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Pinos Project

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Mine TypeUnderground
  • Gold
  • Silver
Mining Method
  • Cut & Fill
Backfill type
  • Unconsolidated rockfill
Mine Life7 years (as of Jan 1, 2018)
SnapshotThe Pinos Gold Project contains a compliant resource (NI43-101 Technical Report, September 2018) with significant expansion potential.

Candelaria Mining Corp have all the permits, under mining, environmental, labor, tax and other Mexican regulations for the construction and operations of the Pinos mining and metallurgical complex.

The focus of efforts within the 2023 financial year has been to assess alternative options to access higher-grade ore veins, including refurbishing existing mine shafts, and new spiral declines directly into the high-grade shoots. Detailed structural interpretations have also continued.

Following the conclusion of the alternative mine plan, revision to the overall project capital, construction schedule and financial models is underway. The Company will then continue to explore alternative funding options to enable the board to decide on construction at Pinos.


Candelaria Mining Corp. 100 % Indirect
The Pinos Project consists of 29 mining concessions for exploration, mining, and production, totalling approximately 3,816 hectares. These concessions are held by Minera Catanava S.A de C.V., an indirect wholly-owned Mexican subsidiary of Candelaria Mining Corp.


ContractorContractDescriptionRef. DateSource
Comisión Federal de Electricidad (CFE) Power supply The Project’s power supply is sourced through Mexican CFE (National Enery commission) grid through a power line which provides power to the Project transformer station; the new operation includes an increase of power from 13,500 Kva to 13,800 Kva. A Diesel plant is considered as providing energy in the event of a power outage, where the mine, process plant, and surface facilities can still function. Sep 13, 2018

Deposit type

  • Vein / narrow vein
  • Epithermal
  • Breccia pipe / Stockwork


Gold and silver mineralization on the Pinos Property is typical of low sulphidation epithermal systems associated with alteration assemblages including quartz and clay minerals, showing ginguro bands in high grade zones. These deposits are formed at relatively shallow depth, typically from just below the surface to a little over one kilometer deep, from reduced, neutral-Ph hydrothermal fluids with temperatures of <150°C to 300°C. Mineralization at Pinos is contained in veins, brecciated vein systems, and stockwork, which are localized by geological structures, and range in size from 0.5m to 10m wide for veins and 200m to 900m for stockworks. The three main mineralized vein structures trends are northeast, north, and northwest. Mineralization is comprised of quartz veins and veinlets, vein stockworks, and hydrothermal breccias that carry gold, silver, and some microscopic sulfide minerals. The alteration halos extending outward in the wall rock away from the vein are typically small in extent and are overprinted by surficial oxidation and argillization. Soil and rock sampling results also indicate a very short dispersion of silver and gold from the mineralized veins structures. Strong silicification and lithocaps related to intermediate and advanced argillic alterations for San Ramón and San Matías, respectively, suggest a possible altered quartz-eye porphyry for Au disseminated deposit. The Pinos Project is part of the important mineralized NW-SE trend in the Mesa Central of Mexico, along with the so-called Fresnillo-Guanajuato Trend with world-class precious metals active mines; such as Fresnillo, La Parrilla, San Martín, La Colorada, Real de Ángeles, and Guanajuato, among others. Gold-silver mineralization in Pinos District occurs in the form of veins and stockworks structurally controlled by NW-SE, NE-SW and N-S fracture-faulting systems described earlier; it is hosted in rocks of the Proaño Group, Fortuna Formation, Caracol Formation and to a lesser extent in rhyolitic flows and ignimbrites of the Pinos volcanic complex. Vein structures show more than 25 kilometers linearly in length within the district besides extensive areas of mineralized breccia and stockworks. Veins are of cavity filling type of mineralization related to fault and fracture systems forming well- defined tabular bodies; vein thicknesses vary from 0.5 up to 6m depending primarily on the suitability of host rocks. The lithological units of Pinos District have varied characteristics; it influenced the position and intensity of subsequent fracturing, dissolution, and mineralization. Grupo Proaño, related to euxinic, deep-basin back arc sediments and ductile deformation, it improved the consolidation of widest veins and ore shoots (3 m – 5 m width). Grupo Proaño is the best host rock at Pinos Gold District, in accordance the information of drill holes and systematic sampling of old workings, possibly the iron-rich sediments contribute to the enrichment of Au-solutions by chemical reactions between iron and sulfide. However, this theory has not been proved yet. Rhyolitic Porphyry, the San Matías Target (Regional Exploration) shows an altered rhyolitic porphyry with advanced argillic alteration and stockwork. The stockwork is formed by quartz veinlets with halos of iron oxides; these veinlets are ranging 5 cm - 20 cm of separation. Stockwork is bisected by major 20 cm - 40 cm high-grade parallel veins separated between 30 - 80 m. The results and historical data of old works and exploratory RC and diamond drill holes indicate the possibility of Au disseminated deposit. Volcanic Rocks, the mineralization associated with felsic rocks is related to veinlets, it usually is millimetric and has not sufficient density, mainly at rhyolitic flows and tuffs. Mineralization is mainly associated with quartz and calcite. There are different textured types of presentation of quartz, varying from chalcedony white banded, crystalline banded, platy, ginguro, massive and smoky, in the middle area of Cinco Estrellas vein pink quartz was also observed. Mineralogy is mainly represented by native gold, argentite, and acanthite, with no presence of base metals, gangue is related to calcite and possibly barite. The correlation of the ratios Ag: Au is null. Gold mineralization is related to Native Gold and Fischesserite (Ag3AuSe2), it was reported in a mineralogical study completed by Terra Mineralogical Services in which a composite sample from the San Gil mine (sample ground to 100% passing 106 microns) contained 12 gold particles and 210 silverbearing mineral grains. The main gold carrier was Fischesserite (Ag3AuSe2), with minor amounts of Native Gold and Electrum. Most of the gold and silver phases occurred as liberated grains. Overall, these precious metal particles had an average diameter of 1.5 microns for gold particles and 2.5 microns for silver particles. Silver occurs primarily in dark sulfide-rich bands within the veins as Argentite and Electrum. Predominate (silver) carriers were Acanthite (Ag2S) (54%), Aguilarite (Ag4SeS) (34%) and Naumannite (Ag2Se) (9%), of Petrovskaite (Ag Au(S, Se)) (3%). Mineralized veins at the Pinos District consist of the classic ginguro, banded and brecciated epithermal variety. The vein textures are attributed to the brittle fracturing-healing cycle of the fault-hosted veins during and after faulting. Primary quartz textures include, massive, crustiform, colloform, cockade and combed. Replacement quartz texture includes platy, pseudo bladed and saccharoidal.

Reserves at September 13, 2018

Classification of mineral resources was performed based on modeled blocks above a cut-off grade of AuEq of 2.2 g/t.
CategoryTonnage CommodityGrade
Measured 85,847 t Gold 1.6 g/t
Measured 85,847 t Silver 82.9 g/t
Indicated 175,697 t Gold 3.6 g/t
Indicated 175,697 t Silver 47.4 g/t
Inferred 529,267 t Gold 3.6 g/t
Inferred 529,267 t Silver 47.7 g/t

Mining Methods

  • Cut & Fill


The primary mining method at the Project is Cut and Fill mining which is a cost-effective method to mine complex geology of Mine District.

Cut and Fill is a favored choice for steeply dipping and sometimes irregular ore bodies and preferred by mines that require the capability of selective mining and adaptability to variations in the rock mass. Cut and Fill mining is generally referred to as a medium & small-scale mining method. Mining is carried out in horizontal slices along the stopes, where the bottom slice is mined first. The excavated area is then backfilled, and production continues upwards. Each production level is accomplished by drifting until the entire slice has been mined. The slice is then backfilled, and the fill becomes the working platform from which the next slice is mined.

Mucking is done for providing access to the top slices within the stope. When a stope is completed, a new access drift from the ramp is created to continue the production within the upper stope. One of the advantages of Cut and Fill mining is the possibility to reuse waste for backfill material, such as waste rock from development.

After of Industrial Safety revisions and underground precision surveys, the first steps of Cut and Fill start with selection of economical mineable widths and the marking of it along the roof of the stope, then a second step depends on the hangingwall conditions and regularity of the mineral grades along vein, normally if the grade is irregular, the process continues with the stope drilling and only the charging and blasting of the best grades zones (mineable width selection), then miners ventilate the blast fumes and the ore selected by selection is mucked out and dumped into an orepass or onto a truck, finally miners continues with charging and blasting of the marginal grades or waste, this material will be used of backfilling.

Before continuing with the next round, the rocks need to be reinforced. How this is done is decided by the mine for each situation. The mining continues until the entire slice of the ore has been mined. Since the mining can be tailored to suit the shape of the orebody, it is possible to minimize dilution of waste rock.

In order to access more production points, a second entrance can be opened at another level in the ore body and excavated in parallel. The equipment used for mining the ore is usually the same as what is used for development. As the ore body is mined, the rock stresses increase in the pillar above the mine area. Cut and Fill method has the advantage of high selectivity with good ore recovery and low dilution.

Waste rock is moved from development to stopping whenever possible; if an area does notexist for wastefill for immediate disposal of waste rock, it is moved to surface waste rock deposit (Tepetatera), then the waste rock is hauled back into the mine as neededto the stopes for final disposal, normally the narrow veins are self-sufficient for backfill.


Crushers and Mills

Jaw crusher 1
Cone crusher 4.25' 1
Cone crusher 3' 1
Ball mill 6' x 6' 1
Ball mill 8' x 7' 1


Ore for processing circuit is stockpiled on a large patio (capacity 10,000 to 15,000 tons) near the crushing zone; during operation, the raw material is usually delivered to the primary crusher’s dump hopper by dump trucks, excavators or directly from San Luis shaft.

The ore is transferred to a Jaw crusher through Conveyor # 01, furthermore, crushed ore is moved to a double deck vibrating screen of 5’ x 12’ through conveyor # 02; with the oversize from screening, it is conveyed to a secondary cone crusher 4’ ¼ using a conveyor # 03, finally crushed ore is transferred to screen of 5’ x 10’, where final product, is moved to ore bin; by the way, due the WI parameter of the Pinos ore, the oversize ore from second screen of 5’ x 10’ (After jaw crusher and secondary cone crusher) is conveyed a tertiary cone crusher of 3’ and reinserted to crushing circuit from conveyor # 02. The final product for milling is reduced to -95 mm (-3/8 inch).

In accordance to milling testing, engineers determined an ideal pulp of 65%-75% passing the -200 mesh (74µm).

Milling of the Pinos ore include an 8’ x 7’ and 6’ x 6’ ball mills, while the classification of particles is done via closed circuit milling - two hydrocyclones D-15 each for each ball mill.


  • Dry Screening
  • Crush & Screen plant
  • Vacuum filtration
  • Agitated tank (VAT) leaching
  • Counter current decantation (CCD)
  • Merrill–Crowe
  • Dewatering
  • Cyanide (reagent)


The Pinos remanufactured process facility (purchased by CAND) will consist of the following circuits and include all pumping, piping, and electrical components.
• ROM crushing Plant to produce a mill feed size of P80 - -3/8-in. Circuit will include jaw crusher with closed circuit secondary and tertiary cone crushers.
• Milling Circuit including two (2) closed circuit balls mills, one (1) primary thickener, four(4) cyanidation leach tanks, four(4) counter current decantation washing thickeners.
• Complete Merrill Crowe Zinc Precipitation including clarification, deaeration, zinc feeding, and gold and silver precipitate filters to produce a saleable precipitate. The process milling rate will be starting with 200 mtpd in the first year, 300 mtpd on 2nd year and and 3rd years and 400 mtpd from 4th year to the 7th year, with designed recoveries of 90% for Gold and 80% for Silver.

Mineral in form of pulp ranging from 25% to 30% solids is deposited in a Primary Thickener of 50’ x 10’, in this deposit start the recovery of rich solutions from the mill, if the process requires a major leaching reaction, engineers add a fresh cyanide solution of 1500 ppm to 1750 ppm NACN.

Rich solution from the primary thickener is transferred to clarifier and the pulp from the discharge of primary thickener is pumped to four agitation tanks type AIR-LIFT de 30’ x 30’, it is to continue with leaching process, the tanks have four lateral siphons, the objective is to make sure the maximal depletion of Au and Ag values.

Residence time of solutions into the agitation tanks is 96 hours (exceeding the required time from the testwork for high gold and silver recovery). Finally, the pulp of fourth agitation tank comeback to primary thickener tank through countercurrent washing, then the pulp continues again the process through agitation tanks, where the final pulp from last fourth agitation tank is pumped to tailings pond. The solution from countercurrent washing is send to primary thickener tank and then it is transferred to Mill Solution Tank for recirculation new use at mill process.

Filtration and Clarification
The pregnant solution from the leaching circuit will have suspended solids (200 – 300 ppm) that are deleterious to the Merrill Crowe Process – thus requiring two(2) stages to clarify the pregnant solution to contain less than 10 ppm, and preferably 5 ppm total suspended solids.

The first stage of solution clarification includes primary sand Filters followed by a second stage vacuum leaf clarifier / filter.

Following clarification of the Au-Ag rich process solution, the stream must deaerated utilizing a “packed” deaeration tower under high vacuum. Typical pregnant solution has dissolved oxygen ranging from 5-8 mg/L and needs to be reduced to 0.5-1.0 mg/L. Again, this ensure efficient utilization of the added zinc for precipitation of the gold and silver.

Pinos project scheduling does not consider the production of doré bars on site. The resultant precipitate from the Merrill Crowe process will be initially sold to refiners with the best refining terms. There is also the possibility of the construction of a refinery either on site or in the nearest commercial city.

Recoveries & Grades:

CommodityParameterAvg. LOM
Gold Recovery Rate, % 90
Gold Head Grade, g/t 3.34
Silver Recovery Rate, % 80
Silver Head Grade, g/t 51
Gold Equivalent Head Grade, g/t 4.7

Water Supply


Potable Water
Potable water is abundant in the town of Pinos and mine site for human consumption. It is supplied from the Pinos aqueduct; it crosses the mine property just 200 meters of San José de Peñitas portal and facilities and local water wells.

Process Water
To accomplish requirements dictated by SEMARNAT to grant the environmental permit EIA (MIA); as well as to secure enough water for processing plant, Candelaria did two hydrological studies; one for underground water in local aquifers performed by Sistemas Tecnológicos e Investigaciones en Ingeniería, S.A. de C.V. “Estudio Geohidrológico Realizado en el Municipio de Pinos, Zacatecas para la Minera Catanava”. April 2016, and the other for surficial, and underground old mining workings performed by the same company titled “Analisis Hidrológico, Tránsito por el Vaso y Diseño de Canal Pluvial para la Presa de Jales de la Mina Catanava en Pinos, Zacatecas.”

Results from these studies reveal that the Oasis Ranch’s well may yield over 400 m3 per day and that San Luis Shaft may produce 200 m3 per day.

Process water estimated consumption is for 200m3 per day. Candelaria will be supplied by San Luis Shaft (Candelaria has an active water use permit with CONAGUA and certified by SEMARNAT), for additional water requirements, the company may pump additional volumes from Candelaria and San Joaquín shafts. Also, if necessary Candelaria may take water for processing mineral from El Oasis Ranch well.


CommodityUnitsAvg. AnnualLOM
Gold oz 75,400
Silver oz 995,400
Gold Equivalent oz 12,70088,934

Operational metrics

Tonnes processed 790,809 t *
* According to 2018 study.

Production Costs

Cash costs Gold Equivalent USD 664.1 / oz *  
Total cash costs Gold Equivalent USD 666 / oz *  
All-in sustaining costs (AISC) Gold Equivalent USD 834.86 / oz *  
Assumed price Silver USD 17 / oz *  
Assumed price Gold USD 1,250 / oz *  
* According to 2018 study / presentation.

Project Costs

MetricsUnitsLOM Total
Initial CapEx $M USD 13.5
Sustaining CapEx $M USD 9.2
Closure costs $M USD 0.2
Total CapEx $M USD 22.7
UG OpEx $M USD 28.1
Processing OpEx $M USD 23
Refining costs $M USD 0.1
G&A costs $M USD 6.7
Total OpEx $M USD 59.1
Royalty payments $M USD 1.7
Gross revenue (LOM) $M USD 111.2
Net revenue (LOM) $M USD 109.4
Pre-tax Cash Flow (LOM) $M USD 27.6
After-tax Cash Flow (LOM) $M USD 18.7
Pre-tax NPV @ 0% $M USD 27.6
Pre-tax NPV @ 5% $M USD 19
Pre-tax NPV @ 10% $M USD 12.9
After-tax NPV @ 0% $M USD 18.7
After-tax NPV @ 5% $M USD 12.2
After-tax NPV @ 10% $M USD 7.6
Pre-tax IRR, % 33
After-tax IRR, % 25
After-tax payback period, years 3.6

Required Heavy Mobile Equipment

Ref. Date: September 13, 2018

HME TypeSizeQuantity
Scoop Tram 1 cu. yd 2
Scoop Tram 2 cu. yd 2
Truck (haul) 6 tons 2
Truck (service) 3


Mine Management

Job TitleNameProfileRef. Date
Consultant - Recovery Methods & Costs David J. Salari LinkedIn Sep 13, 2018
Interim CEO Hector Felix Gonzalez Ramirez LinkedIn Jan 18, 2024


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