Aflease uranium plant to utilise
pressure leaching
BATEMAN has been contracted to carry out the metallurgical process
design for the new uranium plant for Aflease Gold and Uranium Resources
(previously Afrikander Lease Limited) to be located next to the company's
existing Bonanza gold-mining operation in the Klerksdorp area of South
Africa.
The basic costing and design for this project, which commenced in
October 2004, has been completed. The plant will process ore mined
from the Dominion and Rietkuil uranium deposits, which contain potentially
in excess of 136 000 t uranium oxide and represent about 6 % of the
world's uranium resource. The uranium oxide production rate will be
1800 t/yr giving an effective life of resource of 75 years.
The uranium plant will make use of pressure leaching in preference
to atmospheric leaching for the enhanced overall uranium recovery.
In addition to higher recoveries, pressure leaching reduces consumption
of sulphuric acid due to the oxidation of pyrite in the ore, eliminates
of the need for manganese dioxide as an oxidan, and reduces the leach
residence time from 18 to two hours. The precipitation of excess iron
in the leach autoclaves, is also reduced, thereby minimising the amount
of iron build-up in solution.
The design criteria have been based on the original Afrikander Lease
uranium plant, Rietkuil, which was one of the world's first oxygen
pressure leach plants and was commissioned by Anglo American in 1982
but mothballed soon after commissioning. While BATEMAN has retained
the basic design of the Rietkuil plant, improvements have been introduced
into the mechanical design of the pressure-leach autoclaves. These
improvements, gained from mechanical developments over the past 20
years, will enable the vessels to operate at higher temperatures than
in the past. Improvements to the autoclave agitation, feed system
and discharge system have also been incorporated.
After the pressure leach and subsequent counter-current-decantation
and solvent-extraction stages, ammonium diuranate will be precipitated
as yellow cake.
For further information, please contact Johan Verster on
+27-11-899-2026 or email uranium@batemanengineering.com.
