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Dart Mining: metallurgical testing delivers over 92% molybdenum recoveries at Unicorn

Dart Mining (ASX: DTM) has received preliminary results from an ongoing Scoping Study of metallurgical test work for the Unicorn Deposit in north-east Victoria which show high recoveries of 92.3% molybdenum, 96.1% copper and 82.6% silver.

Another plus from the Scoping Study, which is being conducted by Australian Minmet Metallurgical Laboratories, is that saleable grades of 51% molybdenum and 23% copper plus silver concentrates were produced and with further test work it is expected that the metal percentages, especially copper, can be improved.

Importantly, these early results improve the Unicorn development potential.

Based on this initial Scoping Study metallurgical test work and the 105 million tonnes at 0.07% molybdenum equivalent JORC resource, the Unicorn deposit is estimated to contain approximately 38,000 tonnes of recoverable molybdenum, 58,000 tonnes of recoverable copper and 8.6 million ounces of recoverable silver.

A further boost to the potential of Unicorn is that the resource remains open at depth, with the only hole through the middle of the deposit intersecting 40 metres at 0.09% molybdenum equivalent from 348 metres, including 18 metres at 0.11%.

The potential for resource upgrade remains strong once drilling below 400 metres is carried out.

Managing Director Lindsay Ward told Proactive Investors today the test results from this Scoping Study metallurgical progress report were very positive.

"It’s very positive in that it’s saying the ore can be mined, it can be crushed at fairly good grind sizes and we can expect higher recoveries of the metals within that ore using fairly simple flotation and reagents to extract that metal and produce saleable grades of concentrate," he said.

“When combined with an outcropping deposit, low strip ratio, available land tenure, close proximity to hydro power, water and sealed roads, an established logistics chain to market, supportive community and available work force, the Unicorn Deposit appears increasingly likely to move into development phase in the future."

Other highlights from the Scoping Study metallurgical progress report include:

- Reagent suite for molybdenum and copper flotation was simple and relatively inexpensive;
- A grind size of 75 microns was used to achieve the recoveries. This is a typical grind size but a coarser grind, while maintaining high metal recoveries, appears achievable; and
- Ore was indicated to be amenable to upgrading by dense media separation.

Next step

Further test work is proposed for the March quarter of 2012 to further improve recoveries and increase saleable concentrate grades by trialling varying grind sizes, differing pH levels and alternative reagents.

It is expected that once this further test work is completed, it will be used as the basis to complete a Scoping Study for the flotation plant design and cost.

Ward said this is a new porphyry mineral province in Australia. "It hasn’t really been explored before and there is a number of other porphyry targets beyond Unicorn that we’re looking to explore at some stage in the future and I think that’s the real positive thing, this is actually a new find in Australia," he said.

Growing Market

Molybdenum is a growing market of around 220,000 tonnes per annum, with supply shortages predicted. The metal adds strength, hardness and toughness to steel.

It has applications in corrosion resistance in petrochemical industry pipework, as well as in the automotive and aerospace industries.

It is a new age metal with strong potential for use in renewable energy and also has applications in nanotechnology.

Dart Milestones

Just last month Dart reported a higher than expected maiden JORC Resource of 105 million tonnes Indicated and Inferred at 0.07% molybdenum equivalent for the Unicorn Deposit.

However, based on the drilling results to date, and infill drilling planned these tonnages should increase and allow an Indicated Resource to be estimated to 450 metres depth.

The initial Resource estimated for the Unicorn deposit is interpreted to represent only the upper limits of a very large intrusive porphyry system which has already shown multiple stacked high grade molybdenum zones.

Unicorn is comparable to a style of deposit that typically shows economic mineralisation extending well below 1000 metres depth.

A series of deeper diamond drill holes are being planned to test the system below 450 metres in 2012.