Shirley Basin is a past producing uranium mine located in Wyoming, the US. The property is owned by Ur-Energy (URE), a uranium mining, recovery, and processing company based in the US.
The company plans to advance with a commercial satellite uranium in-situ recovery (ISR) operation at the site.
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An Initial Assessment Technical Report Summary on Shirley Basin ISR Uranium Project has also been filed. By May 2021, the project received all major permits and licences required to begin construction.
In March 2024, Ur-Energy announced its decision to build the fully permitted and licenced Shirley Basin Project.
Construction works at Shirley Basin are expected to be completed in late 2025.
Shirley Basin Project Location
The project is located in Carbon County, Wyoming, approximately 64.37km (40 miles) south of Casper city. in northern Wyoming.
Overall, URE controls approximately 3,536 acres of property interests in the project area. Of which, the fully permitted area of the project covers a total of 1,770 acres.
The Shirley Basin ISR Project is accessible by Wyoming Highway 487.
Ownership and Production History
The ownership history dates back to the time when Utah Mining and Tidewater Oil initially acquired the land in the late 1950s.
Initially, Utah acquired the eastern FAB Resource Area and Area 5 from third parties and by 1963, the company acquired title and interest to the unpatented lode claims from third parties. It then merged with Utah Construction and Mining.
In 1973, the company sold its interest to Utah International. Additionally, Tidewater merged with Getty in the same year.
After the merger, Getty received additional patents for lode and mill site claims. This completed the interests in the western FAB Resource Area.
Utah International transferred its interest to Lucky Mc Uranium in 1976 which then changed its name to Pathfinder Mines.
In 1984, Getty transferred its interest to Getty Mining which conveyed it to Petrotomics. Petrotomics then transferred its interest to Pathfinder in 1985. Pathfinder Mines was acquired by COGEMA Mining in the 1980s.
URE became the owner of the Shirley Basin and Lucky Mc mine sites following the acquisition of Pathfinder in 2013.
Historically, the sites have produced more than 71 million pounds of uranium (U3O8) from 1960s through the 1990s.
Operations were suspended in the 1990s due to low uranium pricing.
Geology and Mineralisation
Uranium mineralisation in the project area is primarily hosted within the arkosic sandstones of the Eocene-age Wind River Formation.
The formation was deposited on gently dipping sandstones and shales of the Cretaceous-age Niobrara and Frontier Formations. The Wind River Formation is overlain by the White River Formation.
The Wind River Formation is characterised by thick medium to coarse-grained arkosic sandstones. These sandstones are separated by thick claystone units.
The arkosic sandstones and claystone units are typically 20-75ft thick. The formation also hosts minor thin lignite and carboniferous shale beds.
According to the technical report, the average thickness of the Wind River Formation within the project is approximately 230 ft.
The sandstones are of two types- Main and Lower Sands.
The uranium mineralisation at the project occurs in the form of roll front deposits at the Main Sand or the Lower Sand.
Shirley Basin Mineral Resource Estimate
The Shirley Basin Uranium Project is projected to host 8.8 million pounds eU3O8 (uranium ore equivalent) in the Measured and Indicated categories, averaging 0.23% eU3O8.
The company expected to recover approximately 6.4 million pounds.
Mining at Shirley Basin
As mentioned, URE plans to employ the ISR mining technique at the project. Previous commercial ISR operations in the district were successful.
This mining method will use injection wells to insert a lixiviant into the mineralised zone. The lixiviant is composed of native groundwater, oxygen as an oxidiser, sodium bicarbonate as a complexing agent, and carbon dioxide for pH control.
The oxidiser will convert the uranium compounds from a relatively insoluble state to a soluble state, while the complexing agent will bond with the uranium to form uranyl carbonate.
Uranyl carbonate, which is highly soluble, will be recovered via new production wells and transported to a processing plant.
At the processing plant, the uranyl carbonate will be removed from the solution using ion exchange.
Subsequently, oxidiser and complexing agent will be again added to groundwater and transported back to the wellfield to recover additional uranium.
Processing and Transportation
The ISR method to process and recover uranium from the Shirley Basin ISR Uranium Project will consist of four major solution circuits- Uranium recovery/extraction circuit (IX); Elution circuit; Yellowcake precipitation circuit; and Dewatering, drying, and packaging circuit.
The production fluid from the wellfields will be pumped to the satellite plant for beneficiation. The IX circuit of the plant will process fluid and extract uranium from the pregnant solution in the 6,000 gallons per minute (gpm) IX circuit.
The barren lixiviant is reconstituted and pH is corrected using carbon dioxide before being pumped back to the wellfield for reinjection.
A low volume bleed is removed from the lixiviant flow and is treated by RO to remove salts and metals. The clean permeate is then reused in the process or recycled to aquifers, while brine will be disposed of in evaporation ponds.
Loaded resin is filled onto a trailer and will be transported to the Lost Creek Mine.
Project Infrastructure
Shirley Basin Project infrastructure will include a processing plant, up to six holding ponds to hold wastewater and brine, water wells, wellfields, power facilities, solid and liquid waste disposal facilities.
Currently, well WW22 is being used to supply water to the project. WW22 can produce over 25 gallons per minute (gpm) of water.
The uranium mine is expected to use a regional power transmission line of 69kV passing through the northern part of the project for electricity.
Before operations, the existing substation will be upgraded, and new power lines will be connected to the satellite plant and wellfields.
Key Contractors Involved
Western Water Consultants (WWC) Engineering prepared the March 2024 technical report of the Shirley Basin ISR Uranium Project.
In 2021, URE hired Inberg-Miller Engineers for geotechnical drilling, testing, and analysis for the proposed plant foundation and two westernmost proposed holding ponds.
