Browsing by Author "Machaughton, SJ"

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    Pilot scale production of yellowcake from the Kintyre uranium deposit using a direct precipitation process
    (Institution of Engineers Australia, 1998-09-28) Machaughton, SJ; Collier, DE; Tapsell, GJ; Ring, RJ; Hawley, B; Bellingham, A
    Kintyre is a high grade uranium deposit located in the north west of Western Australia 90 km south of Telfer. Two bulk samples of upgraded ore from the deposit were processed in a pilot plant to produce a saleable uranium oxide concentrate. The pilot plant was operated continuously for 42 days at a throughput of 15 kg h-1. This paper describes the direct precipitation processing route that was employed and the performance of the plant under a range of operating conditions. Ground ore was leached at 56% solids using sulphuric acid and hydrogen peroxide as an oxidant. The leach liquor was recovered using a high rate thickener followed by belt filtration. The resulting leach liquor had a tenor of 6 to 8 g L-1 U3O8 and was treated with hydrogen peroxide to oxidise any ferrous iron to the ferric state. The ferric iron was then removed by precipitation with lime. The iron precipitate was leached with sulphuric acid to recover uranium before disposal with the primary leach tailings. Yellowcake was precipitated from the clarified iron-free liquor using hydrogen peroxide and sodium hydroxide for pH control. The simplicity of the circuit – a leaching stage followed by two precipitation stages – is in marked contrast to conventional uranium circuits which utilise solvent extraction or ion exchange to recover uranium from leach liquors. Operation of the pilot plant successfully demonstrated the technical feasibility of the direct precipitation processing route. In both precipitation circuits the overall efficiency was found to be dependent on the distribution of reagents within each circuit. Optimisation of these variables resulted in high precipitation efficiencies (>99.9%). The design criteria that were established in the pilot plant were generally more favourable than predictions based on laboratory testwork.