Aura Energy makes breakthrough in unlocking value of co-products at Haggan uranium deposit

Australian-listed uranium explorer Aura Energy (ASX: AEE) has increased the likelihood of adding additional value to the Haggan uranium project with results from metallurgical testing on metals other than uranium.

Aura reported the first bioleach results for its giant Häggån Uranium-Molybdenum-Nickel-Vanadium-Zinc Project in central Sweden indicate that significantly higher extraction of these metals has been achieved compared with non-bioleach reference tests.

The company is currently undertaking a multi-directional metallurgical test programme to determine the optimal uranium extraction route for the project, while also trying to maximise the recovery of co-products.

The Haggan uranium deposit is, in terms of global uranium deposits, one of the largest and has an inferred resource estimate 291 million pounds U3O8 and an exploration target of 800-1200 million pounds. Such is the scale of the Storsjön project, this initial resource still only covers less than five per cent of the project, and yet, already the maiden JORC resource ranks Storsjön in the top ten of the largest uranium resources in the world.

Initial work demonstrates that uranium, molybdenum, nickel and zinc have improved extraction rates using bacteria relative to samples without bacteria.

Results indicate the Alum Shales within the Project are likely to be amenable to bioheap leaching.This method of extraction will potentially provide a low capital and low operating cost treatment route.

Previously Aura has reported conventional acid leach recoveries up to 93% for uranium.

This is an important first step to demonstrate a commercial route for multi-metal extraction of the initial inferred resource estimate compliant with the JORC code of:

- 291 million pounds uranium
- 583 million pounds molybdenum
- 570 million pounds nickel, and
- 4,693 million pounds vanadium

Aura commenced bioleaching testwork with the Parker Cooperative Research Centre for hydrometallurgical research in Perth, Western Australia in late 2009.

Bacterial cultures have been established from three sources: the ore; waters from the Project Area in Sweden; and from a coal mine in Western Australia.

The company said these preliminary small-scale tests are encouraging, confirming that bacterially-assisted leaching of uranium from the mineralisation may be technically feasible.

The initial work using bacteria has also shown, evidence of improved extraction percentages of other metals, particularly molybdenum, zinc and nickel using bacteria relative to samples without bacteria.

Bob Beeson, managing director, commented that these initial results represent a significant breakthrough for the processing of the mineralisation.

“The Alum Shale material at Häggån has characteristics that, we believe, make it amenable to bioleaching technologies. The high sulphur content, which the bacteria use to acidify and oxidise ores, and the similarities to ores being processed by bioleaching elsewhere, were the impetus to commence the testwork programme."

“The initial, qualitative results see enhanced extraction of not only the uranium, but also the molybdenum, nickel and zinc. These metals will add considerable value to the resource if they can be economically extracted."

“We are continuing to investigate bioheap leaching as it will potentially provide a low capital and low operating cost treatment route,” Beeson added.

Aura will now extend bioleaching studies at the Parker Centre to begin heap column tests on fresh samples of crushed core from across the resource. This work is aimed at further increasing confidence in the technical amenability and economic viability of the bioheap leaching option.

Work on pre-concentrating the uranium and other metals for conventional acid leaching will continue in parallel, as will mineralogical analysis, to ascertain the optimum treatment method.

Aura also continues to undertake scoping studies in Sweden. In Mauritania, the next drill programme is expected to commence in September or October 2010 with the aim of establishing a JORC compliant resource statement in early 2011 on Aura’s uranium in calcrete deposits.