Australian miner St Barbara reiterated its full-year production guidance of 65 000 oz to 75 000 oz, but said that lower-than-expected output in the second quarter would push production to the lower-end of the target range.

The company initially expected to produce 14 000 oz to 16 000 oz from the Simberi mine, in Papua New Guinea, in the quarter ended December 31, but missed the mark at 10 262 oz.

St Barbara attributed the production shortfall to several issues, including intermittent semiautogenous grinding mill high-power throughput restrictions caused by oversize material during downtime on the existing feeder breaker crusher unit, particularly when processing more competent ore such as Sorowar East. In addition, poor grade reconciliation in November was attributed to ore dilution resulting from stretched dewatering efforts in Sorowar East, as groundwater was reached alongside higher-than-usual rainfall. Further compounding the issue, the operation relied on low-grade stockpiles in the latter half of December owing to contract truck fleet availability issues, primarily caused by chassis cracks detected across the fleet.

The company said it expected an improvement in second-half gold production performance, as it expected an MMD sizer crusher to be installed in early February that would replace the problematic feeder breaker.

Meanwhile, St Barbara also announced a new oxide discovery at Pigibo North and south-west Sorowar.

The trench intercepts at the new oxide discovery included 30 m at 1.3 g/t, 40 m at 2.0 g/t, 20 m at 0.9 g/t, and 25 m at 2.1 g/t.

Encouraging intercepts from surface in sterilisation drilling at the new oxide discovery between Pigibo North and south-west Sorowar included 28 m at 1.0 g/t from 0 m, and 24 m at 1.4 g/t.

“These significant results from trenching and the near surface drilling results are now being followed up with grade control drilling with the objective of commencing mining in the third quarter,” said MD and CEO Andrew Strelein.