Chinalco Mining Corp. International will spend a futher $1.32 billion on its Peruvian Toromocho copper project – one of the biggest in the world – to increase production capacity, reports the Wall Street Journal.

The firm has already invested $3.5 billion on developing the mine, located in central Peru, and is slated to start production late this year with an output of 250,000 tons of copper. The expansion would boost production by 45% and construction will be mostly completed in the spring of 2016.

Chinalco estimates Toromocho project resources at about 7.3 million tonnes of copper, 290,000 tonnes of molybdenum and 10,500 tonnes of silver.