"You could say they picked the bottom of the market," said Jonathan Li, Melbourne-based executive director of Metamor Capital Partners, who has advised Chinese companies on resources deals.

Alumina forecasts 20 million metric tons more bauxite will be needed in each of the next three years to meet rising demand from China, the Middle East and India, Metamor said. Fiona Chan, the Hong Kong-based spokeswoman for CITIC Group at Brunswick Group LLP, declined to comment.

"You can't build a refrigerator without putting in our commodities, you can't build a washing machine, you can't build a car," Sam Walsh, Rio Tinto's chief executive officer, told investors at a Dec 4 seminar in London. While a major shift to consumption-led growth in China has been anticipated, "it's actually already happening", he said.

Chinese homes will use 800 million air conditioners by 2025, double the number in 2013, Rio Tinto estimates. Those appliances alone may require about 9.4 million tons of copper, based on the 23.6 kg used in a typical unit.

Long-term fundamentals for copper are positive on demand from China, said Andrew Michelmore, the chief executive officer of mining company MMG Ltd, on Thursday.

China's move to cut pollution is another driver for copper. A nuclear power station requires 2.5 tons of the metal for every megawatt of capacity, almost double the amount needed in a coal-fired power station. The nation will probably add about 132 gigawatts of nuclear capacity by 2040, more than the current capacity of the US and Russia combined, according to the International Energy Agency.

"China's dependence on imported material will increase, even in infrastructure," said Ernst & Young's Elliott. "As every month goes by, the proportion of imported materials in the total consumption increases. That dependence is not going to change, in fact it's going to grow."