Overview
Stage | Feasibility |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
|
Mine Life | 9 years (as of Jan 1, 2017) |
As at December 31, 2018, Ero and its subsidiaries employed a total of 1,935 employees (consisting of 11 employees of Ero, 1,656 employees of MCSA, 261 employees of NX Gold, 4 employees of Mineração Boa Esperança S/A and 3 employees of Ero Copper (US) Ltd.) and 1,418 contractors (consisting of 7 contractor of the Company, 1,197 contractors of MCSA and 214 contractors of NX Gold). |
Source:
p. 3
MCSA acquired the Boa Esperança copper deposit concession from Corporación Nacional del Cobre (Codelco) in 2007 and became the legal owner of the mineral rights to the Boa Esperança copper deposit. In December 2016, Ero acquired approximately 85.0% interest in MCSA. In June 2017, Ero acquired an additional 14.5% by subscribing for shares from treasury for a total interest in MCSA of approximately 99.5%.
Summary:
The presence of magnetite (iron) in the breccias hosting the copper mineralization suggests a deposit type classified as IOCG (Iron Oxide Copper Gold). However, there are many features that do not match the proposed IOCG deposit type. Among these is the presence of high-sulfur mineral assemblage (chalcopyrite-pyrite), rather than the low-sulfur copper sulfide mineral assemblage characteristic of the IOCG deposit type (chalcopyrite - bornite - chalcocite), as well as the high quartz content, the absence of pervasive hydrothermal alteration of the host rock, in particular sodic (albite) alteration, and the absence of gold.
As such, the Boa Esperança copper deposit is a variant of an IOCG deposit type.
Mineralization consists of a series of brecciated zones, which are aligned N60°-70°E and incline in a SE direction (60°-70°SE). However, another alignment of about N40°E was observed in the field and coincides with the elongation of the Boa Esperança hill.
Summary:
Boa Esperança is a copper deposit, averaging approximately 0.95% Cu diluted grade within the minable pit. The mineralization is close to the surface and the resource is appropriate for an open pit mining operation.
The final pit design in this feasibility phase of the Boa Esperança project totals 19.5 Mt of Proven and Probable Mineral Reserves with an average diluted grade of 0.95% Cu. From this total, 17.5 Mt is classified as high grade material with an average Cu content of 1.02% and the remaining 2.0 Mt as low grade material, with a grade of 0.34% Cu.
Waste materials amount to 37.7 Mt, which is comprised of 19.6 Mt of saprolite, 8.9 Mt of weathered rock and 9.2 Mt of fresh rocks. The Life of Mine (LOM) strip ratio of waste to ore is 1.93.
The operation of the Boa Esperança mine will utilize conventional open pit mining techniques and small size mining equipment to mine a total of 57.2 Mt of material over the life of the mine. This comprises 19.5 Mt of ore and 37.7 Mt of waste materials. A total of 5.1 Mt of ore will be moved from the stockpiles to the plant.
The main mine equipment selected for the Boa Esperança project consists of 4.0 m3 hydraulic
excavators, on-highway 35t trucks and drills.
It has been assumed that 100% of weathered and fresh rocks and 10% of saprolites will be drilled and blasted in 10-meter-high benches. Ore will be hauled to the primary crusher or to the ROM stockpiles close to the primary crusher. Waste materials will be hauled to different dumps and destinations. Grade control will be performed through drilling, sampling and assaying materials within the pit limits using the production drills.
The mine is scheduled to operate in three 8 hour shifts, 7 days per week, 365 days per year. Whenever mine production needs to be reduced or interrupted, the primary crusher will be fed from the regularization pile using a front-end loader.
Flow Sheet:
Summary:
The Boa Esperança concentrator has been designed to process 2.308 Mt of copper ore per year at a nominal processing rate 9,033.6 tonnes per day (t/d) at primary crushing feed and incorporates equipment and process unit operations considered standard for the industry. The process flowsheet includes three-stage crushing, jigging, ball mill grinding, copper rougher flotation, two stages of copper cleaner flotation and pyrite flotation from the copper rougher and scavenger flotation tailing. The final copper concentrate is thickened prior to pressure filtration and the flotation tailing is thickened and classified prior to discharge to the tailing storage facility. The pyrite concentrate from the pyrite flotation is sent to the pond of high sulfur. The flowsheets and material balances have been prepared as part of the Tecnomin’s process design.
Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Copper
|
Head Grade, %
| 0.95 |
Copper
|
Recovery Rate, %
| ......  |
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Projected Production:
Commodity | Product | Units | LOM |
Copper
|
Payable metal
|
M lbs
| 346 |
Copper
|
Metal in concentrate
|
M lbs
| 360 |
Copper
|
Concentrate
|
dmt
| 544,775 |
Operational Metrics:
Metrics | |
Daily milling rate
| ......  |
Stripping / waste ratio
| ......  |
Annual mining capacity
| ......  |
Waste tonnes, LOM
| ......  |
Ore tonnes mined, LOM
| ......  |
Total tonnes mined, LOM
| ......  |
Annual milling capacity
| ......  |
* According to 2017 study.
Reserves at September 7, 2017:
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
18.5281 Mt
|
Copper
|
0.96 %
|
178.05 kt
|
Probable
|
0.975 Mt
|
Copper
|
0.72 %
|
7.02 kt
|
Proven & Probable
|
19.5031 Mt
|
Copper
|
0.95 %
|
185.07 kt
|
Measured
|
41 Mt
|
Copper
|
0.81 %
|
332,100 t
|
Indicated
|
26.17 Mt
|
Copper
|
0.62 %
|
162,254 t
|
Measured & Indicated
|
67.17 Mt
|
Copper
|
0.73 %
|
490,341 t
|
Corporate Filings & Presentations:
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Aerial view:
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