Collahuasi - Multi-discipline process infrastructure solutions

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Multi-discipline process infrastructure solutions

The Collahuasi open-pit copper mine, one of the world’s largest copper mines, is located in northern Chile’s Tarapacá Region at an elevation of 4,300 metres above sea level.

Ausenco has successfully delivered engineering and project execution services for several components of the project’s infrastructure, including the export terminal, copper concentrate pipeline, system controls, tailings management and water treatment systems.

Copper concentrate

Our involvement dates back to 1994 when we first provided services for the development of the copper concentrate transportation system, which transfers slurry from the mine site to a ship loading facility located 203 km away, south of the city of Iquique in Chile.

The pipeline system includes:

  • 203 km, 7-inch diameter, high-density polyethylene (HDPE) lined pipeline, designed for a throughput of one million tonnes per year (Mt/y)
  • Head pump station located at the concentrator plant, intermediate valve station and choke stations
  • Pipeline terminal facilities, including a choke station located at Punta Patache
  • Cathodic protection consisting of exterior coating and impressed current system

In the concentrate pipeline’s initial development stages, our scope included a comprehensive feasibility study (subcontracted through Davy International), detailed conceptual design, basic engineering, route planning, laboratory testing and a high-accuracy cost estimate.

Our controls team also created the pipeline’s SCADA system, which includes highly automated controls for pipeline start-up and shutdown.

Their scope included SCADA design and development; valve control panel design, layout and fabrication; and PLC/HMI programming. In addition, we provided our proprietary Pipeline Advisor™ software for leak detection and process optimisation, and a VHF radio system.

The SCADA system uses Siemens PLCs and PCs running Wonderware Intouch™ software at the pump station and terminal. Communications are conducted between the PLCs and PCs via a redundant, high-speed fibre optic Ethernet network.

Concentrate expansion

In 2002, we continued our work on the concentrate pipeline with a conceptual study, trade-off studies and detailed engineering for the Ujina Rosario Transition project.

In the Ujina Rosario Transition project, the concentrator was expanded to increase concentrate production by 40%, necessitating adjustments to the pipeline to accommodate a higher throughput of 1.65 Mt/y.

The expansion involved replacing 105 km of the concentrate pipeline with 8-inch diameter pipe; installing a third mainline pump in parallel with the two existing units; replacement and upgrade of intermediate valve and choke stations; and upgrades to communication and control systems.

Our scope for this project also included route planning; creating equipment/material bid packages and soliciting vendor bids; developing a construction sequence for tie-ins to minimise impact on operations during construction; CAPEX; and technical evaluations.

Export terminal

In addition to the pipeline transport systems, we also were involved in the development and construction of the copper export terminal between 1996 and 2000. Our scope included port site selection, feasibility studies, and subsequently an EPC contract for Collahuasi’s marine structures and shiploader.

The irregular underwater bedrock profile and the presence of large boulders made pile installation very challenging. Overcoming the lack of any substantial overburden, the required pile design capacities were innovatively achieved by anchoring pile tips into the bedrock.

The seismic design of the shiploader illustrates state-of-the-art design approach permitting the shiploader to withstand a seismic event well in excess of the code requirements without any significant damage.

This project is the first to fully enclose the boom of a quadrant shiploader to contain dust, setting new standards for environmentally friendly design.

The substation, mounted on the shiploader pivot platform, provides all electrical services for the ship-loader system (including feed conveyors and auxiliaries) and is rated 750 kVA at 3.3 kV. The design was particularly challenging due to protection from wave action, moving shiploader equipment and unusual grounding requirements.

The substation was supplied as modular construction and incorporated high voltage switching, transformer, Motor Control Centre (MCC), PLC and fibre optic communications.

Water treatment

In 2002, we also provided services for the system’s Punta Patache water treatment site. Our goal in this phase was to create a water balance model to predict the behaviour of the system for the next 25 years, provide water management alternatives, and perform a cost analysis of the developed options.

The water treatment site includes a passive evaporation pond with a highly variable surface area, a forced evaporation pond using aspirators, and a forest that is used for evapo-transpirative processing of water.

Our designs factored in significant throughput increases in future concentrate pipeline operations and the system’s significant fluctuations in seasonal water treatment capacity.

Tailings and water reclaim

In the following year, we provided solutions for the tailings and reclaim water systems (designed by others), which were experiencing issues due to higher viscous and yield stress. Our scope included systems optimisation and engineering modifications to achieve optimal water system balance.

We performed a study of system alternatives and optimisation, conceptual and basic engineering, detailed design of the system modifications, procurement support and commissioning. Our design scope also included the following:

  • 43-inch diameter, 2.3 km HDPE pipe launder with 0.8% slope to deliver 127,000 tpd (44 Mt/y) from the concentrator to the distribution box
  • Tailings launder pipeline alternatives: HDPE pipe launder or rectangular concrete launder with slope of 1.16%
  • 22 tailings drop structures and total 7.6 km distribution pipe launders with variation in pipe diameter and material between the drop boxes
  • Decant pumping system comprised of 6 reclaim water pumps with total capacity of 2,592 m3/h to the head tank
  • Reclaim water gravity system comprised of a 30-inch diameter, 12 km combination carbon steel and HDPE pipeline from the head tank to the booster station
  • Pozos Infiltracion Pumping System; Captacion Dren and Michincha Pumping System for tailing dam seepage water; Estacion Booster System for reclaim water; and Estacopm PD-06 Booster System for thickener overflow and pumping process water to the concentrator.

Project details

Offerings
Energy transport, Pipeline operations software, Water pipelines
Commodity
Copper
Location
Chile
Client
Compañia Minera Doña Ines de Collahuasi
Timeframe
1994 - 2003
Solution phase
Evaluate, Innovate, Create
Service
Engineering