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United States
Relief Canyon Mine

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 Location:
158 km NE from Reno, Nevada, United States

  Address:
1055 Carnell Ave
PO BOX 1033
Lovelock
Nevada, United States
89419
WebsiteWeb
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Overview

StageProduction
Mine TypeOpen Pit
Commodities
  • Gold
  • Silver
Mining Method
  • Truck & Shovel / Loader
Processing
  • Heap leach
  • Carbon in column (CIC)
  • Carbon adsorption-desorption-recovery (ADR)
  • Solvent Extraction & Electrowinning
  • Cyanide (reagent)
Mine Life6 years (as of Jan 1, 2017)
First gold pour achieved February 2020.
The Relief Canyon mine declared commercial production effective January 11, 2020.
Latest NewsAmericas Gold and Silver Corporation Announces Commercial Production at Relief Canyon     January 11, 2021


Owners

Source: p. 10,43
CompanyInterestOwnership
Americas Gold and Silver Corp. 100 % Indirect
Americas Gold and Silver is the owner of the Relief Canyon mine.

The Relief Canyon mine is 100% owned and operated by Americas’ wholly owned subsidiaries, Pershing Gold (“PG”) and Gold Acquisition Corp. (“GAC”).

Deposit Type

  • Vein / narrow vein
  • Carlin-type
  • Orogenic

Source: Source p.77-81

Summary:

Gold and silver mineralization at Relief Canyon is believed to be largely epithermal in origin, but the deposit also exhibits similarities to Carlin-type deposits (Fifarek et al, 2015) and to orogenic vein deposits.

Gold mineralization at the Relief Canyon mine is primarily found in three zones that are structurally controlled and characterized by distinctive host rocks. From structurally lowest to highest, the zones are the Jasperoid Zone, the Lower Zone, and the Main Zone. The Main Zone hosts the bulk of the current and historical gold resources at Relief Canyon, while the Lower and Jasperoid zones are newly discovered mineral zones encountered below the Main Zone in the North Target area during the recent Pershing Gold drill programs.

The Jasperoid Zone gold mineralization is hosted within the Deformed Limestone package in a sequence of limey ductile tectonites with local stretched and boudinaged quartz veins, stretched-quartz-pebble conglomerate/sandstone, folded and foliated limestone, and altered gabbro, all of which have been replaced by dark-colored quartz. Silicification is also found in a set of sheeted, N30-35°E-striking, steep fractures that may be extensional in origin. In addition, auriferous fluids were localized by brecciation along contacts between lithologies of contrasting competency, such as between the stretched-pebble conglomerate and carbonate units, or less commonly, between pale green schistose volcanic and carbonate horizons. Locally, collapse breccia is also a site of gold deposition in the Jasperoid Zone.

Gold in the Jasperoid Zone shows a strong spatial correlation with silicification, fluorite, and white illite with trace kaolinite. Fine-grained disseminations of pyrite and coarse euhedral pyrite of metamorphic origin are also present. Silver is generally more abundant (> 10 g/t) in this zone than in the Lower or Main zones.

Lower Zone gold mineralization displays a strong spatial association with gabbro sills and/or transposed dikes (i.e., dikes in which progressive ductile deformation has transposed originally discordant contacts into contacts subparallel to foliation, giving the dikes a sill-like appearance). Mineralization is hosted in, or is proximal to, complex tectonic breccias that show multiple generations of structural reactivation and/or shearing, decalcification, locally superimposed carbonate-dissolution collapse breccia, and the presence of illite and/or kaolinite, sulfides iron-oxides and fluorite.

The tectonic breccia was generated by multiple (minimum of two) episodes of movement in the North Target area. The principal clasts in the tectonic breccia comprise dark grey foliated limestone, jasperoid, and quartz. Finegrained gouge material is chiefly composed of quartz flour and kaolinite.

The Main Zone was the source of the historical gold production from the Relief Canyon mine. Gold in the Main Zone is found in a quartz-illite±fluorite-cemented, polyphase, dissolution collapse breccia with cave-fill sedimentary rocks.

As defined by drilling through September 2016, Relief Canyon mineralization occurs as a continuous body over 4,000 feet long north-south and 3,000 feet wide east-west. Mineralization crops out at the surface within the historical open-pits and extends to depths of over 900 feet.


Mining Methods

  • Truck & Shovel / Loader

Source: p.177, 182

Summary:

The Relief Canyon deposit has been mined in the past by open-pit methods. Initially, truck haulage from the crusher was compared to conveyor stacking of the crushed material. The conveyor haulage of material had considerable cost advantages to the truck haulage case, and was assumed as the base case in this study. Both owner and contract mining cases were considered. The operating cost of both cases were fairly close when the equipment lease payments were included in the owner mining case, however, the contract mining case had lower capital requirements. Contract mining was considered to be the base case for this study.

The Relief Canyon mine is currently permitted to mine to a pit bottom elevation of 5,080 feet AMSL. Prior mining was concentrated in three open-pits, with several waste facilities, a heap-leach pad, a heapleach fluid process plant, and associated infrastructure.

A four month mine pre-production period is planned to start in the second quarter of 2018, while production is planned to start in the third quarter of 2018. The mine production schedule was developed by designing a Phase 1 mine plan that was planned only to mine to the 5,080 elevation, and a Phase 2 plan that was developed to stay inside the current permit boundary, but mine below the 5,080 elevation. Using this plan would enable ore supply from the design Phase 1 pit and mostly waste stripping from the design Phase 2 pit. Annual maximum ore production is planned to be about 6 million tons (about 16,700 tons per day), while total production is limited to a total of about 31 million tons of material. Both of these design pit phases utilized out-of-pit haul roads to move material that was above the 5,220 to 5,240 elevation and move the remainder of material out of the pit by nominal 85 foot wide, in-pit, 10 percent ramp systems. Phase 1 was later redesigned to include some material that was originally in the design Phase 2 pit as well as some material that was outside of the permit boundary in the Light Bulb area.


Crushing and Grinding
Source: Source p.201-207


Processing

  • Heap leach
  • Carbon in column (CIC)
  • Carbon adsorption-desorption-recovery (ADR)
  • Solvent Extraction & Electrowinning
  • Cyanide (reagent)

Source: Source p.201-207

Summary:

The process selected for recovery of gold and silver from the Main, Lower and Jasperoid Zones mineralized material is a conventional heap leach recovery circuit. The ore will be mined by standard open pit mining methods, primary crushed to approximately 3 inches in size, agglomerated using cement, and conveyor stacked onto heap leach pads in 20-foot lifts.

Ore will be leached with a dilute cyanide solution, and the leached gold will be recovered from solution using a carbon adsorption circuit. The gold will be stripped from carbon using a pressurized desorption process, followed by electrowinning to produce a precipitate sludge. The precipitate sludge will be processed using a retort oven for drying and mercury recovery, and then refined in a smelting furnace to produce doré bars.

The overall life-of-mine (“LOM”) average gold recovery is 83 percent. Silver is also planned to be recovered. For the Main, Lower, and Jasperoid zones silver recovery is expected to be 36, 28, and 18 percent respectively.

Ore will be transported from the mine in surface haul trucks and dumped at the crusher area into two stockpiles. Ore will be fed to the crusher from one of two ore grade stockpiles: a low fines material stockpile or a high fines material stockpile. All feed to the crusher will bereclaimed by a Cat 992 loader from the stockpiles in a manner to produce a desired blend according to the fines content. Pershing Gold has indicated the average run of mine feed size to the crusher to be approximately 80 percent passing 4 inches.

Ore will be stacked on the heap leach pad using conveyors exclusively. Ore will be stacked in 20-foot high lifts to a maximum total height of 200 feet, with typical 20-foot benches between lifts to give an overall average slope of approximately 2.3 to 1. Dozer ripping to facilitate improved percolation will be performed after each lift has been stacked to the determined height.

After each irrigation cell has been stacked and dozer ripped, the irrigation system will be installed. Dripline emitters will be used to apply a cyanide solution concentration of 0.3 to 0.5 pounds of sodium cyanide per ton of solution, at an application rate of 0.003 gpm per square foot. A minimum primary leach cycle of 60 days is planned for a nominal flow rate of 3,000 gpm.

Barren leach solution pH will be at least 10 and controlled by the cement that has been added for agglomeration of crushed ore.

Barren solution will be delivered from the existing 24,000-gallon barren tank located at the ADR plant, by a pair of vertical multi stage pumps at the nominal flow rate of 3,000 gpm. This solution will be carried by a 14” steel pipeline to the base of the heap and then to a network of subheaders and risers to the top of the heap where it is delivered by the emitters.

Solution passing through the heap will dissolve the gold and silver contained therein and then collect in a network of perforated solution collection pipes, which feed to a common discharge point at the base of the heap. The solution will then be carried by gravity in a single solid HDPE collection pipe down to the existing 22,500-gallon pregnant solution tank. Excess solution from the heap will overflow from the pregnant tank to the existing pregnant solution pond, also called the Operating Pond East (OPE). Solution is pumped from the pregnant tank to the adsorption carbon column circuit at the ADR plant.

The carbon adsorption circuit consists of a series of four pressurized carbon columns, each column approximately 12.5 feet in diameter and 10 feet tall, and each holding 8 tons of carbon.

Pregnant solution is pumped through the existing columns to load the soluble gold onto the carbon. Barren solution exiting the columns is directed to the barren tank where make up cyanide is added and the solution returned to the heap for further leaching. Overflow from the barren tank is directed to a process pond, also called the Operating Pond West (OPW).

At the existing ADR plant, loaded carbon from the carbon adsorption circuit will be passed over a carbon dewatering screen, where process solution and any carbon fines in the undersize will be transferred to a carbon fines tank, and the oversize loaded carbon directed to the acid wash circuit. The loaded carbon will be acid washed in a dilute hydrochloric acid solution to remove scale and other contaminants as required. The existing acid wash capacity is 8 tons and will allow for acid washing after every strip, which is expected for optimum performance of the carbon.

Loaded, acid-washed carbon will then be pumped to the elution circuit where it will be batch stripped in a single 8-ton pressure stripping vessel, in a modified Zadra circuit. The loaded carbon will be eluted using a sodium hydroxide solution at a rate of about two bed volumes per hour at a temperature of 250-275°F. Strip times of 24-36 hours are anticipated, which allow for refurbishment and utilization of the existing plant boiler and associated equipment, and satisfies the expected demand of about three strips per week. The eluted pregnant solution will report to the electrowinning cells.

Eluted carbon will be passed over a sizing screen and then reactivated as necessary using a carbon regeneration kiln. Regenerated carbon will be again screened to remove fine carbon from the circuit, as required.

Carbon fines from the dewatering and sizing screens will be periodically sent to a filter press for collection.

Pregnant strip solution from the CIC strip circuit will be processed by electrowinning for recovery of gold and silver in a precipitated sludge. The gold and silver bearing sludge will be refined by smelting to produce a doré bar.

Solution from the strip vessel will be pumped through a new 100 ft3 electrowinning cell where gold and silver will be precipitated on stainless steel cathodes. The eluted barren solution from electrowinning will then be recycled back to a 11,000-gallon barren solution storage tank. Solution from the eluted barren tank will be pumped back to the strip vessel to be reused for loaded carbon stripping.

When sufficiently loaded, the electrowinning cells will be shut down, and the gold and silver sludge will be removed from the cathodes. The sludge will then be pumped to a filter press for dewatering, followed by manual transfer of the dewatered cake to a 5 ft3 retort oven for drying and removal of mercury.

The dried and retorted sludge will be blended with fluxes and then smelted in a propane-fired crucible furnace (700 lb red brass capacity), to yield doré. The doré will be shipped off site for final processing and sale.

CommodityParameter

Production:

CommodityUnitsAvg. Annual (Projected)LOM (Projected)
Gold koz 94526
Silver koz 441
All production numbers are expressed as metal in doré.


Reserves at June 2, 2017:

CategoryOreTypeTonnage CommodityGradeContained Metal
Proven Total 13,095,400 tons Gold 0.024 oz/ton 308,500 oz
Proven Total 4,123,900 tons Silver 0.095 oz/ton 391,300 oz
Probable Total 17,434,300 tons Gold 0.019 oz/ton 326,500 oz
Probable Total 10,268,600 tons Silver 0.121 oz/ton 1,241,300 oz
Proven & Probable Total 30,529,700 tons Gold 0.021 oz/ton 634,900 oz
Proven & Probable Total 14,392,500 tons Silver 0.113 oz/ton 1,632,600 oz
Measured Mixed 259,000 tons Gold 0.058 oz/ton 15,000 oz
Measured Oxide 14,232,000 tons Gold 0.022 oz/ton 312,000 oz
Measured Total 14,491,000 tons Gold 0.023 oz/ton 327,000 oz
Measured Oxide 10,550,000 tons Silver 0.119 oz/ton 1,260,000 oz
Measured Mixed 259,000 tons Silver 0.251 oz/ton 65,000 oz
Measured Total 10,809,000 tons Silver 0.123 oz/ton 1,325 oz
Indicated Mill / Sulphide 369,000 tons Gold 0.05 oz/ton 18,000 oz
Indicated Mixed 162,000 tons Gold 0.033 oz/ton 5,000 oz
Indicated Oxide 26,854,000 tons Gold 0.016 oz/ton 439,000 oz
Indicated Total 27,385,000 tons Gold 0.017 oz/ton 462,000 oz
Indicated Mill / Sulphide 369,000 tons Silver 0.313 oz/ton 115,000 oz
Indicated Oxide 6,236,000 tons Silver 0.094 oz/ton 584,000 oz
Indicated Mixed 162,000 tons Silver 0.206 oz/ton 33,000 oz
Indicated Total 6,767,000 tons Silver 0.108 oz/ton 732 oz
Measured & Indicated Mill / Sulphide 369,000 tons Gold 0.05 oz/ton 18,000 oz
Measured & Indicated Mixed 421,000 tons Gold 0.048 oz/ton 20,000 oz
Measured & Indicated Oxide 41,086,000 tons Gold 0.018 oz/ton 751,000 oz
Measured & Indicated Total 41,876,000 tons Gold 0.019 oz/ton 789,000 oz
Measured & Indicated Mill / Sulphide 369,000 tons Silver 0.313 oz/ton 115,000 oz
Measured & Indicated Oxide 16,786,000 tons Silver 0.11 oz/ton 1,844,000 oz
Measured & Indicated Mixed 421,000 tons Silver 0.234 oz/ton 98,000 oz
Measured & Indicated Total 17,576,000 tons Silver 0.117 oz/ton 2,057,000 oz


Proposed Heavy Mobile Equipment as of June 2, 2017:
Source: Source p.198
HME TypeModelQuantity
Dozer Caterpillar D10T 1
Dozer Caterpillar D9T 3
Dozer Caterpillar 834 1
Drill Epiroc DM45 3
Excavator Hitachi EX3600 1
Grader Caterpillar 16M 1
Grader Caterpillar 14M 1
Loader Caterpillar 993K 1
Loader Caterpillar 992K 2
Truck (haul) Caterpillar 785D 9
Truck (water) Caterpillar 773 2

Mine Management:

Job TitleNameProfileRef. Date
Environmental Superintendent Shane Johnson LinkedIn Sep 2, 2020
General Manager Phil Dalke LinkedIn Sep 2, 2020
Health, Safety & Security Superintendent Sandra Polanco LinkedIn Sep 2, 2020
Maintenance Superintendent Art Moretti LinkedIn Sep 2, 2020
Mine Manager Todd Sylvester LinkedIn Sep 2, 2020
Process Superintendent Jessie Link LinkedIn Sep 2, 2020


Corporate Filings & Presentations:

DocumentYear
Annual Information Form 2019
Corporate Presentation 2017
Pre-Feasibility Study Report 2017
Corporate Presentation 2016
Corporate Presentation 2016
Form 10-K 2015
Technical Report 2015

News:

NewsDate
Americas Gold and Silver Corporation Announces Commercial Production at Relief Canyon January 11, 2021
Americas Gold and Silver Provides Update on Relief Canyon October 14, 2020
Americas Gold And Silver Provides Update On Relief Canyon September 10, 2020
Americas Gold and Silver Announces Closing of C$39.4 Million Bought Deal Financing September 4, 2020
Americas Gold and Silver Announces Upsize of Previously Announced Bought Deal Financing to C$35.0 Million August 18, 2020
Americas Gold and Silver Announces C$25.0 Million Bought Deal Financing August 17, 2020
Americas Gold And Silver Announces Closing Of C$28.75 Million Bought Deal Financing May 13, 2020
Americas Gold and Silver Announces C$25 Million Bought Deal Public Offering May 5, 2020
Americas Gold and Silver Pours First Gold at Relief Canyon and Provides Other Corporate Updates February 18, 2020
Americas Gold And Silver Announces Initial Ore Placement At Relief Canyon And Provides A Construction Update December 19, 2019
Americas Silver Announces Creation of a Precious Metal Growth Company April 3, 2019
Americas Silver Corporation and Pershing Gold Corporation Announce Business Combination September 30, 2018
Pershing Gold Announces Positive Feasibility Study for Relief Canyon May 30, 2018
Pershing Gold Begins Preliminary Construction Activities at Relief Canyon February 26, 2018

Aerial view:

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