Underground leaching uranium mine

[Gerald Laurence <aduchem@wantree.com.au>]

The mine at Beverley in the north of my state has been approved by the
Environment Minister and should shortly receive approval from other
Ministers involved. I am a member of the local (South Australian) committee
responsible for giving the operation a "pass" for radiological (?radiation)
health.
The uranium is concentrated in an old river bed about 120 metre below
grade, in a sandy aquifer which is effectively isolated by impervious clay
beds. The uranium was carried down from deposits in a mountain range to the
West. In situ leaching has been under trial there for 12 months and was
trialed at another site 200 km away (Honeymoon Creek) in the early
eighties. Honeymoon is also about to apply for a production licence.
The chemistry of in situ leaching of uranium is much the same as
conventional hydrometallurgy fro uranium. Oxidation from U(IV) to U(VI) to
mobilise the uranium, followed by solvent extraction or equivalent to
separate the U from the leachate. [This is done above ground]. The oxidant
can be oxygen or hydrogen peroxide (sometimes ferric iron) and is normally
acid (0.1 molar sulfuric is common).
Waste (chiefly daughters) is returned to the underground aquifer and
operational hazards are much less than for conventional underground mining.
Production will be about 1000 t per year (yellow cake) at a leach flow rate
of 250 L/sec (a LOT of sulfuric acid!).
Interestingly, the company, Heathgate, is a subsidiary of General Dynamics. 
Regards

Gerald Laurence
Dr Gerald Laurence
University Radiation Safety Officer
University of Adelaide and Flinders University of SA

PO BOX 351
BURNSIDE   South Australia  5066
e-mail   aduchem@wantree.com.au
Phone  (61) 8 8379 6839
Mobile  (61) 0411 44 4895
Fax      (61) 8 8379 0657
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