The report describes a proposed in-situ recovery uranium processing scheme employing a satellite ion-exchange plant at Churchrock and a central processing plant at Crownpoint for elution, precipitation, drying, and packaging.
Report context
This technical report, dated January 8, 2024 (SLR Project No. 138.21102.00001), supports a Preliminary Economic Assessment (PEA) for the Churchrock Uranium Project. The processing description covers four major solution circuits: recovery, elution, precipitation and filtration, and drying and packaging. The recovery circuit is located at Churchrock in Section 8, and loaded resin is trucked to the Crownpoint central processing plant (CPP) for processing and packaging of U₃O₈.
Processing route
Recovery circuit and ion exchange
The recovery circuit at the initial production area includes the flow of lixiviant from the wellfield to filters, then onto ion exchange (IX) columns, and then back to the wellfield. Uranium liberated underground is extracted in the ion exchange system of the process plant. A bleed of approximately 1% of the circulating groundwater flow from the circuit is permanently removed from the lixiviant flow. The bleed is disposed of by means of a reverse osmosis system with approximately 0.2% of the circulating lixiviant being rejected as brine to an evaporation pond, and an additional 0.8% used for plant make-up water. Upon the completion of resin loading, the loaded resin from the IX columns is transferred to the Crownpoint CPP elution circuit via truck.
Elution circuit
In the elution circuit, the uranium-loaded resin bed from the IX column is transferred into an elution column and a briny-carbonated solution is circulated through the resin bed to strip the uranium from the ion exchange resin. The barren, or eluted, ion exchange resin is then transferred back to the Churchrock IX column via truck. The elution circuit produces an eluate containing approximately 30 g/L uranium. The eluant is an aqueous solution containing salt and sodium bicarbonate. Chemical equations for the elution process, where R denotes active sites for the ion exchange resin, are listed in the report.
Precipitation and filtration circuit
In the first stage of the precipitation and filtration circuit, acid is added to the uranium-rich eluate to destroy the carbonate portion of the dissolved uranium complex. To de-carbonate the uranium-rich eluate, hydrochloric acid lowers the pH of the system to below 2. The precipitation reagents, hydrogen peroxide and sodium hydroxide, are then added to the eluate to precipitate uranium yellowcake slurry.
Drying and packaging circuit
The precipitated yellowcake slurry is sent through the drying and packaging circuit. In the first step, a filter press washes and partially dries the slurry, yielding a roughly 50 weight percent dry solids cake. The yellowcake is further dried in a rotary vacuum dryer to remove the remaining water, yielding a final product of approximately 99 weight percent U₃O₈. The dried yellowcake is then packaged into drums for final delivery to end users.
Proposed processing facilities
The project uses one satellite plant located at the initial production area for the recovery circuit. Telesto designed a conceptual process flow diagram associated with the satellite plant. Using the desired flow rate of lixiviant and the process flow diagram, a material and flow balance determined the sizing of the equipment. The satellite plant equipment includes sand filters, ion exchange units, settling tanks, bag filters, pumps, a reverse osmosis system, bicarb mixing and pumping equipment, and a diesel generator, among other items. The satellite plant consumes reagents daily and requires stockpiling to maintain production.
Yellowcake production at the Crownpoint CPP consists of three circuits: elution, precipitation and filtering, and drying and packaging. Using the mass of loaded resin produced in the ion exchange column at Churchrock, a mass balance determined the size and quantity of required equipment. The CPP equipment includes elution columns, elution tanks, precipitation tanks, pumps, a plate and frame filter press, a rotary vacuum dryer, and a heat exchanger, among other items.
Loaded resin and stripped resin are transported from Churchrock to the Crownpoint facilities generally once per day, with two trips required every third day. The report states that NuFuels owns the truck and that New Mexico Department of Transportation (DOT) labor rates apply. The shipping rate for loaded resin is 46,200 lb/day (3,000 lb U₃O₈, 43,200 lb beads).
Waste disposal
Liquid effluents are primarily generated from process bleed, process solutions, plant washdown water, eyewash and safety showers, and restoration water. These effluents are disposed of in evaporation ponds. The recovery circuit located in the satellite plant utilizes a reverse osmosis system to purify the water before discharge. The Churchrock evaporation pond accepts the reverse osmosis brine. The Crownpoint CPP uses an evaporation pond for filter press filtrate wash water and water cooled from the rotary vacuum dryer.
The report considers both contaminated and non-contaminated waste based upon gamma readings. Non-contaminated waste includes trash, piping, valves, and filters, estimated at approximately 16,875 ft³. Spent resin, spent personal protective equipment (PPE), and residue from the evaporation ponds comprise the primary contaminated waste. Due to radioactivity, contaminated waste must be shipped to an appropriate disposal facility. The report estimates spent resin waste at approximately 833 ft³ from each of the six columns after eight years of use. The residue from the evaporation pond will be approximately 420,000 ft³ at year 10. Waste from PPE is generated daily and estimated at approximately 40 ft³.
Key reported parameters
| Parameter | Value | Unit | Basis |
|---|---|---|---|
| IX column design flow rate | 3,000 | gpm | Design |
| Process bleed flow | ~1% of pregnant lixiviant (~30 gpm) | gpm | Design |
| Eluate uranium concentration | ~30 | g/L | Design |
| Final product grade | ~99 | wt% U₃O₈ | Design |
| Filter press cake solids | ~50 | wt% | Design |
| Loaded resin shipping rate | 46,200 (3,000 lb U₃O₈, 43,200 lb beads) | lb/day | Design |
| Churchrock evaporation pond size | 100 × 1,680 × 2.5 ft (420,000 ft³) | ft | Design |
| CPP evaporation pond size | 200 × 200 × 10 ft each | ft | Design |
| Satellite plant concrete foundation | 200 × 200 | ft | Design |
| CPP concrete foundation | 150 × 200 | ft | Design |
| Ion exchange resin life | 8 | years | Design |
| Reverse osmosis system capacity | 62 | gpm | Design |
| Reverse osmosis membranes | 18 | EA | Design |
| Evaporation pond liner life | 5 | years | Design |
| Sand filter capacity | 1,500 | gpm | Design |
| Ion exchange units | 6 | EA | Design |
| Ion exchange unit size | 1,000 gpm, 850 ft³ | gpm, ft³ | Design |
| Elution column size | 1,300 | ft³ | Design |
| Plate and frame filter press size | 55 | ft³ | Design |
| Precipitation tank capacity | 15,500 | gallons | Design |
| H₂O₂ consumption at satellite plant | 131 | lb/day | Design |
| NaCl consumption at CPP | 12,750 | lb/batch | Design |
| NaHCO₃ consumption at CPP | 2,969 | lb/batch | Design |
| HCl consumption at CPP | 370 | gal/batch | Design |
| H₂O₂ consumption at CPP | 154 | gal/batch | Design |
| NaOH consumption at CPP | 123 | gal/batch | Design |
Project website: https://laramide.com/projects/crownpoint-churchrock-uranium-project/
Technical qualifications
The report is a PEA-level study. The flows shown in the flow sheets are examples of the capacity for the facilities and do not show regulatory or design limits. The processing facilities are typical for this service and industry standard, and Telesto stated the opinion that processing facilities are suitable for this purpose and can be scaled up or down accordingly. Vendor pricing and actual cost values from existing sites and previous designs support the cost estimates. The report does not present historical operating data or testwork results.
Source: Churchrock Uranium Project , 2024 Technical Report, Section 17.0 Recovery Methods, January 8, 2024, SLR Project No. 138.21102.00001.
