Slurry commissioning has commenced on an upgraded scavenger circuit at New Century Resources’ (ASX: NCZ) Century zinc mine in north-west Queensland.
Commissioning will allow the full capacity of the circuit to be incorporated into the plant’s operations for the first time since the mine re-opened in September 2018.
The scavenger circuit upgrade was delivered on budget and three weeks ahead of schedule, representing completion of the second milestone of the mine’s scheduled ramp up to 12 million tonnes per annum throughput over the 2020 financial year.
The third and final ramp up involves upgrading the rougher circuit and remains on track for completion in March 2020.
New Century said the upgraded scavenger circuit is expected to provide continued improvement to overall plant performance, with the increase in residence time providing further optimisation of throughput, recoveries and concentrate quality.
“With recent operational rates approaching 9Mtpa, the 100% increase in scavenger capacity will provide substantial flexibility in this area of the plant … only an additional [and approximate] 25% throughput is required to bring operations to 12Mtpa,” the company said.
Cleaner circuit upgrade
In other operational improvements, an upgrade to the plant’s cleaner circuit completed in August has had a positive impact, providing a “step change” in New Century’s operational performance for the second half of the September quarter.
“The improvements due to this upgrade are particularly evident in the performance during the month of September, which delivered 10,013t of zinc metal at an average recovery of 52% zinc (against an overall quarterly average recovery of 48% zinc),” the company said.
“Operations have achieved a clear reduction in variability since early September [and] stability is expected to continue as the ramp up progresses, allowing for the continued optimisation of all production parameters.”
Concentrate quality has also continued to improve following the upgrade, with zinc grades increasing to a quarterly average of 49%, compared to 48.1% in the previous three-month period.
The Century zinc mine began its life under former owner MMG Limited (ASX: MMG) in 2000, producing zinc and lead concentrates using conventional open-pit mining, grinding and flotation.
During initial operations, it was one of the world’s largest base metal mines, churning out an average 475,000tpa of zinc and 50,000tpa of lead in concentrate products over its history.
When ore reserves from the original Big Zinc orebody were depleted, MMG sold the mine to Century Bull Pty Ltd, which on-sold an initial 70% equity – and seven months later, the remaining 30% – to New Century Resources (then known as Attila Resources).
Operations were re-started in August 2018 following a feasibility study which indicated the potential for a highly-profitable, large-scale, low-cost operation.
Century has an estimated production capacity of 264,000tpa zinc and 3 million ounces per annum silver over an initial ore reserve mine life of 6.3 years.
In-situ mineral resources provide potential for mine life extension and New Century is engaged in active exploration programs across the 1800 square kilometre tenement package.
At late afternoon trade, shares in New Century were up 12.90% to $0.35.