Complete thickening circuit for Uranium One Africa
In a R47 million contract, Bateman Engineering has supplied the complete thickening circuit for Uranium One Africa’s new uranium plant to be located next to the company’s existing Bonanza gold-mining operation in the Klerksdorp area of South Africa.
The plant, which is expected to commence uranium production in the first quarter of 2007, will process ore mined from the Dominion and Rietkuil uranium deposits. These deposits contain potentially in excess of 136,000 t uranium oxide and represent about 6 % of the world's uranium resource.
The contract covered the supply of nine counter-current decantation (CCD) and high-rate thickeners, as well as a pinned-bed clarifier, and comprised the design, construction and on-site commissioning of the units. The thickeners are manufactured from various metals depending on their application, ranging from mild, rubber-lined steel through to complete stainless steel construction, in both 316L and SAF2205 duplex stainless steel.
The CCD thickener circuit
comprises four uranium thickeners (24.4 m diameter) complete with interstage mixing tanks, with a fifth to be installed in phase two of the project, and two 23 m diameter thickeners to process the base-metals. Additionally, a 24.4 m diameter pre-leach thickener has been installed.
The other high-rate thickeners include one 20 m diameter milling and densification thickener (an additional unit will be supplied in phase two), one 18 m effluent thickener and a 10 m ammonium diuranate (ADU) thickener to concentrate the uranium yellowcake solids from a brine solution.
While the inclusion of a 10 m diameter pinned-bed clarifier into the thickening circuit is an unusual arrangement, it has enabled Bateman Engineering to take a holistic approach to the design of the overall circuit and overcome many of the production problems associated with old-style flow sheets. For example, the excellent clarities produced by the pinned-bed clarifier negated, to a large extent, the need to oversize the thickeners and add additional flocculant to settle the ultra-fine material to eliminate or reduce crud formation from the pre-leach thickeners or CCD circuit.
Extensive preliminary testwork on samples prepared by the South African metallurgical research institute, Mintek, enabled the uranium and base-metals CCD thickeners to be sized. The remaining thickeners and pinned-bed clarifier were sized based on previous Bateman Engineering experience.
Bateman Engineering has also been contracted by Uranium One Africa to carry out the metallurgical process design for the uranium plant. The plant will make use of pressure leaching in preference to atmospheric leaching for enhanced overall uranium recovery.
For further information, contact Craig Gilbert, Manager,
Processing Technologies, on +27-11-210-2300 or
email engtech@bateman-bet.com.
