(Adds details on coal assets) Sept 20 (Reuters) - Global miner...

(Adds details on coal assets)

Sept 20 (Reuters) - Global miner Rio Tinto said on Thursday it will return $3.2 billion to shareholders following the recent sale of some Australian coal assets.

Rio said it will conduct an off-market share buyback for up 41.2 million Rio Tinto Ltd (RIO) shares, worth about $1.9 billion, and further on-market purchases of Rio Tinto plc RIO.L shares.

The buyback is in addition to existing buyback programmes, of which $1.7 billion in shares still remains to be purchased and which will be completed by end-February 2019, it said.

Rio, which had announced plans for a $4 billion buyback in August, noted that the sale of its Dunkerque aluminium smelter in northern France was not yet complete, while Norway's Hydro cancelled plans to buy its ISAL smelter in Iceland.

The $3.2 billion in net proceeds comes from the sale of the Hail Creek coal mine and Valeria coal project to Glencore GLEN.L , Winchester South to Whitehaven Coal (WHC) and the Kestrel coal mine to private equity manager EMR Capital and Indonesia's Adaro Energy Tbk ADRO.JK .