Global miner Rio Tinto scrapped its proposed $19.5 billion tie-up with Chinese firm Chinalco on Friday and instead launched a heavily discounted $15.2 billion right issue.

The world's second-largest iron ore producer killed off the deal, which would have been China's biggest single offshore investment, right after it announced an agreement to combine its Australian iron ore mines with rival BHP Billiton .

The rights-issue shares would be issued in Australia at A$28.29 each and in London at 1,400 pence, on the basis of 21 new shares for every 40 shares currently held, Rio Tinto.

Rio Tinto last traded in Australia at A$66.90 and in London at 2,753 pence.

(Reporting by Mark Bendeich; Editing by Denny Thomas)