Construction of the Southern Expansion of the Cerro do Lobo Waste Facility

Abstract

Neves-Corvo is a copper-zinc mine producing copper, zinc and lead concentrates. The mine is owned and operated by Lundin Mining's Portuguese subsidiary SOMINCOR. Lundin Mining acquired Neves-Corvo through the merger with EuroZinc Mining in 2006. It is located in the Alentejo district of southern Portugal. The ore is processed on site and the tailings are deposited at the Cerro do Lobo Waste Facility. During the operational phase, the mining waste will be deposited vertically, in stages, from the current five levels to thirteen levels (with an average slope of 5 %). In order to accommodate this process, it has been necessary to expand this infrastructure, including the southern expansion of the tailings dam. The dam will contain waste up to level 8 (at an elevation of 272 m), with a maximum height of 17 m, and walls with slopes of 1(V):2.5(H) upstream, allowing the use of geosynthetics, and 1(V):2(H) downstream. Apart from of the left abutment, the dam’s foundation was constructed on the natural terrain. The dam’s lining system consists of a transition layer, composed of a sandy material, a geosynthetic clay liner and a high-density polyethylene (HDPE) geomembrane. This paper provides a detailed description of the methodology employed in the dam’s construction, with particular emphasis on the use of soil-rockfill mixtures as the primary building material. It also outlines the specific techniques employed to ensure the quality and durability of the construction.