Located in the Alentejo district of southern Portugal, the operation is situated approximately 15 km southeast of the town of Castro Verde and approximately 220 km southeast of Lisbon. Neves-Corvo has good connections to the national road network and a dedicated rail link into the Portuguese rail network and to the port of Setúbal. There are no major centres of population close to the mine, although there are many small villages with populations numbered in the hundreds. Most employees travel to the mine by provided buses or private cars.
Neves-Corvo mines underground from five major orebodies. The principal means of mine access are by a shaft and a ramp from surface. The shaft is used to hoist ore from the 700 m level while a conveyor descends from the 700 m level to transport ore from the deeper levels of the mine. The mine is highly mechanized and several different stoping methods are employed with the most significant being bench-and-fill and drift-and-fill.
The processing facility at Neves-Corvo comprises two plants. The copper plant processes copper ores and has a capacity of approximately 2.6 million tonnes per annum (mtpa). The zinc plant, which can process zinc or copper ores, has a capacity of approximately 1.1 mtpa and is currently undergoing a significant expansion to 2.5 mtpa capacity.
Copper and zinc concentrates are transported by rail to a dedicated port facility at Setúbal from where they are shipped to variety of smelter customers that are primarily European based. Lead concentrate is containerized and trucked to ports for overseas shipment.
A Zinc Expansion Project (ZEP) was approved in 2017 and is in construction. The ZEP is to increase zinc mining and processing capacity to approximately 2.5 mtpa generating an average of 150,000 tonnes per annum (tpa) of zinc in concentrate over 10 years at an estimated capital cost of €257 million. Full expanded zinc production is anticipated by the end of 2019.
New mine infrastructure for the ZEP includes a new crusher station, a conveyor system connecting this to the 700 shaft hoisting facilities, an upgrade to the main hoisting shaft together with extensions to the mines ventilation, pumping and electrical distribution systems. Much of the zinc ore for the ZEP will be mined in deep areas of the Lombador orebody using primarily bench and fill mining methods, with limited amounts of drift and fill.
Modifications to the existing zinc plant for the ZEP project include new surface stockpile and feeder facilities, an expanded grinding circuit, expanded flotation capacity, expanded zinc and lead thickeners and filters and associated expansions and upgrades to ancillary services.
Geologic and Exploration Overview
Neves-Corvo is located in the western part of the Iberian Pyrite Belt (IPB), which stretches through southern Spain into Portugal. The mineral deposits at Neves-Corvo are classified as volcano-sedimentary massive sulphide. They typically occur as lenses of polymetallic (copper, zinc, tin, lead) massive sulphides that formed at or near the seafloor in submarine volcanic environments. Seven massive sulphide lenses have been defined comprising Neves, Corvo, Graça, Zambujal, Lombador, Semblana and Monte Branco. The base metal grades are segregated by the strong metal zoning into copper, tin and zinc zones, as well as barren massive pyrite. The massive sulphide deposits are typically underlain by stockwork sulphide zones, which form an important part of the copper orebodies.
Exploration surrounding the mine has focused on the search for additional blind massive sulphide deposits. Exploration techniques include soil geochemistry, geological mapping, various geophysical techniques including airborne magnetics, residual ground gravity survey, airborne gravity survey, ground electromagnetic survey and 3D seismic survey and exploration drilling. Recent exploration work has concentrated on the development of a 3D regional geological model and exploration drilling focusing on the area between Corvo, Zambujal, and Semblana deposits.