ArcelorMittal and Peabody Energy Corp. will pay $5 billion (A$4.7 billion) to purchase Macarthur Coal Ltd.
Luxembourg steel maker ArcelorMittal already owns 16 percent of Macarthur.
The takeover would come from a holding company that will be 40 percent owned by ArcelorMittal and 60 percent owned by Peabody.
Macarthur said its board was not making a recommendation on the offer, but would engage with the two companies.
Macarthur produces pulverized coal, which is a key ingredient in the making of steel.
Macarthur is the world’s largest producer of seaborne low volatile pulverized coal injection coal with production and development assets in the Bowen Basin, Australia, including the Coppabella and Moorvale Joint Venture and Middlemount Mine. It controls total coal reserves of approximately 270 million metric tons and total resources of approximately 2.3 billion metric tons.