Output in the world's top aluminium producing nation is still running below total capacity, seen at 32 million tonnes by the end of this year, said Zhonglin Yin, director of the alumina division in the Zhengzhou Research Institute of Chalco. The Aluminum Corp of China Ltd is typically referred to as Chalco.

The country's aluminium production grew by almost 9% to 16.2 million in the nine months to September, according to China's National Bureau of Statistics. It stood at 19.9 million tonnes for the whole of last year.

Of new capacity this year, 84% will be in the western provinces, Zhonglin said at an industry conference in Singapore.

But he added that aluminium production growth is slowing from an average growth rate of 18% between 2002 and 2012.

For alumina, a mid-process material used to make aluminium, Zhonglin sees production this year at around 43.5 million tonnes, against a backdrop of more than 60 million tonnes of capacity expected by year-end.

Because China has only identified enough supply of aluminium ore bauxite for the next 15-20 years, Beijing has issued new policies to reinvigorate exploration in the country, to seek alternative resources and to use as much overseas bauxite as possible, Zhonglin continued.