Giant mining company Rio Tinto (NYSE:RTP) has been hunting for cash to pay down the first installment of about $10 billion as part of the $38 billion it borrowed to finance its purchase of Canadian aluminum producer Alcan in 2007. Now it appears that help in the form of a $19.5 billion investment may well be on the way from the Aluminum Corp. of China (NYSE:ACH) -- or Chinalco -- a state-owned metals company.

Chinalco, along with Alcoa (NYSE:AA), purchased a 9% stake in Rio Tinto, for which the two companies paid $14 billion last year. The pair had teamed up to have an influence in thwarting a takeover offer for Rio Tinto by Australia's massive mining company, BHP Billiton (NYSE:BHP). On Thursday, it was announced that Chinalco was buying out Alcoa's stake.

It appears that, should the latest Rio Tinto-Chinalco deal transpire, it would involve Chinalco paying about $7.2 billion in bonds that would convert into Rio Tinto shares, roughly doubling Chinalco's stake in the company. The remaining $12.3 billion would take the form of minority investments in Rio's iron-ore, copper, and aluminum assets.

Indeed, it appears that one of the crown jewels of the proposal would involve Chinalco purchasing 25% of Rio Tinto's Kennecott copper mine in Utah. And beyond the cash and asset aspects of the transaction, Chinalco apparently would receive two seats on Rio Tinto's board.

But thus far, the deal is far from a certainty. Rio Tinto -- which on Thursday reported a 50% slide in 2008 earnings to $3.7 billion -- must gain prior approval from various regulatory authorities as well as its own shareholders.

And then there's BHP, which along with Rio Tinto and Brazil's Vale (NYSE:RIO) constitute some of the world's largest mining companies. After months of chasing Rio Tinto -- an effort that was broken off late last year -- it doesn't appear out of the question that BHP could resurface with a renewed offer for it.

So this set of circumstances could become progressively more interesting and fun to watch. For my money, all of the companies mentioned above likely will return to the ranks of the potentially sound investments once the global economy begins to regain its sea legs. For that reason alone, I'd advise my Foolish friends to keep the sector prominently displayed on their watch lists.

Rio Tinto is a four-star company among Motley Fool CAPS players. Why not add your vote to the rating?

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Fool contributor David Lee Smith doesn't own any of the stocks mentioned above. He does, however, welcome your comments or questions. The Fool has a disclosure policy.