Development of the Collahuasi copper deposits—a world-class copper project in the Andes of northern Chile

Abstract

Recent exploration successes at Collahuasi have placed the district as the world’s largest, as yet undeveloped, copper resource. Now, in the final feasibility stage, two separate porphyry copper deposits, each with important secondary enrichment zones, contain a combined total tonnage of over 1.5 billion metric tons, with an average grade exceeding 1.0% copper. The first deposit to be mined, Ujina, contains over 168 million metric tons of strong secondary sulphide enrichment, grading 1.6% copper. The second deposit to be mined, Rosario, contains a minimum of one billion metric tons grading over 1.0% Cu. In addition to the porphyry copper deposits, high grade, copper-silver, copper-gold, and silver vein systems as well as exotic copper oxide deposits increase the resource potential of the district.

The location and geological characteristics of the deposits present a host of challenges for project development. Situated in the arid Andean altiplano, at a mean elevation of 4,500 m.a.s.l., Collahuasi is the highest major mining project in the world.

Designing for altitude must consider significant efficiency derating of both equipment and personnel. The relative remoteness of the project, combined with the altitude, has required creative solutions to the problems of material and product transport and to the work cycles, including adaptation time, for personnel. Water exploration, in one of the world’s most arid deserts, has had to secure a long-term, sustainable yield to the project.

Infrastructure design and siting must consider the highly variable climatic conditions, as well as geologic hazards, including seismic activity and proximity to active volcanoes. Sequencing, sizing and process selection trade-off studies have had to consider that not just one, but several deposits are available to the project in close proximity to each other, and that both leaching and flotation could be applied to the processing of the higher grade secondary sulphide ores.