO (also DEHPA-TOPO, D2EHPA-TOPO): uses di(2-ethylhexyl) phosphoric acid and trioctyl phosphine oxide as extractants (ORNL process)
OPAP: uses octyl phenyl acid phosphate as extractant (ORNL process)
OPPA: uses octyl pyro phosphoric acid as extractant (Dow process)

The DEPA-TOPO process has proven to be the best technology available, according to [IAEA 1989]. It comprises the following steps:

Acid preconditioning and gunk removal
First cycle extraction and strip
Raffinate post treatment
Second cycle extraction, strip and uranium precipitation

Worldwide, there are approximately 400 wet-process phosphoric acid plants in operation from which some 11,000 t U could in principle be recovered each year, according to [IAEA 1989]
A more cautious figure of up to 3700 t U/a for the theoretically possible uranium recovery from phosphates is presented in [IAEA 2001]. This total assumes annual production of phosphate rock of 142 million tonnes per year yielding 66 million tonnes of concentrate. Marine phosphorite deposits account for 80% of the world output of phosphate based fertilizer products, and 70% of this total is converted into wetprocess phosphoric acid, the base for the current uranium extraction process. Assuming an average recoverable content of 100 ppm of uranium, this scenario would result in an annual output of 3700 t U/a. [IAEA 2001]

Eight plants for the recovery of uranium from phosphoric acid have been built and operated in the United States since 1976 (Florida: 6, Louisiana: 2). Plants have also been built in Canada, Spain, Belgium, Israel, and Taiwan, see Facilities for Uranium Recovery from Phosphate.
Historical operating costs for the uranium recovery from phosphoric acid range from 22 to 54 US$/lb U₃O₈. These operating costs are by far higher than past uranium market prices, and most uranium recovery plants have been closed, therefore. In view of the recent increase of the uranium market price, the situation may change, again.