Success for Namibian pilot plant

23 November 2015

Positive results from the second phase of the Etango heap leach demonstration plant in Namibia continue to support the assumptions and projections for the uranium project in earlier feasibility studies, Bannerman Resources has announced.

Etango's heap leach demonstration plant contains four 6-metre high cribs (Image: Bannerman Resources)

The plant was commissioned in March to demonstrate the design and projected performance of the project, as well as building knowledge, and to enable the company to pursue value engineering ahead of full production.

Acid leaching is carried out in four cribs, measuring 2 square metres, in which ore is stacked 5m high. Eight 5m high columns with a 0.183m internal diameter can carry out leaching in parallel to the cribs, using smaller ore samples. This arrangement enables direct comparison of leaching performance for the different sample sizes, enabling optimization work to be carried out on small volumes of ore while providing relevant scale-up information.

Completion of the first phase of the demonstration plant program - the commissioning of the plant and validation of leaching assumptions in the company's 2012 definitive feasibility study (DFS) - was announced by Bannerman in July.

The second phase of the operation - to demonstrate consistent operation and provide further validation for DFS leaching assumptions - entailed the open circuit heap leach operation of two cribs and four columns, using a 60-tonne sample. The operation achieved an average extraction of 93% for the two cribs and 91% for the columns, compared to 87% projected in the DFS.

Sulphuric acid consumption, at 15 kilograms per tonne, was lower than the 18 kg/t projected in the DFS.

Bannerman CEO Len Jubber said that the demonstration plant has now carried out large-scale testing on a total of 180 t of ore, substantially de-risking the planned use of the method at Etango. "We are excited by the results which point to the additional potential to unlock further value in the Etango project," he said.

The third phase of the demonstration, which will involve the operation of three cribs and will look at the effects of recycling the leach solution, is now under way. It will be followed by two further phases, focusing on solvent extraction and value engineering, scheduled to be completed in mid-2016.

Etango has JORC and NI 43-101 compliant ore reserves of 119.3 million pounds U3O8 (45,888 tU). An optimization study on the geological modelling and mine planning aspects of the DFS was published earlier this month, envisaging average annual production of 7.2 million pounds U3O8 (2770 tU) over an initial mine life of 15.7 years, with 9.2 million pounds U3O8 per year (3540 tU) per year during the first five years of full production.

Researched and written
by World Nuclear News