Under the agreement, Klaveness will continue to import caustic soda for South32 for the next six years under new sustainability terms.

Klaveness has been a key shipping contractor for South32 for more than three decades.

South32 imports caustic soda for its alumina refining operations at the Worsley facility, which processes locally mined bauxite into white alumina powder for international export.

Bauxite is crushed and then dissolved in caustic soda before it is filtered and processed using electrolytics.

South32's entire operation in Collie, Western Australia would be null and void without the caustic soda imported through Klaveness.

The updated contract of affreightment with the shipping company will require detailed carbon dioxide emission reporting.

Klaveness will also work to reduce emissions associated with each shipment by as much as 40%.

It did not say how it planned to do this, however, the International Maritime Organisation mandated emissions associated with shipping must be reduced by 40% or more by 2030.

This would require next-generation smart ship technologies and hybrid electric vessels.

Klaveness chief executive Engebret Dahm said in this next era of the relationship the two companies would together address the main challenge of our generation - climate change.

"We have jointly set ambitions to considerably reduce shipping carbon emissions through building on KCC's low carbon caustic soda shipping solution, which already today provides South32 with a 30-40% lower carbon footprint than competing tanker vessels," he said.

South32 aims to be net-zero by 2050.

Its aluminium business accounts for 36% of its emissions. Worsley makes up 18% of that while the Hillside operations by comparison are responsible for nearly 60%.