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Sept 18 (Reuters) - Australia's Titan Minerals on Wednesday announced plans to sell up to 80% stake in its Linderos copper project in Ecuador to a unit of billionaire Gina Rinehart's Hancock Prospecting for up to $120 million.

Under the deal, Hanrine Ecuadorian Exploration and Mining will initially earn a 5% interest in the project after a $2 million payout, Titan Minerals said.

Rinehart's Hanrine Ecuadorian can eventually ramp up its stake to 80% by either spending $120 million or taking a decision to mine at the project within 15 years.

The demand for critical mineral copper is likely to surge over the next few decades as the world transitions away from fossil fuels for its energy needs, supporting the usage of electric vehicles, wind turbines and batteries - all of which require the red metal.

Iron ore miner Hancock has been building stakes in critical minerals projects, including rare-earths. Its investments include a 5.56% stake in Brazilian Rare Earths

and an 8.57% holding in Arafura Rare Earths , according to LSEG data.

(Reporting by Aaditya Govind Rao in Bengaluru; Editing by Subhranshu Sahu and Sherry Jacob-Phillips)

((Aaditya.GovindRao@thomsonreuters.com;))