This 2012 Preliminary Economic Assessment technical report update describes the conceptual design for a uranium in-situ leach project with a central processing plant and satellite ion-exchange facility planned for a nine-year mine life at a production rate of 1 million pounds per year.
Article Body
The Dewey-Burdock uranium project, located in South Dakota, is planned as an in-situ leach (ISR) operation that would use a central processing plant at the Burdock site and a satellite facility at the Dewey site, located approximately 4 miles apart. This 2012 technical report update presents a Preliminary Economic Assessment (PEA) that provides a conceptual design for the processing facilities, including sizing of major equipment, a mass balance for the uranium recovery circuits, a water balance, and an estimate of the full-time workforce required for operation. According to SRK Consulting, which prepared the report, the proposed facility and process design are essentially industry standard for ISR uranium recovery.
The project assumes an annual operating schedule of 350 days, 24 hours per day, with daily production required of 2,857 lb of U3O8. The design basis includes a head grade of 60 ppm uranium from the well field, with an ultimate uranium extraction of 75% assumed during well field operation. The report notes that this recovery value is an estimate based on similar existing operations in Powertech's experience profile. SRK recommends acceptance of the 75% recovery assumption for this Preliminary Assessment. The plant design includes an IX process line at the central processing plant, with loaded resin trucked from the satellite facility to the central plant for elution, precipitation, product washing, filtering, drying, and packaging.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Indicated resources | Not stated | lb U3O8 | Referenced as 1,000,000 in table context for annual production |
| Mine life | 9 | yr | Based on current potentially mineable resource studies |
| Daily operating schedule | 24 | h/d | Not stated |
| Annual operating schedule | 350 | d/yr | Not stated |
| Daily production required | 2,857 | lb U3O8/d | Not stated |
| Annual yellowcake production | 1,000,000 | lb U3O8/yr | Not stated |
| IX feed flow rate (Burdock) | 2,400 | gpm | Not stated |
| IX feed flow rate (Dewey) | 1,600 | gpm | Not stated |
| IX feed flow rate (Total) | 4,000 | gpm | Not stated |
| Head grade from well field to IX | 0.060 | g/L | 60 ppm |
| Barren solution grade | 0.002 | g/L | Not stated |
| Total recovery in IX columns | 97 | % | Not stated |
| Dried yellowcake mass flow | 121 | lb/h | Not stated |
| Dried yellowcake solids | 99.0 | % | Not stated |
| Daily yellowcake production | 2,875 | lb/d | Predicted from mass balance |
| Filter cake solids | 40.7 | % | In precipitation feed |
| Resin volume per IX vessel | 500 | ft³ | Fixed diameter 12 ft |
| Thickener diameter | 30 | ft | Additional storage capacity required |
| Filter press size | 65 | ft³ | Quotes obtained |
| Mobile equipment lease period | 5 | yr | Not stated |
| Workforce (full operation) | 84 | staff | Central and satellite facilities |
| Aquifer feed | 120 | gpm | Production well field |
| Aquifer feed | 52 | gpm | Drilling, roads, etc. |
| Recycle | 3,880 | gpm | From process |
| Total from aquifer | 336 | gpm | Not stated |
| Total to deep disposal well | 127 | gpm | Not stated |
| Resin haul per day | 9 | t | ISR daily yield |
| Truck design | 25 | t | Tandem axle, dual wheel |
| Drying temperature | <300 | °F | Low temperature vacuum dryer |
| Drying batch time | 16 | h | Typical for uranium applications |
| Yellowcake transport | 55 | gal | Steel drums |
| Yellowcake shipments | 295 | Not applicable | Over life of mine |
| Uranium peroxide dried | 3,300 | lb/d | For 1,000,000 lb/yr U3O8 |
| Sludge classification | Not stated | Not stated | 11(e) (2) byproduct material |
| Main floor slab thickness | 12 | in | Double steel reinforcing |
| Deep disposal well injection | Not stated | Not stated | Both formations suitable per preliminary studies |
| Liquid waste disposal method | Not stated | Not stated | Deep well injection with reverse osmosis considered in economic analysis |
| Process water source | Not stated | Not stated | Local aquifer water |
Overview
The Dewey-Burdock project is planned as an in-situ leach uranium recovery operation. The processing design consists of a Central Processing Plant (CPP) at the Burdock site and a Satellite Facility at the Dewey site, with a distance of approximately 4 miles between the two facilities. The conceptual design criteria, summarized in Table 14.1 of the report, provide the basis for the economic analysis. Key parameters include a nine-year mine life, 24-hour daily operation, 350 operating days per year, and daily production of 2,857 lb of U3O8. The average uranium concentration in the well field feed for this design is 60 ppm. SRK Consulting made formatting changes to fit this report, and the report includes SRK comments and opinions where present.
The IX loading vessels are capable of processing 3,000 gpm of 60 ppm lixiviant. The elution, precipitation, product washing/filtering, drying, and packaging circuits are designed to process more than 2,857 lb U3O8 per day, equivalent to 1 million lb per year. The IX vessels were sized using a fixed diameter of 12 ft and a resin volume of 500 ft³. Trucks will transfer resin between the Satellite Facility and the Central Processing Plant. The estimated full-time staff for the Dewey-Burdock project during full operation of the Central Processing Facility, Satellite Facility, and all associated well fields is 84 staff.
Key Process Stages
The recovery of uranium by ion exchange involves the following process circuits, each described in detail in the technical report:
Resin Loading. The Burdock CPP resin loading circuit processes lixiviant from the well field, with a head grade of 60 ppm uranium. The loading vessels have a capacity of 3,000 gpm of 60 ppm lixiviant. The IX columns achieve a predicted total recovery of 97%, with a barren solution grade of 0.002 g/L.
Production Bleed. A production bleed circuit is part of the IX process, though specific details for the bleed stream are not provided in the excerpts.
Resin Elution. The elution process consists of four stages. Three eluant stages contact one 500 ft³ batch of resin with four bed volumes of eluant each, and one rinse stage contacts the batch with four bed volumes of fresh water. Loaded resin is transported by truck from the Dewey satellite facility to the Burdock central processing plant.
Precipitation. The uranium-depleted supernate solution overflows the thickener and is processed further. The report indicates a 30 ft diameter thickener was selected for the project, providing additional storage capacity for yellowcake slurry. The precipitation circuit produces a slurry that is fed to a filter press.
Product Washing, Drying, and Packaging. The slurry is dewatered in a filter press, with the filter cake transferred by enclosed conveyor directly to the yellowcake dryer. Quotes were obtained for 65 ft³ sized filter presses. The yellowcake is dried in a low temperature (<300°F) vacuum dryer. These are batch dryers that typically take 16 hours to process a batch in uranium applications, with one batch equal to one day of production of yellowcake. For instance, production of 1,000,000 lb/yr of U3O8 will require drying of approximately 3,300 lb/d of uranium peroxide (UO4·2H2O) product.
Additional Interesting Data and Summary
The project includes a radium settling pond system at the central processing plant where radium will be precipitated. The resulting sludge is classified as an 11(e)(2) byproduct material. For liquid waste disposal, Powertech retained Petrotek Engineering Corp., with preliminary studies indicating that two formations are suitable for injection of wastewater. Deep well disposal with reverse osmosis was the wastewater disposal option investigated, and only deep well injection was considered in the economic analysis. Powertech is also investigating land application of treated water as a disposal method. The total flow to the deep disposal well is predicted to be 127 gpm.
Solid waste disposal at the ISR facility will include spent resin, empty packaging, tank sediments, and other materials that will be reviewed and entered into waste stream classifications on site. Non-contaminated waste will be disposed of at the nearest permitted sanitary waste disposal facility. The main floor slab in the central processing plant is designed at 12 in thick with double steel reinforcing, based on AASHTO design Tandem Load Vehicle with 25 kip load on each axle. The floor covering requires a special epoxy blend that needs slab preparation and several layers. Soil conditions are unknown.
Yellowcake will be transported in 55 gal steel drums following standard industry protocols, with approximately 295 shipments estimated over the life of the mine based on the present resource estimate. Major mobile equipment will include resin haul trucks, and several pieces of heavy equipment for excavation of mud pits, road maintenance, and reclamation activities. Powertech will lease mobile equipment for a 5-year period. Dedicated maintenance facilities will be constructed along with the central processing plant; the most commonly overhauled equipment will be the submersible pumps utilized on the recovery wells. A single source of process water is planned: local aquifer water. Staff schedules will vary based upon duty.
The predicted mass balance results indicate that the proposed flow rates and recoveries will produce the target daily yellowcake production. The conceptual design criteria and mass balance results were independently spot checked by Lyntek using data from the Design Criteria.
Key Processes
- In-situ leach (ISR) mining with well field
- Ion exchange (IX) resin loading at satellite and central facilities
- Resin transport by truck between sites (approximately 4 miles)
- Production bleed circuit
- Four-stage resin elution (three eluant stages plus one rinse stage)
- Uranium precipitation with thickener (30 ft diameter)
- Filter press dewatering (65 ft³ filter presses)
- Low temperature (<300°F) vacuum drying of yellowcake
- Product washing, packaging, and transport in 55 gal steel drums
- Radium removal via settling pond and precipitation
- Deep well disposal of wastewater
- Solid waste classification and disposal
Source: Dewey-Burdock PEA Update , 2012 Technical Report, 2012. Project website: Powertech Uranium Corp. (https://www.federalregister.gov/documents/2025/12/19/2025-23415/powertech-usa-inc-dewey-burdock-in-situ-uranium-recovery-project-draft-programmatic-agreemen)
Project website: Dewey-Burdock PEA Update, 2012 Technical Report
