Chief executive Jakob Stausholm, who will make way for incoming boss Simon Trott on August 25, said he had often seen higher prices at other times while at the company's helm. Aluminium and copper production has helped boost Rio Tinto's operations. (Lukas Coch/AAP PHOTOS) "But this set of results are the strongest, demonstrating real momentum in improving operational performance, real value from a more diversified portfolio, and excellence in unlocking growth projects," Mr Stausholm told investors at an results presentation in London. Positive earnings and cash flow results were buoyed by strong prices and production in aluminium and copper, which helped offset the weaker iron ore performance, chief financial officer Peter Cunningham said. "It's also important to note that going forward, over the next 10 years, we expect that 40 per cent of (iron ore) production from the majors needs to be replaced," he told investors.