Anglesey Mining PLC (AIM:AYM) has released the results of an internal review of the Northern Copper Zone at Parys Mountain, one of the largest undeveloped copper deposits in the United Kingdom.
In London, meanwhile, the Welsh miner's share price climbed around 16% to trade at 2.5p by midday.
The Northern Copper Zone at Parys Mountain has an inferred resource estimate of 9.4mln tonnes at 1.27% copper, 0.38% zinc, 0.24% lead, five grams per tonne silver, and 0.1 grams gold.
This resource estimate was completed in 2012 by Micon International.
The Northern Copper Zone was discovered in 1962.
The deposit is interpreted as the downdip extension of the historical open pit mined at Parys Mountain, and appears as a wedge-shaped block with a thin, 15-metre edge starting at around 200 metres below surface. It thickens out to around 100 metres at a depth of around 525 metres. The Northern Copper Zone (NCZ) remains open both along strike to the east and at depth.
The company's review of historical drilling and documents shows an earlier internal resource estimate completed in July 1969 of 32.7mln tonnes at 0.81% copper but excluding other metals, which it said should not be considered compliant with any modern JORC or NI43-101 methodologies.
It noted that very few of the holes drilled before 1980 were assayed for gold but it was recognised that the NCZ contains gold with minor silver, zinc and lead. Preliminary metallurgical testwork completed in 1969 at Lakefield in Ontario demonstrated recoveries of up to 93.3% producing a copper concentrate grading 23.2% copper.
Work programmes are now planned over the next 12-months. These will include drilling into the NCZ to confirm historical grades and continuity, increase confidence in the resource, collect samples for metallurgical testwork and conduct downhole geophysical surveying to try and identify further zones of high-grade mineralisation.
“Our internal review of the Northern Copper Zone confirms our belief that there remains substantial upside to the existing resource base and that future optimisations of the mine design could potentially lead to an extraction ratio greater than the projection within in the 2021 preliminary economic assessment of less than 50%,” said Jo Battershill, chief executive of Anglesey Mining in a statement.
“Additional supporting documents show that historical metallurgical testwork demonstrated significantly better recoveries and concentrate grades than the Engine Zone testwork results used in the PEA. Recoveries of over 93% were achieved in the 1969 Northern Copper Zone testwork, which compares to the 80% expected for Engine Zone. While the PEA flowsheet was designed around a polymetallic deposit, the historical testwork suggests future optimisations could potentially lead to higher copper output from the Northern Copper Zone.”
Under the PEA design, first mining from the Northern Copper Zone would commence towards the end of year four, which provides sufficient time to infill drill the first production areas immediately adjacent to the decline as it is advanced into the White Rock & Engine Zones.
“We are currently working on the resource update for the White Rock and Engine Zone, which is expected to be complete over the next six weeks,” Battershill added.
--Updated to include share price detail, first published 8:21am--