Anglesey Mining plc plans work programmes in the Northern Copper Zone (NCZ) after an internal review showed a “substantial upside” to the existing resource base at its Parys Mountain copper project.
NORTHERN COPPER ZONE
The company said that the NCZ, discovered in 1962, was interpreted as the downdip extension of the historical open pit mined at Parys Mountain.
The extension appears as a wedge-shaped block with the thin edge (15m wide) starting 200m below surface that extends down to the thicker end (over 100m width) at a depth of around 525m below surface.
The company added that the NCZ remained open both along strike to the east and at depth.
HISTORICAL DATA
The NCZ has a 2012 inferred resource estimate of 9.4Mt at 1.27% Cu, 0.38% Zn, 0.24% Pb, 5g/t Ag and 0.1g/t Au.
Anglesey Mining added that its review of historical drilling and documents included an earlier internal resource estimate completed in July 1969 of 32.7Mt at 0.81% Cu (excluding other metals), but not compliant with modern JORC or NI43-101 methodologies.
It was also recognised that the NCZ contained gold with minor silver, zinc and lead.
| Resource | Tonnes | Cu | Zn | Pb | Ag | Au | |
| Category | (Mt) | (%) | (%) | (%) | (g/t) | (g/t) | |
| Northern Copper Zone | Inferred | 9.38 | 1.27 | 0.38 | 0.24 | 5.0 | 0.1 |
| Total | 9.38 | 1.27 | 0.38 | 0.24 | 5.0 | 0.1 |
PROGRAMMES
The company said it had set out a series of work programmes on the NCZ for the next 12 months.
These include drilling into the NCZ to confirm historical grades and continuity and increase confidence in the resource.
Anglesey Mining will also collect samples for metallurgical testwork and conduct downhole geophysical surveying to try to identify further zones of high-grade mineralisation.
All information gathered will feed into a resource update.
COPPER RECOVERIES
Chief executive Jo Battershill added 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 (PEA) of less than 50%.
“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.”
He added that first mining from the NCZ would begin towards the end of year 4.
Anglesey Mining is currently revising the resource for the White Rock and Engine Zone, which is expected to complete over the next six weeks.