A Preliminary Economic Assessment for the Westmoreland Uranium Project outlines a processing route based on single-stage SAG milling, sulfuric acid leaching, and continuous ion exchange to produce a uranium oxide concentrate. The project is located in Queensland, Australia, and is owned by Laramide Resources Ltd.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Plant Throughput | 2,900,000 | tpa | Design value |
| Head Grade | 788 | U ppm | Design value |
| U3O8 Production | 4,786,098 | lb/y | Calculated |
| Overall Recovery | 95 | % | Client supplied |
| Crushing Plant Availability | 80.0 | % | Client supplied |
| Plant Availability | 91.3 | % | Client supplied |
| Bond Ball Mill Work Index (BWi) | 19.4 | kWh/t | Testwork result |
| Bond Rod Mill Work Index (RWi) | 21.0 | kWh/t | Assumed |
| Bond Abrasion Index (Ai) | 0.2 | Not stated | Assumed |
| Grind Size | 180 | µm | Design value |
| Mill Discharge pH | 4.0 | Not applicable | Lycopodium supplied |
| Pre-Leach Thickener Solids Loading | 0.38 | t/m2.h | Testwork result |
| Leach Residence Time | 12 | h | Testwork result |
| Leach Temperature | 40 | °C | Testwork result |
| Leach pH | 1.5 | Not applicable | Testwork result |
| Leach [Fe] | >2.5 | g/L | Testwork result |
| Leach ORP | 500 | mV | Testwork result |
| Acid Addition | 24 | kg/t | Testwork result |
| Leach Extraction | 96 | % | Testwork result |
| Leach Filter Flux | 315 | kg d.s./m2.h | Assumed |
| Pyrolusite Grind Size P80 | 45 – 54 | um | Testwork result |
| Pyrolusite Available MnO2 | 75 | % | Assumed |
| Pyrolusite Addition Rate | 6.4 | kg/t | Testwork result |
| Ion Exchange Adsorption | Mod NIMCIX | Not applicable | Assumed |
| Ion Exchange Resin | Amberjet 4400 | Not applicable | Testwork result |
| Exchange Form | SO4 – HCO3 form | Not applicable | Assumed |
| Total Exchange Capacity | >1.4 | eq/L | Assumed |
| Design U Load | 40 | g/L(wsr) | Assumed |
| Elutriation Volume | 7.5 | m3/m3 resin | Assumed |
| Acid Neutralization pH | 2 – 3 | Not applicable | Assumed |
| Acid Neutralization Temperature | 40 | °C | Assumed |
| NaOH to UOC | 4.94 | kg/lb U3O8 | Calculated |
| H2O2 to UOC | 0.21 | kg/lb U3O8 | Calculated |
| Acid Neut. Thickener Area Flux | 16 | t/m2.h | Assumed |
| Acid Neut. Residue Filter Flux | 75 | kg d.s./m2.h | Assumed |
Overview
The process flowsheet for the Westmoreland Uranium Project was selected after evaluating available geology, mineralogy, and metallurgical testwork results. The study basis aims for a robust treatment method that provides a sound foundation for capital and operating cost estimates at a scoping study level of accuracy. The design incorporates recent trends in uranium milling technology.
Run-of-mine ore from an open pit, at a maximum lump size of 900 mm, is transported to the plant by rear tipping dump trucks. Ore is tipped directly into the ROM bin or onto the ROM pad for emergency storage and blending. A rock breaker assists with oversize material on the grizzly above the ROM bin. Ore passes through a vibrating grizzly ahead of a jaw crusher, with fines bypassing the crusher directly to the discharge conveyor.
The process water system integrates recycled streams throughout the plant. Barren solution from the continuous ion exchange circuit is recycled as wash to the leach residue filters. That washate returns to the pre-leach thickener where most of the contained acidity is neutralized by gangue in the ore. Pre-leach thickener overflow, mildly acidic, serves as dilution water in the milling circuit.
The project requires approximately 98,000 tonnes per annum of 98% sulfuric acid for ore leaching and ion exchange elution. An onsite sulfur burning contact acid plant will produce this acid. The Metso process recovers surplus energy as steam, which is sent to a pass out turbo alternator that generates 1.6 MW of electric power for site use.
Key Process Stages
The flowsheet includes ROM pad blending of different ore types for optimum leach recovery. Single stage primary crushing in a jaw crusher produces a crushed product size of P80 130 mm. A crushed ore bin with 1,900 t live capacity provides 5 hours of operation at design throughput.
The grinding circuit is a SS SAG/C type with a closed circuit SAG mill and pebble crusher. The SAG mill operates in closed circuit with hydrocyclones to produce a grind size of P80 180 µm. A 9.14 m diameter by 7.51 m SAG mill with 10.5 MW installed motor power is specified. Grinding media of 125 mm balls are added to the mill.
A pre-leach thickener increases slurry density to the leach circuit, minimizes leach tank volume requirements, and partially neutralizes filter wash returned to the milling circuit. Underflow slurry from the thickener is pumped at 55% solids density.
The leach circuit consists of six mechanically agitated rubber lined and insulated mild steel tanks in series with a total residence time of 12 hours. Sulfuric acid at 98% concentration is added to maintain a pH of 1.5. The first leach tank receives approximately 4°C of heat from acid dilution, with the balance of energy to reach 40°C provided by direct steam addition. Pyrolusite oxidant with 48% soluble manganese is added as a finely ground slurry to maintain an oxidation-reduction potential of 500 to 550 mV.
Leach residue filtration recovers leached uranium in pregnant liquor and produces a washed dry filter cake for disposal. The filtration system uses vertical chamber pressure filters with inflatable membranes. Four primary filters with a total filtration area of 2,380 m2 operate in parallel, each with 62 chambers of 40 mm depth using a 2.5 m by 2.5 m plate size. Secondary filters handle the repulped residue. The washed filter cake is removed at approximately 18.7% free moisture.
Continuous ion exchange separates soluble uranium from the leach pregnant solution. The system uses a two fluid bed modified NIMCIX extract column and eight fixed bed columns for resin receipt, rinse, elution, regeneration, wash, and resin elutriation. A uranium loading of 40 g/L on the resin is targeted. The elution process runs at 40°C using 1.2 molar sulfuric acid to produce a concentrated eluate containing approximately 7.5 g/L uranium.
Impurity removal separates predominantly iron and some manganese, silicon, and aluminum by acid neutralization with caustic soda prior to UOC production. The iron precipitate is thickened, with a portion recycled to the precipitation circuit as seed and the remainder returned to the leach circuit.
Crude UOC is precipitated from the iron-free pregnant eluant using hydrogen peroxide and sodium hydroxide. The UOC is washed through a combination of filtration and centrifuging, then dried in a continuous horizontal kiln and transferred under gravity to a storage hopper. The dry product is weighed into clean, thick wall 200 L drums, with approximately 300 kg of UOC per drum, and packed into 20 t containers for shipment. The UOC product will assay approximately 70% uranium.
Additional Interesting Data and Summary
The process flowsheet avoids patented technologies and excludes limestone addition as an initial acid neutralization step. Sodium hydroxide was selected instead to simultaneously remove soluble iron transferred within the interstitial fluid. The UOC may attract penalties because of this modified impurity removal step. Alternative neutraliing agents could be substituted without significant cost or process implications.
The pre-leach thickener may be unnecessary if future testwork shows cyclone discharge provides adequate discharge density. Emissions from the atmospheric leach circuit are expected to be low, but no allowance has been made for vent collection and scrubbing. This needs further consideration as the project develops.
A 700 m3/h cooling water system with a heat load of 8 MW is required for the acid plant. A 2 tph low pressure steam boiler supports the uranium refinery. Plant and instrument air at 700 kPag is provided by two high pressure air compressors in a lead-lag configuration.
Sulfur for the acid plant will be trucked from Townsville and stored in a covered shed. The annual sulfur requirement is 34,499 tpa of prilled or flaked sulfur.
Key Processes
- ROM pad blending of ore types for optimum leach recovery.
- Single stage primary crushing in a jaw crusher to P80 130 mm.
- Crushed ore bin with 1,900 t live capacity providing 5 hours operation.
- Grinding circuit with SS SAG mill and pebble crusher in closed circuit with hydrocyclones to P80 180 µm.
- Pre-leach thickener to increase slurry density and partially neutralise filter wash.
- Leach circuit with six agitated tanks, 12 hour residence time, sulfuric acid at pH 1.5, and pyrolusite oxidant.
- Leach residue pressure filtration with vertical chambers and inflatable membranes.
- Continuous ion exchange using modified NIMCIX columns and fixed bed columns.
- Impurity removal by acid neutralisation with caustic soda.
- UOC precipitation with hydrogen peroxide and sodium hydroxide.
- UOC washing, drying, and packaging into 200 L drums and20 t containers.
- Onsite sulfuric acid production from sulfur burning with heat recovery and 1.6 MW power generation.
Source: Laramide Resources Ltd. Westmoreland Uranium Project Preliminery Economic Assessment Update National Instrument43-101 Technical Report,22 July2026. Project website: Westmoreland Uranium Project
