Rio Tinto has repurchased $781m (£605m) of its bonds ahead of time as part of a wider $2.5bn debt reduction programme.
The world's second largest miner revealed plans to use cash reserves to reduce its debt burden on 22 May. The first tranche was due to be extinguished by 19 June.
But in a short statement today, Rio Tinto said that as of 5pm New York time yesterday the debt buyback of the tranche on offer was oversubscribed.
In May, Rio Tinto also issued a redemption notice for a further $1.7bn of its 2019 and 2020 bonds. These will be redeemed on 21 June 2017.
Last week, Western Australia authorities went cap in hand to Rio Tinto to ask for cash.
The mineral-rich state has run up more than AU$30bn in debt and hoped Rio Tinto and rival BHP could pay upfront a multi-billion dollar fee for cancelling an ongoing iron ore production levy.
Under the proposal, the two mining houses would pay as much as AU$4bn in exchange for cancelling an ongoing levy on iron ore from their mines, some of which could be running for another 50 years.