The most-traded July copper contract on the Shanghai Futures Exchange ended 0.3 percent higher at 51,070 yuan ($8,036.82) a tonne on Thursday on falling inventories and signs of strong demand in top consumer China, while aluminium retreated for the first time in four trading days. China imported 442,000 tonnes of unwrought copper in April, according to customs data released this week, the highest monthly total so far in 2018.
"Apart from the reduced supply of copper scrap, the strong import appetite was also attributable to an increase in smelting capacity and less than expected ... maintenance scheduled for April," Argonaut Securities analyst Helen Lau wrote in a note. In another report, China's refined zinc production rose 2.1 percent in April from a month earlier to 377,000 tonnes as smelters returned from maintenance, research house Antaike said in a note.
Daily output increased by 5.5 percent last month, which had one less day than March, said the research arm of the China Nonferrous Metals Industry Association. Output was also up 2.7 percent year on year. Zinc smelters in Yunnan, Sichuan, Guangxi and Anhui restored normal operating rates after overhauls, but other plants started maintenance, capping output increases.