Overview
| Stage | Production |
| Mine Type | Underground |
| Commodities |
|
| Mining Method |
- Overhand Cut & Fill
- Sub-level stoping
- Avoca
- Hydraulic backfill
|
| Production Start | ...  |
| Mine Life | 2028 |
El Porvenir is an underground, polymetallic mine located in Peru’s Central Andes mountain region. With a shaft depth of 1,732 m, the El Porvenir shaft is the deepest in South America. |
Source:
p. 9, 30, 45, 47
| Company | Interest | Ownership |
|
Nexa Resources S.A.
|
83.48 %
|
Indirect
|
|
Nexa Resources El Porvenir S.A.C.
(operator)
|
100 %
|
Direct
|
The El Porvenir mine is wholly-owned and operated by Nexa Resources El Porvenir S.A.C., a subsidiary of Nexa Resources Peru S.A.A. (Nexa Peru) in which Nexa Peru has directly and indirectly a 100% (99.99%) equity interest.
Nexa Resources S.A. owns a total of 83.48% in the Mine that corresponds to the sum of Nexa’s direct interest in Nexa Perú (0.17%) and Nexa’s indirect interest in Nexa Perú (83.38%) through its controlled company Nexa Resources Cajamarquilla S.A. (99.91%).
Contractors
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Deposit Type
- Vein / narrow vein
- Skarn
- Stratabound
- Epithermal
Summary:
El Porvenir is situated in the Pasco region of the Western Cordillera of the Andes, within the Eocene-Miocene Polymetallic and Miocene Au-Ag Epithermal Belts.
Three types of mineral deposits are recognized at El Porvenir:
• Skarn (exoskarn and endoskarn),
• Intermediate sulphidation epithermal veins and breccias, and
• Stratabound.
Within the property area, the stratigraphic units of primary interest are the Pucará and the Goyllarisquizga groups. The Goyllarisquizga Group outcrops in the area of the deposit comprising quartz rich sandstone, corresponding to the Goyllarisquizga Formation. Sandstones may vary from quartz arenite to arkose. The matrix is argillaceous to siliceous. Above the 4000 Level, the lithology and stratification are well defined and easy to recognize. Below the 4000 Level, strong alteration has obliterated the original rock intensity forming siliceous breccias and massive silica where it is still possible to recognize quartz grains and in few places the stratification.
Intrusive rocks within the property are variably porphyritic dacite to quartz diorite with hornblende and biotite phenocrysts. The Milpo-Atacocha fault is a major structural feature in the region, which can be traced for nearly 15 km from Yarusyacán in the north to Carmen Chico in the south.
Mineralization is characterized as a skarn, intermediate sulphidation epithermal vein/brecciastyle, or stratabound mineralization in the Goyll ........
Mining Methods
- Overhand Cut & Fill
- Sub-level stoping
- Avoca
- Hydraulic backfill
Summary:
El Porvenir is one of the deepest underground mines in South America, extending more than 1,800 m below the main access level. El Porvenir produces approximately 2.1 Mtpa of zinclead-copper ore using two mining methods, with the predominant method being mechanized overhand cut & fill (C&F). C&F has been used at El Porvenir for many decades and accounts for over 80% of its production. The remainder of the output comes from sub-level stoping (SLS), which was introduced at the operation in 2018. El Porvenir uses a version of this method called Avoca, also referred to as longitudinal longhole retreat mining.
Mine production is presently underway in the Upper Zone, the Intermediate Zone, the Lower North Zone, and the Lower West (El Porvenir 9) Zone.
MINE DESIGN AND MINING METHODS
C&F and SLS have similar development requirements as they both involve dividing a mining zone into horizons between sublevels and excavating the ore in an ascending fashion. Sublevels are typically spaced at 20 m vertical intervals and accessed via spiral ramps. The development on each sublevel includes an access drift, a footwall drive, and crosscuts or attack ramps, which provide access to the orebody. For SLS, the footwall drive can be as close as 15 m from the footwall contact, whereas for C&F, they have to be offset from it by 60 m to provide sufficient distance for fanning the attack ramps.
C&F’s mining cycle: drilling, blasting, mucking, and ground support. Bac ........
Source:
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Flow Sheet:
Summary:
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Reserves at December 31, 2021:
Mineral Reserves are estimated at NSR cut-off values ranging from US$57.63/t to US$62.19/t depending on the zone and mining method. Mineral Reserves are estimated using average long-term prices of Zn: US$2,722.20/t (US$ 1.23/lb); Pb: US$1,997.21/t (US$0.91/lb); Cu: US$7,288.26/t (US$3.31/lb); and Ag: US$19.68/oz.
Mineral Resources are estimated at NSR cut-off values ranging from of US$57.45/t to US$60.39/t for SLS areas and US$ 59.24/t to US$62.18 for C&F areas depending on the zone. Mineral Resources are estimated using average long-term metal prices of Zn: US$3,130.52/t (US$1.42/lb), Pb: US$2,296.79/t (US$1.04/lb); Cu: US$8,381.50/t (US$3.80/lb) and Ag: US$22.63/oz.
| Category | Tonnage | Commodity | Grade | Contained Metal |
|
Proven & Probable
|
15.32 Mt
|
Zinc
|
3.57 %
|
547.5 kt
|
|
Proven & Probable
|
15.32 Mt
|
Lead
|
1.04 %
|
159.8 kt
|
|
Proven & Probable
|
15.32 Mt
|
Copper
|
0.2 %
|
31.3 kt
|
|
Proven & Probable
|
15.32 Mt
|
Silver
|
69.5 g/t
|
34,242 koz
|
|
Measured & Indicated
|
3.68 Mt
|
Zinc
|
2.91 %
|
107 kt
|
|
Measured & Indicated
|
3.68 Mt
|
Lead
|
0.78 %
|
28.5 kt
|
|
Measured & Indicated
|
3.68 Mt
|
Copper
|
0.2 %
|
7.4 kt
|
|
Measured & Indicated
|
3.68 Mt
|
Silver
|
50.4 g/t
|
5,964 koz
|
|
Inferred
|
10.42 Mt
|
Zinc
|
3.85 %
|
401.2 kt
|
|
Inferred
|
10.42 Mt
|
Lead
|
0.95 %
|
99 kt
|
|
Inferred
|
10.42 Mt
|
Copper
|
0.21 %
|
21.9 kt
|
|
Inferred
|
10.42 Mt
|
Silver
|
69.2 g/t
|
23,183 koz
|
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