Icon testwork indicates boost to Mt Carbine tungsten project economics

Icon Resources (ASX: III) has received test work results on bulk samples of low grade stockpiles at its Mt Carbine tungsten project that indicate re-treating is now a viable prospect.

Very significant pre-concentration of tungsten (WO3) was achieved by using an X-ray ore sorter which was completed on schedule and in accordance with the business plan.

Importantly, these results show that in the mineralised waste stockpile alone there is a historical estimate of 12 million tonnes of mineralised rock. The economics of re-treating this stock-pile is enhanced as the already mined rock only needs crushing before being fed to the ore sorters.

Icon would be very encouraged by the results and is now planning to commence production at Mt Carbine by re-treatment of the tailings followed by retreatment of the mineralised waste stockpiles.

The re-treatment of the mineralised stockpiles will provide feed for planned production rates for at least 6 years if this plan proves to be feasible.

The size of the required processing plant should now be greatly reduced, which has the effect of reducing the capital required to build the processing plant and also reduces operating costs.

This low cost, efficient mining and processing system will also place the mine in a very competitive position if metal prices fall.

Ore sorting is a physical beneficiation technique commonly used to separate barren rock fragments from mineralised rock fragments extracted from a mine.

The low-grade ore is bulk mined at low mining cost, and by rejecting the barren rock, ore sorting greatly reduces the amount of ore that has to be further processed to extract the valuable minerals.

The ore sorter was run on 12 hour day shifts with samples meticulously taken every hour from the Feed, Accepts and Rejects conveyor belts. These samples from the individual streams were combined to produce composite samples for further analysis and assaying.

At the end of each 12 hour day the weight of the Accepts and Rejects stockpiles were taken so that detailed mass balancing could be performed. The resultant daily stockpiles were stored separately.

In a statement the company said the "mineralised waste stockpile with a feed grade to the ore sorter of 0.09%WO3 showed an 88% mass rejection at a grade of 0.01% WO3, and an Accepts grade of 0.7% WO3 with a WO3 recovery of 90% to the Accepts .

"The historical Optical Ore Sorter Rejects Stockpile with a feed grade to the ore sorter of 0.05% WO3 showed a 74% mass rejection at a grade of 0.008% WO3, and an Accepts grade of 0.18% WO3 with a WO3 recovery of 89% to the Accepts.

"Preliminary ore sorting testwork on the remnants of the ROM stockpile shows 67% mass rejection at a grade of 0.01% WO3, with a feed grade to the ore sorter of 0.12% WO3 and an Accepts grade of 0.33% WO3 with a WO3 recovery of 93% to the Accepts ," the company added.

Production from the hard rock resource is still anticipated, but Icon will be able to gain a significant role in the tungsten supply chain before hard rock mining is commenced.

During this time further drilling of the ore body is planned, with the intention of increasing the hard rock resource, thus pro-viding a wider range of mining options to be assessed before mining and processing the hard rock resource.

The Mt Carbine Deposit in north Queensland is becoming a stronger tungsten production opportunity for Icon, with the maiden JORC inferred resource of 113.6Mt at 0.06% WO3, containing 68,800 tonnes of tungsten trioxide announced on October 15.

On November 2 Icon raised $1,275,000 through a placement of 8,500,000 ordinary fully paid shares at a price of 15 cents per share for the project.

With the price of tungsten having risen to over US$250/t compared to the US$160/t at the end of 2009, the project is well timed by Icon to take advantage of the improved price.