The Antamina Mine is located in north-central Peru, approximately 100 km east of Huaraz, at an elevation of 4,100 m. The main facilities consist of an open pit copper-zinc mine with rock waste dumps, a processing concentrator, and a tailings impoundment. 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 long-term stockpiles will be depleted in 2022.
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. Klohn Crippen Berger (KCB) developed a progressive reclamation program as well as environmental management plans following closure. KCB designed and constructed an engineered wetland at 4000 m elevation and sediment and water treatment ponds for runoff from the mine waste rock dumps. Cost estimates and closure schedule were developed for progressive reclamation, closure works, engineering, inspections and permits, as well as long term operations and maintenance.
KCB was responsible for the environmental management plans that were submitted along with the environmental impact assessment to the Peruvian Ministry of Energy and Mines. The Antamina expansion project was successfully permitted based on KCB’s work. We also developed the mine-wide water balance and constructed a complex water quality model to predict water quality at mine closure in about 20 years. The model is updated regularly and used by Antamina to run scenario options for planning purposes.