Source:
p. 24
In May, 2016 Endeavour Silver acquired Oro Silver Resources Ltd. which owned the El Compas project through its wholly owned Mexican subsidiary, Minera Oro Silver de Mexico SA de CV.
Deposit Type
- Epithermal
- Vein / narrow vein
Summary:
The El Compas and El Orito veins have the characteristics of a low sulfidation epithermal vein system. They occur in a region characterised by numerous, high silver-grade intermediate sulfidation epithermal vein systems.
At the El Compas concession, northerly trending veins in the Chilitos Formation have finely banded, coliform and crustiform open space fill textures. Bladed quartz after calcite textures are common. Veins in felsic rocks are comprised of saccharoidal to fine-grained quartz, banded veins. Wider veins in felsic rocks are observed in the Cantera pit and at the El Compas shaft. These veins show breccia and bladed quartz-after calcite textures. Calcite is observed in bands in large andesite-hosted quartz veins and in veinlets distal to mineralised zones in very weakly propylitised rocks.
Within the El Compas ramp, the widest calcite veins (>0.75m, both black and white coarse grained calcite) occur as north-west trending veins. Large northerly trending calcite veins have not been observed on surface or in the El Compas ramp; however, thick calciterich quartz veins were intersected by drilling at deeper levels below the mine and elsewhere that appear to correlate with the north-south trending El Compas and other veins. Sulfide abundance in veins rarely exceeds 5%, and is most abundant in the mineralised veins. Pyrite or pyrrhotite are the most common sulfides. Rare sphalerite and exotic copper was observed at the 7th level of the El Compas ramp. Magnetite was identified in panned concentrates from the mineralised veins.
Summary:
Since publishing the El Compas preliminary economic assessment (“El Compas PEA”), the Company continued to optimize mining methods, the crushing circuit and grinding alternatives and was successful on a number of fronts in improving the operating metrics. The work index of the ore and the size on the motor allowed the capacity of the milling circuit to increase to 325 tpd, which allowed for the mining method to be changed to mechanized cut and fill from captive cut and fill. Mechanized cut and fill increases the mining rate but has the same cost profile as captive cut and fill previously disclosed in the El Compas PEA.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
24" x 36"
|
75 HP
|
1
|
Cone crusher
|
.......................
|
4.25'
|
150 HP
|
1
|
Cone crusher
|
.......................
|
4'
|
150 HP
|
1
|
Ball mill
|
|
8' x 9'
|
350 HP
|
1
|
Ball mill
|
.......................
|
7' x 7.5'
|
|
1
|
Summary:
The treatment of the El Compas mineralization will be performed at the La Plata processing facility located 20km from the mine.
The mineralization will be delivered by truck from the mine in 20 tonne loads. Upon arrival at site, each truckload will be weighed on a platform scale. The mineralization will be dumped directly through a 200mm grizzly into a 63 tonne receiving hopper. Oversize (+200 mm) will be broken with a portable rock breaker. Excess material delivered from the mine is placed in separate coarse mill feed material pads, capable of accommodating up to 3,200 tonnes of mill feed. The mineralization from local miners will also be stored on pads before crushing and milling. The stockpiles will be located near the hopper in order to be fed into the plant with a front end loader.
Crushing will be done for 12 hours per day to ensure mill feed is available over the evening shift and with sufficient contingency to allow for scheduled crusher maintenance. The coarse mill feed material is delivered from the receiving hopper via a belt feeder to a 75 HP 0.6 m X 0.9 m Manyu jaw crusher. Primary crushing reduces the rock to a nominal 50 mm (2”) which is conveyed onto secondary crushing in a standard 150 HP 1.3m (4.25”) Symons cone crusher.
The secondary product is sent to a double deck vibrating screen, incorporating a 9.5mm (3/8”) bottom slot opening providing for a product particle size 80% passing (P80) of 6.4 mm (1/4”). The plus 9.5mm material is sent to a 150 HP 1.2 m (4”) Symons short head cone crusher operated in closed circuit with the screen. The minus 9.5 mm screened undersize is sent to a fine mill feed material bin having a 372 tonne live load capacity.
Mill feed is delivered from a fine mill feed material bin on a conveyor to feed the ball mill. The ball mill consists of an Avante 350 HP, 8’ dia. X 9’ mill.
The ball mill will operate in closed cycle with a dedicated hydrocyclone using a 300% circulating load. The hydrocyclone overflow would target a particle size of P80 of 75 microns that is directed to flotation. Hydrocyclone underflow would be sent to a splitter box, from where it will be pumped to a 1.7 mm (10 Tyler mesh) vibrating screen for gravity feed.
Processing
- Gravity separation
- Filter press plant
- Centrifugal concentrator
- Flotation
Flow Sheet:
Summary:
The treatment of the El Compas mineralization will be performed at the La Plata processing facility located 20km from the mine.
The plant will be modified to produce a single gold-silver concentrate which would be sold to smelters and refiners. The process flowsheet will consist of conventional comminution, gravity and froth flotation. Endeavour Silver will upgrade the existing plant so that it can safely and reliably process 250tpd (200tpd from Endeavour Silver mining and 50tpd from toll mining) of mineralization averaging ± 5 g/t Au and ± 96 g/t Ag.
The projected recoveries of gold and silver based on open-circuit rougher and cleaner flotation tests are 83.5% and 73%, respectively. The cleaner concentrate grade will be 868 g/t Au and 12,095 g/t Ag.
The mineralization will be delivered by truck from the mine in 20 tonne loads. Upon arrival at site, each truckload will be weighed on a platform scale. The mineralization will be dumped directly thro ........

Recoveries & Grades:
Commodity | Parameter | 2021 | 2020 | 2019 |
Gold
|
Recovery Rate, %
| ......  | ......  | ......  |
Gold
|
Head Grade, g/t
| ......  | ......  | ......  |
Silver
|
Recovery Rate, %
| ......  | ......  | ......  |
Silver
|
Head Grade, g/t
| ......  | ......  | ......  |
Reserves at December 31, 2021:
El Compas Mineral Resources cut-off grades are based on a 3.42 g/t gold equivalent.
Category | Tonnage | Commodity | Grade | Contained Metal |
Indicated
|
20 kt
|
Gold
|
6.42 g/t
|
4,000 oz
|
Indicated
|
20 kt
|
Silver
|
78 g/t
|
49,000 oz
|
Indicated
|
20 kt
|
Silver Equivalent
|
592 g/t
|
373,000 oz
|
Inferred
|
18 kt
|
Gold
|
5.96 g/t
|
3,400 oz
|
Inferred
|
18 kt
|
Silver
|
70 g/t
|
40,000 oz
|
Inferred
|
18 kt
|
Silver Equivalent
|
547 g/t
|
311,000 oz
|
Aerial view:
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