This Preliminary Economic Assessment describes the processing facilities and recovery methods designed to produce yellowcake from uranium-bearing lixiviant at the Dewey Burdock in-situ recovery project in South Dakota.
Article Body
The 2025 Preliminary Economic Assessment for the Dewey Burdock uranium project outlines a central processing plant (CPP) located on the Burdock property and a satellite facility at Dewey. The two facilities are separated by approximately four miles, and loaded resin is transferred between them by truck. The processing circuits recover uranium from pregnant lixiviant solution through ion exchange, elution, precipitation, dewatering, drying, and packaging. The CPP houses the complete processing flow sheet, while the satellite contains an ion exchange circuit and a resin transfer system.
The process begins with the recovery of uranium from pregnant lixiviant using an ion exchange circuit. Each IX vessel is designed to contain a 500 cubic foot batch of anionic ion exchange resin. Vessels are configured in parallel trains of multiple columns operating in series, using a pressurized downflow methodology for loading. Production booster pumps are located upstream of the IX trains, and injection booster pumps are located downstream. An interior stainless steel piping manifold distributes lixiviant evenly across the resin bed. Dissolved uranium adsorbs onto the resin, and the resultant barren lixiviant exits the vessels with less than 2 ppm uranium before being returned to the wellfield where oxygen and carbon dioxide are added prior to reinjection.
A production bleed is drawn from the injection stream prior to reinjection into the wellfield to maintain control of hydraulic conditions in the production zone. This bleed is directed to a smaller bleed column where residual uranium is collected. The barren bleed is discharged at a constant flow rate to the radium treatment system before entering settling ponds designed for a minimum of 13 days residence time. Water from the settling ponds is tested periodically to confirm conformance with discharge standards and then disposed of via deep disposal wells.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Production flow rate | 4,000 | gpm | Basis for water balance |
| Bleed rate | 40 | gpm | 1% of production flow |
| IX resin batch | 500 | ft³ | Per vessel |
| Barren lixiviant uranium | <2 | ppm | After IX loading |
| Settling pond residence | ≥13 | days | Minimum design |
| Fresh water supply rate | 1.9 | gpm | From Madison formation |
| CPP make-up and washdown | 12 | gpm | Approximate |
| Restoration RO feed | 250 | gpm | During restoration |
| Restoration RO permeate return | 175 | gpm | Returned to wellfield |
| Restoration RO concentrate | 75 | gpm | To liquid effluent management |
| Propane for drying | 1 | MBTUH | One dryer, 12 hours per day |
| Propane for heating | 3.9 | MBTUH | CPP and Satellite, winter months |
| Electricity | 12 | million kWh/yr | CPP and wellfields, peak production |
| Dryer temperature | <300 | °F | Low temperature vacuum dryer |
| Fresh water makeup | 1.9 | gpm | Madison formation well |
| Deep injection wells | 4 | wells | UIC Class V, draft permit contested |
| Deep injection wells installed | 2 | wells | After final approval |
| Product packaging | 55 | gallon | Steel drums |
Overview
The Dewey Burdock project is an in-situ recovery uranium development in the planning stage. The processing scheme is built around ion exchange technology to recover uranium from a pregnant lixiviant solution. The design differentiates between the CPP and satellite functions, with the satellite dedicated to IX loading and resin transfer while the CPP contains the full elution, precipitation, and product finishing circuits. The water balance is based on a production flow rate of 4,000 gpm with a 1% bleed for hydraulic control. Liquid waste disposal is planned through Class V deep injection wells, for which a permit application has been submitted to the EPA and a draft permit issued, though the permit is currently in contestation. Land application is noted as an option but is not included in this PEA.
Key Process Stages
The processing flow sheet follows a sequential series of stages from pregnant lixiviant through to packaged yellowcake. The IX circuit is the primary recovery step, followed by elution, precipitation, and product finishing. Water management and waste disposal are treated as integral process requirements, with specific design criteria for bleed handling and restoration activities.
Ion exchange recovers uranium from the pregnant lixiviant. The IX circuit uses anionic resin in parallel trains of multiple columns operating in series. The vessels are designed to optimize contact time between pregnant lixiviant and resin. The barren lixiviant is returned to the wellfield with less than 2 ppm uranium after oxygen and carbon dioxide are added. The loaded resin transfers to the elution circuit, where a brine solution strips the uranium, and the eluted resin is rinsed and returned to the IX vessels.
The elution circuit uses a sodium chloride and sodium carbonate brine solution to strip uranium from the loaded resin, producing a uranium-rich eluate. The precipitation circuit then adjusts the pH with sulfuric acid to bring the eluate to a pH range of 2 to 3, which breaks down uranyl carbonate and liberates carbon dioxide. Sodium hydroxide raises the pH to 4 to 5, after which hydrogen peroxide is added in a batch process to form an insoluble uranyl peroxide compound. The pH is then raised to approximately 7, and the slurry pumps to a thickener where uranium settles and gravity-thickens into a yellowcake slurry. The uranium-depleted supernate overflows the thickener and is disposed of via a deep injection well after treatment to remove radium and other radionuclides.
Product filtering, drying, and packaging complete the processing circuit. Yellowcake from the thickener underflow is washed to remove excess chlorides and other soluble contaminants. The slurry is dewatered in a filter press, and the filter cake transfers in an enclosed conveyor directly to a low-temperature vacuum dryer. The dryer operates at less than 300°F and is heated by circulating thermal fluid through an external jacket. Off-gases, primarily water vapor, are filtered through a bag house to remove entrained particulates and then condensed. Compared with conventional high-temperature drying using multi-hearth systems, this dryer produces no significant airborne particulate emissions. The dried yellowcake is packaged into 55-gallon steel drums for storage before transport by a licensed trucking contractor to a conversion facility. The drying and packaging stations are segregated within the processing plant for worker safety, with dust abatement and filtration equipment deployed in this area. Filled drums are staged in a dedicated and locked storage until transport.
Solid waste disposal follows classification-based segregation. Non-contaminated waste is disposed of at the nearest permitted sanitary waste disposal facility. Hazardous non-radiological waste is segregated and sent to the nearest permitted hazardous waste facility. Radiologically contaminated solid wastes that cannot be decontaminated are classified as 11.e.(2) byproduct material, and are packaged and stored on site temporarily, then periodically shipped to a licensed 11.e.(2) byproduct waste facility or a licensed mill tailings facility.
Additional Interesting Data and Summary
The water balance includes a production flow rate of 4,000 gpm with a bleed of 40 gpm (1%) to maintain hydraulic control of the mine units. Make-up water for the CPP is supplied from a local fresh water supply well at approximately 12 gpm for process make-up and washdown. Restoration activities include a 250 gpm feed to reverse osmosis, with 175 gpm returned to the wellfield and 75 gpm directed to a liquid effluent management system using lined impoundments and treated water injection into permitted Class V injection wells. Fresh water from a Madison formation well is estimated at 1.9 gpm to meet demand, and a Madison well provides make-up water to minimize wellfield drawdown if necessary.
Liquid waste disposal options include deep well injection and land application. The PEA does not include land application, relying on two Class V wells permitted under EPA, with two additional wells possible if new or additional disposal capacity is needed. In the case of land application, the bleed stream would be treated with ion exchange to remove residual uranium followed by barium chloride treatment to remove radium, with sludge separation achieved in a radium settling pond. Reagent tanks for radium removal are located within the CPP and satellite. Liquid waste will be injected and isolated from any underground source of drinking water. The EPA has issued a draft permit, though it is currently in contestation. Upon final approval, enCore plans to install two wells, one at the CPP and one at the satellite.
Energy requirements are estimated at nearly 12 million kWh annually of electricity to operate the CPP and wellfields during peak production with simultaneous mining and restoration activities. Approximately 3.9 MBTUH of propane is required to heat the CPP and satellite during winter months, and approximately 1 MBTUH of propane is consumed to operate one dryer for 12 hours per day.
Key Processes
- Ion exchange: anionic resin in parallel trains, pressurized downflow loading
- Elution: sodium chloride and sodium carbonate brine strip, uranium-rich eluate
- Precipitation: sulfuric acid acidification, sodium hydroxide pH adjustment, hydrogen peroxide batch precipitation, pH raised to approximately 7
- Thickening: gravity settling of uranyl peroxide precipitate
- Filtration: filter press dewatering, enclosed conveyor
- Drying: low-temperature vacuum dryer at less than 300°F, thermal fluid heating, bag house off-gas filtration
- Packaging: 55-gallon steel drums, dedicated storage
- Bleed management: 40 gpm bleed, radium treatment, settling ponds, deep injection
- Water treatment: reverse osmosis for restoration, barium chloride radium removal, Class V injection
Source: Dewey Burdock PEA , 2025 Technical Report, January 2025. Project website: enCore Uranium Dewey Burdock project
Editorial note: The technical source reports both that land application "has not been included in this PEA" and describes land application treatment processes as options that "can be used for disposal of liquid waste generated during production and restoration." The article shows the source's direct statement that the PEA does not include land application, while retaining the description of the option. No other contradictions were identified in the source material.
Project website: Dewey Burdock PEA, 2025 Technical Report
