Heron starts processing underground ore at Woodlawn zinc-copper mine

Heron Resources says it has started crushing and processing the first underground ore from the high-grade G2 lens at its Woodlawn zinc-copper mine in New South Wales, Australia.

The ore from the G2 lens was mined 135 m below surface and was discovered during Heron’s on-mine exploration drilling programs during 2017.

Since the commencement of the underground campaign, around 10,000 t of G2 stoped ore was delivered to the plant at 3.9% Zn, 1.3% Pb, 0.3% Cu, 31 g/t Ag and 0.6 g/t Au. This was in addition to 6,000 t of G “hangingwall” ore at 4.7% Zn, 2.6% Pb, 0.7% Cu, 268 g/t Ag, 2 g/t Au; plus 2,000 t of high-grade development ore at 7.3% Zn, 3.7% Pb, 4.9% Cu, 30 g/t Ag and 0.9 g/t Au.

The first stages of commissioning were completed using tailings reclaim feed material, with some preliminary commissioning of the crushing and ball mill plant during August and September.

Heron says the plant is now receiving run of mine underground ore and will complete a campaign solely on this feed source. This will facilitate the next phase of commissioning for the crusher and ball mill and marks the start of the ramp-up phase for this part of the circuit.

In steady state, the plant will alternate between campaigns of tailings reclaim feed and underground ore.

With stope ore now being mined and processed, paste fill activities have also been progressed, with the final commissioning of the paste plant and a number of placements underground of paste fill now complete.

Heron’s Chairman, Stephen Dennis, said: “The first ore mined and now processed from the G2 lens is a significant achievement for the operations at Woodlawn. The high-grade G2 lens was planned to be the first underground ore through the plant and will generate early revenue in these first stages of underground mining.”

The forecast development includes access to the G3 (north) area that contains stopes that are in an independent sequence from the current G2, G3 (south) and GH stoping area.

Processing of reclaimed tailings is ongoing and underground ore campaigns are being scheduled in line with the current production plan. Ramp-up of the processing plant continues and the plant is scheduled to achieve rated capacity on a sustainable basis from mid-2020.