The most-traded copper contract on the Shanghai Futures Exchange closed 0.6 percent lower at 55,250 yuan ($8,506.94) a tonne on Tuesday on bets that demand in top consumer China will improve in 2018, keeping prices near four-year highs at the start of trading in the new year. ShFE nickel ended 2.36 percent higher while tin closed 1 percent higher. Zinc finished 0.76 percent higher, while aluminium closed down 0.33 percent.

China is the world's largest consumer of industrial metals and accounts for nearly half of global copper demand. The metal has been supported by Beijing's attack on polluting industries, supply reforms and robust demand growth. China's copper smelters on Friday lowered the floor for their treatment and refining charges (TC/RCs) in the first quarter of 2018 by 8.4 percent, signalling tighter supply of copper concentrate in the first three months of the New Year.

Guinea's government has approved a more than $2.8 billion investment by Chinese company TBEA Co Ltd in a new bauxite mine, an aluminium refinery and an aluminium smelter, the mines ministry said on Friday.

Copyright Reuters, 2018