The mineral deposits at Neves-Corvo are classified as volcano-sedimentary massive sulphide (VMS). They typically occur as lenses of polymetallic (Cu, Zn, Sn, Pb) massive sulphides that formed at or near the seafloor in submarine volcanic environments. They formed from accumulations of the focussed discharges of hot metal-enriched fluids associated with seafloor hydrothermal convection, typically in tectonic areas of active submarine volcanism, including rift spreading centres and island arc subduction zones. The massive sulphide lenses are commonly underlain by sulphide-silicate stockwork vein systems, although the stockwork systems may extend into the hanging-wall strata above the massive sulphide lenses. The immediate host rocks can be either volcanic or sedimentary. The deposits are overlain by a repetition of volcano-sedimentary and flysch units.

VMS deposits readily accommodate strain during regional deformation because of the ductile nature of massive sulphide bodies, and can therefore display much higher degrees of recrystallisation and remobilisation than the surrounding volcanic and sedimentary strata. The tectonic remobilisation may result in duplication of the stratigraphy further localising the sulphide mineralisation.

Six massive sulphide mineralised zones have been defined within the Neves-Corvo Mining Area and comprise Neves, Corvo, Graça, Zambujal, Lombador and Monte Branco. The Semblana massive sulphide zone is located within the Semblan ........

The ZEP (Zinc Expansion Project) assumes maintaining the mining methods unaltered in the existing areas. In the expansion area LP2 (Lombador Phase 2) the mining method used for mining zinc ores is optimised bench and fill (OBF) as per LP1.

The development of the Lombador decline ramp provided access for further geological drilling of deeper areas of the resource, which identified further extensions to the Lombador orebody. Subsequent analysis indicated that additional zinc Mineral Reserves would be required to justify further expanding the zinc processing plant. It was also recognised that to achieve effective and economic production from the new deeper area, it would require a new underground materials handling system to more efficiently transport ore from a depth of approximately 1,200m below surface, this system upgrade forms an integral part of what has been termed; Lombador Phase 2 (“LP2”).

Two mining methods make up the majority of production at Neves-Corvo, these being Drift and-Fill and Bench-and-Fill stoping. Both of these methods have been well adapted and tailored to the large but locally complex high grade ores present throughout the operations.

Drift-and-fill was the original mining method selected for Neves-Corvo. Although the method has relatively low productivity rates and high unit costs, it was chosen because it is highly flexible and can achieve high recovery rates in high grade orebodies with complex and flat dipping geomet ........

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The ZEP (Zinc Expansion Project) Feasibility Study has examined further expanding zinc plant throughput capacity to 2.5 mtpa coupled with the development of LP2. The forecast increase in zinc ore production will be sourced by maximizing production from the existing zinc mining areas and by mining from LP2.

In October 2015, SOMINCOR, in conjunction with AMEC, completed the ZEP FS aimed at increasing zinc ore production from the current 1.1Mtpa to 2.5Mtpa. The processing component of the study included an assessment of:
- New surface zinc ore stockpiles (principal stockpile covered) and a materials handling system feeding the mill;
- An expanded zinc processing plant, including a new building for grinding (new SAG Mill and VertiMill) and flotation; upgrades to flotation in the existing plant; expanded zinc and lead thickeners and filters; new blowers; expanded compressed air systems; new tailings cyclones and pumping; upgraded and expanded process control systems; an ........