Hong Kong-listed Yankuang Energy said it was considering issuing US$1.8 billion worth of convertible bonds to acquire the remainder of Yancoal.
However, the proposed offer only values Yancoal at A$3.60 per share, well below yesterday's closing price of $6.08.
Yankuang's board has approved the deal but it also requires shareholder approval.
The deal would also require Foreign Investment Review Board approval.
Yancoal is currently Australia's largest pure coal producer with 38.6 million tonnes of equity saleable coal production in 2021, comprising 31.1Mt of thermal coal and 7.5Mt of metallurgical coal from the Hunter Valley operations, Mount Thorley Warkworth and Moolarben mines.