Milled production at Impala Rustenburg decreased by 12% to 2.59 million tonnes. This was partially offset by higher milled grade, as well as yield gains, and resulted in a 9% decline in 6E in concentrate production to 315 000 ounces.
Production was impacted by unprotected industrial action among the contractor workforce, compounded by unstable power supply, increased safety stoppages, cable theft and community disruptions. Targeted interventions to mitigate the impact of each of these factors were developed and implemented at the operation.
Refined 6E production of 292 000 ounces declined by 22% during the quarter from 372 000 ounces in the prior comparable period. In FY2020, the Group expedited annual processing maintenance scheduled for Q1 FY2021 to better match the expected ramp-up in mining production and third-party concentrate receipts following the Covid-19 lockdown in South Africa. As a result, refined volumes in the prior comparable period benefitted from increased availability of processing capacity.
Tonnes milled were stable at 1.68 million tonnes, with planned maintenance at the Selous concentrator completed in the period. Delivered mill grade declined by 1% due to changes in the ore mix as Ngwarati Mine returned to full production following rehabilitation of the box cut. 6E concentrate production was 2% lower at 144 000 ounces, while matte volumes of 143 000 ounces improved by 1% following a scheduled furnace reline in the prior comparable period.
Marula benefitted from improved operational continuity following safety stoppages in Q4 FY2021, with higher stoping and development efficiencies achieved during the period. Milled volumes of 523 000 tonnes were largely unchanged, but a 9% improvement in milled head grade offset lower yields and 6E in concentrate production increased by 5% to 71 000 ounces.