Trial of Pilot Scale Nanofiltration Unit for Improvement of Precipitation Circuit at Tummalapalle Mill

Alkaline pressure leaching is used in the Tummalapalle Uranium Ore processing plant due to the ore’s high carbonate content (85%). About 70% of the uranium-laden liquor from the leached slurry filter is recycled to repulp the pre-leach filter cake, increasing the mother liquor concentration. This creates a large inventory of concentrated slurry, affecting precipitation efficiency and settling characteristics. Higher mother liquor concentration may improve settling after precipitation. A laboratory nanofiltration unit at UCIL Tummalapalle was tested to enhance clarified mother liquor concentration. Preliminary experiments showed reproducible results, suggesting an increase in uranium concentration from 0.5 gpl to 0.9 gpl. This process reduces leach liquor recycling, improves wash liquor flexibility, and operates with lower leach liquor values. This paper presents pilot-scale nanofiltration trials at Tummalapalle Mill, which could enhance U3O8 recovery. Further study is needed to assess water balance for full-scale implementation.