Vancouver (BC), Canada – The feasibility study, prepared under the
direction of Tetra Tech, is based on mining 1.2 million tonnes from the
main and footwall ore bodies above the valley floor (probable tungsten
reserve 13.3 million tonnes at 0.425 per cent WO3 with a cut-off of 0.24 per cent WO3).
The feasibility considers a window of 11.5 year mine life based on
reserves. Infill drilling is ongoing in the eastern hanging wall and
western extensions of all three mineralised zones above the valley floor
with a view to further upgrading the 53.9 million tonnes of inferred
resources and extending the mine life.
The ore will be mined by
mechanised drift and fill methods and trucked to surface, crushed
through a two stage crushing circuit and delivered to a fine ore bin.
Comminution is via a primary rod and secondary ball mill that grinds and
feeds the ore to a sulphide molybdenum/bismuth flotation circuit. The
tail of the sulphide float is then processed through a tungsten (WO3)
oxide float at a recovery of 85 per cent of the tungsten in
concentrate. The concentrate is then processed through an APT refining
plant to produce approximately 400,000 mtu (metric tonne units (10
kilogram) equivalent to 4000 tonnes) of Tungsten (WO3) per year in the form of Ammonia Para Tungstate (APT) which is then sold for the manufacture of hard metal tooling.
The
feasibility study further makes provision for the extraction of
by-product molybdenum and bismuth in a sulphide concentrate circuit.
However no value has been attributed to the recovered metal as the
downstream process for the concentrate is still in a design stage.
Further it was believed prudent to include the capital and mining costs
for owner mining; however, it is likely that one of the many tunneling
contract companies in Korea will be used to develop the mine at a
substantially lower unit cost. This has not been considered as tenders
were not available at the closing date for the feasibility study inputs.
The feasibility study builds upon the technical and economic criteria
established during the pre-feasibility stage undertaken by Tetra Tech
and confirms the technical and financial viability of constructing and
operating a 1.2 million tonnes per year underground tungsten mine
including a process plant and an APT plant to produce an Ammonium
Para-Tungstate final product.
First ore accepted to the process
plant is targeted for 2013 following a 15 month construction phase
beginning in 2012. Probable Mineral Reserves of 13.3 million tonnes of
ore grading 0.425 per cent WO3 results in an 11.5 year mine
life. Initial capital costs are estimated to be USD 151.3 million
including a pre-development cost of USD 8.2 million and including a
contingency of USD 7.8 million.
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