Overview
| Stage | Production |
| Mine Type | Open Pit |
| Commodities |
|
| Mining Method |
|
| Processing |
- Filter press plant
- ROM/dump leach
- Leaching plant / circuit
- Merrill–Crowe
- Cyanide (reagent)
|
| Production Start | 1997 |
| Mine Life | 11.8 years (as of Jan 1, 2021) |
Herradura is one of Mexico’s largest open pit gold mines. |
Source:
p. 56,278
La Herradura is operated by Penmont which is a wholly-owned subsidiary of Fresnillo.
Contractors
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Deposit Type
- Vein / narrow vein
- Hydrothermal
Summary:
La Herradura deposit is located in the Sonora state in northwestern Mexico, approximately 80 km northwest of the town of Caborca.
Gold rich veins are restricted to the Proterozoic rocks which consist of biotite-feldspar-quartz and quartz-feldspar gneisses of sedimentary and plutonic origin. The hydrothermal system is structurally controlled and the higher grade mineralization occurs in quartz-sulfide veins filling tensional fractures. Quartz-sericite-albite alteration is widespread in the core of the deposit and grades to propylitic in the outer parts where the gneisses are more biotite rich.
Summary:
La Herradura is an open pit gold mine with a heap leach pad, Merrill Crowe Plant, two pregnant solution ponds, three contingency ponds, and associated pipework.
La Herradura is developed via conventional truck and shovel method with preliminary drilling and blasting operations. Approximately 250 Cat haulage trucks are utilized for the haulage ore and waste.
In 2019 Fresnillo began rolling out dual fuel systems into our haulage fleet. This programme involved the installation of engines which are able to automatically switch between powering the trucks by diesel and by Liquefied Natural Gas (LNG), depending on the terrain. By the end of 2021, the entire 785 and 793 haulage fleet had been converted.
Processing
- Filter press plant
- ROM/dump leach
- Leaching plant / circuit
- Merrill–Crowe
- Cyanide (reagent)
Flow Sheet:
Summary:
La Herradura Processing Facilities is includes a heap leach pad, Merrill Crowe Plant, two pregnant solution ponds, three contingency ponds, and associated pipework.
The run-of-mine mineral from the open pit is sent directly to the heap leach pad. The mine has one heap leach pad which has been sub divided into 13 phases. The leach pad was constructed with a composite liner of compacted clay and geomembrane. Once in the leach pad, a cyanide solution is applied by drip irrigation.
The pipelines between the leach pad and plant are contained within a geomembrane liner. The pump stations are constructed of concrete with leak detection sumps. There are two pregnant solution ponds and three contingency ponds (i.e., Contingency Pond 1, Contingency Pond 6, and the Megapond). The pregnant ponds are double lined (geomembrane) with leak detection, collection, and recovery systems. The contingency ponds are single lined (geomembrane).
The pregnant solution from the ........
Recoveries & Grades:
| Commodity | Parameter | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|
Gold
|
Head Grade, g/t
| ...... | ...... | ...... | 0.76 | 0.68 | 0.71 | 0.73 |
|
Silver
|
Head Grade, g/t
| ...... | ...... | ...... | 2.7 | 1.1 | 1.2 | 1.2 |
Production:
| Commodity | Units | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|
Gold
|
oz
| ...... | ...... | ...... | 474,168 | 473,638 | 520,366 | 398,866 |
|
Silver
|
oz
| ...... | ...... | ...... | ...... | ...... | ...... | ...... |
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Operational Metrics:
| Metrics | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 |
|
Total tonnes mined
| ...... | ...... | 124,486 kt | 124,024 kt | 130,025 kt | 118,841 kt |
|
Ore tonnes mined
| ...... | ...... | 22,926 kt | 22,157 kt | 26,027 kt | 25,159 kt |
|
Tonnes processed
| ...... | ...... | 22,926,542 t | 22,156,792 t | 26,027,466 t | 25,158,600 t |
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Reserves at May 31, 2021:
Ore Reserves that are attributed to the heap leach are reported at cut-off grades of 0.21 g/t Au for oxide ore and 0.22 g/t Au for transition and sulphide ore. Oxide material above 0.83 g/t Au and transitional and sulfide material above 0.44 g/t Au are attributed to the mill.
Mineral Resources are reported at various cut-offs dependent on material types and grade. Oxide material above 0.20 g/t Au and below 0.72 g/t Au reports to the heap leach; transitional and sulfide material above 0.20 g/t and below 0.40 g/t Au reports to the heap leach; oxide material above 0.72 g/t Au reports to the mill; transitional and sulfide material above 0.40 g/t Au reports to the mill.
| Category | Tonnage | Commodity | Grade | Contained Metal |
|
Proven
|
216,616 kt
|
Gold
|
0.74 g/t
|
5,127 koz
|
|
Probable
|
23,985 kt
|
Gold
|
0.66 g/t
|
511 koz
|
|
Proven & Probable
|
240,601 kt
|
Gold
|
0.73 g/t
|
5,638 koz
|
|
Measured
|
272,932 kt
|
Gold
|
0.73 g/t
|
6,375 koz
|
|
Indicated
|
45,253 kt
|
Gold
|
0.7 g/t
|
1,021 koz
|
|
Measured & Indicated
|
318,185 kt
|
Gold
|
0.72 g/t
|
7,396 koz
|
|
Inferred
|
10,529 kt
|
Gold
|
0.59 g/t
|
201 koz
|
Corporate Filings & Presentations:
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Aerial view:
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