Overview
Stage | Feasibility |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Smelting
- Agitated tank (VAT) leaching
- Counter current decantation (CCD)
- Merrill–Crowe
- Cyanide (reagent)
|
Mine Life | 11 years (as of Jan 1, 2014) |
In 2014, Coeur contracted M3 Engineering & Technology Corporation of Tucson, Arizona (M3) to prepare a Feasibility Study Technical Report on the Project. On July 30, 2014, Coeur announced the results of the La Preciosa NI 43-101 Feasibility Study. The Feasibility Study Technical Report was filed on September 4, 2014, with an effective date of July 29, 2014 and an issue date of August 29, 2014.
Tetra Tech was retained by Avino Silver & Gold Mines Ltd. (Avino) to compile an independent Technical Report on the Project. The purpose of the Technical Report is to support the News Release dated October 27, 2021 entitled: “Avino acquires neighboring La Preciosa project; adds significant production potential to growth profile, and substantially enhances its Mineral Resources”.
On March 21, 2022, Avino announced the closing of the acquisition of La Preciosa from Coeur Mining Inc. |
Latest News | Avino Closes Acquisition of La Preciosa from Coeur Mining March 21, 2022 |
Source:
p. 1
On March 21, 2022, Avino Silver & Gold Mines Ltd. closed the acquisition with Coeur Mining, Inc. for the acquisition (the “Transaction”) of all of the issued and outstanding shares of Proyectos Mineros La Preciosa S.A. de C.V., a Mexican corporation, and Cervantes LLC, a Delaware LLC, that together hold the La Preciosa property in Mexico (“La Preciosa”).
Deposit Type
- Epithermal
- Vein / narrow vein
Summary:
Silver and gold mineralization in the Project area can be grouped into the low sulphidation epithermal model of precious metal deposits. These types of deposits are found worldwide and have been commonly formed during the Cretaceous to Holocene.
The veins in the Project area consist of several stages of banded, crustiform (to colloform; quartz and cryptocrystalline quartz at shallow depths, adularia, barite and typically later carbonates both calcite and rhodochrosite, "illitic clay" (illite) commonly replaces the adularia (Coote, 2010). There are variable amounts of pyrite, sphalerite and galena plus argentite, and variable amounts of tetrahedrite-tennantite, freibergite and Ag sulfosalts.
The Ag:Au ratio is high, approximately 500:1 for the resource. Supergene oxidation extends to at least 300 m depth, and includes manganese oxide. There is abundant adularia, bladed calcite textures and coexisting vapor-rich and liquid-rich inclusions, all indicating an ascending, boiling fluid, consistent with the abundant evidence for brecciation, which suggests that that mixing caused metal deposition and carbonate formation.
Petrographic studies of the veins in Deposit, find that multiple stages of silver and base metal mineralization are associated with repeated fluid boiling and mixing events, defined by crustiform banded fill/cement assemblages within a framework of intermittent and more significant fracturing/rupturing of wall rock and pre-existing vein/cement assemblages. There is a repetition of common hydrothermal fill/cement mineralogy, including ore minerals, such that correlation of vein/cement assemblages/events between drillhole intersections would be difficult.
The occurrence of adularia and style of early quartz and chalcedonic quartz replacement amongst wall rock replacement and fracture-fill/cement assemblages confirms silver and base metal mineralization associated with low sulphidation, epithermal style systems developed on the Martha and Olin structures at the Project. Significant widths of mineralized quartz and carbonate dominated fracture-fill and breccia cement assemblages have developed as a result of extended episodes of hydrothermal fluid flow and repeated rupturing of wall rock and pre-existing vein/cement assemblages. Internal crustiform banding within the different voluminous fill/cement assemblages represents incremental opening and filling of fractures/cavities between major rupturing events.
The Martha vein is the largest vein in the deposit by far, with at least 3 times the volume of the next largest vein, La Abundancia. Both veins are low angle, the Martha vein dips ~20-30°, following the SW-dipping contact of volcaniclastic rocks overlying an immature conglomeratic unit (consisting mainly of polylithic clast-supported fragmental rock with angular to sub-rounded clasts), or the underlying schist.
There are also high-angle veins in the west on the ridge, such as La Gloria vein, the largest of this set of veins. These high-angle veins can be considered as a mineralized zone or lode of stock work, silicification, breccias, veins, vein breccias, veinlets, and a general mix of multiple styles of mineralization. Within this broader zone, for example the Martha lode ranges from 1 m to 35 m thicknesses and averages approximately 5m.
Summary:
The Project mine plan was developed using conventional hard rock open pit mining methods. No underground resource was envisioned in this mine plan. While a smaller, higher grade portion of the resource could be recovered in an underground mine, the scale and percent recovery of the resource would be substantially diminished. In addition, the complicated structure of the low angle Martha vein which makes up 60% of the resource would make underground mining complicated and costly.
Scoping studies indicated that a production schedule filling the mill at 10,000 tpd maximized the Project return on investment. The total material rate is tied to equipment productivity. The total material moved ramps up to 214,000 tonnes per day in year 6, and averages 60,400 ktonnes/yr or 167,700 tpd for the first 10 years. The mine is scheduled to operate 365 days/yr with two, 12-hour shifts/day.
The mine plan was developed with a phased approach to facilitate sufficient ore release to provide the mill feed desired. In addition to the phases, mining was envisioned on 5 m in ore and 10 m in waste to increase productivity and ore release.
Seven phases were designed for Project with a minimum of 100 m of operating width on each bench within a phase, in general.
Phase Design Parameters:
- Haul Road Width - 30 meters;
- Haul Road Grade - 10% Maximum;
- Interramp Slope Angles - by sector;
- Operating width between pushbacks - 100 meters nominal.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
|
|
1
|
SAG mill
|
|
|
|
1
|
Ball mill
|
|
|
|
1
|
Summary:
The proposed crushing and grinding operations are summarized as follows:
- Crushing of the feed by primary jaw crusher to reduce the feed size from run of mine to minus 152 mm.
- Stockpiling primary crushed feed in a coarse feed stockpile and then reclaiming by feeders and conveyor belt.
- Grinding feed in a SAG mill / ball mill circuit prior to processing in a cyanide leach circuit. The SAG mill will operate in closed circuit with a vibrating screen. Crushed pebbles will be stacked on the ground for return to the SAG mill. The ball mill will operate in closed circuit with a hydro-cyclone to produce the desired grinding product size distribution of 80% (P80) passing 74 microns.
Processing
- Smelting
- Agitated tank (VAT) leaching
- Counter current decantation (CCD)
- Merrill–Crowe
- Cyanide (reagent)
Flow Sheet:
Summary:
The design basis for the feed processing facility is 10,000 dry metric tonnes per day (dtpd) or 3.65 million dry metric tonnes per year (dtpy). It is contemplated that feed will be transported from the mine to the concentrator facility by off-highway haulage trucks. The mineralized material would then be processed to produce silver and gold doré that would be loaded onto highway haul trucks and transported to a metal refinery.
The proposed process operations are summarized as follows:
- Crushing, Stockpiling and Grinding.
- Leaching of the slurry at 40% solids by weight with cyanide solution in agitated leach tanks to dissolve the silver and gold contained in the slurry.
- Recovering soluble silver and gold using multi-stage counter current decantation technology (CCD). Barren solution will be added in the final CCD thickener as the washing solution.
- Clarifying of the pregnant solution followed by adding zinc dust to the solution ........

Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Silver
|
Recovery Rate, %
| 84 |
Silver
|
Head Grade, g/t
| 105.77 |
Gold
|
Recovery Rate, %
| 61 |
Gold
|
Head Grade, g/t
| 0.17 |
Projected Production:
Commodity | Product | Units | LOM |
Silver
|
Payable metal
|
koz
| 105,790 |
Silver
|
Metal in doré
|
koz
| 106,643 |
Gold
|
Payable metal
|
koz
| ......  |
Gold
|
Metal in doré
|
koz
| ......  |
Operational Metrics:
Metrics | |
Stripping / waste ratio
| 15.5 * |
Daily mining rate
| 167,700 t * |
Daily milling capacity
| 10,000 t * |
Waste tonnes, LOM
| 583,674 kt * |
Ore tonnes mined, LOM
| 37,326 kt * |
Total tonnes mined, LOM
| 621,000 kt * |
Tonnes milled, LOM
| 37,326 kt * |
Annual milling capacity
| 3,650 kt * |
Annual mining rate
| 60,400 kt * |
* According to 2014 study.
Reserves at December 31, 2021:
Open Pit Mineral Resource estimate is reported using a net smelter return (“NSR”) cutoff of US$23/tonne and Underground Mineral Resources are reported using a NSR cut-off of $71/tonne.
Category | Tonnage | Commodity | Grade | Contained Metal |
Measured
|
9,536 k tons
|
Silver
|
3.04 oz/ton
|
29,001 koz
|
Measured
|
9,536 k tons
|
Gold
|
0.005 oz/ton
|
45 koz
|
Indicated
|
19,141 k tons
|
Silver
|
3.98 oz/ton
|
76,185 koz
|
Indicated
|
19,141 k tons
|
Gold
|
0.006 oz/ton
|
118 koz
|
Measured & Indicated
|
28,677 k tons
|
Silver
|
3.67 oz/ton
|
105,186 koz
|
Measured & Indicated
|
28,677 k tons
|
Gold
|
0.006 oz/ton
|
163 koz
|
Inferred
|
1,761 k tons
|
Silver
|
3.31 oz/ton
|
5,835 koz
|
Inferred
|
1,761 k tons
|
Gold
|
0.003 oz/ton
|
6 koz
|
Mine Management:
Job Title | Name | Profile | Ref. Date |
.......................
|
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|
|
Feb 23, 2022
|
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