Carlyle makes bid for Rio's Northparkes, mine worth as much as $US1bn ONE of the world's largest private equity firms, Carlyle Group, has made an initial bid for Rio Tinto's majority stake in an Australian copper-gold mine, a person familiar with the matter said. The move underscores growing interest among private equity in resources, as valuations of assets like active mines tumble in line with metals prices, and major mining companies look to conserve cash rather than pursue deals. KKR had earlier shown an interest in Rio's Northparkes mine in New South Wales, but didn't follow up with an indicative offer ahead of this week's deadline for bids, another person said.