PERTH (miningweekly.com) – Gold miner St Barbara has lowered its production guidance for 2021 as low grades at its Leonora operation, in Western Australia, and workforce availability at Simberi, in Papua New Guinea, impacted results.

Consolidated production for the full year is now forecast to reach between 330 000 oz and 360 000 oz, down from the previous estimate of between 370 000 oz and 380 000 oz.

All-in sustaining costs (AISC) for the full year are expected to be between A$1 547/oz and A$1 695/oz, up from the previous estimate of between A$1 440/oz and A$1 520/oz.

Gold production from St Barbara’s Atlantic operations was still expected to reach between 100 000 oz and 110 000 oz, with AISC of between A$958/oz and A$1 050/oz.

However, the production guidance at the Leonora operation has been downgraded from the previous guidance of 175 000 oz, to between 150 000 oz and 160 000 oz, with AISC expected to reach A$1 815/oz to A$1 950/oz, up from the previous estimate of between A$1 590/oz and A$1 630/oz.

St Barbara told shareholders that the strong mill and development rate performance in the month of March continued into the fourth quarter. April mill throughput remained above nameplate capacity of 1.2-million tonnes a year and development advance rates were sustained at over 400 m for the third consecutive month.

However, the miner noted that negative grade reconciliation in both stope ore and Jasper stockpile material impacted gold production. The lower grade in the short term, based on mine position and timing, is a contributor to the change in 2021 guidance for Leonora.

In addition, the transition to Macmahon as contractor at Leonora has been slower than predicted.

St Barbara said that the recruitment of critical roles and experienced operators by Macmahon has been well below expectations, with the resultant shortfall in personnel a further factor in this guidance change.

“While St Barbara continues to work with Macmahon, Western Australia-based workforce availability has ultimately impacted the planned mine schedule and has led to the deferral of mined ore tonnages from 2021 into 2022,” the company said.

Meanwhile, production at Simberi is now expected to reach between 80 000 oz and 90 000 oz, down from the previous estimate of 95 000 oz, with AISC reaching between A$1 790/oz and A$2 030/oz, up from the previous guidance of between A$1 720/oz and A$1 810/oz.

Operations at Simberi continue to be impacted by ore variability, as a result of low mining rates not achieving planned face positions, which is affecting gold recovery, said St Barbara.

A related factor is workforce availability owing to Covid-19. The miner noted that the Covid-19 situation in Papua New Guinea remains dynamic and managing the pandemic at Simberi continues to put pressure on the operation and the workforce.