ASX-listed platinum group metals (PGMs) miner Zimplats has reported a quarter-on-quarter increase of 9% in mined tonnage and an increase of 4% in milled tonnage for the quarter ending June 30.

This translated to a 4% year-on-year increase in ore mined, with no change in tonnes of ore milled.

Zimplats attributed these improvements to the full recovery of the Mupfuti mine from the effects of decreased trackless mining equipment availability, as well as an increase in the number of operating days and improvement in the milling rate.

The increase in mining and milling mean that 6E PGMs production – comprising platinum, palladium, rhodium, ruthenium, iridium and gold – increased by 2% over the previous quarter but decreased by 2% year-on-year.

Zimplats said this was mainly attributable to the increase in mill volumes, which were partly offset by negative inventory movement in the smelter. Production for the same period last year benefitted from a release of smelter inventory, which meant that metal in final product was less than last year.

6E head grade improved by 1% to 3.44 g/t from 3.40 g/t in the previous quarter, mainly driven by the increase in the contribution of high-grade ore from Mupfuti mine. The previous quarter’s head grade was adversely affected by processing of low-grade development ore from the Mupani mine stockpile.

Meanwhile, total operating cash costs increased by 3% from the prior quarter, driven mainly by the 9% and 4% increase in tonnes mined and milled, respectively.

A total of $1.1-million was transferred from operating costs to closing stocks owing to the planned build-up of run-of-mine ore stocks in preparation for the commissioning of the third concentrator plant in August. This resulted in the cost of metal produced decreasing 2% compared with the previous quarter.

The decrease in cash costs of metal produced, together with the 2% increase in 6E ounces produced, resulted in a 3% improvement in 6E unit costs from $752/oz in the previous quarter to $726/oz.

Year-on-year unit costs increased by 2% mainly because of the inflationary increase in operating cash costs.

A total of $500 000 was spent on exploration projects, with a further $700 000 committed. Exploration activities included mineral resource evaluation, comprising about 2 190 m of surface diamond drilling over existing projects on the two mining leases. Exploration activities increased geological and geotechnical confidence in production schedules, Zimplats said.

The development of Mupani mine and upgrade of Bimha mine to replace the Rukodzi, Ngwarati and Mupfuti mines, which will be depleted in 2022, 2025 and 2028, respectively, progressed well during the quarter, the company said.

A total of $228-million had been spent on the project and $81-million had been committed against a project budget of $468-million.

Zimplats said the third concentrator plant, which will increase milling capacity by 900 000 t/y – equivalent to about 80 000 oz of 6E PGMs – was on course for commissioning in August.

Cumulative project expenditure for the quarter amounted to $79-million, with $14-million committed against a project budget of $94-million.

Implementation of the $521-million smelter expansion and sulphur dioxide (SO₂) abatement plant project, which began in the previous quarter, remained on course. The project consists of the construction of a 38 MW furnace and the establishment of an acid plant for the abatement of SO₂ generated by the smelter operations.

A total of $19-million had been spent on the project and $218-million committed as at the end of the quarter.

Procurement processes for the $37-million Phase 1 implementation of Zimplats’ 185 MW solar project started during the quarter. Phase 1 involves a 35 MW plant being established at the Selous metallurgical complex. It is scheduled for completion in 2024.

Overall, the project has four implementation phases, with the last phase scheduled for completion in 2027 at a total project cost estimate of $201-million.

In terms of occupational health and safety, Zimplats recorded two lost-time injuries and ten new Covid-19 cases during the quarter, all of whom have fully recovered, increasing the total number of confirmed and fully recovered cases within the company since the start of the pandemic to 86.