The world's biggest iron ore producer Rio Tinto will raise $9 billion in U.S. investment-grade bonds as it seeks to fund its recently-closed buyout of Arcadium Lithium, the miner said on Wednesday. Rio is offering the fixed and floating rate debt in eight tranches with terms varying from two years to 40 years.

Rio Tinto has completed its acquisition of Arcadium Lithium plc ("Arcadium Lithium") (NYSE: ALTM) (ASX: LTM) for $6.7 billion, following the sanctioning of the Scheme of Arrangement by the Royal Court of Jersey on 5 March.

Rio Tinto Group said it’s seeking to sell bonds in the US to help repay a bridging loan used to finance its $6.7 billion acquisition of Arcadium Lithium Plc.