Zinc metal production from the Century mine in Queensland rose from 18,170 tonnes to 20,450t.
While recovery reached up to 55% in April at a 6 million tonne per annum mining rate and two cannons online, it averaged 44% for the quarter as the third cannon was commissioned, taking the operation to 8Mtpa.
The company said recovery rates had reached up to 48% so far in July as the plant stabilises at 8Mtpa.
The full cleaning circuit is set to be commissioned early next month, which should remove the current recovery bottleneck for efficient production at the 8-9Mtpa rate and allow capacity for up to 12Mtpa.
New Century is targeting a A$40 million expansion to 12Mtpa this financial year, which will be funded from cash reserves and an undrawn debt facility, subject to a positive bankable feasibility study and final investment decision.
New Century maintained September quarter production guidance of 23,000-29,000t of zinc metal at C1 costs of US95c-$1.07 per pound, including treatment charges.
The company said continued refurbishment efforts to double plant capacity would drive down C1 costs to a life-of-mine average of 56c/lb.
Shares in New Century dropped 10.4% to A34.5c, a 52-week low.