Chile's copper industry set to use much more water, power

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Tuesday, January 9, 2018

The ageing of Chile's copper deposits and the recent reactivation of a number of projects thanks to higher prices have led state copper commission Cochilco to increase its 10-year forecasts for water and power use.

Copper miners will require 22.7m3/s of water and 29.2TWh of electricity annually for their operations by 2028, Cochilco announced Tuesday.

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The figures represent increases of 40% in water use and 38% for energy versus 2017, while mined copper production is expected to grow just 19% to 6.33Mt in 2028 versus 5.33Mt in 2017 – and the 2017 number would have been noticeably higher if not for a lengthy strike at the country's biggest mine, Escondida, early in the year.

The explanation lies in the growing proportion of production attributable to the water and energy-intensive concentration process versus leaching followed by SX-EW, which in turn is due to the depletion of the surface oxide ores amenable to the latter process.

Declining copper grades are another feature of the ageing of Chile's mineral resources and require more ore to be processed to recover the same amount of copper, further contributing to water and power needs. And, as miners must dig continually deeper to extract copper, they also encounter harder ore, which requires more energy to crush and grind.

Chile's mined copper recovered via concentration will grow by 55.6%, while SX-EW will shrink by 66.3%. SX-EW processing represented 30% of Chile's mined copper in 2017, and will account for less than 9% in 2028.

SEAWATER LEADS THE WAY

The industry's concentration in the dry north means water is a scarce resource, and miners are turning increasingly to seawater. Cochilco predicts the use of seawater to grow 289% over the coming decade to 11.2m3/s, while the use of "continental" water sources will inch down by 6.3% to 11.5m3/s.

Seawater use will also drive energy demand growth due to the power needed to pump the water up the mountains to the mines.

The use of seawater is an alternative but it is not "cost free," said Cochilco studies director Jorge Cantallopts during a presentation Tuesday in Santiago, noting the environmental considerations and metallurgical difficulties as well as the expense.

"When the country uses seawater, sure, it makes the projects viable, but it loses competitiveness," said Cantallopts.

The expert also noted Chile's integration of its northern and central power grids as key to ensuring sufficient power supply for miners in the north, in particular by supporting the country's booming development of non-conventional renewable sources.