A cap on Chinese smelting capacity and constraints to European production due to higher electricity prices have chipped away at global inventories, while the demand outlook from the construction and renewable sectors remains robust. Copper also resumed gains Friday after capping the biggest annual gain since 2009 on tight supply, while nickel jumped after PT Vale Indonesia halted mining following a delayed approval to a work plan from authorities. Delays are not unusual in the Southeast Asian nation, but traders are honing in on supply after Indonesia said it planned to cut output this year.