Despite producer efforts to improve energy efficiency and reduce costs, energy use in copper mining is rising. As global mined copper output increases, ore grades decline, open pits get deeper, ore gets harder and use of seawater is more widely adopted, total energy demand and energy used per tonne of copper produced are increasing. BHP Billiton’s Escondida faces higher energy demand when its new desalination plant is commissioned and three concentrators are operating from late 2017.
Energy Inputs into Copper
Production
Energy is a major cost
component in producing copper. It represented 20% of mine site operating costs
for the 1.92Mt of copper produced by Freeport-McMoRan in the United States,
Peru, Indonesia and Chile in 2016. Grupo Mexico’s Southern Copper subsidiary,
which produced 0.90Mt of copper in 2016 from mines in Mexico and Peru, describes
energy as the principal cost in mining. Fuel, gas and power made up 30% of
Southern Copper’s total production costs in 2016.
Producers are striving to
improve energy efficiency and reduce costs. Freeport’s Cerro Verde concentrator
expansion in Peru, completed in 2015, includes a High Pressure Grinding Roll
circuit that is some 40% more efficient than a traditional Semi-Autogenous
Grinding mill circuit. However, as individual mines mature and as seawater is
increasingly used for ore processing, fuel and electricity demand increase.
Lower grade ores require more ore to be mined, transported to the processing
plant, crushed and milled per tonne of copper produced. As open-pit mines
become deeper, trucking distances increase. Where ore hardness is increasing,
as is the case at Antofagasta’s 360ktpa Los Pelambres and Anglo American’s
400ktpa Los Bronces mines in Chile, more energy is required to crush and grind
the ore. Desalination of seawater is energy intensive, and whether seawater is
desalinated or used directly, moving the water from the coast to the mine
requires electricity to power the pumps.