However, the miner said that needed to improve to ensure the viability of two longwalls at the Appin mine.

In a report covering the September quarter South32 said the metallurgical coal production at Appin and Dendrobium had jumped by 54 per cent to 1.9 million tonnes.

“Illawarra metallurgical coal enjoyed a strong start to the [financial] year as an improvement in longwall productivity underpinned an annualised production rate of 7.6 megatonnes in the quarter,” South32 CEO Graham Kerr said.

The report included a note that this improvement would not be enough on its own to secure the future of a pair of longwalls at Appin.

“Notwithstanding the improvement in longwall productivity at Appin, an uplift in development rates is required to sustain the operations of two longwalls in parallel from [the second half] FY20,” the report noted.

This year Appin had been hit with industrial unrest, with miners going on strike at least twice during protracted negotiations with Illawarra Metallurgical Coal for a new enterprise agreement.

While stating an agreement at Dendrobium had been reached, any such deal at Appin was still outstanding.

“We continue to renegotiate several other labour agreements at Illawarra Metallurgical Coal and this process is being closely managed,” the report stated.