Gas Hills Uranium Project PEA — 2021 Technical Report

This technical report describes a preliminary economic assessment for a satellite uranium ion-exchange facility feeding a central processing plant.

Report context

The Gas Hills Uranium Project PEA was prepared for Azarga Uranium Corporation in August 2021. The project is designed as an in-situ recovery (ISR) satellite facility that will operate in conjunction with the company’s Dewey-Burdock Project. The satellite plant will house only the ion-exchange (IX) circuit, with loaded resin transported to the Dewey-Burdock Project for elution, precipitation, drying, and packaging.

Processing route

Overall ISR circuit structure

ISR operations consist of four major solution circuits: ion exchange to extract uranium from the mining solution, an elution circuit to remove uranium from the IX resin, a yellowcake precipitation circuit, and a dewatering, drying, and packaging circuit. Because the project will be a satellite facility to the Dewey-Burdock Project, only the first circuit (IX) will be located at the project site.

Satellite operations (proposed design)

Production fluid containing dissolved uranyl sulfate from the wellfields is pumped to the satellite IX plant for beneficiation. The satellite plant considered in this PEA will have an available flow rate of 4,400 gpm. The planned average production flow rate for the project is approximately 2,400 gpm.

The IX circuit will be housed in a metal building that will also house the resin transfer equipment and the restoration circuit. Uranium is extracted from the pregnant solution in the IX circuit. The barren lixiviant is then reconstituted as needed and pH is corrected prior to being pumped back to the wellfield for reinjection.

A low-volume bleed is permanently removed from the lixiviant flow to maintain an inward gradient within the wellfields. The wellfield bleed is disposed of by injection into an Underground Injection Control (UIC) Class I Deep Disposal Well (DDW). During groundwater restoration activities, the bleed is treated by reverse osmosis (RO) to remove metals and salts (calcium, sodium, sulfate) and the clean permeate is reused in the process. The RO brine is then disposed of by injection into the DDW.

Associated with the satellite operation will be office, construction, maintenance, warehouse, and drilling support buildings. Satellite construction is expected to commence in Year -1 upon receipt of the last required permit.

Transportation (proposed design)

Once the IX resin is loaded to a point where it is no longer economically capturing uranium, the IX resin column is taken offline and the loaded resin is moved to a trailer. The resin will be shipped in 1,000 cu. ft. loads with the majority of water drained off prior to shipping. Bulk pneumatic trailers will transport loaded resin to and unloaded resin from the Dewey-Burdock processing plant, located on the Wyoming-South Dakota border between Dewey and Burdock, South Dakota. A contract carrier licensed to haul radioactive materials in Wyoming and South Dakota will be used.

Two possible routes are identified. The preferred route is approximately 250 miles, going north on Gas Hills Road, east on U.S. Highway 20/26, east on Interstate 25, northeast on U.S. Highway 18/85, then east on gravel roads to the Dewey-Burdock Project. The alternate route is approximately 290 miles, going north on Gas Hills Road, east on Wyoming Highway 20/26, north on Interstate 25, east on Wyoming Highways 259, 387, and 450, south on U.S. Highway 85, then east on gravel roads. Once a loaded trailer is delivered, an empty trailer will be immediately returned to the project.

Energy, water and process materials (basis of estimate)

The Gas Hills satellite plant will generally be identical in flow rates and operation to the planned satellite plant at the Dewey-Burdock facility, for which the design is much further advanced. Energy and reagent use will be identical to Dewey-Burdock, adjusted for a change to sulfuric acid and for inflation. The low pH recovery methods are expected to result in higher headgrades and lower water flow rates than the alkaline recovery methods considered for Dewey-Burdock. No reductions in operational costs were made to adjust for this change.

Liquid disposal (proposed design and historical basis)

Typical ISR mining operations generate limited quantities of wastewater that cannot be returned to the production aquifers. Wastewater will come from two sources: wellfield production bleed and satellite processes. The production bleed is a net withdrawal generating an area of low hydrostatic pressure within the mining zone. The wellfield production bleed rate is estimated at 0.5 to 1.0 percent of the total mine flow rate. The wastewater flow rate from satellite processes will be minimal, on the order of 1 gpm, because the facilities will house only the IX circuit. At the planned average production flow rate of 2,400 gpm, liquid wastes for deep disposal will be approximately 22 gpm. One DDW is planned, with a surge pond holding 30 days of wellfield bleed as backup. The CAPEX and OPEX estimates assume this well will support production and restoration operations. Restoration wastewater treatment will entail passing portions of the fluid through a RO system, with permeate returning to the wellfield and brine injected into the DDW.

Solid waste disposal (estimates from similar facilities)

Non-contaminated solid waste is waste not contaminated with radioactive material or waste that can be decontaminated and reclassified. Current estimates from similar uranium ISR facilities are approximately 700 cubic yards per year. This waste will be collected and disposed of in an approved industrial solid waste landfill.

Contaminated solid waste is waste contaminated with radioactive material that cannot be decontaminated, classified as 11e.(2) byproduct material under NRC regulations. This includes filters, personal protective equipment, spent resin, piping, and similar items. It will be shipped by truck to a licensed disposal site. Based on waste generation rates of similar uranium ISR facilities, the project is estimated to produce approximately 90 cubic yards of 11e.(2) byproduct material per year.

Key reported parameters

Technical qualifications

The PEA assumes the Gas Hills satellite plant will be identical in flow rates and operation to the planned satellite plant at the Dewey-Burdock facility, for which design is much further advanced. Energy and reagent use estimates are based on Dewey-Burdock costs adjusted for increased sulfuric acid costs and inflation. No reductions in operational costs were made to adjust for the change to low pH recovery methods. Solid waste generation estimates are based on similar uranium ISR facilities, not site-specific data. The wellfield production bleed rate is estimated at 0.5 to 1.0 percent of total mine flow. The CAPEX and OPEX estimates assume the DDW will support both production and restoration operations.

Source: Gas Hills Uranium Project PEA , 2021 Technical Report, August 2021, Azarga Uranium Corporation, Section 17.0 Recovery Methods through Section 17.5 Solid Waste Disposal.