Platinum group metals (PGMs) miner Zimplats has reported an 11% year-on-year and a 4% quarter-on-quarter decrease in mined volumes for the quarter ended March 31, owing to lower availability of trackless mobile machinery.

The company says, however, that, in January, opencast mining was resuscitated within the Ngezi mining lease area to mitigate the impact on mining volumes, contributing 76 000 t, or 4.3% of mined volumes, in the quarter.

Meanwhile, six-element (6E) PGM head grade improved by 1% year-on-year but declined by 1% quarter-on-quarter owing to the addition of lower-grade ore from the opencast mining efforts.

Ore supply, therefore, negatively impacted milled volumes, which decreased by 17% year-on-year and 8% quarter-on-quarter, respectively, while concentrator recoveries remained largely the same as the prior comparable period but decreased 1% quarter-on-quarter in line with head grade.

An adjusted 6E concentrate production of 135 172 oz was 20% lower year-on-year and 15% lower quarter-on-quarter. Final metal production in the period was impacted by optimisation works at the 38 MW furnace and converters.

As such, 60 000 t of concentrates were smelted in the quarter, clearing accumulated inventory from the prior quarter. This was partly countered by the accumulation of about 12 100 6E ounces in furnace reverts and furnace matte.

6E metal in final product of 139 506 oz was 16% lower year-on-year but was 8% higher quarter-on-quarter. About 16 000 6E ounces of accumulated in-process inventory is expected to be released in the fourth quarter of the current financial year, the company says.

On the financial front, Zimplats’ total operating cash costs increased by 3% year-on-year and was negatively impacted by higher power costs of operating the new 38 MW smelter, resuscitated opencast mining operations and timing differences on the replacement of major engineering components.

Total operating cash costs improved by 2% from the prior quarter, positively impacted by lower variable costs associated with lower mined and milled volumes. $6.4-million was transferred from stocks to operating costs in the period as some previously accumulated concentrate stocks were processed in the current quarter.

The cash cost of metal produced increased by 6% year-on-year and 18% quarter-on-quarter. Lower reported volumes negatively impacted on 6E operating cash unit costs of $1 026/oz, which increased by 25% year-on-year and 10% quarter-on-quarter.

In terms of exploration, Zimplats said eight exploration drillholes and a total of 2 178 m were drilled along the declines at Bimha and Mupani mines in the period, focusing on guiding decline development and investigating geological structures within the scheduled five-year mining footprint.

The company also says that, during the period, the development of Mupani mine, which will replace the depleted Rukodzi and Ngwarati mines, had progressed well and remained on schedule, with full production of 3.6-million tonnes a year planned for the first half of the 2029 financial year. A total of $342-million had been spent so far against a budget of $386-million.

Further, Zimplats’ smelter expansion and sulphur dioxide (SO₂) abatement plant project progressed steadily during the period, with $452-million spent to date against a project budget of $544-million.

The first phase of the project, which encompasses the smelter expansion and Phase 1 SO₂ abatement, which includes SO₂ off-gas handling facilities and shared services, is technically complete, with $384-million spent to date against a budget of $398-million.

Zimplats says the second phase of the project, which encompasses the Phase 2 SO₂ abatement (wet gas cleaning and wet sulphuric acid plants), is also progressing with a total of $68-million spent so far against a budget of $146-million.

The company added that its 35 MW solar plant project, which was commissioned in August last year, was ramped up to design generation capacity in December. The project was completed within the approved budget of $37-million.

Finally, Zimplats reported that a cumulative total of $33-million was spent on the base metal refinery refurbishment project, against a total budget of $190-million.