The most-traded copper contract on the Shanghai Futures Exchange rose 1.1 percent to 50,110 yuan ($7,292) a tonne on Tuesday. Shanghai, zinc and lead each slipped by less than a half-percent, while aluminium gained 2.9 percent. Copper built on hefty overnight gains on Tuesday amid supply concerns from two of the world's biggest sources of the metal.
At Escondida, workers went on strike last Thursday after the collapse of wage talks with owner BHP Billiton.
A day later, Freeport-McMoRan Inc said an export ban remained in place at the Grasberg mine over a permit dispute.
Freeport has also confirmed that copper concentrate production came to a halt on Friday.
"The copper market saw further pressure on supply, after Freeport halted copper concentrate output after it failed to secure a new mining permit for its Grasberg operation in Indonesia," Australia and New Zealand Bank said in a note.