Overview
| Stage | Production |
| Mine Type | Underground |
| Commodities |
|
| Mining Method |
- Overhand Cut & Fill
- Sub-level stoping
- Avoca
- Hydraulic backfill
|
| Production Start | ...  |
| Mine Life | 6 years (as of Jan 1, 2022) |
Pasco Complex includes Atacocha and El Porvenir mines.The strategy is to optimize the integration of EL Porvenir and Atacocha mines, upgrade El Porvenir mine hoisting system improving its capacity to accommodate ore from underground Atacocha; and Improve tailings capacity and Increase El Porvenir plant capacity. Expects to submit for board approval: 4Q23. |
Source:
p. 9,31,45,47
| 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 uses two mining methods: mechanized overhand C&F and SLS. C&F is the predominant method, accounting for over 80% of the mine’s production. El Porvenir uses a version of SLS called Avoca, also referred to as longitudinal longhole retreat mining. 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. The sublevels are typically spaced at a vertical interval of 20 m and accessed via a spiral ramp. 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 drives can be as close as 15 m from a 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. The geotechnical conditions at El Porvenir result from the rock mass’s characteristics and the mine’s depth. The host rock and the mineralized zones are generally classified as fair to good, with rock mass ratings (“RMR”) ranging from 40 to 60. El Porvenir is one of South America’s deepest mines, extending more than 1,800 m below the main access level. Its depth contributes to the occurrence of seismic events, including rock bursts.
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 METHO ........
Source:
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Flow Sheet:
Summary:
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Reserves at December 31, 2022:
The Mineral Reserves were estimated at a NSR cut-off values ranging from US$57.99/t to US$60.71/t for SLS areas and US$59.65/t to US$62.37 for C&F areas depending on the zone Mineral Reserves are estimated using average long-term metal prices of Zn: US$2,826.35/t (US$1.28/lb); Pb: US$2,043.95/t (US$0.93/lb); Cu: US$7,398.47/t (US$3.36/lb); and Ag: US$19.93/oz.
Mineral Resources are estimated at NSR cut-off grade values ranging from US$57.99/t to US$60.71/t for SLS areas and US$ 59.65/t to US$62.37 for C&F areas depending on the zone. Mineral Resources are estimated using average long term metal prices of Zn: US$3,250.31/t (US$1.47/lb), Pb: US$2,350.54/t (US$1.07/lb); Cu: US$8,508.24/t (US$3.86/lb); and Ag: US$22.92/oz.
| Category | Tonnage | Commodity | Grade | Contained Metal |
|
Proven & Probable
|
15.5 Mt
|
Zinc
|
3.6 %
|
558.6 kt
|
|
Proven & Probable
|
15.5 Mt
|
Copper
|
0.19 %
|
30.4 kt
|
|
Proven & Probable
|
15.5 Mt
|
Silver
|
66 g/t
|
32,894 koz
|
|
Proven & Probable
|
15.5 Mt
|
Lead
|
1.07 %
|
165.6 kt
|
|
Measured & Indicated
|
3.39 Mt
|
Zinc
|
3.07 %
|
104 kt
|
|
Measured & Indicated
|
3.39 Mt
|
Copper
|
0.2 %
|
6.8 kt
|
|
Measured & Indicated
|
3.39 Mt
|
Silver
|
58.5 g/t
|
6,374 koz
|
|
Measured & Indicated
|
3.39 Mt
|
Lead
|
0.94 %
|
31.9 kt
|
|
Inferred
|
10.68 Mt
|
Zinc
|
3.83 %
|
409 kt
|
|
Inferred
|
10.68 Mt
|
Copper
|
0.19 %
|
20.3 kt
|
|
Inferred
|
10.68 Mt
|
Silver
|
72.9 g/t
|
25,032 koz
|
|
Inferred
|
10.68 Mt
|
Lead
|
1.05 %
|
112.1 kt
|
Source:
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Corporate Filings & Presentations:
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