Toromocho Copper Tailings System

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Basic engineering for thickened tailings system

Minera Peru Copper S.A. (MPCopper) is developing the Toromocho Copper Project, a large copper-molybdenum ore body located 140 km east of Lima, Peru, at an elevation of 4,480 – 5,000 metres above sea level (masl). Toromocho contains an estimated 7.3 million tons of copper and 4.7 million tons of molybdenum, silver and other metals.

Initially, Ausenco was retained by contractor Montgomery Watson Harza to provide a feasibility study for the tailings system, including the tailings delivery, tailings classification, tailings distribution and water recovery components. Subsequently, we were subcontracted by Aker Kvaerner to perform basic engineering for the 42-inch diameter, 5.0 km bare steel tailings transport pipeline.

In the basic design, the pipeline route began at the concentrator at an elevation of 4,550 masl, and ended at the thickening facility at an elevation of 4,900 masl.

The system was designed to accommodate a planned nominal throughput increase from 40.6 Mt/y to 51.4 Mt/y after the first two years.

The pumping system included two booster pump stations designed to deliver tailings slurry at 55% solids from the thickeners at the concentrator to the paste thickening facility. Booster Station 1 housed two pump trains (one operating and one standby) with four horizontal centrifugal pumps in series in each train. Booster Station 2, located halfway down the pipeline, was the same in configuration with the exception that it utilises three pumps in series rather than four.

At the thickening facility, the tailings were to be thickened to approximately 69% solids and distributed through spigots into the impoundment. Thickener overflow was to be returned by gravity to a mill water pond located above the concentrator.

Our scope included:

  • Hydraulic design, including pipeline diameter selection, hydraulic gradient calculations, pumping, power and energy dissipation (choke) requirements
  • Transient analysis to consider pump trips, power failures, etc. and size safety systems
  • Trade-off study of positive displacement versus centrifugal pumps
  • Pump selection
  • Trade-off study of single versus dual pipeline systems
  • Layout drawings of sumps, pump stations and receiving facilities
  • Electrical single lines, communication block diagrams and SCADA architecture as required to provide cost estimates
  • PFDs and P&IDs
  • Operating and control philosophy
  • Materials selection
  • Major equipment and material lists
  • CAPEX/OPEX to +/-10%.

Commissioning of the tailings pipeline was carried out and the mine started operations in 2013. It began commercial production 18 months after its start-up.

Project details

Offerings
Slurry pipeline, Tailings
Commodities
Copper, Silver
Location
Lima, Peru
Business line
Process Infrastructure
Client
Montgomery Watson Harza (MWH)/ Aker Kvaerner/ Minera Peru Copper S.A.
Timeframe
2008
Solution phase
Create (Basic Engineering)
Services
Engineering, Studies and technical solutions