Overview
Status | Care and Maintenance |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Sulfuric acid (reagent)
- Heap leach
- ROM/dump leach
- Solvent Extraction & Electrowinning
|
Mine Life | 8 years (as of Jan 1, 2015) |
October 16th, 2018 - Berta operation was placed on care and maintenance. |
Latest News | Coro Announces the Sale of the Berta Mine February 19, 2019 |
Company | Interest | Ownership |
Santiago Metals Ltda.
|
100 %
|
Indirect
|
Santiago Metals Proyecto Quadros Ltda.
|
100 %
|
Direct
|
Deposit Type
- Porphyry
- Breccia pipe / Stockwork
Summary:
Berta corresponds to a porphyry copper system. In detail, Berta Sur exhibits evidence of alteration and mineralization which is comparable with that observed in the deepest parts of such systems. In particular the textural variations from TON to a crystal rich PTC, the background potassic alteration, the development of muscovite and greisen", and the Ca-Na alteration, are typical characteristics of the roots of porphyry systems (Dilles, et. al., 2000; Seedorf et. al., 2008). These characteristics also explain the lack of development of significant mineralization at depth. Rather the mineralization decreases in grade with depth or has a root-like shape becoming narrower in depth.
The interpretation at a local level shows variations from north to south, with the development of propyllitic alteration and NW oriented D type vein system with sericitic halo in the north passing to zones of breccia and the development of porphyry with potassic alteration in the south. This suggests a relatively deeper level of erosion toward the south and east, produced by NW oriented block faulting, which have segmented the porphyry system.
The copper oxide mineralization at Berta extends to depths of 30 to 100 m with mineralization outcropping at surface and with effectively no overburden. It has a simple mineral material and gangue mineralogy, excellent response to leaching and fairly continuous Cu grades and sharp contacts with low-grade margin mineralization. These favorable conditions are due to oxidation of the hypogene mineralization with simple alteration and mineralogy: dominant chalcopyrite hosted in breccias, porphyry and tonalite affected by potassic alteration. The lack of pyrite and unreactive hostrock has allowed the generation of in-situ oxidation, with only minor Cu re-mobilization and migration, without the formation of significant supergene sulfides.
The primary mineralization consists of Cu sulfide, dominated by chalcopyrite that occurs as breccia cement and disseminations in the breccias and their contact zones with PTC and TON. Occasionally bornite has been observed in the hypogene zones of Berta Sur breccias. There is gradation in the chalcopyrite percentage from higher grade centers (> 0.5% Cu) controlled by zones of greater permeability and potassic alteration in the breccia bodies, toward areas of lower Cu grades on the margins. This variation is truncated in the N by faults cutting the body, while in the S and SW part, there is an abrupt decrease to grades approximating 0.2% Cu, due to reduced dissemination of chalcopyrite. The mineralization is controlled by the distribution of the breccias and by the NE oriented pre-mineral structures. There is a close relationship between potassic alteration, with K-feldspar and grey green sericite, and the presence of chalcopyrite. The form of the sulfide mineralization is irregular however, such that good grade Cu oxides overly equivalent grade sulfides in some areas, in others this relationship does not exist and in contrast, an abrupt decrease of good grade oxides to underlying low grade sulfides is suggestive of an inverted cone-shape or root to the mineralization. These relationships, coupled with variable shape of the breccia bodies and variations in alteration with depth permits an interpretation of the deeper parts of the system.
Summary:
Mining at Berta would be carried out by open pit methods using contract miners.
The Crushing Plant at Nora is a three stage circuit, with the final tertiary stage in close circuit with a cutoff at ¾”, which yields approximately 80% passing a ½” sieve, which is the size sent to Agglomeration and then to stacking and leaching process. Trinidad the previous operator ran one 12- hr shift and based on this the crusher had a capacity of 360,000 tpy or 30,000 tonnes per month. To achieve the requiring crushing capacity of 40,000 tonnes per month, the Company would need to run the crusher at more than a 12-hour shift per day. The past production profile is also supportive of the ability to crush the amount of mineral material required.
At the Nora plant, the mineral from the crushing plant goes directly to the agglomerator drum, which was designed to treat 135 tons of mineral per hour. The drum is 1.8 meters in diameter and 5.8 meters long, and was designed for a residence time of 39 seconds, by allowing the slope to be adjusted between 5º and 11º. In this stage the mineral is treated with sulphuric acid and thensent to the leaching pads in dump trucks.Based on the requirement to treat ~40,000 tonnes per month of material at a rate of 135 tonnes per hour then the Agglomeration drum would have to run for ~300 hours in a given month or ~12.5 hours per day.
Processing
- Sulfuric acid (reagent)
- Heap leach
- ROM/dump leach
- Solvent Extraction & Electrowinning
Flow Sheet:
Summary:
The Berta Project involves the exploitation of an open pit mine and the design of facilities for the production of 5,000 copper tonnes per year of high concentration Pregnant Leaching Solution (PLS), which will be transported to Nora Plant where this solution will be processed in the SXEW Plant, thus producing high purity copper cathodes, 99.99%. Berta mine site facilities will be located 15km west of the village Inca de Oro at an elevation of 1,700m.a.s.l. and the existing Nora Plant is located 42 km north from Berta.
The mine plan assumes a first phase using a variable cut-off grade in year 1 of between 0.60% and 0.70%CuT, in order to maintain a constant feed to theexisting Nora crusher for a period of 11 months, thus postponing part of the capital investment until year 2 of operations. A total of 0.4mt at 0.83%Cu will be mined and trucked to the Nora plant while 1.2mt of lower grade heap leach material and 0.6mt of ROM will be stockpiled for processing in year 2. In addit ........

Production:
Commodity | Units | Avg. Annual (Projected) | LOM (Projected) |
Copper
|
t
| 4,700 | 37,821 |
All production numbers are expressed as cathode.
Reserves at September 24, 2015:
Category | Tonnage | Commodity | Grade | Contained Metal |
Measured
|
14,125 kt
|
Copper
|
0.38 %
|
|
Indicated
|
3,479 kt
|
Copper
|
0.29 %
|
|
Measured & Indicated
|
17,604 kt
|
Copper
|
0.37 %
|
143.6 M lbs
|
Mine Management:
Job Title | Name | Profile | Ref. Date |
.......................
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Oct 13, 2020
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