Overview
Stage | Pre-Feasibility |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Smelting
- Heap leach
- Carbon in column (CIC)
- Carbon adsorption-desorption-recovery (ADR)
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 5.3 years (as of Jan 1, 2014) |
Deposit Type
- Porphyry
- Epithermal
- Breccia pipe / Stockwork
Summary:
RNC and Bikermann Engineering (2002) consider the Cerro Quema deposits to be high-sulphidation epithermal deposits. Corral et al. (2011) also consider that the mineralogy and spatial distribution of hydrothermal alteration observed in Cerro Quema fit well within the classical high-sulfidation epithermal gold deposit model. Hydrothermal alteration is interpreted to be related to the circulation of acidic fluids of magmatic origin and to the presence of a porphyry copper system at depth in a calc-alkaline volcanic arc in both, sub-aerial and submarine environment (Sillitoe et al., 1996). Corral et al. (2011) consider that despite the Cerro Quema deposit being consistent with the high sulphidation epithermal model, the presence of a porphyry copper at depth could not be proved at the time. On the other hand, a model based on an oxidized gold and copper deposit that shares characteristics of both epithermal and volcanogenic massive sulphide deposits (Nelson, 2007) is not preferred, as no signs of bedded massive sulphides have been found in the alteration zones, in the vicinity of the dacitic lava domes or associated hyaloclastitic sediments.
In the Cerro Quema Project area, several gold mineralized zones are located along a 15 km long, east-west trend. These zones include the La Pava Quemita-Quema and La Mesita deposits. RNC and Bikerman Engineering (2002) describe the mineralized zones as hosted in a belt of hornblende-pyrite pyroclastic flows and lavas of dacitic and andesitic composition. The volcanic belt is up to 1.5 km wide and conformably bounded to the north and south by epiclastic submarine sediments. The sequence dips south at 45o to 60o north. The main rock types within the mineralized zones are saprolitic dacitic clay, silicieous dacite with various degrees of acid leaching and iron-oxide cemented breccia.
Gold occurs as disseminated submicroscopic grains and as invisible gold within the crystalline structure of pyrite (Corral et al., 2011), especially in the advanced silica alteration zone. Strong supergene alteration results in the formation of an oxidation cap or gossan and released the gold contained in the pyrite. The highest grades of gold mineralization are near the surface and decrease toward the lower limit of oxidation.
The gold and copper mineralization are associated with disseminated pyrite, chalcopyrite, enargite and a stockwork of quartz, pyrite, chalcopyrite, and barite with traces of galena and sphalerite. The presence of vuggy silica, alunite, natro-alunite and enargite in addition to the hydrothermal alteration pattern is compatible with a high-sulfidation epithermal system.
At Cerro Quema, RNC and Bikerman Engineering (2002) reported that the silica-pyrite alteration is characterized by a highly fractured, vuggy, locally brecciated rock composed of silica and iron-oxides at the surface. The oxidized rock extends from surface to a depth of up to 150 m. Beneath the oxidation boundary, pyrite is abundant and accounts for up to 35% of the rock. With few exceptions, gold mineralization above the cut-off grade is restricted to the silica-rich alteration type within the oxidized and leached cap. RNC and Bikerman Engineering (2002) also report that on the south side of the La Pava deposit, steeply-dipping chalcopyrite veins appear to be associated with late stage fracturing. In this area, a zone of high grade supergene mineralization (0.5 to 5.0% copper) is present beneath the oxidation surface.
A large network of steeply-dipping NW-SE and NE-SW trending normal faults have been observed in the Rio Quema area. The east-west striking Rio Joaquin fault zone is the major mapped fault Corral et al. (2011). The fault can be easily observed about 3 km south of the Cerro Quema mineralization zone. The Rio Joaquin fault has had an apparent reverse slip sense with a minimum of 300 to 400 metres of vertical displacement (Corral et al. 2011). Fault movement has uplifted the southern block with respect to the northern block and has juxtaposed with the lower and upper units of the Rio Quema Formation.
Summary:
The mining method proposed for the Cerro Quema Project will be a conventional open-pit mine. Mining will occur in two open pits; the La Pava Pit and the Quema Pit. A fleet of hydraulic excavators and trucks consisting of 50 tonne rigid frame trucks and 40 tonne articulated trucks will be used to mine the ore and waste materials. The drilling and blasting of both ore and waste rock will be required although some materials will be free-digging.
The ore production rate delivered to the heap leach pad area is approximately 3.6 million tonnes per year of silica and fresh rock type ore. Clay type ore will be stockpiled and processed at the end of the mine life since this ore requires a different crushing method and agglomeration.
Overall total annual mining rates will range from a high of 7.1 Mt of combined ore and waste to a low of 5.5 Mt with an average of about 6.4 Mt/year. This results in an average total daily mining rate of 18,000 tpd, of which 10,000 tpd would consist of ore.
Haul Roads
Ore and waste from the La Pava pit will be hauled to the crusher and Chontal waste dump sites. The upper part of the La Pava haul road will be located along sloping topography and therefore will ?onsist of both road cuts and earth fills. The lower portion of the La Pava road will consist of a large ramp built from waste material from La Pava prestripping.
The La Pava haul road would be required for the 4th quarter of Year -1, therefore its construction would commence in the early part of Year -1. The cut & fill road length would be about 600 meters with an operating width of 18 meters and a maximum grade of 10%.
Waste Rock Disposal
The mining operation will require the stripping and disposal of waste rock. Generally the overall mining waste-to-ore ratio is relatively low, about 0.7:1 and the total waste quantity is about 14.3 million tonnes.
Open-Pit Operation
The open pit would operate using 5-meter high benches and conventional mining equipment. No specific equipment manufacturers or models have been selected at this level of study and hence discussions tend to be generic.
The various activities associated with the mining operation will consist of:
- Drilling and blasting,
- Grade control,
- Loading and hauling of waste rock and ore,
- Pit dewatering,
- Mine services and supervision.
Equipment Scheduling
For equipment scheduling purposes, the mine would operate on a two 10-hour shifts per day, 7 days per week basis throughout the year.
Drilling and Blasting
The rock mass is considered a weaker rock and heavy blasting is not likely required. A powder factor in the range of 0.12 to 0.15 kg/t is anticipated. It is assumed that 80% of the silica rock and 100% of the fresh rock will require drilling and blasting although the weathered clay-like materials near surface will be free-digging.
The blast holes would be drilled using top-hammer or in-the-hole type drills. The proposed drill would be diesel-powered, crawler mounted, top-head drive multi-pass drill rig. The rig would be equipped with a carousel-type drill pipe changer and a control system that enables drill pipe changing to be accomplished remotely from the operator’s cab. The projected overall drilling penetration rates in the relative soft ore and waste rock are 50 m/h.
A licensed explosive supplier would provide the supply of explosives, blasting agents and blasting accessories. The Owner would undertake the blasting and drilling activities with a blasting engineer, lead blaster and blasting crew.
The explosive supplier would provide the explosive transport and delivery mix trucks, and crew trucks to charge the holes with explosive. The Owner would provide the explosive storage facilities, crushed rock for use as stemming; diesel fuel for use in the explosive supplier’s on- site equipment; and electrical power, water and sanitary services at the explosive supplier’s on- site building.
A conventional blast initiation system would be used. One non-electric type down line with one detonator and booster would be used in each blast hole. It is expected that a 70% emulsion-30% ANFO blasting agent would be used due to the expected wet conditions in the mine, especially during the wet season.
Loading and Haulage
The ore and waste mined materials would be excavated using diesel-powered backhoe excavators (6.5 m3) supported by a front end loader (7 m3). The materials would be hauled to the appropriate destinations (i.e., ore crusher or waste dump) using a mixed fleet of 50 tonne rigid frame haul trucks and 40 tonne articulated trucks. The rigid frame trucks provide better productivity and lower unit cost however the articulated trucks can operate better in soft wet conditions and re- start production quicker after rain storms. It is assume that about 80% of the overall material tonnage would be hauled by the rigidframe trucks with 20% of the tonnage allocated to the articulated trucks.
Support Equipment
The major mining equipment fleet will be supplemented with a fleet of support equipment such as dozers, graders, water trucks, and service vehicles.
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
|
|
1
|
Cone crusher
|
|
|
|
1
|
Summary:
Crushing
Run-of-mine ore will be delivered by haul trucks from one of the open pit mines to the primary crusher. As much as possible, material will be direct-dumped by haul trucks into the primary crusher dump hopper. Ore will also be reclaimed from stockpiles by frontend loader into the dump hopper located above the apron feeder as required for either
blending or haul truck availability.
A stationary grizzly over the dump hopper will be included to prevent oversized material
(+500 mm) from plugging the feeder. A rock breaker will be used to break up any
oversized material. An apron feeder will deliver the run of mine at a rate of 556 dry t/h to
a vibrating grizzly with 130 mm openings, grizzly oversize will be crushed primary jaw
crusher.
The primary jaw crusher will crush grizzly oversize to 100% passing 130 mm. The jaw
crusher product will combine with the grizzly undersize and discharge to the primary
crusher discharge conveyor which feeds the secondary screen feed hopper. The
secondary screen feed hopper provides 15 minutes of storage capacity for the secondary
crusher.
The secondary screen belt feeder will feed primary crushed rock to a secondary screen.
The secondary screen will scalp material at 70 mm. Oversize will be crushed in the
secondary mineral cone crusher. Cone crusher product and screen undersize will
discharge to the crushed ore stockpile stacker which feeds secondary crushed material to
the crushed ore stockpile.
Processing
- Smelting
- Heap leach
- Carbon in column (CIC)
- Carbon adsorption-desorption-recovery (ADR)
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
The Cerro Quema project will be a 10,000 tonnes per day heap leach facility. Processing at Cerro Quema will be by conventional heap leaching of crushed ore stacked on a single use pad. Gold will be leached from the mineralized material with dilute cyanide solution and recovered from the solution using a carbon adsorption-desorption-recovery plant to produce doré bars.
The crushed ore stockpile is filled by the crushed ore stockpile stacker. The stockpile will be conical and contain about 5,300 t of live feed and a total of 26,000 t of crushed material. The stockpile will be constructed over a subterranean tunnel containing two reclaim belt feeders and the reclaim tunnel conveyor. Each belt feeder will be able to reclaim and feed crushed material to the reclaim tunnel feeder at the design rate of 556 dry tph.
Stacking
The heaps will be constructed using a conveyor stacking system. The conveyor stacking system includes the following components:
• "Ramp" po ........

Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Gold
|
Recovery Rate, %
| ......  |
Gold
|
Head Grade, g/t
| 0.77 |
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Projected Production:
Commodity | Units | Avg. Annual | LOM |
Gold
|
oz
| 78,800 | 417,812 |
All production numbers are expressed as metal in doré.
Operational Metrics:
Metrics | |
Stripping / waste ratio
| 0.72 * |
Daily mining rate
| 18,000 t * |
Daily ore mining rate
| 10,000 t * |
Waste tonnes, LOM
| 14,258 kt * |
Ore tonnes mined, LOM
| 19,708 kt * |
Total tonnes mined, LOM
| 33,966 kt * |
Plant annual capacity
| 3.6 Mt * |
Daily processing capacity
| 10,000 t * |
* According to 2014 study.
Reserves at June 30, 2014:
A cut-off grade of 0.21 g/t of gold is used for reporting mineral reserves.
Category | OreType | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
Oxide
|
6,820 kt
|
Gold
|
0.8 g/t
|
176 koz
|
Probable
|
Oxide
|
12,890 kt
|
Gold
|
0.75 g/t
|
312 koz
|
Proven & Probable
|
Oxide
|
19,710 kt
|
Gold
|
0.77 g/t
|
488 koz
|
Measured
|
Mill / Sulphide
|
802 kt
|
Gold
|
0.44 g/t
|
11 koz
|
Measured
|
Oxide
|
7,053 kt
|
Gold
|
0.82 g/t
|
185 koz
|
Measured
|
Total
|
7,855 kt
|
Gold
|
0.78 g/t
|
196 koz
|
Indicated
|
Mill / Sulphide
|
10,204 kt
|
Gold
|
0.42 g/t
|
136 koz
|
Indicated
|
Oxide
|
16,880 kt
|
Gold
|
0.67 g/t
|
367 koz
|
Indicated
|
Total
|
27,084 kt
|
Gold
|
0.58 g/t
|
503 koz
|
Measured & Indicated
|
Mill / Sulphide
|
11,006 kt
|
Gold
|
0.41 g/t
|
146 koz
|
Measured & Indicated
|
Oxide
|
23,932 kt
|
Gold
|
0.72 g/t
|
552 koz
|
Measured & Indicated
|
Total
|
34,938 kt
|
Gold
|
0.62 g/t
|
698 koz
|
Inferred
|
Mill / Sulphide
|
373 kt
|
Gold
|
0.3 g/t
|
4 koz
|
Inferred
|
Oxide
|
667 kt
|
Gold
|
0.37 g/t
|
8 koz
|
Inferred
|
Total
|
1,040 kt
|
Gold
|
0.34 g/t
|
12 koz
|
Mine Management:
Job Title | Name | Profile | Ref. Date |
.......................
|
.......................
|
|
Oct 22, 2020
|
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