Under the deal, the Commonwealth and state of NSW will split the cost down the middle, with Rio Tinto contributing at least $1.1 billion to reduce its power usage and gear toward renewables.

Prime Minister Anthony Albanese and NSW Premier Chris Minns are expected to travel to Tomago just outside Newcastle to announce the deal on Thursday.

Anthony Albanese and NSW Premier Chris Minns are poised to sign a bailout agreement for the beleaguered Tomago aluminium smelter, ending months of uncertainty for workers.