Image: Escondida Copper Mine: Oxide leach expansion project

Minerals & Metals2 min read

Escondida Copper Mine: Oxide leach expansion project

Antofagasta, Chile
Minera Escondida
2004 - Present

The Escondida Mine is located in the Atacama Desert, Chile. In 2012 it accounted for five per cent of global copper production and around 15 per cent of Chilean copper production. The mining operation includes an oxide ore heap leach plant processing approximately 20 mt/y of ore.

The Escondida Mine is the largest copper mine in the world and is located in the Atacama Desert in Chile. Mining operations include both sulfide and oxide ore heap leach operations. Currently, mine operations in focusing on oxide ore operations and the current plant throughput is approximately 44 Mt/y of ore.

Ausenco has been working with Minera Escondida over the last 12 years providing them world class heap leach engineering services that started with the design sulfide leach pad in 2005.

Ausenco developed the Escondida Bio-leach Sulfide Project (EBP) heap leach pad that included innovative design of material handling and an air-injection system to promote bio-leaching. It is the largest single use sulfide leach pad in the world with over 9 Mm2 of pad.

Subsequently, Ausenco provided conceptual through detailed engineering services along with construction support, construction quality assurance (CQA) for the Oxide Leach Expansion (OLE) project, which has over 2 Mm2 pad. Ausenco developed pioneering practices to minimize cost and maximize operation efficiency during the design phase that include:

  • Stacking with a shiftable conveyor and spreader that allowed for the placement of primary liner system and solution collections below the retreating stacking system, which allows for a small crew to install the liner and collections system without disrupting operations.
  • The utilization of PVC liner and elimination of overliner for the primary liner system since the conveyor system is no longer on top of the liner system, requiring an overliner to project the liner from damage from the forces of the stacking equipment.
  • Utilization of interlift liner system consisting of only compacting the surface of the previous lift and installing solution collection piping, eliminating the needs for a geomembrane liner, further reducing operating costs.
  • Using a multi-platform for leach and stacking operations maximizing ground slope and minimizing earthworks.

Based on the OLE’s operations, Ausenco performed a selection study looking at the best technology and economics of continued operations of the OLE, a single use pad, verses operating an on/off pad, which lead to the development of the OLAP, a 1.2 Mm2 on/off leach pad. In addition to design the leach pad, Ausenco’s expert knowledge in stacking system helped optimize on/off operations by moving away from traditional stacking methodology along with integration of the spent ore disposal facility.

Ausenco continues to provide engineering support services for the Escondida project. The main challenges for this project were topography, area constraints and mineral processing.

Ausenco’s scope of services include:

  • Environmental impact study support
  • Heap leach modelling, optimization, and stacking management
  • Geotechnical studies
  • Pipeline crush testing under heap loading
  • Design of material handling system
  • Conceptual to detail design engineering
  • CQA for earthworks and geosynthetic installation