Recovery of uranium from the iron-rich phosphoric acid of Arafura

Arafura Resources is an Australian based mineral exploration and development company currently developing the Nolans Rare Earths-Uranium project. Raw Phosphoric Acid (PA @ 18% P₂O₅) to be obtained by Solvent Extraction (SX) from the leach solution of Nolans ore is expected to contain ~100 mg/L U and ~8 g/L Fe. It was clear that the acid has to be purified before being concentrated to a salable product. While most extractants remove either Fe alone (removal of Fe from the PA is well known in the phosphoric acid industry and is usually done by Alamine 336 or similar, in a process named "amine wash"), or both U and Fe, the challenge was to remove both metals, with Uranium to be recovered separately as a valuable product. This paper describes the work carried out in an effort to find a solvent that could extract both U and Fe and from which they can be recovered in two separate, distinctive steps. The process takes place in four batteries: extraction, acidic stripping, alkaline stripping and regeneration. The extraction battery consists of two MS or a Bateman Pulsed column (BPC). The acidic stripping is carried out either in 2 MS or a single BPC. The second (alkaline) stripping and the regeneration are done in a single MS each. The heights of the columns, at a diameter of 40 mm, are 4 m for extraction and 3 m for stripping. An efficient process was developed.