BEIJING, June 4 (Reuters) - Aluminum Corp of China , known as Chinalco, at the weekend said it had started work on a $1.3 billion expansion of its Toromocho copper mine in central Peru. The investment will increase the mine's copper output by 45 percent by 2020, with the value of production exceeding $2 billion annually, Chinalco Chairman Ge Honglin said at a groundbreaking ceremony in Peruvian capital Lima late last week, according to a company statement issued on Saturday.
The statement gave no tonnage figures, but China's official Xinhua news agency said Chinalco wanted the expansion to take Toromocho's copper concentrate processing capacity to 157,000 tonnes a day and annual refined copper output to 300,000 tonnes.
China is the world's biggest copper consumer, while Peru, whose President Martin Vizcarra also attended the ceremony, is the second-biggest producer of the metal after South American neighbor Chile.
Chinalco is China's largest state-owned aluminum producer but also has some copper assets, including in China's southwestern Yunnan province.
It took control of Toromocho in 2007, bringing the project on stream in late 2013. The company had agreed a preliminary deal in November 2016 to take the development into a second phase through the $1.3 billion expansion.
The project, which is mined for silver and molybdenum as well as copper, contains 1.526 billion tonnes of ore, according to Chinalco's local unit Minera Chinalco Peru. The average copper content is 0.48 percent. (Reporting by Tom Daly Editing by Joseph Radford)