Designing water management facilities for the mine life cycle, in the high Andes of Peru
The Antamina Mine is a large copper-zinc-molybdenum mine located 270 km north of Lima in the high Andes of Peru, at approximately 4,200 meters above sea level. It is one of the largest mines in the world in terms of production volumes.
The mine consists of an open pit with rock waste dumps, a processing concentrator, a tailings impoundment, and a low-grade stockpile. Associated facilities include a 302 km-long concentrate pipeline and a concentrate dewatering and ship loading facility located at Puerto Punta Lobitos near Huarmey. The mine will cease primary production in 2019 and the stockpiles will be depleted in 2022.
The site has a surface water management system composed of lined ponds, ditches, pump back stations, and sodium hydroxide dosing to control the quality of surface water released to the environment. The water pump back system consists of three pump stations, each containing 3 to 4 pumps and operating in series – Pump Station No. 1, a Booster Station and Pump Station No. 2 – and two new surface water containment ponds. The system is designed for 24/7 operation. KCB was retained to carry out preliminary design, which led to the detailed design of the pump back system.
Closure plan preparation included assessing works, physical and geochemical stability for the open pit, waste dumps, tailings, low-grade and marginal grade stockpile areas. Closure plans were also prepared for the concentrator, mine site and port facilities, pipelines, valve stations and power lines. KCB developed a progressive reclamation program and post-closure environmental management plans. We designed and constructed an engineered wetland at 4,000 m elevation, and sediment and water treatment ponds for runoff from the mine waste rock dumps. Cost estimates and closure schedules were developed for progressive reclamation, closure works, engineering, inspections and permits, and long term operations and maintenance.
KCB was responsible for the environmental management plans and environmental impact assessment submitted to the Peruvian Ministry of Energy and Mines. The Antamina expansion project was successfully permitted based on our work. We also developed the site-wide water balance model and built a complex water quality model to predict water quality post-closure. The model is updated regularly and used by Antamina to run scenario options for planning purposes.