The Revenue-Virginius mine is a polymetallic deposit located 8.8km away from Ouray, in the Sneffels mining district in south-west Colorado, US.
Owned by Aurcana, the mine is estimated to produce 3.1 million ounces (Moz) of silver-equivalent a year over its life of mine (LOM) of 6.5 years. The mine development is expected to involve an initial investment of $36.8m.
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Revenue-Virginius mine history and background
The Revenue-Virginius mine was discovered in 1876 and started production in 1880. The operations at the mine were terminated due to flooding in 1906.
Star Mine Operations acquired the mine in 2011 and resumed production at the mine in 2014. Lower production and tumbled commodity prices, however, forced to close the operations at the mine for the second time.
Fortune Minerals purchased the mine through its subsidiary Fortune Revenue Silver Mines in 2014 using funding from LRC Group. LRC was foreclosed and Fortune Revenue Silver Mines was renamed as Ouray Silver Mines in 2015.
The LRC Group signed a letter of intent (LoI) to further sell the mine to Aurcana Corporation in July 2018.
Geology and mineralization
Silver, gold, copper, lead and zinc mineralization is found in three quartz veins hosted in San Juan volcanic rocks within the property. The veins are respectively named Virginius, Terrible and Yellow Rose. The veins in the property have a maximum width of 6ft.
Revenue-Virginius mine reserves
The proven and probable mineral reserves of the mine as of June 2018 were estimated to be 575.1 kilo short tonne (kst) grading 24.7oz/st silver, 0.06oz/st gold, 4.97% lead and 2.15% zinc containing 14,202 kilo ounces (koz) of silver, 32.8koz of gold, 57,138klb of lead and 24,707klb of zinc.
Mining method
The mine will employ rescue mining method using waste rock as backfill for the stope, which is then advanced in an overhand manner. The method will enable mining narrow vein structures with widths up to 0.5ft.
Mining stopes/panels will be identified in the long section based on the resource model. The economic viability to mine a stope will be identified by calculating the average dilution of the stope.
The mining widths of the stopes measure up to 1.5ft in Virginius and Terrible deposits, and 2.5ft in Yellow Rose.
Stopes measuring up to 1,000ft along strike and up to 300ft height will be identified. An off-ore access along the length of the stope, cribbed manways to any level of the stope, and a three-compartment service raise with a manway, ore pass and equipment slide will be created as the primary access.
Processing at Revenue-Virginius mine
The processing plant at Revenue-Virginius mine will use conventional crushing, grinding, flotation, and concentrate dewatering process to produce zinc and lead concentrates separately.
The processing plant will have a capacity of 91,390t/y and will be capable of recovering 95% lead and 86% zinc.
The run-of-mine (RoM) ore from the mining site will be transported by rail to the crushing circuit and will then be transferred to a rod mill in open circuit and a ball mill in closed circuit.
The ball mill slurry will be sent to a flotation circuit equipped with rougher, cleaner and final column facility for concentration.
Up to 30 super sacks of concentrates will be produced a day and will be transported to the Ouray warehouse for shipping to customers.
Infrastructure
The mine will utilize infiltrated groundwater, which is collected in a settling pond and treated by a bio-reactive treatment system.
Power supply to the mine will be through an existing three-phase 12.47kV overhead powerline. An existing 1MW generator at the mine will be replaced by a new 3MW emergency generator as part of the plant restart operations.
The mine is currently served by an existing warehouse in Ouray. The warehouse accommodates administrative offices, a parking lot, and a laydown yard.
Contractors involved with Revenue-Virginius mine
SRK was contracted for preparing the feasibility study of the project.
S&P Global Market Intelligence was contracted for analyzing the appropriate price of the products of the project.
Bluequest Resources conducted a study to finalize the smelter price for the products of the mine.
Barr Engineering was contracted to estimate the capital cost of the processing plant at Revenue-Virginius mine.
