Results of larger sized heap leach column tests indicate faster leach kinetics and have the potential to enhance the modelled study outcomes.
The PFS has to this point identified a conventional open pit mining operation with an on/off heap leach pad as the preferred option for development of the 5-7Mlb U3O8 per annum Etango Project.
During July 2009, Bannerman Resources has received the results of further (larger sized) heap leach column tests as well as preliminary flotation tests. These results have the potential to materially influence both the ultimate choice of processing route and the scale of the plant concerned. The recent developments include:
Heap leach testwork – The scale and cost of the modelled heap leach operation, including continuous stacking and reclaiming equipment, is sensitive to the acid leach kinetics and, accordingly, Bannerman Resources is currently undertaking an extensive and systematic metallurgical testwork program. Favourable heap leach test results recently received from larger sized column tests (four metre high by 190mm diameter) have indicated faster leach kinetics than achieved in previous smaller scale testing which has formed the basis of the PFS to date. If confirmed, faster leaching times would be expected to provide improved operating flexibility and potentially enhanced project economics. Bannerman Resources is now drilling to obtain a 15-20 tonne bulk metallurgical sample for further larger scale heap leach column testwork for use in confirming the design layout and costs of the modelled heap leach operation to a greater confidence level.
Flotation testwork – Beneficiation testing has recently returned positive preliminary flotation test results which have the potential to impact materially on the choice of processing flowsheet. Beneficiation through flotation methods is universally understood and successfully applied in mineral processing operations globally. Initial laboratory testwork has been sufficiently encouraging to warrant follow up. If confirmed to be technically and commercially viable, an agitated tank leach process flowsheet including a flotation circuit delivering a low mass pull concentrate would potentially be a lower cost and risk alternative to heap leaching.
Mineral resource update – The PFS has to date been based on the February 2009 Etango Project mineral resource estimate. However, Bannerman Resources recently announced a substantial increase in mineral resources following an increase in the Oshiveli resource estimate and inclusion of the inaugural estimate for the adjacent Onkelo deposit. The combined resource strike length now totals 5km with approximately two thirds of the resource located within 200 metres of the surface. The inclusion into the PFS of additional near-surface material at the Oshiveli and Onkelo deposits in the initial years of mining may have the advantage of reducing the waste to ore strip ratio thereby lowering unit operating costs.
As a consequence of the above positive events, and after detailed consultation with the study team, the Board has decided to investigate the impact of the above activities prior to finalising and releasing the PFS results. The next round of flotation testwork is expected to take approximately 3-4 months, such that during the December 2009 quarter a more robust understanding of the viability of incorporating a flotation circuit in an agitated tank leach processing route should be known.
Len Jubber, Bannerman Resources’ chief executive officer said: “While we had initially planned to release the results of the preliminary feasibility study in the current quarter, we feel the recent favourable results obtained from continued heap leach testwork and, in particular, from flotation testwork, are significant for Bannerman and demand to be fully evaluated prior to finalising the preferred processing flowsheet. An extension to the study timeframe is therefore fully warranted. This new work will be conducted concurrently with the ongoing heap leach testwork and resource drilling activities.”
