Milling
Key Lake is currently processing ore from the McArthur River mine and from stockpiles on site. The mill has an annual production capacity of 18.7 million pounds U3O8, the largest capacity in the world. In addition, ammonium sulphate fertilizer is produced by recycling reagents.
Each major step in the milling process is contained in separate buildings. Material is transported from building to building in pipelines as a solution or slurry. The major steps in the process include:
- grinding, which breaks rocks into sand
- leaching to dissolve uranium
- separation of uranium solution from waste solids
- solvent extraction to produce a purified uranium solution
- yellowcake precipitation and calcining which recovers uranium as granular powder
- crystallization which recovers ammonia reagent as ammonium sulphate fertilizer
- bulk neutralization to treat waste from the solid-liquid separation and solvent extraction processes as well as water from the mine and tailings area