Overview
Status | Care and Maintenance |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Smelting
- Filter press plant
- Heap leach
- Carbon in column (CIC)
- Merrill–Crowe
- Cyanide (reagent)
|
Mine Life | 22 years (as of Jan 1, 2021) |
While mining operations were placed on care and maintenance in 2019, Lagunas Norte’s gold recovery plant has continued to produce gold from leach pad ore and Boroo expects to recover approximately in excess of 100koz of gold inventory by 2023.
The next phase of the mine will be to recover gold from carbonaceous oxide ore through the Carbonaceous Material Oxides Project (“CMOP”) and sulphide ore through the Refractory Material Project (“PMR”).
The CMOP project is designed to process about 15.0 million tonnes of high-grade gold bearing oxides mined early in the life of Lagunas Norte property. |
Latest News | Boroo completes acquisition of Lagunas Norte mine June 1, 2021 |
Source:
Company | Interest | Ownership |
Minera Boroo Misquichilca S.A.
(operator)
|
100 %
|
Direct
|
Boroo Pte Ltd.
|
100 %
|
Indirect
|
On June 1, 2021, Boroo Pte. Ltd. completed the acquisition of a 100% interest in the Lagunas Norte mine in Peru from Barrick Gold Corporation.
The Mine is owned and operated by Minera Barrick Misquichilca S.A. (MBM).
Deposit Type
- Epithermal
- Vein / narrow vein
Summary:
Lagunas Norte differs from many other large high- sulphidation epithermal gold deposits of the Andes in that a majority of the known resource is contained within Cretaceous siliciclastic sedimentary rocks, and a relatively small portion is within the Tertiary volcanic sequence that is the primary host elsewhere (e.g., Yanacocha, Pierina). The main host rock sequence at Lagunas Norte consists of quartz sandstones and subordinate interlayered mudstone, siltstone, and carbon-rich siltstone, correlated with the Lower Cretaceous Chimú Formation (Lewis, 2002).
The Lagunas Norte mineralization occurs in the southeast portion of the Alto Chicama property. The mineralization is finely disseminated and is hosted mostly by siliclastic sedimentary strata.
The mineralization within the present pit extends for approximately two kilometres in the north-northwest direction by approximately two kilometres in the east-northeast direction and for more than 200 m vertically.
Mineralization is the result of multiple volcanic and hydrothermal events. It is hosted in both the Tertiary volcanics of the Calipuy Group and the underlying Cretaceous sedimentary rocks of the Chimú Formation. The alteration associated with the mineralization is typical of a highsulphidation epithermal environment, characterized by silica (SiO 2 ), surrounded by alunite [KAl3(SO4)2(OH)6], dickite [Al2Si2O5(OH)4] and pyrophyllite [Al2Si4O10(OH)2]. Trace elements typically associated with these deposits include copper, arsenic, barium, bismuth, zinc, lead, and variable amounts of mercury (Silberman and Berger, 1985). The deposit has very low concentrations of carbonate minerals or other potentially acid neutralizing minerals.
There are both stratigraphic and structural controls on the mineralization. Mineralizing fluids ascended along the main fault systems and migrated laterally along stratigraphic contacts in both the sedimentary and volcanic rocks. At least two stages of sulphide mineralization are recognized. The sulphide assemblage comprises mainly pyrite (FeS2) with lesser amounts of enargite (Cu3AsS4) and occurs as replacement structures, veins, and disseminations in volcanic breccias and highly fractured and locally brecciated Chimú sandstones. Most of the mineralization (75%) occurs as oxide material, with approximately 25% occurring as sulphide material. Supergene oxidation has altered a large part of the sulphide assemblage to iron oxides and, to a lesser extent, sulphates. The extent of this oxidation ranges from a few metres to more than 300 m below surface. Approximately 90% of the mineralization is contained within the Chimú sediments and the balance is hosted in the Calipuy volcanic rocks.
The gold grade times thickness contours clearly show the Lagunas Norte deposit is approximately two kilometres by one kilometre wide.
Summary:
The Lagunas Norte Mine is a traditional open pit truck/shovel heap leach operation that has been in continuous production since 2005.
Open pit mining operations are located on a mountain top with gentle to extreme terrain between elevations of 3,800 MASL and 4,200 MASL.
The Lagunas Norte ultimate pit measures approximately 2.5 km along strike, typically 0.8 km to 1.2 km across with a surface footprint of approximately 240 ha, and has a maximum depth of approximately 250 m. There are four main areas of development identified within the ultimate pit: Dafne, Josefa, Alexa, and the moraines furthest to the north. The open pit is overlooked by the Shulcahuanca Dome, a sacred feature, and there is an approximate 50 m standoff from the base of the Shulcahuanca Dome for mine planning and operations.
Final arrangement of the Lagunas Norte waste rock facilities is for the continued development of surface dumps surrounding the Lagunas Norte ultimate pit other than to the south-southeast where the HLF is located, resulting in a relatively compact overall footprint.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Gyratory crusher
|
|
|
|
1
|
Cone crusher
|
.......................
|
|
|
2
|
Summary:
The recovery process used at Lagunas Norte is a two-stage conventional crushing circuit, followed by heap leaching, and a Merrill Crowe zinc cementation plant and CIC for recovery of the precious metals.
CRUSHING CIRCUIT
The crushing circuit was originally designed to crush 42,000 tpd, but the capacity is permitted to 63,000 tpd. Historically, it was determined that the gold recovery from heap leaching at Lagunas Norte is not overly dependent on crush size so the size has been increased over time to allow more material to be processed through the crushing circuit. Haul trucks dump ore directly into the gyratory crusher. A rock breaker is available to break large rocks at the mouth of the primary crusher. The ore is discharged through an apron feeder onto belt conveyor number one which conveys it to a 2,000 tonne live capacity stockpile.
From the stockpile the ore is fed to the secondary crushers by conveyor belt number two. A splitter divides the feed into two parallel lines. Each line has a double deck screen. Oversize material passes to an MP800 secondary crusher which reduces the size to 80% passing (P80) approximately 50 mm. The product from each line is delivered to belt conveyors number three and number four, which in turn deliver the crushed ore to conveyor belt number five. Finally, the material is stored in the 1,000 tonne live capacity ore bin. From the bin the crushed ore is loaded into haul trucks that transport the ore to the leach pad. Lime is added to the trucks to raise the pH of the bleach solution.
Processing
- Smelting
- Filter press plant
- Heap leach
- Carbon in column (CIC)
- Merrill–Crowe
- Cyanide (reagent)
Flow Sheet:
Summary:
The recovery process used at Lagunas Norte is a two-stage conventional crushing circuit, followed by heap leaching, and a Merrill Crowe zinc cementation plant and CIC for recovery of the precious metals. The major components of the process are:
• Primary crushing;
• Secondary crushing;
• Heap leaching;
• Recovery plant;
• Refinery;
• Water discharge treatment plant.
HEAP LEACH PAD
The leach pad stacking plan is developed by the leach department and the Technical Services department at Lagunas Norte. Stacking of the crushed ore is done in 10 m high lifts. A high precision GPS dozer assists in the stacking operation by pushing the material over the edge of the surface while maintaining a level surface and preventing excessive segregation of the material. After completing the stacking of one cell, the surface is ripped using dozers to scarify the upper layer that has been compacted by the operation of the haul trucks on the leach pad during ma ........

Recoveries & Grades:
Commodity | Parameter | 2019 | 2018 | 2017 | 2016 | 2015 | 2014 |
Gold
|
Head Grade, g/t
| ......  | 0.91 | 1.05 | 1.12 | 1.02 | 0.99 |
Gold
|
Recovery Rate, %
| ......  | | | 70 | 78 | 83 |
Production:
While mining operations were placed on care and maintenance in 2019, Lagunas Norte’s gold recovery plant has continued to produce gold from leach pad ore.
Commodity | Units | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
Gold
|
koz
| ......  | ......  | ......  | 245 | 387 | 435 | 560 |
Silver
|
koz
| | | | | | ......  | |
All production numbers are expressed as metal in doré.
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Operational Metrics:
Metrics | 2019 | 2018 | 2017 | 2016 | 2015 | 2014 | 2013 |
Total tonnes mined
| 12,388 kt | 31,357 kt | 32,859 kt | 40,847 kt | 49,126 kt | 50,030 kt | 36,934 kt |
Ore tonnes mined
| 2,396 kt | 9,774 kt | 17,201 kt | | | | |
Waste
| 9,992 kt | 21,583 kt | 15,658 kt | | | | |
Stripping / waste ratio
| 4.17 | 2.21 | 0.91 | 1.5 | 1.2 | 0.9 | |
Tonnes processed
| 2,693 kt | 8,837 kt | 17,874 kt | 17,253 kt | 21,880 kt | 22,110 kt | 21,089 kt |
Daily mining rate
| | | | 112 kt | 135 kt | 137 kt | |
Daily processing rate
| | | | 47.1 kt | 59.9 kt | 60.6 kt | |
Reserves at June 30, 2021:
Lagunas Norte Mineral Resources are estimated at gold cut-off grades that vary by material type from 0.286 g/t to 0.387 g/t for heap leach processing, from 0.738 g/t to 0.966 g/t for CMOP processing, and from 0.880 g/t to 1.482 g/t for PMR processing.
Lagunas Norte Mineral Reserves are estimated at gold cut-off grades that vary by material type from 0.312 g/t to 0.422 g/t for Heap Leach processing, from 0.806 g/t to 1.087 g/t for CMOP processing, and from 0.960 g/t to 1.618 g/t for PMR processing.
Lagunas Norte Mineral Reserves are estimated at gold cut-off grades that vary by material type from 0.312 g/t to 0.422 g/t for Heap Leach processing, from 0.806 g/t to 1.087 g/t for CMOP processing, and from 0.960 g/t to 1.618 g/t for PMR processing.
The Mineral Reserve estimate includes stockpile inventory as of June 30, 2021.
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
21,467 kt
|
Gold
|
2.52 g/t
|
1,738 koz
|
Proven
|
21,467 kt
|
Silver
|
6.07 g/t
|
4,190 koz
|
Probable
|
27,936 kt
|
Gold
|
2.47 g/t
|
2,214 koz
|
Probable
|
27,936 kt
|
Silver
|
6.37 g/t
|
5,726 koz
|
Proven & Probable
|
49,404 kt
|
Gold
|
2.49 g/t
|
3,952 koz
|
Proven & Probable
|
49,404 kt
|
Silver
|
6.24 g/t
|
9,916 koz
|
Measured
|
1,749 kt
|
Gold
|
0.8 g/t
|
45 koz
|
Measured
|
1,749 kt
|
Silver
|
2.82 g/t
|
158 koz
|
Indicated
|
23,901 kt
|
Gold
|
0.8 g/t
|
618 koz
|
Indicated
|
23,901 kt
|
Silver
|
2.64 g/t
|
2,027 koz
|
Measured & Indicated
|
25,650 kt
|
Gold
|
0.8 g/t
|
663 koz
|
Measured & Indicated
|
25,650 kt
|
Silver
|
2.65 g/t
|
2,186 koz
|
Inferred
|
2,432 kt
|
Gold
|
0.9 g/t
|
70 koz
|
Inferred
|
2,432 kt
|
Silver
|
3.15 g/t
|
246 koz
|
HME Type | Model | Quantity | Ref. Date |
Backhoe
|
.......................
|
.......................
|
Dec 31, 2015
|
Backhoe
|
.......................
|
.......................
|
Dec 31, 2015
|
Dozer (crawler)
|
.......................
|
.......................
|
Dec 31, 2015
|
Dozer (crawler)
|
.......................
|
.......................
|
Dec 31, 2015
|
Dozer (rubber tire)
|
.......................
|
.......................
|
Dec 31, 2015
|
Dozer (rubber tire)
|
.......................
|
.......................
|
Dec 31, 2015
|
Drill
|
.......................
|
.......................
|
Dec 31, 2015
|
Drill
|
.......................
|
.......................
|
Dec 31, 2015
|
Drill
|
.......................
|
.......................
|
Dec 31, 2015
|
Drill
|
.......................
|
.......................
|
Dec 31, 2015
|
Drill
|
.......................
|
.......................
|
Dec 31, 2015
|
Grader
|
.......................
|
.......................
|
Dec 31, 2015
|
Loader
|
.......................
|
.......................
|
Feb 22, 2017
|
Shovel
|
.......................
|
.......................
|
Feb 22, 2017
|
Truck (haul)
|
.......................
|
.......................
|
Feb 22, 2017
|
Truck (haul)
|
.......................
|
.......................
|
Feb 22, 2017
|
Truck (water)
|
.......................
|
.......................
|
Dec 31, 2015
|
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